Guedes v. Bureau of Alcohol, Tobacco, Firearms

United States Court of Appeals

FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued March 22, 2019 Decided April 1, 2019

No. 19-5042

DAMIEN GUEDES, ET AL.,

APPELLANTS

v.

BUREAU OF ALCOHOL, TOBACCO, FIREARMS AND EXPLOSIVES,

ET AL.,

APPELLEES

Consolidated with 19-5044

Appeals from the United States District Court

for the District of Columbia

(No. 1:18-cv-02988)

(No. 1:18-cv-03086)

Erik S. Jaffe argued the cause for appellants Damien

Guedes, et al. With him on the briefs were Joshua Prince and

Adam Kraut.

Stephen D. Stamboulieh and Alan Alexander Beck were on

the brief for appellants David Codrea, et al.

2

Ilya Shapiro was on the brief for amicus curiae Cato

Institute in support of appellants.

Conor Shaw and Nikhel S. Sus were on the brief for amici

curiae Citizens for Responsibility and Ethics in Washington

and Former Government and Ethics Officials in support of

appellants.

Steven M. Simpson was on the brief for amici curiae The

New Civil Liberties Alliance and W. Clark Aposhian in support

of appellants.

J. Carl Cecere, Jr. was on the brief for amicus curiae

Morton Rosenberg in support of reversal.

Bradley Hinshelwood, Attorney, and Hashim M.

Mooppan, Deputy Assistant Attorney General, U.S.

Department of Justice, argued the causes for appellees. With

them on the brief were Matthew J. Glover, Counsel to the

Assistant Attorney General, and Scott R. McIntosh, Michael S.

Raab, and Abby C. Wright, Attorneys.

Ian Simmons, Matt Schock, and Anthony G. Beasley were

on the brief for amicus curiae Giffords Law Center to Prevent

Gun Violence in support of appellees.

Before: HENDERSON, SRINIVASAN and MILLETT, Circuit

Judges.

Opinion for the Court filed PER CURIAM.

Opinion concurring in part and dissenting in part filed by

Circuit Judge HENDERSON.

3

PER CURIAM: In October 2017, a lone gunman armed with

bump-stock-enhanced semiautomatic weapons murdered 58

people and wounded hundreds more in a mass shooting at a

concert in Las Vegas, Nevada. In the wake of that tragedy, the

Bureau of Alcohol, Tobacco, Firearms and Explosives

(“Bureau”) promulgated through formal notice-and-comment

proceedings a rule that classifies bump-stock devices as

machine guns under the National Firearms Act, 26 U.S.C.

§§ 5801–5872. See Bump-Stock-Type Devices, 83 Fed. Reg.

66,514 (Dec. 26, 2018) (“Bump-Stock Rule”). The then-

Acting Attorney General Matthew Whitaker initially signed the

final Bump-Stock Rule, and Attorney General William Barr

independently ratified it shortly after taking office. Bump-

stock owners and advocates filed separate lawsuits in the

United States District Court for the District of Columbia to

prevent the Rule from taking effect. The district court denied

the plaintiffs’ motions for a preliminary injunction to halt the

Rule’s effective date. Guedes v. Bureau of Alcohol, Tobacco,

Firearms, and Explosives, 356 F. Supp. 3d 109 (D.D.C. 2019).

We affirm the denial of preliminary injunctive relief.

I

A

The National Firearms Act (i) regulates the production,

dealing in, possession, transfer, import, and export of covered

firearms; (ii) creates a national firearms registry; and (iii)

imposes taxes on firearms importers, manufacturers, and

dealers, as well as specified transfers of covered firearms. 26

U.S.C. §§ 5801–5861. Failure to comply with the National

Firearms Act’s requirements results in penalties and forfeiture,

and subjects the violator to the general enforcement measures

available under the internal revenue laws. Id. §§ 5871–5872.

4

The firearms subject to regulation and registration under

the National Firearms Act include “machinegun[s].” 26 U.S.C.

§ 5845(a).1 The statute defines a “machinegun” as “any

weapon which shoots, is designed to shoot, or can be readily

restored to shoot, automatically more than one shot, without

manual reloading, by a single function of the trigger.” 26

U.S.C. § 5845(b). The definition also covers “the frame or

receiver of any such weapon,” as well as “any part” or

“combination of parts designed and intended, for use in

converting a weapon into a machinegun,” and “any

combination of parts from which a machinegun can be

assembled” as long as those “parts are in the possession or

under the control of a person.” Id.

Congress expressly charged the Attorney General with the

“administration and enforcement” of the National Firearms

Act, 26 U.S.C. § 7801(a)(1), (a)(2)(A), and provided that the

Attorney General “shall prescribe all needful rules and

regulations for the enforcement of” the Act,” id. § 7805; see id.

§ 7801(a)(2)(A).

The Gun Control Act of 1968, 18 U.S.C. § 921 et seq., as

amended by the Firearm Owners’ Protection Act, Pub. L. No.

99-308, 100 Stat. 449 (1986), imposes both a regulatory

licensing scheme and criminal prohibitions on specified

firearms transactions. See 18 U.S.C. § 923 (licensing scheme);

id. § 922 (criminal prohibitions). The Gun Control Act

incorporates by reference the definition of machine gun in the

National Firearms Act, 26 U.S.C. § 5845(b). See 18 U.S.C.

§ 921(a)(23). The Gun Control Act also expressly delegates

administrative and rulemaking authority to the Attorney

General to “prescribe only such rules and regulations as are

1

Except when quoting sources, we use the two-word spelling of

machine gun.

5

necessary to carry out the provisions of this chapter.” Id.

§ 926(a).

The Attorney General has delegated the responsibility for

administering and enforcing the National Firearms Act and the

Gun Control Act to the Bureau. See 28 C.F.R. § 0.130(a).

B

1

Machine guns are generally prohibited by federal law. See

18 U.S.C. § 922(o). On the other hand, many firearms that

require a distinct pull of the trigger to shoot each bullet are

lawful. See generally id. § 922; 26 U.S.C. § 5845.

A “bump stock” is a device that replaces the standard

stationary stock of a semiautomatic rifle—the part of the rifle

that typically rests against the shooter’s shoulder—with a non-

stationary, sliding stock that allows the shooter to rapidly

increase the rate of fire, approximating that of an automatic

weapon. 83 Fed. Reg. at 66,516. A bump stock does so by

channeling and directing the recoil energy from each shot “into

the space created by the sliding stock (approximately 1.5

inches) in constrained linear rearward and forward paths.” Id.

at 66,518. In so doing, the bump stock “harnesses the firearm’s

recoil energy as part of a continuous back-and-forth cycle that

allows the shooter to attain continuous firing” following a

single pull of the trigger. Id. at 66,533. That design allows the

shooter, by maintaining constant backward pressure on the

trigger as well as forward pressure on the front of the gun, to

fire bullets continuously and at a high rate of fire to “mimic”

the performance of a fully automatic weapon. Id. at 66,516.

6

Exercising his regulatory authority, the Attorney General

first included a bump-stock type device within the statutory

definition of “machinegun” in 2006. See ATF Ruling 2006-2;

see also Akins v. United States, 312 F. App’x 197, 199 (11th

Cir. 2009) (summary order). In later years, some other bump-

stock devices were not categorized as machine guns. 83 Fed.

Reg. at 66,514.

2

On October 1, 2017, a shooter used multiple

semiautomatic rifles equipped with bump stocks to fire several

hundred rounds of ammunition into a crowd of concert

attendees within a roughly ten-minute span of time. The

“‘rapid fire’ operation” of the shooter’s weapons enabled by

the bump stocks left 58 dead and approximately 500 wounded.

83 Fed. Reg. at 66,516.

The Las Vegas massacre prompted an immediate outcry

from the public and members of Congress. See Guedes, 356 F.

Supp. 3d at 120, 123. In response, President Trump “direct[ed]

the Department of Justice, * * * as expeditiously as possible, to

propose for notice and comment a rule banning all devices that

turn legal weapons into machineguns.” Application of the

Definition of Machinegun to “Bump Fire” Stocks and Other

Similar Devices, 83 Fed. Reg. 7,949, 7,949 (Feb. 20, 2018).

The Bureau then revisited the status of bump stocks and

addressed the variation in its prior positions. 83 Fed. Reg. at

66,516–66,517. On March 29, 2018, then-Attorney General

Sessions issued a Notice of Proposed Rulemaking that

suggested “amend[ing] the Bureau of Alcohol, Tobacco,

Firearms, and Explosives regulations to clarify that [bump-

stock-type devices] are ‘machineguns’” under 26 U.S.C.

§ 5845(b). See Bump-Stock-Type Devices, 83 Fed. Reg.

13,442 (March 29, 2018).

7

The Bureau promulgated its final rule on December 26,

2018. With respect to the statutory definition of machine gun,

the Bump-Stock Rule provided that the National Firearms

Act’s use of “the term ‘automatically’ as it modifies ‘shoots, is

designed to shoot, or can be readily restored to shoot,’” 26

U.S.C. § 5845(b), “means functioning as the result of a self-

acting or self-regulating mechanism that allows the firing of

multiple rounds through a single function of the trigger.” 83

Fed. Reg. at 66,553–66,554 (codified at 27 C.F.R. §§ 447.11,

478.11, 479.11). The Rule further defined “single function of

the trigger,” 26 U.S.C. § 5845(b), to mean “a single pull of the

trigger and analogous motions.” 83 Fed. Reg. at 66,553–

66,554 (codified at 27 C.F.R. §§ 447.11, 478.11, 479.11).

In light of those definitions, the Bump-Stock Rule

concluded that the statutory term “‘machinegun’ includes a

bump-stock-type device”—that is, “a device that allows a

semiautomatic firearm to shoot more than one shot with a

single pull of the trigger by harnessing the recoil energy of the

semiautomatic firearm to which it is affixed so that the trigger

resets and continues firing without additional physical

manipulation of the trigger by the shooter.” 83 Fed. Reg. at

66,553–66,554 (codified at 27 C.F.R. §§ 447.11, 478.11,

479.11).

In adopting the Bump-Stock Rule, the Bureau relied on

both the “plain meaning” of the statute and the agency’s charge

to implement the National Firearms Act and the Gun Control

Act. 83 Fed. Reg. at 66,527 (citing and invoking Chevron

U.S.A. v. Natural Res. Def. Council, 467 U.S. 837 (1984)). The

Bureau explained that the Bump-Stock Rule both “accord[s]

with the plain meaning” of the statute, and “rests on a

reasonable construction of” any “ambiguous” statutory terms.

Id. In the Bureau’s view, by not further defining the terms

“automatically” and “single function of the trigger,” Congress

8

“left it to the [Attorney General] to define [them] in the event

those terms are ambiguous.” Id. (citing Chevron, 467 U.S. at

844); see also id. at 66,515 (citing delegations of regulatory

authority under 26 U.S.C. §§ 7801(a)(2)(A), 7805(a), and 18

U.S.C. § 926(a)).

The Bureau was explicit that the Bump-Stock Rule would

only become “effective” on March 26, 2019, ninety days after

promulgation. 83 Fed. Reg. at 66,514. The Bureau further

assured that individuals would be subject to “criminal liability

only for possessing bump-stock-type devices after the effective

date of regulation, not for possession before that date.” Id. at

66,525; see also id. (providing that the Rule “criminalize[s]

only future conduct, not past possession of bump-stock-type

devices that ceases by the effective date”); id. at 66,539 (“To

the extent that owners timely destroy or abandon these bump-

stock-type devices, they will not be in violation of the law[.]”).

Bump-stock owners were directed to destroy their devices or

leave them at a Bureau office by March 26, 2019. Id. at 66,514.

Although most of the rulemaking process occurred during

the tenure of Attorney General Jefferson Sessions, he resigned

his office on November 7, 2018. The President then invoked

the Federal Vacancies Reform Act of 1998 (“Reform Act”), 5

U.S.C. § 3345(a)(3), to designate Matthew Whitaker, who had

been Sessions’ chief of staff, “to perform the functions and

duties of the office of Attorney General, until the position is

filled by appointment or subsequent designation.”

Memorandum from President Donald Trump to Matthew

George Whitaker, Chief of Staff, Department of Justice (Nov.

8, 2018), J.A. 277. The final Bump-Stock Rule was signed by

then-Acting Attorney General Whitaker. Whitaker served as

the Acting Attorney General for 98 days, until William Barr

was sworn in as the Attorney General on February 14, 2019.

9

See Bump-Stock-Type Devices, 84 Fed. Reg. 9,239, 9,240

(March 14, 2019).

On March 11, 2019, Attorney General Barr announced that

he had “independently reevaluate[d]” the Bump-Stock Rule

and the “underlying rulemaking record.” 94 Fed. Reg. at 9,240.

“[H]aving reevaluated those materials without any deference to

[Whitaker’s] earlier decision,” Attorney General Barr

“personally c[a]me to the conclusion that it is appropriate to

ratify and affirm the final rule,” and did so. Id.

C

Three groups of bump-stock owners and advocates filed

suit in the United States District Court for the District of

Columbia to prevent the Bump-Stock Rule from taking effect.

See Damien Guedes v. Bureau of Alcohol, Tobacco, Firearms,

and Explosives, No. 18-cv-2988; David Codrea v. William P.

Barr, No. 18-cv-3086; Firearms Policy Coalition, Inc. v.

William P. Barr, No. 18-cv-3083. As relevant here, the Guedes

plaintiffs (“Guedes”) and the Codrea plaintiffs (“Codrea”)

argued that the Bureau promulgated the Bump-Stock Rule in

violation of the Administrative Procedure Act, 5 U.S.C. § 500

et seq. Also, the Firearms Policy Coalition (“Coalition”) and

Codrea argued that Acting Attorney General Whitaker lacked

the legal authority to promulgate the Rule because his

designation as Acting Attorney General violated the Attorney

General Act, 28 U.S.C. § 508, and the Appointments Clause of

the Constitution, Article II, Section 2, Clause 2.

The district court denied all three motions for a

preliminary injunction. Guedes, 356 F. Supp. 3d at 119. The

district court concluded that Guedes, Codrea, and the Coalition

had not demonstrated a likelihood of success on the merits.

The court first held that “[m]ost of the plaintiffs’ administrative

10

law challenges are foreclosed by the Chevron doctrine,” and

the Rule “adequately explained” the agency’s decision to

classify bump-stock-type devices as machine guns. Id. at 120.

As to the challenges to Whitaker’s authority, the district court

held that the Reform Act permits the President to deviate from

the line of succession that the Attorney General Act provides,

subject to certain statutory limitations that indisputably were

satisfied with Whitaker’s appointment. Guedes, 356 F. Supp.

3d at 120–121. The court also rejected the Coalition’s and

Codrea’s Appointments Clause challenge as “foreclosed by

Supreme Court precedent and historical practice.” Id. at 121.

Guedes, Codrea, and the Coalition all appealed. But none

of them sought a stay or an injunction pending appeal. They

chose instead to seek highly expedited disposition, which this

court granted. While the appeal was pending, Attorney

General Barr ratified and individually endorsed the final

Bump-Stock Rule. At the post-argument request of the

Coalition, we voluntarily dismissed its appeal. Order, Guedes

v. Bureau of Alcohol, Tobacco, Firearms, and Explosives, No.

19-5042 (March 23, 2019) (per curiam). But because Codrea

presses the same challenge to Whitaker’s authority to

promulgate the Rule as the Coalition had raised, Codrea Br.

20–21, that issue remains before us in reviewing the district

court’s denial of a preliminary injunction.

II

A preliminary injunction is “an extraordinary remedy that

may only be awarded upon a clear showing that the plaintiff is

entitled to such relief.” Winter v. Natural Res. Def. Council,

Inc., 555 U.S. 7, 22 (2008). The plaintiffs bear the burden of

persuasion in seeking preliminary relief. Cobell v. Norton, 391

F.3d 251, 258 (D.C. Cir. 2004). Specifically, Guedes and

Codrea must establish that: (1) they are “likely to succeed on

11

the merits”; (2) they are “likely to suffer irreparable harm in the

absence of preliminary relief”; (3) the “balance of equities” tips

in their favor; and (4) “an injunction is in the public interest.”

Winter, 555 U.S. at 20; accord Aamer v. Obama, 742 F.3d

1023, 1038 (D.C. Cir. 2014). The last two factors “merge when

the Government is the opposing party.” Nken v. Holder, 556

U.S. 418, 435 (2009).

We review a district court’s denial of a preliminary

injunction for an abuse of discretion, but in doing so we review

the district court’s legal conclusions de novo and any findings

of fact for clear error. Serono Labs., Inc. v. Shalala, 158 F.3d

1313, 1318 (D.C. Cir. 1998).

III

A foundational requirement for obtaining preliminary

injunctive relief is that the plaintiffs demonstrate a likelihood

of success on the merits. See Nken, 556 U.S. at 434 (“The first

two factors of the traditional standard [i.e., likelihood of

success on the merits and irreparable injury] are the most

critical.”); Sherley v. Sebelius, 644 F.3d 388, 393 (D.C. Cir.

2011) (raising the possibility that “likelihood of success is an

independent, free-standing requirement for a preliminary

injunction”) (quoting Davis v. Pension Benefit Guar. Corp.,

571 F.3d 1288, 1296 (D.C. Cir. 2009) (Kavanaugh, J.,

concurring)).

Neither the challenge to Acting Attorney General

Whitaker’s authority nor the objections to the substantive

validity of the Bump-Stock Rule clears that hurdle. And

because the plaintiffs have shown no likelihood of success on

the merits, we choose not to “proceed to review the other three

preliminary injunction factors.” Arkansas Dairy Coop. Ass’n

12

v. United States Dep’t of Agric., 573 F.3d 815, 832 (D.C. Cir.

2009).

