Amicus Curiae Brief — Gilbert P. Hyatt, Petitioner v. John A. Squires, Under Secretary of Commerce for Intellectual Property and Director, United States Patent and Trademark Office

No. 25-1049

In the

Supreme Court of the United States

____________________

GILBERT P. HYATT,

Petitioner,

v.

JOHN A. SQUIRES, UNDER SECRETARY OF COMMERCE FOR

INTELLECTUAL PROPERTY AND DIRECTOR OF THE UNITED

STATES PATENT AND TRADEMARK OFFICE,

Respondent.

On Petition for Writ of Certiorari to the United

States Court of Appeals for the Federal Circuit

BRIEF OF AMICI CURIAE US INVENTOR, SAN DIEGO

INVENTORS FORUM, TAMPA BAY INVENTORS COUNCIL,

MICHIGAN

INVENTORS

COALITION,

INVENTORS

NETWORK OF MINNESOTA, ACTURE NETWORK

(FORMERLY INVENTORS NETWORK KENTUCKY),

INVENTORS ASSOCIATION OF SOUTH CENTRAL KANSAS,

JACKSON INVENTORS NETWORK, LANSING INVENTORS

NETWORK, AND INVENTORS SOCIETY OF SOUTH

FLORIDA, ALL IN SUPPORT OF PETITIONER

ROBERT P. GREENSPOON

DUNLAP BENNETT & LUDWIG PLLC

333 North Michigan Avenue, Suite 2700

Chicago, Illinois 60601

(312) 551-9500

rgreenspoon@dbllawyers.com

Counsel of Record

April 3, 2026

i

TABLE OF CONTENTS

Page

TABLE OF CONTENTS ..............................................i

TABLE OF AUTHORITIES ....................................... ii

INTEREST OF AMICI CURIAE ............................... 1

SUMMARY OF ARGUMENT ..................................... 4

ARGUMENT ............................................................... 6

I. The applicant has a statutory right to a

patent—not a privilege to be extinguished

by equitable power of judicial discretion............... 7

I.A The proceeding under § 145 is a civil

action at law...................................................... 7

I.B Equitable defenses cannot be interposed

in a § 145 proceeding as it is an action

at law............................................................... 12

I.C All cases the Federal Circuit relied upon

adjudicated underlying equitable claims

by the patent holder ....................................... 15

II. Argument that the 1952 Patent Act

codified the equitable defense of

prosecution laches is unavailing ......................... 16

III.The compelling reasons for granting

certiorari ............................................................... 19

CONCLUSION .......................................................... 20

ii

TABLE OF AUTHORITIES

Pages

CASES

Bruesewitz v. Wyeth LLC, 562 U.S. 223 (2011) ........18

Caddington v. United States,

178 F. Supp. 604, 607 (Ct. Cl. 1959)....................11

Coca-Cola Co. v. Dixi-Cola Labs.,

155 F.2d 59 (4th Cir. 1946) ..................................13

County of Oneida v. Oneida Indian Nation of N.Y.,

470 U.S. 226 (1985) .................................................12

Crown Cork & Seal Co. v. Ferdinand

Gutmann Co., 304 U.S. 159 (1938) ......................15

Deweese v. Reinhard, 165 U.S. 386 (1897) ...............13

Gandy v. Marble, 122 U.S. 432 (1887) ......................17

General Talking Pictures Corp. v. Western

Electric Co., 304 U.S. 175 (1938) .........................15

Gould v. Quigg, 822 F.2d 1074 (Fed. Cir. 1987).........8

Grupo Mexicano de Desarrollo, S.A. v. All.

Bond Fund, Inc., 527 U.S. 308 (1999) ........... 13, 14

Hyatt v. Hirshfeld,

998 F.3d 1347 (Fed. Cir. 2021) ............ 6, 16, 17, 19

Hyatt v. Stewart,

148 F. 4th 1376 (Fed. Cir. 2025) ...................... 6, 19

In re Technology Licensing Corp.,

423 F.3d 1286 (Fed. Cir. 2005) ..............................8

Lantry v. Wallace, 182 U.S. 536 (1901) ....................12

Manufacturers’ Finance Co. v. McKey,

294 U.S. 442 (1935) ..............................................12

iii

Microsoft Corp. v. I4I Limited Partnership,

564 U.S. 91 (2011) ..................................................8

Overland Motor Co. v. Packard Motor Co.,

274 U.S. 417 (1927) ..............................................16

Petrella v. Metro Goldwyn Mayer, Inc.