A

Codrea levels a broadside attack on the rule as

categorically invalid because Acting Attorney General

Whitaker allegedly lacked the legal authority to approve the

Bump-Stock Rule’s issuance. Specifically, Codrea argues that

Whitaker’s designation to serve as Acting Attorney General

violated both the Attorney General Act, 28 U.S.C. § 508, and

the Constitution’s Appointments Clause, U.S. Const. Art. II,

§ 2, cl. 2. Whether or not those arguments would otherwise

have had merit (something we do not decide), Codrea has no

likelihood of success on this claim because the rule has been

independently ratified by Attorney General William Barr,

whose valid appointment and authority to ratify is

unquestioned.

The Appointments Clause requires that “all * * * Officers

of the United States” be appointed by the President “by and

with the Advice and Consent of the Senate.” U.S. Const. Art.

II, § 2, cl. 2. This requirement is the “default manner of

appointment,” Edmond v. United States, 520 U.S. 651, 660

(1997), with the only exception being that Congress may vest

the appointment of “inferior Officers” in “the President alone,”

“Courts of Law,” and “the Heads of Departments,” U.S. Const.

Art. II, § 2, cl. 2 .

One stark consequence of this scheme is that “the

responsibilities of an office * * * [can] go unperformed if a

vacancy arises and the President and Senate cannot promptly

agree on a replacement.” National Labor Relations Bd. v. SW

Gen., Inc., 137 S. Ct. 929, 934 (2017); Buckley v. Valeo, 424

U.S. 1, 132 (1976) (per curiam) (“[A]ll officers of the United

States are to be appointed in accordance with the Clause.”).

13

“Since the beginning of the nation,” Congress has addressed

this problem through “vacancy statutes” that grant the

President the authority to designate acting officials to “keep the

federal bureaucracy humming.” SW General, Inc. v. National

Labor Relations Bd., 796 F.3d 67, 70 (D.C. Cir. 2015)

(quotation marks omitted), aff’d, 137 S. Ct. 929 (2017).

The Reform Act is the most recent iteration of that

interbranch accommodation. It provides for three options

whenever a Senate-confirmed officer “dies, resigns, or is

otherwise unable to perform the functions and duties of the

office[.]” 5 U.S.C. § 3345(a). The default is for the “first

assistant” to take the helm. Id. § 3345(a)(1). But the Reform

Act allows the President to choose another person instead, as

long as that person is either a Senate-confirmed appointee, id.

§ 3345(a)(2), or an employee within the same agency, subject

to certain duration-of-service and pay-scale requirements, id.

§ 3345(a)(3). Mr. Whitaker was designated under the latter

option, since his service as chief of staff comported with the

Reform Act’s duration-of-service and pay grade requirements.

Guedes, 356 F. Supp. 3d at 138 (“The parties do not dispute

that Whitaker satisfies the eligibility criteria in the [Reform

Act.]”).

Congress broadly designated the Reform Act to be the

“exclusive means for temporarily authorizing an acting official

to perform the functions and duties of any” Executive office

that would otherwise require Senate confirmation. 5 U.S.C.

§ 3347(a). But there is an “unless”—Congress crafted

exceptions to that exclusivity. Id. As relevant here, Section

3347(a) does not control if another “statutory provision

expressly * * * designates an officer or employee to perform

the functions and duties of a specified office temporarily in an

acting capacity[.]” Id. § 3347(a)(1)(B).

14

The Attorney General Act, 28 U.S.C. § 508, is one of those

office-specific vacancy statutes. That statute specifies a line of

succession for a vacancy in the Office of the Attorney General.

First in line is the Deputy Attorney General, who “may exercise

all the duties of th[e] office” and who, “for the purpose of

section 3345 of [the Reform Act],” is deemed “the first

assistant to the Attorney General.” 28 U.S.C. § 508(a). If the

Deputy Attorney General is unavailable, the Attorney General

Act directs that “the Associate Attorney General shall act as

Attorney General,” and “[t]he Attorney General may designate

the Solicitor General and the Assistant Attorneys General, in

further order of succession, to act as Attorney General.” Id.

§ 508(b).

Codrea and the Department have battled at length over the

interaction between the Reform Act and the Attorney General

Act in the event of a vacancy in the position of the Attorney

General. The Government maintains, and the district court

agreed, that the two statutes provide the President with

alternative means of designating an acting replacement.

Guedes, 356 F. Supp. 3d at 139; Gov’t Br. 40–58. Codrea, by

comparison, reads the Attorney General Act as the exclusive

path for designating an acting Attorney General, with the

Reform Act available only after the line of succession in the

Attorney General Act has been exhausted. Codrea Br. 20–21

(incorporating Coalition Br. 6). Codrea also argues that the

designation of a mere employee to perform the duties of a

principal office like that of the Attorney General, even on an

acting basis, raises substantial constitutional questions, at least

when no exigency requires that designation. Id. (adopting

Coalition Reply Br. 15).

We need not wade into that thicket. While this appeal was

pending, Attorney General Barr independently “familiarized

[him]self with the rulemaking record [and] * * * reevaluated

those materials without any deference to [Whitaker’s] earlier

15

decision.” 84 Fed. Reg. at 9,240. Following this

“independent[] reevaluat[ion] [of] the * * * rule and the

underlying rulemaking record,” Attorney General Barr

“personally c[a]me to the conclusion that it [wa]s appropriate

to ratify and affirm the final rule.” Id.

Codrea accepts the validity of Attorney General Barr’s

ratification as to both his statutory and his Appointments

Clause claims. Codrea Br. 20–21 (adopting Coalition Reply

Br. 22). See also 5 U.S.C. § 3348(d)(1)–(2) (only prohibiting

the ratification of nondelegable duties); 28 U.S.C. § 510

(authorizing delegation of “any function of the Attorney

General”). And with that act of ratification and the concession,

Codrea’s likelihood of success on the merits of his challenge to

the rule based on Acting Attorney General Whitaker’s role in

its promulgation reduces to zero.

Codrea insists otherwise. He argues that Attorney General

Barr’s ratification does not moot the claim because of the

mootness doctrine’s exceptions for a defendant’s voluntary

cessation of challenged conduct or for acts capable of repetition

yet evading review. Codrea Br. 20–21 (adopting Coalition

Reply Br. 17). That argument fails because ratification is

generally treated as a disposition on the legal merits of the

appointments challenge and, in any event, no mootness

exception applies in this case.

1

The mootness doctrine “ensures compliance with Article

III’s case and controversy requirement by ‘limit[ing] federal

courts to deciding actual, ongoing controversies.’” Aref v.

Lynch, 833 F.3d 242, 250 (D.C. Cir. 2016) (quoting American

Bar Ass’n v. FTC, 636 F.3d 641, 645 (D.C. Cir. 2011)). A case

is moot if our decision will neither “presently affect the parties’

rights nor have a more-than-speculative chance of affecting

16

them in the future.” Id. (internal quotation marks omitted)

(quoting American Bar Ass’n, 636 F.3d at 645).

We have repeatedly held that a properly appointed

official’s ratification of an allegedly improper official’s prior

action, rather than mooting a claim, resolves the claim on the

merits by “remedy[ing] [the] defect” (if any) from the initial

appointment. Wilkes-Barre Hosp. Co. v. National Labor

Relations Bd., 857 F.3d 364, 371 (D.C. Cir. 2017). This is so

regardless of whether “the previous [officer] was” or was not

“validly appointed under either the Vacancies Act or the

Appointments Clause.” Intercollegiate Broad. Sys. Inc. v.

Copyright Royalty Bd., 796 F.3d 111, 119 n.3 (D.C. Cir. 2015)

(ratification defeats Appointments Clause challenge) (citing

Doolin Sec. Sav. Bank, F.S.B. v. Office of Thrift Supervision,

139 F.3d 203, 205, 207, 212–214 (D.C. Cir. 1998), superseded

by statute on other grounds, Federal Vacancies Reform Act of

1998, Pub. L. No. 105-277, 122 Stat. 2681, as recognized in

SW Gen., Inc., 796 F.3d at 70–71); FEC v. Legi-Tech, Inc., 75

F.3d 704, 706, 708–710 (D.C. Cir. 1996) (similar).

In Doolin, we treated the curative effects of ratification as

analogous to rendering any defect in the agency’s action

“harmless error” under the Administrative Procedure Act, 5

U.S.C. § 706. 139 F.3d at 212. So viewed, ratification purges

any residual taint or prejudice left over from the allegedly

invalid appointment. Legi-Tech, 75 F.3d at 708 n.5 (“[T]he

issue is not whether Legi-Tech was prejudiced by the original

[decision], which it undoubtedly was, but whether, given the

FEC’s remedial actions, there is sufficient remaining prejudice

to warrant dismissal.”); Intercollegiate Broad., 796 F.3d at 124

(citing Legi-Tech for the same proposition). When viewed as

analogous to harmless-error analysis, ratification is treated as

resolving the merits of the challenger’s claim in the agency’s

favor. Cf. Doolin, 139 F.3d at 212; Combat Veterans for Cong.

Political Action Comm. v. FEC, 795 F.3d 151, 157 (D.C. Cir.

17

2015) (rejecting a procedural challenge to a Federal Election

Commission fine on the merits because the alleged infirmity

produced no “prejudice”).

Those cases’ treatment of ratification as resolving the

merits of a claimed appointment flaw parallels how this court

analyzes the agency practice of post-promulgation notice and

comment. When an agency “issues final regulations without

the requisite comment period and then tries to cure that

Administrative Procedure Act violation by holding a post-

promulgation comment period,” we have repeatedly held that

the agency prevails on the merits as long as it can demonstrate

that it has kept an “open mind” throughout the subsequent

comment period. See, e.g., Intermountain Ins. Serv. of Vail v.

Commissioner, 650 F.3d 691, 709 (D.C. Cir. 2011) (emphasis

added), vacated and remanded on other grounds, 566 U.S. 972

(2012), dismissed on unopposed motion, No. 10-1204, 2012

WL 2371486, at *1 (D.C. Cir. June 11, 2012); Advocates for

Highway & Auto Safety v. Federal Highway Admin., 28 F.3d

1288, 1291–1293 (D.C. Cir. 1994) (same).

Codrea points to Landry v. FDIC, 204 F.3d 1125 (D.C.

Cir. 2000), in which this court resolved the merits of an

Appointments Clause challenge to an administrative law

judge’s decision, notwithstanding the subsequent de novo

review and affirmance of that decision by the agency itself, id.

at 1131. That case is of no help to Codrea. Landry carved out

a narrow exception to ratification’s curative effect for

Appointments Clause challenges to the acts of “purely decision

recommending employees.” Id. at 1131–1132. This court

explained that, if ratification were an escape hatch in those

cases, “then all such arrangements would escape judicial

review” because the challenged ALJ action would never obtain

judicial review without first exhausting that ratifying internal

agency review process. Id. Only when that particular “catch-

22” is present does the Landry approach apply. Id.; accord

18

Intercollegiate Broad., 796 F.3d at 124 (distinguishing Landry

on that basis). The succession of a Presidentially appointed

and Senate-confirmed Attorney General does not remotely

implicate the Landry scenario.

2

Codrea argues that we should analyze the effect of

ratification through the lens of mootness rather than treating

ratification as resolving the case on the merits. Codrea Br. 20–

21 (adopting Coalition Reply Br. 16–17).

Codrea notes that all of our prior ratification cases dealt

with appointments challenges that arose as defenses to

enforcement actions that were being prosecuted by a properly

appointed official, but that were allegedly “tainted” by some

preceding action of an unlawfully appointed official. Codrea

Br. 20–21 (adopting Coalition Reply Br. 20). See, e.g.,

Intercollegiate Broad., 796 F.3d at 124 (raising Appointments

Clause defense in a “subsequent proceeding” based on the

“continuing taint arising from the first” proceeding); Doolin,

139 F.3d at 212 (raising Appointments Clause challenge to

officer who issued the initial “Notice of Charges” to

collaterally attack the ultimate cease-and-desist order issued by

a validly appointed officer).

In that scenario, Codrea reasons, the appointment issue

arose only as an affirmative defense; no act intervened during

litigation to eliminate the factual basis for an affirmative claim

for relief in a way that generally would trigger mootness

analysis. Here, by contrast, Codrea has raised as a plaintiff an

independent, pre-enforcement challenge to an agency rule in an

attempt to avert a present duty to comply, and he filed suit at a

time when the allegedly improperly appointed official was still

in office and enforcing his own challenged decision. For that

reason, the effect of Attorney General Barr’s intervening

ratification must be guided not by a merits analysis, but rather

19

by mootness. Codrea Br. 20–21 (adopting Coalition Reply Br.

17); see, e.g., EEOC v. First Citizens Bank of Billings, 758 F.2d

397, 399–400 (9th Cir. 1985) (treating congressional

ratification as causing mootness); see also Thomas v. Network

Solutions, Inc., 176 F.3d 500, 506 (D.C. Cir. 1999) (assuming

that congressional ratification mooted an unauthorized-tax

claim).

The problem for Codrea is that, even if we were to adopt

his proposed analytical approach, his claim still lacks any

discernible likelihood of success on the merits because no

exception to mootness fits this scenario.

First, this case does not implicate the exception to

mootness for cases that are “capable of repetition, yet evading

review.” United States v. Sanchez-Gomez, 138 S. Ct. 1532,

1540 (2018). For a controversy to be “capable of repetition,”

Codrea bears the burden of showing that (i) the challenged

action is “in its duration too short to be fully litigated prior to

its cessation or expiration,” and (ii) there is a “reasonable

expectation that the same complaining party will be subject to

the same action again.” Davis v. FEC, 554 U.S. 724, 735

(2008) (citations omitted); Honeywell Int’l, Inc. v. Nuclear

Regulatory Comm’n, 628 F.3d 568, 576 (D.C. Cir. 2010) (party

asserting capable of repetition bears burden of proof) (citing

Southern Co. Servs., Inc. v. FERC, 416 F.3d 39, 43 (D.C. Cir.

2005)). Under that test, “[t]he ‘wrong’ that is, or is not, ‘capable

of repetition’ must be defined in terms of the precise

controversy it spawns.” People for Ethical Treatment of

Animals, Inc. v. Gittens, 396 F.3d 416, 422–423 (D.C. Cir.

2005) (emphasis added). This demand for particularity ensures

“that courts resolve only continuing controversies between the

parties.” Id.

Here, Codrea has wholly failed to show that appointments

claims like his are too short-fused to obtain judicial resolution,

20

or that there is anything more than the most remote and

“theoretical[ ] possib[ility]” of repetition. Nelson v. Miller, 570

F.3d 868, 882 (7th Cir. 2009). For Codrea’s legal injury to

recur, (i) the Attorney General would have to leave office; (ii)

the President would then have to appoint a mere employee in

his stead (something Codrea argues has not happened more

than a “handful” of times in history (Codrea Br. 20-21

(adopting Coalition Br. 38; Coalition Reply Br. 15–16)); (iii)

that the new Acting Attorney General would then have to

promulgate a legislative rule; and (iv) by sheer coincidence,

that rule would have to adversely affect Codrea or his co-

plaintiffs’ legal rights. It takes more than such quixotic

speculation to save a case from mootness, even when the

Executive continues to defend its prerogatives in litigation. See

Larsen v. United States Navy, 525 F.3d 1, 4 (D.C. Cir. 2008).

Second, Codrea’s invocation of the rule that a defendant’s

voluntary cessation of challenged activity will not moot a case

fares no better. See Friends of the Earth, Inc. v. Laidlaw

Environmental Servs., 528 U.S. 167, 189 (2000). The

voluntary-cessation rule is designed to deter the wrongdoer

who would otherwise “engage in unlawful conduct, stop when

sued to have the case declared moot, then pick up where he left

off, repeating this cycle until he achieves all his unlawful

ends.” Already, LLC v. Nike, Inc., 568 U.S. 85, 91 (2013). For

that reason, a party’s voluntary cessation of challenged conduct

will not moot a case unless it is “absolutely clear that the

allegedly wrongful behavior could not reasonably be expected

to recur.” Laidlaw Environmental Servs., 528 U.S. at 189

(internal quotation marks omitted).2

2

It bears noting that the merits-based analysis of prejudice that

Codrea seeks to avoid includes a somewhat analogous exception for

a defendant’s strategic manipulation of the process to avoid judicial

21

The voluntary-cessation doctrine has no apparent

relevance here. That is because the power to effect the legally

relevant ratification by a duly installed Attorney General—the

supposed source of “cessation”—lies beyond the unilateral

legal authority of any of the named defendants, the Office of

the Attorney General, or even the President of the United

States. Under the peculiar circumstances of this case, where

the ratification was a result of the combined actions of a

presidential nomination and an independent Senate

confirmation, the “voluntariness” in “voluntary cessation” is

not implicated.

Aimed as it is at party manipulation of the judicial process

through the false pretense of singlehandedly ending a dispute,

the voluntary-cessation exception presupposes that the

infringing party voluntarily exercises its own unilateral power

not only to terminate the suit and evade judicial review, but also

to “pick up where he left off” and complete the devious “cycle”

after the litigation is dismissed. Already, LLC, 568 U.S. at 91;

see City News & Novelty, Inc. v. City of Waukesha, 531 U.S.

278, 284 n.1 (2001) (explaining that the “rule traces to the

principle that a party should not be able to evade judicial

review, or to defeat a judgment, by temporarily altering

questionable behavior”) (emphasis added); Knox v. Service

Emps. Int’l Union, 567 U.S. 298, 307 (2012) (voluntary

cessation concerns a defendant’s “resumption of * * *

challenged conduct as soon as the case is dismissed”)

review. See Sugar Cane Growers Coop. of Fla. v. Veneman, 289

F.3d 89, 96 (D.C. Cir. 2002) (“[I]f the government could skip [the

APA’s rulemaking] procedures, engage in informal consultation, and

then be protected from judicial review unless a petitioner could show

a new argument—not [already] presented informally,” then the

APA’s prescribed rulemaking process “obviously would be

eviscerated.”).

22

(emphasis added); United States v. W.T. Grant Co., 345 U.S.

629, 632 (1953) (voluntary-cessation doctrine rooted in

concern over leaving a “defendant * * * free to return to his old

ways”).

That framework ill fits a situation where, as here, the

intervening acts of independent third parties are essential to

accomplish a legally relevant change in circumstances. Here,

ratification materially changed the circumstances of the

litigation only because it was undertaken by a validly appointed

Attorney General whose authority to act Codrea does not

challenge. Codrea Br. 20–21 (adopting Coalition Reply Br. 22)

(“Plaintiff assumes that the ratification was not tainted by Mr.

Whitaker’s actions in promulgating the Rule in the first

place.”). That “cessation” of the legal challenge was outside

the hands of the named defendants—then-Acting Attorney

General Whitaker, the Bureau of Alcohol, Tobacco, Firearms

and Explosives, Acting Bureau Director Thomas Brandon, and

Attorney General William Barr. The essential predicate for

that legally relevant form of cessation was the (non-defendant)

President’s nomination and the (non-defendant) Senate’s

independent confirmation of a new Attorney General, and their

endowment of him with the authority to “cease” the litigation

by way of ratification.

In other words, the defendants in this case lacked the

unilateral power, or the power at all, to voluntarily cease and

restart the conduct complained of—having a Reform-Act-

appointed Acting Attorney General promulgate or enforce a

rule adversely affecting Guedes and Codrea. Without such

power, the risk of manipulating the litigation process

evaporates. In addition, the deliberative burdens of the

Senate’s intervening and independent advice-and-consent role

extinguish the strategic concerns animating the voluntary-

cessation doctrine in the first place. Cf. Clarke v. United States,

915 F.2d 699, 705 (D.C. Cir. 1990) (en banc) (raising “serious

23

doubts” about “applying the doctrine to Congress” because, “in

the absence of overwhelming evidence (and perhaps not then),

it would seem inappropriate for the courts either to impute such

manipulative conduct to a coordinate branch of government, or

to apply against that branch a doctrine that appears to rest on

the likelihood of a manipulative purpose”); United States Dep’t

of the Treasury v. Galioto, 477 U.S. 556, 560 (1986) (analyzing

the mooting effects of Congressional amendment without

reference to voluntary cessation). At the very least, Codrea has

a vanishingly low likelihood of prevailing on that theory.3

In sum, because Codrea has shown no likelihood of

success on his appointment-based challenges due to Attorney

General Barr’s independent and unchallenged ratification of

the Bump-Stock Rule, the district court did not abuse its

discretion in denying a preliminary injunction based on those

statutory and constitutional claims.

3

This case does not present, and we need not decide, whether the

President’s unilateral designation of a different acting Attorney

General would have implicated the voluntary-cessation doctrine. See

Trinity Lutheran Church of Columbia, Inc. v. Comer, 137 S. Ct.

2012, 2019 n.1 (2017) (no mootness when Governor ordered state

Department of Natural Resources to rescind challenged policy,

where there was no evidence the Department “could not revert to its

policy of excluding religious organizations”); cf. Doe v. Harris, 696

F.2d 109, 113 (D.C. Cir. 1982) (applying the capable of repetition

doctrine to “different official actors” within the same U.S. Attorney’s

Office). What matters in this case is not that the Bump-Stock Rule

was ratified by someone other than Acting Attorney General

Whitaker, but that it was ratified by someone whose authority to

undertake such a ratification—by virtue of Presidential nomination

and Senate confirmation—Codrea admits he cannot challenge.

24

B

We next consider the plaintiffs’ contention that the Bureau

lacked statutory authority to promulgate the Bump-Stock Rule.

Specifically, Guedes and Codrea argue that the statutory

definition of “machinegun” cannot be read to include bump-

stock devices. Guedes and Codrea have not demonstrated a

substantial likelihood of success on that claim.

1

At the outset, we must determine the standard by which to

assess the Rule’s conclusion that bump-stock devices amount

to “machineguns” under the statutory definition. In particular,

should we examine the Rule’s conclusion to that effect under

the Chevron framework, or is Chevron inapplicable?

If Chevron treatment is in order, we first ask if the statute

is ambiguous concerning whether bump-stock devices can be

considered “machineguns”; and if so, we sustain the Rule’s

conclusion that bump-stock devices are machine guns as long

as it is reasonable. See, e.g., Entergy Corp. v. Riverkeeper, Inc.,

556 U.S. 208, 218 (2009). Crucially, at this second step under

Chevron, an “agency need not adopt * * * the best reading of

the statute, but merely one that is permissible.” Dada v.

Mukasey, 554 U.S. 1, 29 n.1 (2008). Conversely, if Chevron’s

two-step framework is inapplicable, we accept the agency’s

interpretation only if it is the best reading of the statute.

Much, then, can turn on whether an agency’s interpretation

merits treatment under Chevron. For that reason, and because

none of the parties presents an argument for applying the

Chevron framework (the plaintiffs contend that Chevron is

inapplicable and the government does not argue otherwise), we

devote considerable attention to the question of Chevron’s

25

applicability to the Bump-Stock Rule. We conclude that the

Rule warrants consideration under Chevron.

a

The applicability of Chevron materially depends on what

kind of rule the Bump-Stock Rule represents. There is a

“central distinction” under the Administrative Procedure Act

between legislative rules and interpretive rules. Chrysler Corp

v. Brown, 441 U.S. 281, 301 (1979); see 5 U.S.C. § 553(b), (d).

And that distinction centrally informs the applicability of

Chevron. “Legislative rules generally receive Chevron

deference,” Nat’l Mining Ass’n v. McCarthy, 758 F.3d 243, 251

(D.C. Cir. 2014), whereas “interpretive rules * * * enjoy no

Chevron status as a class,” United States v. Mead Corp., 533

U.S. 218, 232 (2001); see also Nat’l Mining Ass’n, 758 F.3d at

251 (observing that interpretive rules “often do not” receive

Chevron deference).

Legislative rules result from an agency’s exercise of

“delegated legislative power” from Congress. Am. Mining

Cong. v. Mine Safety & Health Admin., 995 F.2d 1106, 1109

(D.C. Cir. 1993). Accordingly, legislative rules have the “force

and effect of law.” Encino Motorcars, LLC v. Navarro, 136 S.

Ct. 2117, 2122 (2016). Interpretive rules, on the other hand,

are “issued by an agency to advise the public of the agency’s

construction of the statutes and rules which it administers.”

Shalala v. Guernsey Mem’l Hosp., 514 U.S. 87, 99 (1995).

Because they are not an exercise of delegated legislative

authority, interpretive rules “do not have the force and effect of

law and are not accorded that weight in the adjudicatory

process.” Id. While legislative rules generally require notice

and comment, interpretive rules need not issue pursuant to any

formalized procedures. See 5 U.S.C. § 553(b).

26

To determine whether a rule is legislative or interpretive,

we ask whether the agency “intended” to speak with the force

of law. Encino Motorcars, 136 S. Ct. at 2122; Am. Mining

Cong., 995 F.2d at 1109. Central to the analysis is the

“language actually used by the agency.” Cmty. Nutrition Inst.

v. Young, 818 F.2d 943, 946 (D.C. Cir. 1987) (per curiam). We

also consider “whether the agency has published the rule in the

Code of Federal Regulations” and “whether the agency has

explicitly invoked its general legislative authority.” Am.

Mining Cong., 995 F.2d at 1112.

All pertinent indicia of agency intent confirm that the

Bump-Stock Rule is a legislative rule. The Rule unequivocally

bespeaks an effort by the Bureau to adjust the legal rights and

obligations of bump-stock owners—i.e., to act with the force

of law. The Rule makes clear throughout that possession of

bump-stock devices will become unlawful only as of the Rule’s

effective date, not before.

To that end, the Rule informs bump-stock owners that their

devices “will be prohibited when this rule becomes effective.”

83 Fed. Reg. at 66,514 (emphasis added). It correspondingly

assures bump-stock owners that “[a]nyone currently in

possession of a bump-stock-type device is not acting

unlawfully unless they fail to relinquish or destroy their device

after the effective date of this regulation.” Id. at 66,523

(emphasis added). And the Rule “provides specific

information about acceptable methods of disposal, as well as

the timeframe under which disposal must be accomplished to

avoid violating 18 U.S.C. § 922(o).” Id. at 66,530 (emphasis

added). Reinforcing the point, the Rule says it will

“criminalize only future conduct, not past possession of bump-

stock-type devices that ceases by the effective date.” Id. at

66,525 (emphasis added).

27

Those statements, and others like them in the Rule,

embody an effort to “directly govern[] the conduct of members

of the public, affecting individual rights and obligations.”

Long Island Care at Home, Ltd. v. Coke, 551 U.S. 158, 172

(2007) (internal quotation marks omitted). That is powerful

evidence that the Bureau “intended [the Rule] as a binding

application of its rulemaking authority.” Id.

The Bureau further evinced its intent to exercise legislative

authority by expressly invoking the Chevron framework and

then elaborating at length as to how Chevron applies to the

Rule. The Rule observes that, “[w]hen a court is called upon

to review an agency’s construction of the statute it administers,

the court looks to the framework set forth in Chevron U.S.A.,

Inc. v. Natural Resources Defense Council, Inc.” 83 Fed. Reg.

at 66,527. The Rule then contains several paragraphs of

analysis describing the application of each of Chevron’s two

steps to the Rule. That discussion is compelling evidence that

the Bureau did not conceive of its rule as merely interpretive.

Because “interpretive rules * * * enjoy no Chevron status as a

class,” Mead, 533 U.S. at 232, the Bureau’s exegesis on

Chevron would have served no purpose unless the agency

intended the Rule to be legislative in character.

Other evidence of agency intent points to the same

conclusion. One consideration under our decisions is “whether

the agency has explicitly invoked its general legislative

authority.” Am. Mining Cong., 995 F.2d at 1112. The Rule

does exactly that, invoking two separate delegations of

legislative authority. See 83 Fed. Reg. at 66,515. The first is

18 U.S.C. § 926(a), which empowers the Attorney General to

“prescribe only such rules and regulations as are necessary to

carry out the provisions of [the Gun Control Act].” The second

is 26 U.S.C. § 7805(a), which grants the Attorney General

authority to “prescribe all needful rules and regulations” for the

28

enforcement of the National Firearms Act. See 26 U.S.C.

§ 7801(a)(2)(A). Both of those provisions, the Rule states, vest

“the responsibility for administering and enforcing the NFA

and GCA” in the Attorney General. 83 Fed. Reg. at 66,515.

The Rule’s publication in the Code of Federal Regulations

also indicates that it is a legislative rule. See Am. Mining

Cong., 995 F.2d at 1112. By statute, publication in the Code

of Federal Regulations is limited to rules “having general

applicability and legal effect.” 44 U.S.C. § 1510 (emphasis

added). The Bump-Stock Rule amends three sections of the

Code, modifying the regulatory definition of “machine gun”

and “adding a sentence to clarify that a ‘machine gun’

includes * * * a bump-stock-type device.” 83 Fed. Reg. at

66,519 (amending 27 C.F.R. §§ 447.11, 478.11, 479.11).

Those sorts of amendments would be highly unusual for a mere

interpretive rule.

In short, the Rule confirms throughout, in numerous ways,

that it intends to speak with the force of law. It contained all

of those indicia uniformly conveying its intended legislative

character when Acting Attorney General Whitaker issued it.

And it still contained those indicia when Attorney General Barr

subsequently ratified it.

Notwithstanding all of that, the government’s litigating

position in this case seeks to reimagine the Rule as merely

interpretive. The government’s briefing says that the Rule is

“not an act of legislative rulemaking,” and that the Rule instead

only “sets forth the agency’s interpretation of the best reading

of the statutory definition of ‘machinegun.’” Gov’t Br. 38.

The government’s position to that effect has highly

significant implications for owners of bump-stock devices.

Whereas a legislative rule, as an exercise of delegated

29

lawmaking authority, can establish a new legal rule going

forward, an interpretive rule by nature simply communicates

the agency’s interpretation of what a statute has always meant.

So here, if the Bump-Stock Rule is merely interpretive, it

conveys the government’s understanding that bump-stock

devices have always been machine guns under the statute. The

government says exactly that in its brief, observing that, per the

interpretation set out in the Rule, “any bump stock made after

1986 has always been a machinegun.” Gov’t Br. 38.

That in turn would mean that bump-stock owners have

been committing a felony for the entire time they have

possessed the devices. Under 18 U.S.C. § 922(o)(1), it is

“unlawful for any person to transfer or possess a machinegun,”

and violators “shall be fined [or] imprisoned not more than 10

years, or both,” id. § 924(a)(2). As the government

acknowledges, under the view it espouses in its brief that the

Rule is interpretive, the possession of bump stocks “has always

been banned.” Gov’t Br. 38. And that would be so

notwithstanding a number of prior contrary interpretations by

the agency. See 83 Fed. Reg. at 13,444–13,446.

The government’s account of the Rule in its brief—

including its position that bump-stock owners have always

been felons—is incompatible with the Rule’s terms. The Rule

gives no indication that bump stocks have always been

machine guns or that bump-stock owners have been

committing a felony for the entire time they have possessed the

device. The Rule in fact says the opposite. After all, it

establishes an effective date, after which (and only after which)

bump-stock possession will be prohibited. 83 Fed. Reg. at

66,523. A future effective date of that kind cannot be

reconciled with a supposed intent to convey that bump-stock

possession “has always been banned.” Gov’t Br. 38.

30

The government now characterizes the Rule’s effective

date as merely marking the end of a period of discretionary

withholding of enforcement, in that the Rule informs the public

that the Department will “not pursue enforcement action

against individuals who sold or possessed bump stocks prior to

the effective date.” Id. at 38–39. Once again, that is not what

the Rule says. The government engages in enforcement

discretion when it voluntarily refrains from prosecuting a

person even though he is acting unlawfully. The Rule, by

contrast, announces that a person “in possession of a bump-

stock type device is not acting unlawfully unless they fail to

relinquish or destroy their device after the effective date of this

regulation.” 83 Fed. Reg. at 66,523 (emphases added). That is

the language of a legislative rule establishing when bump-stock

possession will become unlawful, not an interpretive rule

indicating it has always been unlawful.

In short, the government cannot now, in litigation,

reconceive the Bump-Stock Rule as an interpretive rule. The

character of a rule depends on the agency’s intent when issuing

it, not on counsel’s description of the rule during subsequent

litigation. See Encino Motorcars, 136 S. Ct. at 2122; cf. SEC

v. Chenery Corp., 318 U.S. 80, 87–88 (1943). Here, that intent

is unmistakable: the Bump-Stock rule is a legislative rule.

b

Ordinarily, legislative rules receive Chevron deference.

See Nat’l Mining Ass’n, 758 F.3d at 251. This legislative rule

is no different.

The Supreme Court has established that we afford

Chevron deference if we determine (i) “that Congress

delegated authority to the agency generally to make rules

carrying the force of law,” and (ii) “that the agency

31

interpretation claiming deference was promulgated in the

exercise of that authority.” Mead, 533 U.S. at 226–227 (2001).

Here, both are true.

First, we know Congress intended a delegation of

legislative authority to the agency because Congress made the

relevant delegations express. As noted, the Attorney General

has the power to prescribe “such rules and regulations as are

necessary to carry out the provisions of” the Gun Control Act.

18 U.S.C. § 926(a). And the Attorney General “shall prescribe

all needful rules and regulations for the enforcement of” the

National Firearms Act. 26 U.S.C. § 7805(a); see id.

§ 7801(a)(2)(A). “[A] general conferral of rulemaking

authority” of that variety “validate[s] rules for all the matters

the agency is charged with administering.” City of Arlington v.

FCC, 569 U.S. 290, 306 (2013). The Supreme Court has said

exactly that for § 7805(a), one of the delegations of authority

at issue. Specifically discussing that very provision, the Court

explained that it has “found such ‘express congressional

authorizations to engage in the process of rulemaking’ to be ‘a

very good indicator of delegation meriting Chevron

treatment.’” Mayo Found. for Med. Educ. & Research v.

United States, 562 U.S. 44, 57 (2011) (quoting Mead, 533 U.S.

at 229).

Second, we know that the Bureau promulgated the Bump-

Stock Rule “in the exercise of that authority” to “make rules

carrying the force of law” because that criterion is the defining

characteristic of a legislative rule. Mead, 533 U.S. at 227. And

we have already determined that the Rule is legislative in

character. We are then firmly within Chevron’s domain.

Nonetheless, the parties protest the applicability of

Chevron on several grounds. The plaintiffs first argue that

Chevron deference has been waived or forfeited by the

32

government. Next, the parties (including the government)

submit that Chevron deference is inapplicable in the context of

criminal statutes. And finally, Guedes contends that Chevron

deference for criminal statutes is displaced by the rule of lenity.

None of those objections to applying Chevron, we conclude, is

likely to succeed in the context of the Bump-Stock Rule.

(i)

The agency plainly believed it was acting in a manner

warranting Chevron treatment given that it expressly invoked

the Chevron framework in the Rule. The plaintiffs assert that

the government nonetheless has forfeited, or even waived, the

application of Chevron deference by declining to argue for it in

this litigation. And while the government has not taken a

definitive position before us on whether Chevron can be

waived or forfeited, it has declined to invoke Chevron

throughout the course of the litigation.

In particular, in its briefing before the district court, the

government expressly disclaimed any entitlement to Chevron

deference. And after the district court nonetheless relied on

Chevron to affirm the Rule, the government filed notices in

other pending challenges to the Rule, stating that it “ha[s] not

contended that the deference afforded under Chevron * * *

applies in this action.’” E.g., Notice of Supplemental Authority

at 2, Gun Owners of Am., Inc. v. Barr, No. 1:18-cv-1429 (W.D.

Mich. Feb. 27, 2019), ECF No. 38. Now, in this appeal, the

government affirmatively disclaims any reliance on Chevron.