572 U.S. 663 (2014) ................................ 4, 6, 13, 14

SCA Hygiene Prod. Aktiebolag v. First Quality

Baby Prod., LLC, 580 U.S. 328 (2017) ........ 4, 6, 14

Stainback v. Mo Hock Ke Lok Po,

336 U.S. 368 (1949) ..............................................13

Sun Oil Co. v. Burford,

130 F.2d 10 (5th Cir. 1942) ..................................13

Symbol Technologies, Inc. v. Lemelson Med,

277 F.3d 1361 (Fed. Cir. 2002) ............................15

Tull v. United States, 481 U.S. 412 (1987) .................8

Webster Electric Co. v. Podlesak,

255 F. 907 (D. Ill. 1919) .......................................15

Webster Electric Co. v. Splitdorf Electrical Co.,

264 U.S. 463 (1924) ..............................................15

Weinberger v. Romero-Barcelo,

456 U.S. 305 (1982) ..............................................13

Woodbridge v. United States,

263 U.S. 50 (1923) ................................................15

STATUTES

15 U.S.C. § 1069 ........................................................18

15 U.S.C. § 1115(b)(9) ...............................................18

15 U.S.C. § 1116(a) ....................................................18

15 U.S.C. § 1117(a) ....................................................18

28 U.S.C. § 1295 ........................................................20

iv

35 U.S.C. § 101 ............................................................7

35 U.S.C. § 102 ............................................................9

35 U.S.C. § 102(a) ........................................................7

35 U.S.C. § 131 ............................................................9

35 U.S.C. § 141 ..........................................................10

35 U.S.C. § 145 .............. 4, 5, 6, 7, 8, 10, 11, 12, 14, 17

35 U.S.C. § 261 ............................................................7

35 U.S.C. § 282 .................................... 5, 16, 17, 18, 19

35 U.S.C. § 282(b) ......................................................16

RS § 4915 ...................................................................17

PUBLIC LAWS AND STATUTES AT LARGE

Patent Act, Pub. L. No. 82-593,

66 Stat. 792 (1952) ..................................... 7, 16, 18

Trademark Act, Pub. L. No. 79-489,

60 Stat. 427 (1946) ...............................................18

RULES

Fed. R. Civ. Proc. § 2 .................................................14

Fed. R. Civ. Proc. § 52(a)(1) ......................................13

Supreme Court Rule 37.2 ............................................1

Supreme Court Rule 37.6 ............................................1

OTHER AUTHORITIES

P.J. Federico, Commentary on the New Patent

Act, 35 U.S.C.A. 1 (West 1954; reprinted in

75 J. Pat. & Trademark Off. Soc'y 161

(March 1993))

17

INTEREST OF AMICI CURIAE 1

Amici Curiae national and regional inventor

organizations listed below have substantial interests

in the results of this case and in contributing to this

Court’s understanding of reasons for reviewing and

correcting the decisions of the Court of Appeals for

the Federal Circuit below. Therefore, amici hereby

support the grant of certiorari.

1. US Inventor, Inc., is a not-for-profit

§ 501(c)(4) corporation, with a mission to restore

innovation in the US by establishing a strong patent

system. Our members include individual inventors

and startup inventor companies. We support our

mission by publishing information and videos on our

website at www.usinventor.org, by our newsletters

(www.usinventor.org/subscribe), and by conferences

(https://usinventor.org/usi-third-annual-conference/).

2. San Diego Inventors Forum includes

inventor members throughout San Diego County,

helping inventors become product developers and

entrepreneurs. The group meets once per month,

where members provide advice and encouragement

for other inventors to pursue their creativity.

https://sdinventors.org/.

1 Pursuant to Supreme Court Rule 37.6, counsel for the amici

curiae certifies that no counsel for any party authored this brief

in whole or in part and that no person or entity other than the

amici made a monetary contribution intended to fund the

preparation or submission of the brief. Rule 37.2 notice of the

intent to file this brief was timely provided by email to counsel

of record for Petitioner and for Respondent.

-23. Tampa Bay Inventors Council is an

inventor

organization

fostering

inventors’

networking, connecting and learning about inventing

and taking one’s innovations to market. The Council

brings innovative people together twice a month to

discuss various aspects of inventing. Speakers

discuss issues from patenting to packaging and all

the steps in between and taking it to market.

www.meetup.com/tbic-us/.

4. Michigan Inventors Coalition is an

inventor organization dedicated to help grow and

sustain Michigan’s economy by facilitating education

and collaboration among Michigan Inventors and

local support networks. www.miinventors.org

5. Inventors Network of Minnesota is a

voluntary membership organization composed of

individuals wishing to encourage the development of

new ideas and to promote the spirit of innovation

through the seeking and sharing of information. It

accomplishes this goal by focusing the individual and

collective experience and expertise of its members,

and others, to assist inventors and innovators

through the process of bringing their ideas to use.

www.inventorsnetwork.org

6. Acture Network (formerly Inventors

Network Kentucky) conducts a variety of monthly,

quarterly and annual programs that teach valuable

principles and engage participants in activities

designed to move their inventions, products or

businesses forward, through in-person and online

formats. Hosting three meetings every month on

distinct topics. www.acturenetwork.org

7. Inventors Association of South Central

Kansas is a non-profit organization assisting

regional

inventors

through

counseling

and

-3educational programs. Individuals are encouraged to

attend monthly educational meetings to learn from

technical experts regarding patent development and

protection and are encouraged to present their ideas

to association members to obtain feedback regarding

development

direction.