See Gov’t Br. 37. And at oral argument, the government went

so far as to indicate that, while it believes the Rule should be

upheld as the best reading of the statute without any need for

Chevron deference, if the Rule’s validity turns on the

applicability of Chevron, it would prefer that the Rule be set

33

aside rather than upheld under Chevron. Oral Argument at

42:38–43:45.

To the extent Chevron treatment can be waived, we

assume that the government’s posture in this litigation would

amount to a waiver rather than only a forfeiture. See Wood v.

Milyard, 566 U.S. 463, 470 n.4 (2012) (“A waived claim or

defense is one that a party has knowingly and intelligently

relinquished; a forfeited plea is one that a party has merely

failed to preserve.”). But our court has yet to address whether,

when an agency promulgates a rule that would otherwise

plainly occasion the application of Chevron, agency counsel

could nonetheless opt to effect a waiver of Chevron treatment

when later defending against a challenge to the rule.

We have, however, held that an agency’s lawyers cannot

forfeit the applicability of Chevron deference unless the

underlying agency action fails to “manifests its engagement in

the kind of interpretive exercise to which review under

Chevron generally applies—i.e., interpreting a statute it is

charged with administering in a manner (and through a

process) evincing an exercise of its lawmaking authority.”

SoundExchange, Inc. v. Copyright Royalty Bd., 904 F.3d 41, 54

(D.C. Cir. 2018). We grounded our holding in the principle

that “it is the expertise of the agency, not its lawyers,” that

underpins Chevron. Id. (quoting Peter Pan Bus Lines, Inc. v.

Fed. Motor Carrier Safety Admin., 471 F.3d 1350, 1354 n.3

(D.C. Cir. 2006)); see also Chenery, 318 U.S. at 87–88. We

see no reason that the same limitations on forfeiture of Chevron

should not also govern waiver of Chevron.

Forfeiture and waiver involve, respectively, a failure to

invoke, or an affirmative decision not to invoke, a party’s “right

or privilege.” Johnson v. Zerbst, 304 U.S. 458, 464 (1938).

But Chevron is not a “right” or “privilege” belonging to a

34

litigant. It is instead a doctrine about statutory meaning—

specifically, about how courts should construe a statute.

If a statute contains ambiguity, Chevron directs courts to

construe the ambiguity as “an implicit delegation from

Congress to the agency to fill in the statutory gaps.” FDA v.

Brown & Williamson Tobacco Corp., 529 U.S. 120, 159

(2000). If there is ambiguity, the meaning of the statute

becomes whatever the agency decides to fill the gaps with, as

long as the agency’s interpretation is reasonable and “speak[s]

with the force of law.” Mead, 533 U.S. at 229. And insofar as

Chevron concerns the meaning of a statute, it is an awkward

conceptual fit for the doctrines of forfeiture and waiver.

We, for example, would give no mind to a litigant’s failure

to invoke interpretive canons such as expressio unius or

constitutional avoidance even if she intentionally left them out

of her brief. “[T]he court is not limited to the particular legal

theories advanced by the parties, but rather retains the

independent power to identify and apply the proper

construction of governing law.” Kamen v. Kemper Fin. Servs.,

Inc., 500 U.S. 90, 99 (1991). The “independent power” to

identify and apply the correct law presumably includes

application of the Chevron framework when determining the

meaning of a statute.

Allowing an agency to freely waive Chevron treatment in

litigation also would stand considerably in tension with basic

precepts of administrative law. As we have explained, a

legislative rule qualifying for Chevron deference remains

legislative in character even if the agency claims during

litigation that the rule is interpretive: Chenery instructs that the

proper subject of our review is what the agency actually did,

not what the agency’s lawyers later say the agency did. See

318 U.S. at 87–88. Accordingly, we have held that a particular

35

rule is legislative rather than interpretive over the protestations

of the agency. See, e.g., Cmty. Nutrition Inst., 818 F.2d at 946.

And once we conclude that a rule is legislative, it follows that

we generally review the rule’s validity under the Chevron

framework. See Nat’l Mining Ass’n, 758 F.3d at 251.

A waiver regime, moreover, would allow an agency to

vary the binding nature of a legislative rule merely by asserting

in litigation that the rule does not carry the force of law, even

though the rule speaks to the public with all the indicia of a

legislative rule. Agency litigants then could effectively amend

or withdraw the legal force of a rule without undergoing a new

notice-and-comment rulemaking. That result would enable

agencies to circumvent the Administrative Procedure Act’s

requirement “that agencies use the same procedures when they

amend or repeal a rule as they used to issue the rule in the first

instance.” Perez v. Mortg. Bankers Ass’n, 135 S. Ct. 1199,

1206 (2015). And an agency could attempt to secure rescission

of a policy it no longer favors without complying with the

Administrative Procedure Act, or perhaps could avoid the

political accountability that would attend its own policy

reversal by effectively inviting the courts to set aside the rule

instead.

We thus conclude, consistent with SoundExchange’s

approach to forfeiture of Chevron, that an agency’s lawyers

similarly cannot waive Chevron if the underlying agency action

“manifests its engagement in the kind of interpretive exercise

to which review under Chevron generally applies.”

SoundExchange, 904 F.3d at 54. In that event, we “apply

Chevron * * * even if there is no invocation of Chevron in the

briefing in our court.” Id.

In this case, the Bump-Stock Rule plainly indicates the

agency’s view that it was engaging in a rulemaking entitled to

36

Chevron deference. That observation naturally follows from

the Rule’s legislative character, which generally yields

treatment under Chevron. See Nat’l Mining Ass’n, 758 F.3d at

251. And for this Rule in particular, another telltale sign of the

agency’s belief that it was promulgating a rule entitled to

Chevron deference is the Rule’s invocation of Chevron by

name. To be sure, an agency of course need not expressly

invoke the Chevron framework to obtain Chevron deference:

“Chevron is a standard of judicial review, not of agency

action.” SoundExchange, 904 F.3d at 54. Still, the Bureau’s

invocation of Chevron here is powerful evidence of its intent

to engage in an exercise of interpretive authority warranting

Chevron treatment.

The Bureau, in rejecting objections that the agency’s

interpretation “would not be entitled to deference under

Chevron,” 83 Fed. Reg. at 66,526, specifically invoked the

Chevron framework and marched through its two-step

analysis, id. at 66,527. At step one, the agency explained that

its interpretation “accord[ed] with the plain meaning” of the

statute. And at step two, the agency explained that it “ha[d] the

authority to interpret elements of the definition of

‘machinegun’ like ‘automatically’ and ‘single function of the

trigger,’” concluding that its “construction of those terms is

reasonable under Chevron [Step Two].” Id.

The Rule expressly defends the agency’s reading of the

statute as an interpretive exercise implicating Chevron.

Agency counsel’s later litigating decision to refrain from

invoking Chevron thus affords no basis for our denying the

Rule Chevron status.

37

(ii)

Next, the plaintiffs submit that Chevron deference has no

application to regulations interpreting statutes like the National

Firearms Act and the Gun Control Act because they impose

criminal penalties on violators. Chevron deference in the

context of such statutes, the plaintiffs urge, would flout an

understanding that “criminal laws are for courts, not for the

Government, to construe.” Abramski v. United States, 573 U.S.

169, 191 (2014). And the plaintiffs are not the only parties who

question Chevron’s salience in the criminal context. The

government’s decision to refrain from invoking Chevron in this

litigation appears to stem from the same concerns. See Gov’t

Br. 36–37.

Guedes and Codrea, however, have failed to demonstrate

a likelihood of success in establishing a general rule against

applying Chevron to agency interpretations of statutes that

have criminal-law implications. To the contrary, precedent

says otherwise.

Start with Chevron itself. At issue in Chevron was the

meaning of the term “stationary source” in the Clean Air Act.

See Chevron, 467 U.S. at 840. The scope of that term defined

the statutory obligation of private parties, under state

implementation plans, to obtain permits for the construction

and operation of “new or modified major stationary sources of

air pollution.” 42 U.S.C. § 7502(a)(1), (b)(6) (1982). But at

the time, any person who knowingly violated any requirement

of a state implementation plan (after notice from the EPA)

faced a fine of $25,000 a day or imprisonment for up to a year,

or both. See id. § 7413(c)(1) (1982). Nevertheless, the

Chevron Court established the decision’s namesake deference.

38

For another example, consider the securities laws. The

SEC’s interpretation of those laws regularly receives Chevron

treatment, e.g., Nat’l Ass’n of Mfrs. v. SEC, 748 F.3d 359, 366

(D.C. Cir. 2014); Am. Equity Inv. Life Ins. Co. v. SEC, 613 F.3d

166, 172–173 (D.C. Cir. 2010); Markowski v. SEC, 274 F.3d

525, 528–529 (D.C. Cir. 2001), even though their violation

often triggers criminal liability. The Securities Exchange Act,

for instance, imposes criminal sanctions for willful violations

of “any provision” of the Act or “any rule or regulation

thereunder the violation of which is made unlawful.” 15 U.S.C.

§ 78ff(a). Yet in United States v. O’Hagan—a criminal case—

the Supreme Court accorded Chevron deference to an SEC rule

that interpreted a provision of the Act in a manner rendering

the defendant’s conduct a crime. 521 U.S. 642, 667, 673

(1997) (citing Chevron, 467 U.S. at 844). The Court noted that

Congress had authorized the Commission “to prescribe

legislative rules,” and held that the rule in question, issued in

an exercise of that authority, should receive “controlling

weight” under Chevron. Id. at 673 (quoting Chevron, 467 U.S.

at 844).

While the Court in O’Hagan applied Chevron in a criminal

case, it (like Chevron itself) did not specifically address

whether the criminal context should have afforded a basis for

denying deference to the agency’s interpretation. But the Court

engaged with that precise issue in Babbitt v. Sweet Home

Chapter of Communities for a Great Oregon, 515 U.S. 687

(1995). There, the Court reviewed a regulation interpreting the

term “take” in the Endangered Species Act. The challengers

argued that Chevron deference was inappropriate because the

Endangered Species Act included criminal penalties for certain

violations. See id. at 704 n.18. The Court disagreed, holding

that, notwithstanding the statute’s criminal penalties, it would

defer “to the Secretary’s reasonable interpretation” under

Chevron. See id. at 703–704 & 704 n.18.

39

Our circuit precedent is in accord. Recently, in

Competitive Enterprise Institute v. United States Department

of Transportation, 863 F.3d 911 (D.C. Cir. 2017), we explained

that “[w]e apply the Chevron framework * * * even though

violating [the statute] can bring criminal penalties,” id. at 915

n.4 (citing Babbitt, 515 U.S. at 704 n.18); see id. at 921

(Kavanaugh, J., concurring) (“I join the majority opinion[.]”).

That precedent is controlling here. See also Humane Society v.

Zinke, 865 F.3d 585, 591, 595 (D.C. Cir. 2017) (applying

Chevron even though the challenged rule interpreted the

Endangered Species Act, the violation of which results in

“criminal sanctions”).

Also, at least twice before, we afforded Chevron deference

to an agency’s construction of a statute in the criminal context

over the express objection of a defendant. In United States v.

Kanchanalak, 192 F.3d 1037 (D.C. Cir. 1999), the defendants

“argue[d] that this court should not give Chevron deference to

the FEC’s interpretation of an ambiguous statute in a criminal

proceeding,” id. at 1047 n.17. We disagreed: “That criminal

liability is at issue does not alter the fact that reasonable

interpretations of the act are entitled to deference.” Id. (citing

Babbitt, 515 U.S. at 703–705). And in In re Sealed Case, 223

F.3d 775 (D.C. Cir. 2000), we again declined to forgo Chevron

in a criminal context, holding that “[d]eference is due as much

in a criminal context as in any other,” id. at 779 (citing Babbitt,

515 U.S. at 703–705).

To be sure, the Supreme Court has signaled some wariness

about deferring to the government’s interpretations of criminal

statutes. See Abramski, 573 U.S. at 191; see also United States

v. Apel, 571 U.S. 359, 369 (2014) (“[W]e have never held that

the Government's reading of a criminal statute is entitled to any

deference.”). But those statements were made outside the

context of a Chevron-eligible interpretation—that is, outside

40

the context of an agency “speak[ing] with the force of law.”

Mead, 533 U.S. at 229. In Abramski, the Court declined to

extend deference to informal guidance documents published by

the Bureau. See 573 U.S. at 191. And in Apel, the Court

declined to defer to an interpretation contained in “Executive

Branch documents” that were “not intended to be binding.”

571 U.S. at 368. When directly faced with the question of

Chevron’s applicability to an agency’s interpretation of a

statute with criminal applications through a full-dress

regulation, the Court adhered to Chevron. See Babbitt, 515

U.S. at 704 n.18.

That holding, and our court’s precedents, govern us here

and call for the application of Chevron. The parties have

identified no distinction between the provision at issue in this

case and the provisions with criminal penalties to which

Chevron deference has been applied. The briefing contains

nary a word suggesting any distinction between this case and

prior decisions applying Chevron in criminal contexts. And

neither Guedes nor counsel for the government offered any

distinction even when specifically asked at oral argument. See

Oral Argument at 6:08–7:15, 45:45–49:00.

Nothing in the relevant statutory delegations of authority,

moreover, suggests a basis for denying Chevron treatment for

agency actions with criminal implications The Supreme Court

has instructed that the inquiry turns on whether the “language

of the delegation provision” is sufficiently “broad” such that it

is “clear * * * the statute gives [the] agency * * * power to

enforce all provisions of the statute.” Gonzales v. Oregon, 546

U.S. 243, 258 (2006) (emphasis added). In Gonzales, for

example, the Court found that the Attorney General lacked

power to interpret a particular criminal provision of the

Controlled Substances Act because the delegation of

rulemaking authority was too narrow and “did not delegate to

41

the Attorney General authority to carry out or effect all

provisions of the CSA.” Id. at 259 (emphasis added). By

contrast, the two pertinent delegation provisions in this case are

framed in broad terms. See 18 U.S.C. § 926(a) (delegating to

Attorney General the power to prescribe “such rules and

regulations as are necessary to carry out the provisions of [the

Gun Control Act]”); 26 U.S.C. § 7805(a) (delegating to

Attorney General, see id. § 7801(a)(2)(A), the power to

“prescribe all needful rules and regulations for the enforcement

of [the National Firearms Act]”).

The statutory context bolsters the inference that Congress

intended those delegations to encompass regulations with

criminal implications. The Gun Control Act, found at Chapter

44 of Title 18, is a purely criminal statute. See 18 U.S.C.

§ 924(a)(2). Yet § 926(a) expressly delegates to the Attorney

General the power to promulgate “such rules and regulations

as are necessary to carry out the provisions of th[at] chapter.”

Similarly, the National Firearms Act, found at Chapter 53 of

Title 26, has criminal applications. See 18 U.S.C. § 924(a)(2);

United States v. Thompson/Center Arms Co., 504 U.S. 505, 517

(1992). The penalty for “fail[ing] to comply with any provision

of th[at] chapter” is a fine of up to $10,000, or imprisonment

for up to 10 years, or both. 26 U.S.C. § 5871. And yet

§ 7801(a)(2)(A) tasks the Attorney General with “[t]he

administration and enforcement of * * * Chapter 53,” including

“prescrib[ing] all needful rules and regulations for * * *

enforcement.” Id. § 7805(a).

The plaintiffs rely on United States v. Thompson/Center

Arms Co., in which the Supreme Court applied the rule of lenity

to an ambiguous provision of the National Firearms Act. 504

U.S. at 517–518. But Babbitt later made clear that the Court in

Thompson/Center had no occasion to apply Chevron:

Thompson/Center, the Babbitt Court explained, “rais[ed] a

42

narrow question concerning the application of a statute that

contain[ed] criminal sanctions * * * where no regulation was

present.” Babbitt, 515 U.S. at 704 n.18 (emphasis added). If

anything, then, Babbitt implies that Chevron should apply in a

case—like this one—involving an interpretation of the

National Firearms Act where a regulation is present.

The plaintiffs also cite United States v. McGoff, 831 F.2d

1071 (D.C. Cir. 1987), a pre-Babbitt decision that interpreted

the statute-of-limitations provision of the Foreign Agents

Registration Act. We observed in passing that, “[n]eedless to

say, in this criminal context, we owe no deference to the

Government’s interpretation of the statute.” Id. at 1080 n.17.

As in Thompson/Center, however, the McGoff Court had no

occasion to apply Chevron because the government never

asserted reliance on a regulation or other Chevron-eligible

instrument. See id.

At oral argument, the plaintiffs suggested that permitting

an agency’s interpretation to carry the force of law in the

criminal context would infringe the separation of powers. See

Oral Argument 6:51–6:58. That suggestion is difficult to

square with the Supreme Court’s decision in Touby v. United

States, 500 U.S. 160 (1991). There, the Court upheld a

delegation of legislative authority to the Attorney General to

schedule substances under the Controlled Substances Act

against a challenge under the nondelegation doctrine. Id. at

164. The Court held that, in the criminal context, as in all

contexts, the separation of powers “does not prevent Congress

from seeking assistance * * * from its coordinate Branches” so

long as Congress “lays down by legislative act an intelligible

principle to which the person or body authorized to act is

directed to conform.” Id. at 165 (alterations omitted) (quoting

J.W. Hampton, Jr., & Co. v. United States, 276 U.S. 394, 409

43

(1928)). And no party suggests that such an intelligible

principle is lacking in this case.

In short, Congress delegated authority to administer the

National Firearms Act and the Gun Control Act to the Attorney

General, and the Attorney General promulgated a legislative

rule in the exercise of that authority. Under binding precedent,

Guedes and Codrea have failed to demonstrate a likelihood of

success on their claim that the Rule is invalid just because of

its criminal-law implications.

(iii)

Relatedly, Guedes argue that Chevron is inapplicable

because a different canon of interpretation, the rule of lenity,

should control instead. Under the rule of lenity, “ambiguity

concerning the ambit of criminal statutes should be resolved in

favor of lenity.” Rewis v. United States, 401 U.S. 808, 812

(1971). Guedes reasons that because Chevron is premised on

the existence of statutory ambiguity, and because the rule of

lenity resolves ambiguity in favor of the defendant, there is no

remaining ambiguity to which Chevron can apply.

It is true that the rule of lenity generally applies to the

interpretation of the National Firearms Act and the Gun

Control Act. But in circumstances in which both Chevron and

the rule of lenity are applicable, the Supreme Court has never

indicated that the rule of lenity applies first. In fact, the Court

has held to the contrary. In Babbitt, the Court squarely rejected

the argument that “the rule of lenity should foreclose any

deference to the Secretary’s interpretation of the ESA because

the statute includes criminal penalties.” 515 U.S. at 704 n.18.

The Court observed that it had “never suggested that the rule

of lenity should provide the standard for reviewing facial

challenges to administrative regulations whenever the

44

governing statute authorizes criminal enforcement.” Id. The

Court proceeded to apply Chevron deference. Id. at 703.

Our precedent takes the same tack. In Kanchanalak, we

expressly rebuffed the argument that Guedes now presses: “To

argue, as defendants do, that the rule of lenity compels us to

reject the FEC’s otherwise reasonable interpretation of an

ambiguous statutory provision [under Chevron] is to ignore

established principles of law.” 192 F.3d at 1050 n.23 (citing

Babbitt, 515 U.S. at 704 n.18).

Those precedents are in line with the Supreme Court’s

characterization of the rule of lenity as a canon of “last resort.”

The Court has instructed that “[t]he rule comes into operation

at the end of the process of construing what Congress has

expressed, not at the beginning as an overriding consideration

of being lenient to wrongdoers.” Callanan v. United States,

364 U.S. 587, 596 (1961). Accordingly, the rule of lenity

applies only “when the ordinary canons of statutory

construction have revealed no satisfactory construction.”

Lockhart v. United States, 136 S. Ct. 958, 968 (2016). And

Chevron is a rule of statutory construction, insofar as it is a

doctrine that “constru[es] what Congress has expressed.”

Callanan, 364 U.S. at 596.

Finally, our approach coheres with the rule of lenity’s

purposes. The doctrine serves to ensure that “legislatures and

not courts [are] defin[ing] criminal activity” and to secure “fair

warning” about the content of criminal law. United States v.

Bass, 404 U.S. 336, 348 (1971) (internal quotation marks

omitted). Chevron deference vindicates both purposes.

First, Chevron is consistent with the separation of powers,

including for regulations defining criminal activity, because

delegations of legislative authority in the criminal sphere are

45

constitutional. See Touby, 500 U.S. at 165. The parties would

have us disregard Congress’s textual delegations to the agency

and do the interpretive work instead. That course, though,

would not respect the notion that “legislatures and not courts”

should take the lead. Bass, 404 U.S. at 348.

Second, Chevron promotes fair notice about the content of

criminal law. It applies only when, at Congress’s direction,

agencies have followed “relatively formal administrative

procedure tending to foster the fairness and deliberation that

should underlie a pronouncement of such force.” Mead, 533

U.S. at 230. Importantly, such procedures, which generally

include formal public notice and publication in the Federal

Register, do not “provide such inadequate notice of potential

liability as to offend the rule of lenity.” Babbitt, 515 U.S. at

704 n.18. Tellingly, there is no suggestion of inadequate notice

here. Rather, if the Rule is a valid legislative rule, all are on

notice of what is prohibited.

For substantially the same reasons, plaintiffs’ challenge

under the Due Process Clause cannot succeed. To apply

Chevron, Codrea notes, we must first determine that the statute

is ambiguous, but that, in Codrea’s view, would imply that the

statute is facially void for vagueness. Codrea’s challenge is

misconceived. A criminal statute is void for vagueness if it

fails to provide ordinary people “fair notice” of the conduct it

proscribes. Sessions v. Dimaya, 138 S. Ct. 1204, 1223 (2018).

But the promulgation of the Bump-Stock Rule through notice-

and-comment procedures afforded “fair notice” of the

prohibited conduct.

2

Having concluded that the Chevron framework is

applicable, we now proceed to examine the Bump-Stock Rule

46

under it. We first ask whether the agency-administered statute

is ambiguous on the “precise question at issue.” Chevron, 467

U.S. at 842. If the statute’s meaning is unambiguous, then we

need go no further. But if we find ambiguity, we proceed to

the second step and ask whether the agency has provided a

“permissible construction” of the statute. Id. at 843. At that

stage, “the task that confronts us is to decide, not whether [the

agency’s interpretation is] the best interpretation of the statute,

but whether it represents a reasonable one.” Atl. Mut. Ins. Co.

v. Comm’r, 523 U.S. 382, 389 (1998).

The National Firearms Act and the Gun Control Act both

define “machinegun” to mean “any weapon which shoots, is

designed to shoot, or can be readily restored to shoot,

automatically more than one shot, without manual reloading,

by a single function of the trigger.” 26 U.S.C. § 5845(b); see

18 U.S.C. § 921(a)(23). The definition of “machinegun” also

includes “any part designed and intended solely and

exclusively, or combination of parts designed and intended, for

use in converting a weapon into a machinegun, and any

combination of parts from which a machinegun can be

assembled if such parts are in the possession or under the

control of a person.” 26 U.S.C. § 5845(b).

The Bump-Stock Rule determines that semiautomatic

rifles equipped with bump-stock-type devices are

“machineguns” because they “function[] as the result of a self-

acting or self-regulating mechanism that allows the firing of

multiple rounds” through “a single pull of the trigger.” 83 Fed.

Reg. at 66,553. Applying Chevron, we determine that the

statutory definition of “machinegun” is ambiguous and the

Bureau’s interpretation is reasonable. The plaintiffs therefore

are unlikely to succeed on the merits of their claim that the Rule

is out of step with the statutory definition.

47

a

At Chevron’s first step, two features of the statutory

definition of “machinegun” render it ambiguous. The first is

the phase “single function of the trigger.” The second is the

word “automatically.” We discuss them in that order.

(i)

As the district court recognized, the statutory phrase

“single function of the trigger” admits of more than one

interpretation. It could mean “a mechanical act of the trigger.”

Guedes, 356 F. Supp. 3d at 130. Or it could mean “a single

pull of the trigger from the perspective of the shooter.” Id.

The first interpretation would tend to exclude bump-stock

devices: while a semiautomatic rifle outfitted with a bump

stock enables a continuous, high-speed rate of fire, it does so

by engendering a rapid bumping of the trigger against the

shooter’s stationary finger, such that each bullet is fired

because of a distinct mechanical act of the trigger. The second

interpretation would tend to include bump-stock devices: the

shooter engages in a single pull of the trigger with her trigger

finger, and that action, via the operation of the bump stock,

yields a continuous stream of fire as long she keeps her finger

stationary and does not release it. See 83 Fed. Reg. at 66,519.

Neither of those interpretations is compelled (or

foreclosed) by the term “function” in “single function of the

trigger.” The word “function” focuses our attention on the

“mode of action,” 4 Oxford English Dictionary 602 (1933), or

“natural * * * action,” Webster’s New International Dictionary

876 (1933), by which the trigger operates. But the text is silent

on the crucial question of which perspective is relevant.

48

A mechanical perspective, for instance, might focus on the

trigger’s release of the hammer, which causes the release of a

round. From that perspective, a “single function of the trigger”

yields a single round of fire when a bump-stock device moves

the trigger back and forth. By contrast, from the perspective of

the shooter’s action, the function of pulling the trigger a single

time results in repeated shots when a bump-stock device is

engaged. From that perspective, then, a “single function of the

trigger” yields multiple rounds of fire.

In light of those competing, available interpretations, the

statute contains a “gap for the agency to fill.” Chevron, 467

U.S. at 843.

Guedes argues that the phrase “single function of the

trigger” unambiguously compels a focus on the trigger’s

mechanical operation. He contends, for example, that

“[r]egardless of the mechanism by which the shooter acts * * *

it is the movement of the trigger releasing the hammer * * *

that define[s] the boundaries of two distinct ‘single’ functions

of the trigger.” Guedes Br. 12–13. That argument begs the

crucial question of perspective. It may be reasonable to take

the view, as Guedes does, that the mechanical operation of the

trigger is the lens through which to view its function. But to

establish a likelihood of success on the merits, Guedes and

Codrea would have to establish that reading the statute to mean

a “single pull of the trigger” by the shooter is impermissible.

They have not done so.

At Chevron’s first step, we do not ask which of those

interpretations is the better reading of the statute. Rather, we

ask whether either of those interpretations is unambiguously

“compel[led]” by the statute, to the exclusion of the other one.

Chevron, 467 U.S. at 860. Here, we think the answer is no.

49

Nor does Staples v. United States, 511 U.S. 600 (1994),

compel a particular interpretation of “single function of the

trigger.” There, in a footnote, the Court observed that a weapon

is “automatic” if it “fires repeatedly with a single pull of the

trigger”—“[t]hat is, [if] once its trigger is depressed, the

weapon will automatically continue to fire until its trigger is

released or the ammunition is exhausted.” Id. at 602 n.1. The

Court’s description, then, speaks both in terms of a “single pull

of the trigger” and a “release[]” of the trigger, id. (emphasis

added), which ultimately sheds limited light on the choice

between the two competing understandings of “function of the

trigger” that are at issue here. Regardless, the precise definition

of “single function of the trigger” was not at issue in Staples.

See id. at 602. And the Court did not purport to exclude any

interpretation as foreclosed by the statute. Cf. Nat’l Cable &

Telecomms. Ass’n v. Brand X Internet Servs., 545 U.S. 967,

996 (2005).

(ii)

Similarly, the statutory term “automatically” admits of

multiple interpretations. The statute speaks in terms of a

“weapon which shoots * * * automatically more than one shot,

without manual reloading, by a single function of the trigger.”

26 U.S.C. § 5845(b); see 18 U.S.C. § 921(a)(23). The term

“automatically” does not require that there be no human

involvement to give rise to “more than one shot.” Rather, the

term can be read to require only that there be limited human

involvement to bring about more than one shot. See, e.g.,

Webster's New International Dictionary 157 (defining

“automatically” as the adverbial form of “automatic”); id. at

156 (defining “automatic” as “self-acting or self-regulating,”

especially applied to “machinery or devices which perform

parts of the work formerly or usually done by hand” (emphasis

50

added)). But how much human input in the “self-acting or self-

regulating” mechanism is too much?

The plaintiffs would read the phrase “by a single function

of the trigger” to provide “the starting and the ending point of

just how much human input is allowable.” Codrea Br. 14. In

their view, then, a gun cannot be said to fire “automatically” if

it requires both a single pull of the trigger and constant pressure

on the gun’s barrel, as a bump-stock device requires. We are

unpersuaded. After all, a quite common feature of weapons

that indisputably qualify as machine guns is that they require

both a single pull of the trigger and the application of constant

and continuing pressure on the trigger after it is pulled. We

know, therefore, that the requirement of some measure of

additional human input does not render a weapon

nonautomatic. To purloin an example from the district court:

an “automatic” sewing machine still “requires the user to press

a pedal and direct the fabric.” Guedes, 356 F. Supp. 3d at 131

(emphasis added).

That workaday example illustrates another, perhaps more

natural, reading of “automatically”: the “automatic[]”

mechanism need only be “set in motion” by a single function

of the trigger. United States v. Olofson, 563 F.3d 652, 658 (7th

Cir. 2009) (emphasis added); see also United States v. Evans,

978 F.2d 1112, n.2 (9th Cir. 1992) (“‘[B]y a single function of

the trigger’ describes the action that enables the weapon to

‘shoot automatically without manual reloading, not the

‘trigger’ mechanism.” (ellipses omitted)). That is, rather than

reading the phrase “by a single function of the trigger” to mean

“by only a single function of the trigger,” the phrase can

naturally be read to establish only the preconditions for setting

off the “automatic” mechanism, without foreclosing some

further degree of manual input such as the constant forward

pressure needed to engage the bump stock in the first instance.

51

And if so, then the identified ambiguity endures. How much

further input is permitted in the mechanism set in motion by

the trigger? The statute does not say.

In sum, the statutory definition of “machinegun” contains

two central ambiguities, both of which the agency has

attempted to construe. We therefore proceed to Chevron’s

second step.

b

At the second step, “the question for the court is whether

the agency’s [construction] is based on a permissible

construction of the statute.” Chevron, 467 U.S. at 843. Guedes

and Codrea are not likely to succeed in showing that the agency

has impermissibly interpreted both ambiguities.

The Bureau’s interpretation of “single function of the

trigger” to mean “single pull of the trigger” is a permissible

reading of the statute. The Bureau is better equipped than we

are to make the pivotal policy choice between a mechanism-

focused and shooter-focused understanding of “function of the

trigger.” And the Bureau’s interpretation comports with how

some courts have read the statute, which is a strong sign of

reasonableness. In United States v. Akins, 312 F. App’x 197

(11th Cir. 2009), for example, the Eleventh Circuit held that the

Bureau’s reading of “single function of the trigger” to mean

“single pull of the trigger” was “consonant with the statute and

its legislative history.” Id. at 200. The court relied on that

definition to conclude that an “Accelerator”—a type of bump

stock—was reasonably classified as a machine gun. Id. And

“single pull of the trigger” has been the definition the agency

has employed since 2006. See 83 Fed. Reg. at 66,543.

52

The Rule’s interpretation also accords with how the phrase

“single pull of the trigger” was understood at the time of the

enactment of the National Firearms Act. See 83 Fed. Reg. at

66,518. The Rule cites a congressional hearing for the National

Firearms Act in which the then-president of the National Rifle

Association testified that the term “machine gun” included any

gun “capable of firing more than one shot by a single pull of

the trigger, a single function of the trigger.” 83 Fed. Reg.

66,518. And the House Report accompanying the bill that

eventually became the National Firearms Act states that the bill

“contains the usual definition of a machine gun as a weapon

designed to shoot more than one shot * * * by a single pull of

the trigger.” H.R. Rep. No. 73-1780, at 2 (1934).

The Bureau’s interpretation of “automatically” is

permissible too. The Rule’s requirement of a “self-acting or

self-regulating mechanism” demands a significant degree of

autonomy from the weapon without mandating a firing

mechanism that is completely autonomous. That definition

accords with the everyday understanding of the word

“automatic.” And it focuses the inquiry about what needs to be

automated right where the statute does: the ability of the trigger

function to produce “more than one shot, without manual

reloading.” 26 U.S.C. § 5845(b). It also tracks the

interpretation reached by the Seventh Circuit in United States

v. Olofson, 563 F.3d 652 (7th Cir. 2009), in which the court

interpreted the term to require a “self-acting mechanism”

without requiring more, id. at 658.

The plaintiffs argue that the Bureau’s definition of

“machinegun” is unreasonable because it has the effect of

reaching all semiautomatic rifles. Because “virtually all”

semiautomatic rifles can be “bump-fired” with the use of

common household items, the plaintiffs contend, the Bureau’s

53

definition covers even unmodified semiautomatic rifles, which

renders it unreasonable. Guedes Br. 18.

The Rule explains why the plaintiff’s understanding is

incorrect, and the Rule’s explanation in that regard is

reasonable. See 83 Fed. Reg. at 66,532–66,534. The Bureau

acknowledges that bump firing—a technique using a stable

point like a belt loop to approximate the function of a bump

stock—is possible with semiautomatic weapons. See id. at

66,533. But even when a semiautomatic weapon is bump fired

using an object like a belt loop or a rubber band, the Bureau

explained, the weapon does not fire “automatically” because

there is no “self-acting or self-regulating mechanism.” Rubber

bands and their ilk do not “capture and direct the recoil energy”

to “harness[] [it] as part of a continuous back-and-forth cycle.”

Id. at 66,533. Rather, “the shooter must do so” herself. Id.

Bump firing without the aid of a bump-stock-type device is

therefore “more difficult” because it relies solely on the shooter

“to control the distance that the firearm recoils and the

movement along the plane on which the firearm recoils.” Id.

Bump stocks, on the other hand, are specifically designed

to “direct[] the recoil energy of the discharged rounds * * * in

constrained linear rearward and forward paths.” Id. at 66,532.

By capturing the recoil energy of the gun and directing it

through a specified “distance” and along a specified “plane,”

bump stocks “incorporate[] a self-acting or self-regulating

component” that would otherwise be absent. Id. at 66,533.

Thus, belt loops, unlike bump stocks, do not transform

semiautomatic weapons into statutory “machineguns.” Or so

the Bureau reasonably concluded in the Rule.

“If a statute is ambiguous, and if the implementing

agency’s construction is reasonable, Chevron requires a federal

court to accept the agency's construction of the statute, even if

54

the agency's reading differs from what the court believes is the

best statutory interpretation.” Brand X, 545 U.S. at 980. Here,

the Bump-Stock Rule sets forth a permissible interpretation of

the statute’s ambiguous definition of “machinegun.” It

therefore merits our deference.

C

In addition to their argument that the Rule is incompatible

with the statutory definition of a machine gun, the plaintiffs

also contend that the Rule is arbitrary and capricious. Agency

action is arbitrary or capricious if “the agency has relied on

factors which Congress has not intended it to consider, entirely

failed to consider an important aspect of the problem, offered

an explanation for its decision that runs counter to the evidence

before the agency, or is so implausible that it could not be

ascribed to a difference in view or the product of agency

expertise.” Motor Vehicle Mfrs. Ass’n v. State Farm Mut. Auto.

Ins. Co., 463 U.S. 29, 43 (1983). Here, the plaintiffs claim that,

for various reasons, the Rule is arbitrary in applying the

statutory definition of “machinegun” to bump stocks. None of

their claims is likely to succeed.

First, the plaintiffs argue that the Rule fundamentally

mischaracterizes the operation of bump-stock devices. In their

view, the Rule disregards that, for each shot, “the shooter must

manually and volitionally push the trigger into [a] stationary

finger.” Guedes Br. 24. It is true that, for a bump-stock-

equipped device to repeatedly fire, the shooter must keep the

bumpstock engaged by maintaining constant forward pressure

on the gun. But in the Rule, the Bureau correctly describes the

operation of bump-stock-equipped devices: the shooter must

“maintain[] constant forward pressure [on the gun] with the

non-trigger hand” in order to maintain continuous fire. 83 Fed.

Reg. at 66,532. The bump stock takes advantage of the gun’s

55

recoil, channeled into a linear back-and-forth cycle, to permit

the shooter to fire continuously by maintaining steady forward

pressure on the gun. There is thus no disagreement about the

basic mechanics of bump-stock devices.

Guedes takes particular issue with the Rule’s

characterization of recoil. He argues that bump-stock-

equipped devices cannot “harness[] the recoil energy of the

firearm” because they do not use “a device such as a spring or

hydraulics * * * [to] automatically absorb the recoil and use

this energy to activate itself.” Guedes Br. 16–17. But the Rule

does not adopt such an impoverished definition of

“automatically.” The Rule requires only that the recoil be used

in service of a “self-acting or self-regulating mechanism.” A

bump stock “direct[s] the recoil energy of the discharged

rounds * * * in constrained linear rearward and forward paths,”

83 Fed. Reg. at 66,518 (quoting 83 Fed. Reg. at 13,443), which

qualifies as a “self-regulating mechanism.”

Second, the plaintiffs assert that the Rule is arbitrary

because its definition encompasses all semiautomatic weapons.

That argument is largely redundant of the plaintiffs’ Chevron

step two argument to the same effect, which we have already

addressed. We dispose of this iteration of the same argument

on the same grounds: Bump stocks, unlike commonplace

household objects, are specifically designed to “direct[] the

recoil energy of the discharged rounds * * * in constrained

linear rearward and forward paths.” Id. Bump stocks, unlike

household objects, are machine guns because they alone

involve a “self-acting or self-regulating mechanism.” Id.

Third, the plaintiffs submit that the Rule arbitrarily

excludes binary-trigger guns from its definition of

“machinegun.” Binary-trigger guns shoot one round when the

trigger is pulled and another round when the trigger is released.

56

83 Fed. Reg. at 66,534. The Rule concludes that such devices

are not machine guns because the second shot is “the result of

a separate function of the trigger.” Id. The plaintiffs argue that

if the release of the trigger is a separate function, the operation

of a bump stock—which requires the shooter to keep the trigger

finger stationary while steadily pushing the gun forward into

the finger—must also involve multiple functions of the trigger.

But the Rule reasonably distinguishes binary-trigger guns on

the ground that they require a second act of volition with the

trigger finger. The release of a trigger is a volitional motion.

But merely holding the trigger finger stationary—which is

what operation of a bump stock entails—is not.

Fourth, Guedes contends that the Rule is arbitrary because

its definition of “automatically” is ambiguous. The Rule’s

definition, Guedes notes, does not specify how much manual

input is too much. But the existence of latent ambiguity does

not render an interpretation arbitrary or capricious. Agencies

are permitted to promulgate regulations interpreting

ambiguous statutes without having to resolve all possible

ambiguity.

Fifth, Codrea argues that the Rule arbitrarily failed to

consider reliance interests, “an important aspect of the

problem.” State Farm, 463 U.S. at 43. It is true that “the APA

requires an agency to provide more substantial justification

when * * * its prior policy has engendered serious reliance

interests that must be taken into account.” Perez, 135 S.Ct. at

1209 (quoting FCC v. Fox Television Stations, Inc., 556 U.S.

502, 515 (2009)). But the only reliance interest identified by

Codrea is the pecuniary interest of current possessors of bump-

stock devices. See Codrea Br. 19–20 & 19 n.4; Comment of

Maryland Shall Issue at 6. And in the Rule, the Bureau

engaged in a cost-benefit analysis that considered, among other

57

things, the cost incurred by owners of bump-stock devices. See

83 Fed. Reg. at 66,546.

Finally, Guedes argues that the Rule is arbitrary because it

is the product of “naked political desire.” Guedes Br. 18.

Insofar as Guedes means to claim that the Rule arises from

political considerations, he is surely right. All would agree that

the Bureau enacted this Rule in response to the urging of “the

President, Members of Congress, and others,” as part of an

“immediate and widespread” outcry in the wake of the 2017

mass shooting in Las Vegas. Guedes, 356 F. Supp. 3d at 120,

123. The Rule itself describes its origins in a memorandum

issued by President Trump to then–Attorney General Sessions

“direct[ing] the Department of Justice * * * ‘as expeditiously

as possible, to propose for notice and comment a rule banning

all devices that turn legal weapons into machineguns.’” 83

Fed. Reg. at 66,516–66,517 (quoting Application of the

Definition of Machinegun to ‘Bump Fire’ Stocks and Other

Similar Devices, 83 Fed. Reg. 7,949 (Feb. 23, 2018)). But that

is hardly a reason to conclude that the Rule is arbitrary.

Presidential administrations are elected to make policy. And

“[a]s long as the agency remains within the bounds established

by Congress, it is entitled to assess administrative records and

evaluate priorities in light of the philosophy of the

administration.” Nat’l Ass’n of Home Builders v. EPA, 682

F.3d 1032, 1043 (D.C. Cir. 2012) (quoting State Farm, 463

U.S. at 59 (Rehnquist, J., concurring in part and dissenting in

part)).

Guedes might instead mean to contend that the Bureau was

so eager to enact the policy preferences of the President that it

failed to engage in reasoned consideration of the issues. The

central purpose of arbitrary or capricious review is to assure

that the agency has engaged in “reasoned decisionmaking.”

State Farm, 463 U.S. at 52. We ordinarily do so, however, by

58

examining whether the agency has “articulate[d] a satisfactory

explanation for its actions.” Id. at 43. Here, the agency has

articulated a satisfactory explanation for the Bump-Stock Rule.

And the administrative record reflects that the agency kept an

open mind throughout the notice-and-comment process and

final formulation of the Rule. See Air Transp. Ass’n of Am. v.

Nat’l Mediation Bd., 663 F.3d 476, 487–488 (D.C. Cir. 2011);

C&W Fish Co. v. Fox, 931 F.2d 1556, 1564–1565 (D.C. Cir.

1991). In the absence of any actual evidence of delinquent

conduct, we accord the Bureau a “presumption of regularity”

in its promulgation of the Rule. Citizens to Pres. Overton Park,

Inc. v. Volpe, 401 U.S. 402, 415 (1971).

D

Finally, Codrea argues that the Rule must be vacated

because it is impermissibly retroactive, violating both 26

U.S.C. § 7805(b)’s bar on retroactive rulemaking and the Ex

Post Facto Clause. That claim has been forfeited because the

plaintiffs failed to raise it in the district court. The Rule, at any

rate, cannot be characterized as retroactive: As we have

explained, the Rule itself made clear that the possession of

bump stocks would become unlawful only after the effective

date.

Further, it matters not that the government’s post hoc

litigation strategy has been to characterize the Rule as merely

interpretive and, consequently, backward looking.

Irrespective of that litigating position, the Rule is legislative in

character and therefore purely prospective. Any criminal

consequences did not attach until the Rule’s effective date.

And notice to the public has been clear and explicit.

59

* * * * *

The plaintiffs have failed to establish a likelihood of

success both for their challenge to Acting Attorney General

Whitaker’s appointment and for their objections to the

substantive validity of the Rule. For the foregoing reasons, we

affirm the district court’s denial of a preliminary injunction.

So ordered.

KAREN LECRAFT HENDERSON, Circuit Judge, concurring

in part and dissenting in part: Federal law makes it a crime to

possess or transfer a “machinegun.” 18 U.S.C. § 922(o)(1).

This case is about a Bureau of Alcohol, Tobacco, Firearms, and

Explosives (ATF) regulation that reinterprets the statutory

definition of “machinegun” and applies it to all bump stock

type devices. Bump-Stock-Type Devices, 83 Fed. Reg. 66,514

(Dec. 26, 2018) (Bump Stock Rule or Rule). Individual

firearms owners and non-profit groups sued the ATF, seeking

preliminary injunctive relief to stop the Bump Stock Rule from

going into effect. The issue before us on this expedited appeal

of the district court’s denial of preliminary injunctive relief,

Guedes v. ATF, 356 F. Supp. 3d 109 (D.D.C. 2019), is whether

the plaintiffs are likely to succeed on the merits of their

challenge to the Bump Stock Rule as contrary to the statutory

definition of “machinegun.” Unlike my colleagues, I believe

the Bump Stock Rule does contradict the statutory definition

and, respectfully, part company with them on this issue. 1

A “machinegun” is a firearm “which shoots . . .

automatically more than one shot, without manual reloading,

by a single function of the trigger.” 26 U.S.C. § 5845(b). In

my view, the Rule impermissibly adds to the language

“automatically . . . by a single function of the trigger,”

including within its definition a firearm that shoots more

rapidly only by a single function of the trigger and the shooter’s

additional manual input. The statute specifies a single

function; the Rule specifies a single function plus. “Whether

the Government interprets a criminal statute too broadly (as it

sometimes does) or too narrowly,” we have “an obligation to

correct its error.” Abramski v. United States, 573 U.S. 169, 191

(2014).

1

I concur in Parts II and III.A of the majority opinion.

2

I. BACKGROUND

A. Statutory Framework

The National Firearms Act of 1934, Pub. L. No. 73-474,

48 Stat. 1236, “imposes strict registration requirements on

statutorily defined ‘firearms.’” Staples v. United States, 511

U.S. 600, 602 (1994). In the 1934 legislation, the Congress

defined “machinegun” as a specific type of “firearm.” The

original text defined a “machinegun” as “any weapon which

shoots, or is designed to shoot, automatically or

semiautomatically, more than one shot, without manual

reloading, by a single function of the trigger.” National

Firearms Act § 1(b). A few decades later, the Gun Control Act

of 1968, Pub. L. No. 90-618, 82 Stat. 1213, amended the

definition in two key ways, deleting the phrase “or

semiautomatically” and including “parts” designed and used to

“convert a weapon into a machinegun.” 2 Gun Control Act, tit.

II, § 201, 82 Stat. at 1231 (codified at 26 U.S.C. § 5845(b)).

The definition of “machinegun” in effect today includes “any

weapon which shoots, is designed to shoot, or can be readily

restored to shoot, automatically more than one shot, without

manual reloading, by a single function of the trigger.” 26

U.S.C. § 5845(b).

The Firearms Owners’ Protection Act of 1986 (Act), Pub.

L. No. 99-308, 100 Stat. 449, effectively banned private

ownership of machine guns. Firearms Owners’ Protection Act,

§ 102(9) (codified at 18 U.S.C. § 922(o)(1)). The Act makes it

2

It thus extends to “the frame or receiver of any such weapon,

any part designed and intended solely and exclusively, or

combination of parts designed and intended, for use in converting a

weapon into a machinegun, and any combination of parts from which

a machinegun can be assembled if such parts are in the possession or

under the control of a person.” 26 U.S.C. § 5845(b).

3

“unlawful for any person to transfer or possess a machinegun,”

18 U.S.C. § 922(o)(1)), and “machinegun” has “the meaning

given . . . in section 5845(b) of the National Firearms Act,” id.

§ 921(a)(3). A person who “knowingly” violates the ban can

be “fined . . . [or] imprisoned not more than 10 years, or both.”

Id. § 924(a)(2). The ban has two exceptions: one for “a transfer

to or by, or possession by or under the authority of” the federal

government or a state government, id. § 922(o)(2)(A), and the

other grandfathers any “machinegun” lawfully possessed

before the Act went into effect, id. § 922(o)(2)(B).

B. History of Bump Stock Regulation

Firearms manufacturers have created various devices that

allow a lawful semiautomatic rifle to perform more rapidly. A

bump stock is one such device. It replaces the standard stock

of a rifle—the part that rests against the shooter’s shoulder. A

bump stock “free[s] the weapon to slide back and forth

rapidly.” Bump-Stock-Type Devices, 83 Fed. Reg. at 66,516.

The sliding motion allows a shooter to increase his rate of fire.

A rifle produces recoil energy upon firing. The bump stock

helps direct the firearm’s recoil and convert the recoil energy

into rapidly firing rounds. It works like this: the shooter pulls

the trigger; the recoil causes the firearm to slide backward; the

shooter maintains backward pressure on the trigger with the

index finger of his shooting hand and forward pressure on the

barrel with his other hand. Id. This process causes the firearm

to slide back and forth rapidly, bumping the shooter’s

stationary trigger finger and thereby firing additional rounds.

Id.

Some bump stock devices use only the shooter’s physical

pressure to channel the recoil energy and do not include springs

or mechanical parts. Id. For these devices, a single pull of the

trigger alone—without the shooter’s additional forward

4

pressure—does not cause the firearm to shoot more than one

round. Video evidence in the record makes this clear. 3 In the

video, the shooter fires a rifle equipped with a non-mechanical

bump stock. The shooter holds the rifle with one hand, the

trigger hand. He then pulls the trigger and the rifle fires a single

shot. Without his other hand’s forward pressure on the barrel,

the rifle equipped with a non-mechanical bump stock fires only

a single round with each pull of the trigger.

The ATF first classified a bump stock type device in 2002,

concluding that it was not a “machinegun.” Id. at 66,517. The

classification involved a product called the Akins Accelerator,

a bump stock that used internal springs. “To operate the device,

the shooter initiated an automatic firing sequence by pulling the

trigger one time, which in turn caused the rifle to recoil within

the stock, permitting the trigger to lose contact with the finger

and manually reset.” Id. “Springs in the Akins Accelerator

then forced the rifle forward, forcing the trigger against the

finger, which caused the weapon to discharge the ammunition.”

Id. The ATF interpreted the statutory language “single

function of the trigger” to mean a “single movement of the

trigger.” Id. A semi-automatic rifle fires only a single round

each time the trigger is pulled and reset. According to the ATF,

because the Akins Accelerator did not modify how a

semiautomatic rifle’s trigger “moves” with each shot, it was not

a “machinegun.”

In 2006, the ATF reclassified the Akins Accelerator as a

“machinegun.” It reinterpreted the phrase “single function of

the trigger” from “single movement of the trigger” to “single

pull of the trigger.” Id. The reinterpretation made all the

difference. Once a shooter pulls and maintains pressure on the

trigger, the internal springs of the Akins Accelerator start an

3

The declaration of Rick Vasquez, a former senior ATF

Technical Expert, attests to the accuracy of the video evidence.

5

automatic sequence that keeps the rifle firing until the shooter

removes his finger or depletes the ammunition. The firing of

multiple rounds based on a single continuous pull of the trigger

made the device a “machinegun” under the ATF’s

reinterpretation. The Akins Accelerator inventor challenged

the ATF’s changed reading in federal district court (M.D. Fla.),

arguing that the Agency misinterpreted the statutory definition

of “machinegun.” The district court upheld the ATF’s

determination and the Eleventh Circuit affirmed. Akins v.

United States, 312 F. App’x 197 (11th Cir. 2009). The

appellate court concluded that “the interpretation by the Bureau

that the phrase ‘single function of the trigger’ means a ‘single

pull of the trigger’ is consonant with the [National Firearms

Act] and its legislative history.” Id. at 200 (quoting 26 U.S.C.

§ 5845(b)).

“In ten letter rulings between 2008 and 2017, ATF applied

the ‘single pull of the trigger’ interpretation to other bump-

stock-type devices” and determined that none qualified as a

“machinegun.” Bump-Stock-Type Devices, 83 Fed. Reg. at

66,517. Although each device fired more than one round with

a single pull of the trigger, the ATF concluded that none was a

“machinegun” because the firing sequence did not occur

“automatically.” Unlike the Akins Accelerator, the devices did

not rely on springs or mechanical parts. In order to use them,

“the shooter [had to] apply constant forward pressure with the

non-shooting hand and constant rearward pressure with the

shooting hand.” Joint Appendix (J.A.) at 278. Thus, the ATF

drew a distinction between a bump stock with mechanical parts

like springs that cause a more rapid firing sequence and a bump

stock that uses both of the shooter’s hands to do the same. E.g.,

Letter from Richard W. Marianos, Assistant Dir. Pub. and

Governmental Affairs, to Congressman Ed Perlmutter (April

16, 2013), reprinted at J.A. 281–82.

6

C. The Bump Stock Rule

In October 2017, a gunman armed with several

semiautomatic rifles killed 58 people and wounded 500 more

in Las Vegas, Nevada. The rifles were equipped with bump

stock devices, which “were readily available in the commercial

marketplace through online sales directly from the

manufacturer, and through multiple retailers.” Bump-Stock-

Type Devices, 83 Fed. Reg. at 66,514. Using these devices, the

gunman was able to fire hundreds of rounds in a matter of

minutes. Within months, the ATF began to promulgate a

regulation to classify any bump stock type device as a

“machinegun.” President Trump directed the DOJ to “dedicate

all available resources to . . . propos[ing] for notice and

comment a rule banning all devices that turn legal weapons into

machineguns.” Application of the Definition of Machinegun to

“Bump Fire” Stocks and Other Similar Devices, 83 Fed. Reg.

7,949 (Feb. 20, 2018).

In December 2018, the ATF promulgated the Bump Stock

Rule. 4 Bump-Stock-Type Devices, 83 Fed. Reg. at 66,514. It

declares that all bump stock type devices “are ‘machineguns’

as defined by the National Firearms Act of 1934 and the Gun

Control Act of 1968 because such devices allow a shooter of a

semiautomatic firearm to initiate a continuous firing cycle with

a single pull of the trigger.” Id. According to the Rule, the

“devices convert an otherwise semiautomatic firearm into a

machinegun by functioning as a self-acting or self-regulating

mechanism that harnesses the recoil energy of the

semiautomatic firearm in a manner that allows the trigger to

reset and continue firing without additional physical

manipulation of the trigger by the shooter.” Id. (emphasis

4

The Rule amends three separate regulations, 27 C.F.R.

§§ 447.11, 478.11, 479.11, reinterpreting with identical language the

statutory definition of “machinegun” in each.

7

added). Thus, “a semiautomatic firearm to which a bump-stock

device is attached is able to produce automatic fire with a single

pull of the trigger.” Id.

The Bump Stock Rule was scheduled to go into effect on

March 26, 2019. 5 There were then an estimated 280,000 to

520,000 previously legal bump stocks in circulation in the

United States. See Bump-Stock-Type Devices, 83 Fed. Reg.

13,442, 13,451 (March 29, 2018). Under the Rule, “[b]ump-

stock-type devices . . . possessed by individuals [had] to be

destroyed or abandoned” before March 26. Bump-Stock-Type

Devices 83 Fed. Reg. at 66,546. Anyone who possesses or

transports the device after that date faces criminal liability. 18

U.S.C. § 922(o)(1).

D. Procedural History

The plaintiffs, five individual firearms owners and four

non-profit organizations, challenge the Bump Stock Rule’s

legality on several grounds. Their primary challenge is that the

Rule misinterprets the statutory definition of “machinegun”

and mistakenly extends that definition to cover bump stock

type devices. They also attack the Rule for alleged procedural

gaps in the rulemaking process and for taking property without

just compensation in violation of the Fifth Amendment’s Due

Process Clause. Finally, the plaintiffs contend that former

Acting Attorney General Matthew Whitaker was not properly

appointed to his position and thus lacked authority to approve

the Rule. The plaintiffs separately moved for preliminary

injunctive relief.

5

After hearing argument on March 22, 2019, we issued an

administrative order staying the Rule’s effective date but only as to

the plaintiffs. Per Curiam Order, Guedes v. ATF, No. 19-5042 (D.C.

Cir. March 23, 2019).

8

The district court consolidated and denied the motions. “A

plaintiff seeking a preliminary injunction must establish that he

is likely to succeed on the merits, that he is likely to suffer

irreparable harm in the absence of preliminary relief, that the

balance of equities tips in his favor, and that an injunction is in

the public interest.” Winter v. Nat. Res. Def. Council, Inc., 555

U.S. 7, 20 (2008). The district court determined that the Rule

reasonably interprets “machinegun” to include bump stock

devices. It also rejected the plaintiffs’ other challenges either

as unlikely to succeed on the merits or as unsuitable for

equitable relief. Accordingly, the district court denied relief

without reaching the other three preliminary-injunction factors.

The plaintiffs then filed a timely interlocutory appeal. See 28

U.S.C. § 1292(a)(1).

II. ANALYSIS

A. STANDARD OF REVIEW

The district court’s denial of preliminary injunctive relief

rests on its legal determination that the Bump Stock Rule does

not misinterpret or misapply the statutory definition of

“machinegun.” Our review is therefore de novo. City of Las

Vegas v. Lujan, 891 F.2d 927, 931–32 (D.C. Cir. 1989) (de

novo review of denial of preliminary injunctive relief where

“district judge did not make any factual determinations . . .

since he was sitting in appellate review of agency action” and

“denied the preliminary injunction because, and only because,

he believed the [agency] was likely to succeed on the merits”);

see also Athens Cmty. Hosp., Inc. v. Shalala, 21 F.3d 1176,

1178 (D.C. Cir. 1994) (“Upon the issue whether an

administrative regulation is lawful, we do not defer to the

judgment of the district court.”).

Despite the parties’ agreement that the de novo standard of

review applies, my colleagues, like the district court, see

9

Guedes, 356 F. Supp. 3d at 126–27, nonetheless review the

ATF’s interpretation under the two-step framework set out in

Chevron, U.S.A., Inc. v. Natural Resources Defense Council,

Inc., 467 U.S. 837, 842–43 (1984). 6 But the United States

Supreme Court has recently clarified whether the Chevron

framework applies to a statute—and, by extension a rule—

enforced by a criminal sanction. United States v. Apel, 571

U.S. 359, 369 (2014) (“[W]e have never held that the

Government’s reading of a criminal statute is entitled to any

deference.”). In another recent decision, Abramski v. United

States, the ATF had taken one view of 18 U.S.C. § 922(a)(6)

for “almost two decades,” concluding that a straw purchaser’s

“misrepresentation” counted as “material” under the statute

notwithstanding the true buyer could legally possess a gun.

573 U.S. at 191. The defendant pointed out that the ATF had

until 1995 taken the opposite position, requiring the true buyer

to be ineligible to possess a gun in order to make the straw

purchaser’s misrepresentation “material.” Id. The Supreme

Court responded that the “ATF’s old position [is] no more

6

Even under Chevron, “[a]n agency construction of a statute

cannot survive judicial review if a contested regulation reflects an

action that exceeds the agency’s authority.” Aid Ass’n for Lutherans

v. U.S. Postal Serv., 321 F.3d 1166, 1174 (D.C. Cir. 2003). Because

the Bump Stock Rule exceeds the ATF’s authority by veering from

the plain meaning of the statute, I would reach the same conclusion

whether Chevron step one or de novo review applies.

In reply to my colleagues’ insistence that, at the rulemaking

stage, the ATF emphasized its reliance on Chevron, Maj. Op. at 26–

28, I would note that the ATF in fact declared that the Rule’s

interpretations of “single function of the trigger” and “automatically”

“accord with the plain meaning of those terms.” Bump-Stock-Type

Devices, 83 Fed. Reg. at 66,527 (emphasis added). Its “fallback”

position at that stage was “even if those terms are ambiguous, this

rule rests on a reasonable construction of them.” Id. (emphasis

added).

10

relevant than its current one—which is to say, not relevant at

all.” Id. Indeed, “[w]hether the Government interprets a

criminal statute too broadly (as it sometimes does) or too

narrowly (as the ATF used to in construing § 922(a)(6)), a court

has an obligation to correct its error.” Id. In its Apel and

Abramski decisions, then, “[t]he Supreme Court has expressly

instructed us not to apply Chevron deference when an agency

seeks to interpret a criminal statute.” Gutierrez-Brizuela v.

Lynch, 834 F.3d 1142, 1156 (10th Cir. 2016) (Gorsuch, J.,

concurring).

My colleagues believe that this case is different because

the 26 U.S.C. § 5845(b) definition of “machinegun” has both

civil 7 and criminal 8 enforcement implications. They reach

their conclusion regarding the applicable standard of review

based in part on a footnote in Babbitt v. Sweet Home Chapter

of Communities for a Great Oregon, 515 U.S. 687 (1995). That

case involved a regulation interpreting the definition of “harm”

under the Endangered Species Act, a regulation with both

criminal and civil enforcement implications. Id. at 704 n.18.

7

See 26 U.S.C. § 5872(a) (“Any firearm involved in any

violation of the provisions of this chapter shall be subject to seizure

and forfeiture, and (except as provided in subsection (b)) all the

provisions of internal revenue laws relating to searches, seizures, and

forfeitures of unstamped articles are extended to and made to apply

to the articles taxed under this chapter, and the persons to whom this

chapter applies.”)

8

See 18 U.S.C. § 922(o)(1) (“[I]t shall be unlawful for any

person to transfer or possess a machinegun.”); 18 U.S.C.

§ 921(a)(23) (“The term ‘machinegun’ has the meaning given such

term in section 5845(b) of the National Firearms Act (26 U.S.C.

5845(b)).”); 18 U.S.C. § 924(a) (establishing penalties for

“knowing[]” or “willful[]” violation of, inter alia, section

922(o)(1)’s ban on machinegun possession or transfer).

11

The Supreme Court deferred to the Secretary of the Interior’s

interpretation under Chevron. Id. at 703–04. The majority

reads Babbitt—and some of our precedent—to establish a

bright-line rule that any regulation with both civil and criminal

enforcement provisions merits Chevron deference. Maj. Op. at

36–40; see In re Sealed Case, 223 F.3d 775, 779 (D.C. Cir.

2000); United States v. Kanchanalak, 192 F.3d 1037, 1047 n.17

(D.C. Cir. 1999). 9

With respect, I am not convinced that my colleagues’

reading of Babbitt as the last word on this topic is correct. See

Solid Waste Agency of N. Cook Cty. v. U.S. Army Corps of

Eng’rs, 531 U.S. 159, 174 n.8 (2001) (declining, post-Babbitt,

to address relationship between Chevron and agency regulation

interpreting statute with criminal sanction). The Supreme

Court’s most recent decisions indicate, as the ATF and the

plaintiffs argue here, Government Br. 36–37; Codrea Opening

Br. at 9–11, that Chevron review does not apply to a statute/rule

with criminal sanctions. 10 Apel, 571 U.S. at 369; Abramski,

573 U.S. at 191. And if Chevron review does not apply to a

9

One post-Apel and Abramski Circuit decision applies the

Chevron framework to a regulation with criminal and civil

enforcement provisions. Competitive Enter. Inst. v. U.S. Dep’t of

Transp., 863 F.3d 911, 915 (D.C. Cir. 2017). But only one judge

signed on to that view; one dissented and another wrote separately to

explain that he would reach the same result under de novo review,

which made Chevron’s applicability vel non unnecessary to his vote,

id. at 921 (Kavanaugh, J., concurring).

10

I leave for another day whether the Government can “waive”

Chevron review, as my colleagues view the ATF’s stance here. Maj.

Op. at 32–36; but see Glob. Tel*Link v. FCC, 866 F.3d 397, 417

(D.C. Cir. 2017) (“it would make no sense for this court to determine

whether” agency action “warrant[s] Chevron deference” if the

agency “no longer seeks deference”). I view the ATF’s stance to be

that Chevron is inapplicable—period. Government Br. 36–37.

12

statute/rule with criminal sanctions, Chevron cannot apply to a

statute/rule with both criminal and civil sanctions. See Clark

v. Martinez, 543 U.S. 371, 380 (2005) (a statute can have only

a single meaning and “[t]he lowest common denominator, as it

were, must govern”); Leocal v. Ashcroft, 543 U.S. 1, 11 n.8

(2004) (“[W]e must interpret [a] statute consistently, whether

we encounter its application in a criminal or noncriminal

context.”). Again, with respect, the majority may misread

Babbitt, which itself includes language that can allow its

holding to be reconciled with recent Supreme Court decisions:

We have never suggested that the rule of lenity

should provide the standard for reviewing facial

challenges to administrative regulations

whenever the governing statute authorizes

criminal enforcement. Even if there exist

regulations whose interpretations of statutory

criminal penalties provide such inadequate

notice of potential liability as to offend the rule

of lenity, the “harm” regulation, which has

existed for two decades and gives a fair warning

of its consequences, cannot be one of them.

515 U.S. at 704 n.18. Footnote 18 suggests, I submit, that a

regulation with a criminal sanction can violate the rule of lenity

but concluded that the regulation at issue, with its longstanding

definition of “harm,” did not do so. Id. My reading allows

Babbitt to be harmonized with more recent decisions: Chevron

does not apply to a regulation enforced both civilly and

criminally unless the regulation gives fair warning sufficient to

avoid posing a rule of lenity problem. The ATF’s

interpretation of “machinegun” gives anything but fair

warning—instead, it does a volte-face of its almost eleven

years’ treatment of a non-mechanical bump stock as not

constituting a “machinegun.”

13

Although I do not dispute that the ATF has been delegated

general rulemaking authority to implement section 5845(b),

inter alia, I am less certain than my colleagues that we owe

deference to the ATF’s interpretation of section 5845(b).

“Deference under Chevron to an agency’s construction of a

statute that it administers is premised on the theory that a

statute’s ambiguity constitutes an implicit delegation from

Congress to the agency to fill in the statutory gaps.” FDA v.

Brown & Williamson Tobacco Corp., 529 U.S. 120, 159

(2000). Statutory ambiguity, if it exists, does not necessarily

constitute an implicit delegation. King v. Burwell, 135 S. Ct.

2480, 2488–89 (2015); United States Telecom Ass’n v. FCC,

855 F.3d 381, 419–24 (D.C. Cir. 2017) (Kavanaugh, J.,

dissenting from denial of rehearing en banc). The Congress

must, for instance, “speak clearly if it wishes to assign to an

agency decisions of vast economic and political significance.”

Util. Air Regulatory Grp. v. EPA, 573 U.S. 302, 324 (2014)

(quotation marks omitted). There is good reason to believe that

a similar clear-statement rule applies in the criminal law

context. Under longstanding separation-of-powers principles,

the Congress defines the criminal law and must speak distinctly

to delegate its responsibility. 11 United States v. Bass, 404 U.S.

336, 348 (1971); United States v. Grimaud, 220 U.S. 506, 519,

522 (1911); United States v. Eaton, 144 U.S. 677, 688 (1892).

Unlike with civil statutes, then, ambiguity in the criminal law

is presumptively for the Congress—not the ATF—to resolve.

Whitman v. United States, 135 S. Ct. 352, 354 (2014) (Scalia,

J., statement respecting denial of certiorari) (“Congress cannot,

through ambiguity, effectively leave that function to the

courts—much less to the administrative bureaucracy.”).

11

The Supreme Court has upheld executive branch

interpretations of the criminal law based on express delegations of

interpretive authority. See United States v. O’Hagan, 521 U.S. 642,

667 (1997) (Securities Exchange Act of 1934); Touby v. United

States, 500 U.S. 160, 165–69 (1991) (Controlled Substances Act).

14

Accordingly, I would treat an ambiguous criminal statute to be

of “vast economic and political significance” and apply

Chevron only if the Congress expressly delegates its

lawmaking responsibility. See Util. Air Regulatory Grp., 573

U.S. at 324. The Congress has made no such clear statement;

instead the ATF relies solely on its general rulemaking power

and statutory ambiguity. 18 U.S.C. § 926(a); 26 U.S.C. §§

7801(a)(2)(A), 7805(a). Chevron is inapplicable. See King,

135 S. Ct. at 2489.

I believe the applicable standard of review is de novo and

therefore we should go “the old-fashioned” route and “decide

for ourselves the best reading” of “machinegun.” Miller v.

Clinton, 687 F.3d 1332, 1342 (D.C. Cir. 2012) (quoting

Landmark Legal Found. v. IRS, 267 F.3d 1132, 1136 (D.C. Cir.

2001)). As is always the case in construing a statute, the

inquiry focuses on “the plain meaning of the text, looking to

the ‘language itself, the specific context in which that language

is used, and the broader context of the statute as a whole.’”

Blackman v. District of Columbia, 456 F.3d 167, 176 (D.C. Cir.

2006) (quoting United States v. Barnes, 295 F.3d 1354, 1359

(D.C. Cir. 2002)). The Bump Stock Rule declares that any

bump stock device qualifies as a “machinegun.” Although the

Rule—in my view—correctly interprets “single function of the

trigger,” it misreads “automatically.” Moreover, it misapplies

its interpretation of “single function of the trigger” to bump

stock type devices.

B. “Single Function of the Trigger”

The Rule determines that “single function of the trigger”

within the statutory definition of “machinegun” means “single

pull of the trigger and analogous motions.” Bump-Stock-Type

Devices, 83 Fed. Reg. at 66,554. To me, the “function” of the

trigger means “action” of the trigger. Webster’s New

15

International Dictionary 1019 (2d ed. 1934). According to the

section 5845(b) definition, the trigger function “shoots” the

firearm. 26 U.S.C. § 5845(b) (“The term ‘machinegun’ means

any weapon which shoots . . . automatically more than one

shot, without manual reloading, by a single function of the

trigger.”); see also Fortier v. Olin Corp., 840 F.2d 98, 101 (1st

Cir. 1988) (discussing mechanics of lever-action rifle). “Pull

of the trigger,” then, describes how the trigger works. See

Staples, 511 U.S. at 602 n.1; United States v. Camp, 343 F.3d

743, 745 (5th Cir. 2003) (using trigger “pull” and “function”

interchangeably); United States v. Oakes, 564 F.2d 384, 388

(10th Cir. 1977) (same). The Rule recognizes that not all

firearms feature a pull trigger; some involve “fire initiated by

voice command, electronic switch, swipe on a touchscreen or

pad, or any conceivable number of interfaces.” Bump-Stock-

Type Devices, 83 Fed. Reg. at 66,534; see also United States v.

Fleischli, 305 F.3d 643, 655–56 (7th Cir. 2002) (minigun fired

by “electronic switch” is machinegun). To include these non-

pull methods used to shoot a firearm, the Rule includes the

phrase “and analogous motions.” Bump-Stock-Type Devices,

83 Fed. Reg. at 66,553.

The plaintiffs claim that the Rule’s interpretation of

“single function” impermissibly shifts the statutory focus from

the trigger’s action to the trigger finger’s action. But the Rule

defines “single function” to mean “single pull of the trigger and

analogous motions.” The Rule’s definition describes the

“motion” of the trigger, not of the trigger finger. Id. at 66,554.

Indeed, nothing in the Rule’s definition refers to a shooter’s

finger or a volitional action. Id. The plaintiffs challenge the

Rule because the ATF determines therein that a bump stock

device allows the firearm to shoot more than one shot with only

a single pull. But that is a question of application, not

definition. As for the definition, I believe the Rule correctly

16

reads “function” by focusing on how the trigger acts—that is,

through a pull.

C. “Automatically”

The Bump Stock Rule defines “automatically” to mean “as

the result of a self-acting or self-regulating mechanism that

allows the firing of multiple rounds through a single pull of the

trigger.” Id. at 66,519. The plaintiffs challenge this definition

because it does not account for the additional physical input the

shooter must provide in the firing sequence to make a firearm

with a bump stock shoot more rapidly. That “pull plus” action,

they say, invalidly expands the statutory text: a “‘single

function of the trigger’ is the starting and the ending point of

[making] a firearm automatic.” Codrea Br. at 14. I agree. 12

The Rule’s fatal flaw comes from its “adding to” the

statutory language in a way that is—at least to me—plainly

ultra vires. 1A Sutherland Statutory Construction § 31.02, at

521 (4th ed. 1985) (“The legislative act is the charter of the

administrative agency and administrative action beyond the

authority conferred by the statute is ultra vires.”); see Burnet v.

Marston, 57 F.2d 611, 612 (D.C. Cir. 1932) (“While the

[agency] was clothed with authority to promulgate regulations,

[it] was not authorized to add to or take from the plain language

12

A portion of the Bump Stock Rule’s definition of

“automatically” strikes me as unobjectionable. It adopts the phrase

“functioning as the result of a self-acting or self-regulating

mechanism” as a substitute for “automatically.” Bump-Stock-Type

Devices, 83 Fed Reg. at 66,554. It does so because dictionaries in

use at the time the 1934 Act was enacted defined “automatically”

that way. Id. at 66,519; see also Webster’s New International

Dictionary 187 (2d ed. 1934) (“automatic” means “[h]aving a self-

acting or self-regulating mechanism that performs a required act at a

predetermined point in an operation”).

17

of the statute, for, ‘where the intent is plain, nothing is left to

construction.’” (quoting United States v. Fisher, 6 U.S. 358,

386 (1805))). “Automatically” cannot be read in isolation. On

the contrary, it is modified—that is, limited—by the clause “by

a single function of the trigger.” 26 U.S.C. § 5845(b);

Webster’s New International Dictionary 307 (2d ed. 1934)

(defining “by” as “through the means of”). Section 5845(b)’s

awkward syntax does not equal ambiguity, as illustrated by the

lost art of diagramming. 13 “Automatically . . . by a single

function of the trigger” is the sum total of the action necessary

to constitute a firearm a “machinegun.” 26 U.S.C. § 5845(b).

A “machinegun,” then, is a firearm that shoots more than one

round by a single trigger pull without manual reloading. 14 The

13

Section 5845(b) can be diagrammed as follows:

See generally Marye Hefty et al., Sentence Diagramming 7–11, 17–

20, 24–25, 30–31, 33, 49 (2008).

14

In United States v. Olofson, 563 F.3d 652 (7th Cir. 2009), the

Seventh Circuit discussed the meaning of “machinegun.” It

explained that “‘automatically’ is the adverbial form of ‘automatic,’”

meaning “[h]aving a self-acting or self-regulating mechanism.” Id.

at 658 (alteration in original) (quoting Webster’s New International

Dictionary 187 (2d ed. 1934)). It then read section 5845(b)’s

“automatically” as follows: “the adverb ‘automatically,’ as it

modifies the verb ‘shoots,’ delineates how the discharge of multiple

rounds from a weapon occurs: as the result of a self-acting

18

statutory definition of “machinegun” does not include a firearm

that shoots more than one round “automatically” by a single

pull of the trigger AND THEN SOME (that is, by “constant

forward pressure with the non-trigger hand”). Bump-Stock-

Type Devices, 83 Fed. Reg. at 66,532. By including more

action than a single trigger pull, the Rule invalidly expands

section 5845(b), as the ATF itself recognized in the

rulemaking. See id. (shooter “maintain[s] constant forward

pressure with the non-trigger hand on the barrel-shroud or fore-

grip of the rifle,” and “maintain[s] the trigger finger on the

device’s extension ledge with constant rearward pressure.”).

My reading of the statute comports with the common sense

meaning of the language used. Suppose an advertisement

declares that a device performs a task “automatically by a push

of a button.” I would understand the phrase to mean pushing

the button activates whatever function the device performs. It

would come as a surprise, I submit, if the device does not

operate until the button is pushed and some other action is

taken—a pedal pressed, a dial turned and so on. Although the

device might be “automatic” under some definition, it would

not fit the advertised definition of “automatic”: by a push of a

button period.

More importantly, my reading of the statute—unlike the

ATF’s reading—maintains the longstanding distinction

between “automatic” and “semiautomatic” in the firearms

context. The original definition of “machinegun” in the 1934

Act included a firearm that shoots more than one round

mechanism.” Id. My rejection of the Bump Stock Rule creates no

tension with Olofson. That court did not consider whether additional

manual input from the non-shooting hand—“pull plus”—takes a

device outside section 5845(b)’s definition of “automatically.” Nor

did Olofson consider whether “pull” refers to how the trigger works

or to the movement of the shooter’s trigger finger.

19

“automatically or semiautomatically.” 26 U.S.C. § 2733(b)

(1940). At the time, an “automatic gun” was understood to be

“[a] firearm which, after the first round is exploded, by gas

pressure or force of recoil automatically extracts and ejects the

empty case, loads another round into the chamber, fires, and

repeats the above cycle, until the ammunition in the feeding

mechanism is exhausted, or pressure on the trigger is released.”

Webster’s New International Dictionary 187 (2d ed. 1934). A

“semiautomatic gun” was (and is) “[a] firearm in which part,

but not all, of the operations involved in loading and firing are

performed automatically, as when the recoil is used to open the

breech and thus prepare for reloading by hand.” Webster’s

New International Dictionary 187 (2d ed. 1934). At the time

of the 1934 Act’s enactment, then, the difference between an

“automatic” and a “semiautomatic” gun depended on whether

the shooter played a manual role in the loading and firing

process. My interpretation fits the historical context by

limiting “automatic[]” to a firearm that shoots more than one

round by a single trigger pull with no additional action by the

shooter. By contrast, the Bump Stock Rule reinterprets

“automatically” to mean what “semiautomatically” did in

1934—a pull of the trigger plus. The Congress deleted

“semiautomatically” from the statute in 1968 and the ATF is

without authority to resurrect it by regulation.

The ATF insists that my interpretation renders

“automatically” superfluous—a result inconsistent with the

well-established principle that “‘[a] statute should be construed

so that effect is given to all its provisions, so that no part will

be inoperative or superfluous, void or insignificant.’” Corley

v. United States, 556 U.S. 303, 314 (2009) (alteration in

original) (quoting Hibbs v. Winn, 542 U.S. 88, 101 (2004)).

Not even close. “[A]utomatically” means that the firearm

shoots more than one shot as the result of a self-acting

mechanism effected by a single pull of the trigger. Thus, the

20

combination of “automatically” and “by a single pull” explains

how the shooter accomplishes the firing sequence of a

“machinegun.” Under my reading, “automatically” excludes a

“machinegun” that uses a self-acting firing sequence effected

by action in addition to a single pull of the trigger.

Finally, the ATF, as well as the district court, posits that

the Bump Stock Rule meets one ordinary meaning of

“automatically”—that is, “perform[s] parts of the work

formerly or usually done by hand.” Webster’s New

International Dictionary 187 (2d ed. 1934). Both believe that

a bump stock “makes it easier to bump fire because it controls

the distance the firearm recoils and ensures that the firearm

moves linearly—two tasks the shooter would ordinarily have

to perform manually.” Guedes, 356 F. Supp. 3d at 132. Maybe

so. But the Rule does not use the “formerly done by hand”

meaning of “automatically.” Bump-Stock-Type Devices, 83

Fed. Reg. at 66,519. It defines “automatically” to mean “as the

result of a self-acting or self-regulating mechanism.” Id.

Whether that definition is consistent with section 5845(b)’s

definition is the question before us. 15

D. Is a Bump Stock a “Machinegun?”

Having interpreted “automatically” and “single function of

the trigger,” the Rule declares that a “‘machinegun’ includes a

bump-stock-type device, i.e., a device that allows a semi-

automatic firearm to shoot more than one shot with a single pull

15

I am not quibbling about semantics. The two definitions of

“automatically” have different aims: one refers to a self-acting

object; the other refers to automating a formerly “by-hand” task.

Webster’s Third New International Dictionary 148 (1993). The

“formerly by-hand” definition would shift the focus from whether a

bump stock provides a self-acting mechanism to fire multiple rounds

to whether a bump stock automates any action in the firing sequence.

21

of the trigger by harnessing the recoil energy of the semi-

automatic firearm to which it is affixed so that the trigger resets

and continues firing without additional physical manipulation

of the trigger by the shooter.” Id. at 66,553–54. There are at

least two defects in this classification. It ignores the fact that a

non-mechanical bump stock—a type of bump stock device

covered by the Rule—does not allow the firearm to shoot more

rapidly with a single pull of the trigger because the shooter

must provide “constant forward pressure with the non-trigger

hand” for the device to function. Id. at 66,532. It also

erroneously determines that a bump stock allows a

semiautomatic rifle to fire more than one round with a single

pull of the trigger. For these reasons, I agree with the plaintiffs

that a bump stock is not a “machinegun.”

First, a firearm equipped with a non-mechanical bump

stock does not fire “automatically” because the shooter must

also provide constant forward pressure with his non-shooting

hand. The Rule’s very description of a non-mechanical bump

stock manifests that its proscription is ultra vires:

[Bump stock] devices replace a rifle’s standard

stock and free the weapon to slide back and

forth rapidly, harnessing the energy from the

firearm’s recoil either through a mechanism like

an internal spring or in conjunction with the

shooter’s maintenance of pressure (typically

constant forward pressure with the non-trigger

hand on the barrel-shroud or fore-grip of the

rifle, and constant rearward pressure on the

device’s extension ledge with the shooter’s

trigger finger).

Id. at 66,516 (emphases added). This description covers two

types of bump stocks, one that includes a mechanism like an

22

internal spring and the other that requires the shooter to

maintain pressure with his non-trigger hand. Id. The first type,

including the original Akins Accelerator, has been classified as

a “machinegun” and hence illegal since 2006. Id. at 66,517.

The Rule must—and does—aim at the second type—the non-

mechanical bump stock—which operates only in conjunction

with the shooter’s added physical pressure. 16 But that added

physical pressure is inconsistent with the statutory definition of

a “machinegun,” which fires multiple rounds with a self-acting

mechanism effected through a single pull of the trigger

simpliciter. In short, the statute uses “pull” and the Rule—

invalidly—uses “pull plus.”

Other parts of the Rule expose the ATF’s error. In

discussing its interpretation of “automatically,” the ATF gave

the following explanation: “[s]o long as the firearm is capable

of producing multiple rounds with a single pull of the trigger

until [1] the trigger finger is removed, [2] the ammunition

supply is exhausted, or [3] the firearm malfunctions, the

firearm shoots ‘automatically’ irrespective of why the firing

sequence ultimately ends.” Id. at 66,519. Yet elsewhere the

ATF describes the firing process of a firearm with a bump stock

as follows: “the shooter ‘pulls’ the trigger once and allows the

firearm and attached bump-stock-type device to operate until

the shooter releases the trigger finger or the constant forward

pressure with the non-trigger hand.” Id. at 66,532 (emphasis

added). In my view, this assertion is an explicit recognition

that a bump stock device does not continue shooting rounds

with a single trigger pull if the shooter does not maintain

16

At oral argument, the ATF asserted that the non-trigger

hand’s “additional forward pressure” is part of the “automatic” firing

process. Transcript of Oral Argument 73–74. “Automatic” means

“self-acting or self-regulating.” Bump-Stock-Type Devices, 83 Fed.

Reg. at 66,553. The non-trigger hand’s constant forward pressure

requires physical, not automatic, action.

23

“constant forward pressure with the non-trigger hand.” Id. at

66,532.

Moreover, I find it difficult to ignore the ATF’s repeated

earlier determinations that non-mechanical bump stocks do not

initiate an automatic firing sequence. Three ATF

determination letters from 2010 to 2013 explained why non-

mechanical bump stocks are not “machineguns”:

[Our] evaluation confirmed that the submitted

stock (see enclosed photos) does attach to the

rear of an AR-15 type rifle which has been fitted

with a sliding shoulder-stock type buffer-tube

assembly. The stock has no automatically

functioning mechanical parts or springs and

performs no automatic mechanical function

when installed. In order to use the installed

device, the shooter must apply constant forward

pressure with the non-shooting hand and

constant rearward pressure with the shooting

hand.

Determination Letter signed by John R. Spencer, Chief,

Firearms Tech. Branch, ATF (June 7, 2010), reprinted at J.A.

278; see also Determination Letter signed by John R. Spencer,

Chief, Firearms Tech. Branch, ATF (April 2, 2012), reprinted

at J.A. at 279–80; Letter from Richard W. Marianos, Assistant

Dir. Pub. and Governmental Affairs, to Congressman Ed

Perlmutter (April 16, 2013), reprinted at J.A. 281–82. The

Rule does not fairly treat the ATF’s repeated determinations

that a non-mechanical bump stock “performs no automatic

mechanical function when installed.” J.A. 278. Instead, it

rejects its previous reading as based on an incomplete legal

definition of “automatically.” Bump-Stock-Type Devices, 83

24

Fed. Reg. at 66,521. 17 But those determinations made factual

findings that the non-mechanical bump stock operates only if

the shooter applies “constant forward pressure with the non-

shooting hand and constant rearward pressure with the shooting

hand.” Determination Letter signed by John R. Spencer, Chief,

Firearms Tech. Branch, ATF (June 7, 2010). And those factual

findings dictate that a non-mechanical bump stock is not a

“machinegun” under section 5845(b).

Second, a semiautomatic rifle equipped with a bump stock

cannot fire more than one round with a single function of the

trigger. The plaintiffs argue—and the ATF does not dispute—

that the trigger of a semiautomatic rifle must release the

hammer for each individual discharge. Nor is there any dispute

that a semiautomatic rifle cannot fire again until the trigger is

released, which causes the hammer to reset. The Rule refers to

the release of the trigger as a “separate” function. Bump-Stock-

Type Devices, 83 Fed. Reg. at 66,534 (“While semiautomatic

firearms [equipped with certain devices] may shoot one round

when the trigger is pulled, the shooter must release the trigger

before another round is fired. Even if this release results in a

second shot being fired, it is as the result of a separate function

of the trigger.”). Once the trigger shoots, it must be released to

reset the hammer and the trigger must be pulled again for each

subsequent shot. Verified Declaration of Richard (Rick)

17

During the rulemaking, the ATF repeatedly declared that its

earlier determinations “did not include extensive legal analysis of the

statutory terms ‘automatically’ or ‘single function of the trigger.’”

Bump-Stock-Type Devices, 83 Fed. Reg. at 66,516; see also id. at

66,514, 66,521, 66,528, 66,531. I defy a careful reader of the

rulemaking to find any legal, as opposed to functional, analysis of a

bump stock device, much less substantial legal analysis. Id. at

66,518 (“[P]rior ATF rulings concerning bump-stock-type devices

did not provide substantial or consistent legal analysis regarding the

meaning of the term ‘automatically.”’).

25

Vasquez, former Acting Chief of the Firearms Tech. Branch of

ATF, at 4 (with bump stock, “after the first shot is discharged,

the trigger must be released, reset, and pulled completely

rearward, before the subsequent round is discharged”),

reprinted at J.A. 275. Thus, a semiautomatic rifle equipped

with a bump stock cannot shoot more than one round with a

single pull of the trigger. 18

Still, the ATF insists that a bump stock allows a firearm to

shoot multiple shots with a single pull. Bump-Stock-Type

Devices, 83 Fed. Reg. at 66,553–54. The ATF focuses on

whether the shooter must pull his index finger more than once

to fire multiple shots. Because a bump stock allows the firearm

to fire more than once with a single pull of the index finger, the

ATF concludes that a bump stock is a “machinegun.”

Remember, however, section 5845(b) uses “single function of

the trigger,” not single function of the shooter’s trigger finger.

If the focus is—as it must be—on the trigger, a bump stock

does not qualify as a “machinegun.” A semiautomatic rifle

shoots a single round per pull of the trigger and the bump stock

changes only how the pull is accomplished. Without a bump

stock, the shooter pulls the trigger with his finger for each shot.

With a bump stock, however, the shooter—after the initial

pull—maintains backward pressure on the trigger and puts

18

Record evidence supports my point. As discussed earlier, the

record includes a video of a shooter firing a rifle equipped with a

bump stock. The video is in slow motion and focuses on the trigger.

For each shot the rifle fires, the trigger is pulled by the shooter’s

stationary trigger finger. The trigger is then released between each

shot. And the trigger is pulled again for the next shot. This trigger

movement confirms that a bump stock does not allow a rifle to shoot

more than one round with only a single pull of the trigger. Attached

as an appendix are photographs, taken from the video, that illustrate

the trigger’s movement during the bump stock’s firing sequence.

26

forward pressure on the barrel with his non-shooting hand;

these manual inputs cause the rifle to slide and result in the

shooter’s stationary finger pulling the trigger. Bump-Stock-

Type Devices, 83 Fed. Reg. at 66,533 (“The constant forward

pressure with the non-trigger hand pushes the firearm forward,

again pulling the firearm forward, engaging the trigger, and

firing a second round.”). The bump stock therefore affects

whether the shooter pulls his trigger finger or keeps it

stationary. It does not change the movement of the trigger

itself, which “must be released, reset, and fully pulled rearward

before [a] subsequent round can be fired.” Verified

Declaration of Richard (Rick) Vasquez, former Acting Chief

of the Firearms Tech. Branch of ATF, at 3–4.

Like countless other Americans, I can think of little

legitimate use for a bump stock. That thought, however, has

nothing to do with the legality of the Bump Stock Rule. For

the reasons detailed supra, I believe the Bump Stock Rule

expands the statutory definition of “machinegun” and is

therefore ultra vires. In my view, the plaintiffs are likely to

succeed on the merits of their challenge and I would grant them

preliminary injunctive relief.

Accordingly, I respectfully dissent.

27

APPENDIX

Photograph One: Trigger separates from stationary index

finger.

Photograph Two: Trigger comes into contact with stationary

index finger.