https://resourcenavigator.networkkansas.com/resourcenavigator/detail/180632/15/

8. Jackson Inventors Network is a

Michigan-based, non-profit support group for

inventors, marketers, and creators. It provides

networking,

educational,

and

mentoring

opportunities for members to help bring their

inventions

and

product

ideas

to

market.

www.facebook.com/JacksonInventorsNetwork/about

9. Lansing Inventors Network is a local

group, often associated with the Lansing Makers

Network, that provides a collaborative space for

inventors to connect, share, and develop their ideas.

It serves as a community resource for makers and

innovators in the Lansing area to foster local

invention.

www.facebook.com/LansingInventorsNetwork

10. Inventors Society of South Florida is a

§ 501(c)(3) non-profit organization dedicated to the

advancement of the independent inventor through

the use of Education, Motivation and Collaborative

Support. To that end, we provide a wealth of

information to our members and the general public

regarding all aspects of the invention process

through our newsletters, website, speakers, and

webinars conducted on the second Saturday of every

month. www.inventors-society.net/

-4SUMMARY OF ARGUMENT

The decision below permits an equitable defense

of prosecution laches to defeat an applicant’s claim

to a statutory right in a civil action under 35 U.S.C.

§ 145, notwithstanding this Court’s precedents

holding that equitable doctrines of laches cannot bar

relief in actions at law. The Patent Act confers a

statutory entitlement to a patent upon satisfaction of

specified conditions, and a § 145 proceeding is a civil

action at law to adjudicate that entitlement, not a

suit invoking equitable discretion. Section 145

authorizes the district court to “adjudge” that the

applicant is entitled to receive a patent, language

characteristic of a judgment at law rather than a

decree in equity. The proceeding vindicates a legal

right created by statute—not a privilege in common

law—and the remedy sought is a determination of

entitlement, not discretionary equitable relief.

The statute’s structure further confirms its lawside character: it provides a mutually exclusive

alternative to appellate review of the same agency

determination and imposes mandatory expenses on

the applicant including those of the agency, even

when the applicant prevails—features inconsistent

with traditional equitable adjudication and reflective

of a fixed statutory legal remedy. Because the action

seeks a judgment that the applicant “is entitled to

receive a patent,” and the resulting issuance follows

as a legal consequence of that determination, the

proceeding mirrors traditional actions at law rather

than equitable proceedings. Under settled principles

reaffirmed in Petrella and SCA Hygiene, equitable

defenses such as laches are unavailable to defeat

claims at law, and nothing in § 145 authorizes courts

-5to deny a statutory entitlement based on equitable

considerations. The Federal Circuit nevertheless

permitted

prosecution

laches

to

extinguish

Petitioner’s claim, effectively converting a statutory

right into a discretionary privilege.

The Federal Circuit further erred in concluding

that the 1952 Patent Act preserved such equitable

defenses. 35 U.S.C. § 282 governs defenses in actions

involving the validity or infringement of issued

patents, not proceedings concerning patent

applications, and thus does not apply to § 145

actions. Even if § 282 incorporated certain equitable

doctrines, this Court has already held that such

doctrines cannot bar legal relief. Congress’ silence in

the Patent Act contrasts with statutes, such as the

trademark Lanham Act, that expressly authorize

equitable doctrines, confirming that no such

authority exists here. By allowing prosecution laches

to defeat an applicant’s statutory entitlement, the

Federal Circuit departed from longstanding

distinctions between law and equity and from this

Court’s precedents preserving those limits.

Review is warranted because the decision below

creates a presumption that patents issued from

multiple

continuing

applications

may

be

unenforceable. It creates uncertainty regarding the

nature of the patent right and threatens broader

erosion of statutory entitlements by permitting

equitable defenses to defeat claims at law. The

Federal Circuit’s precedential rulings is binding in

all patent cases nationwide and without the

diversity benefit of “circuit splits” are unlikely to be

reconsidered absent this Court’s intervention,

leaving applicants and patent holders subject to

discretionary denial of statutory rights. The petition

-6therefore presents an important federal question

concerning the availability of equitable defenses in

actions at law and the proper interpretation of the

Patent Act, warranting this Court’s review. This

brief takes no position on the patentability or the

prosecution at the US Patent and Trademark Office

(“PTO”)

of

Petitioner’s

underlying

patent

applications.

ARGUMENT

In the two separate decisions below in this case,

Hyatt v. Hirshfeld, 998 F. 3d 1347 (Fed. Cir. 2021)

(“Hyatt I”), and Hyatt v. Stewart, 148 F. 4th 1376

(Fed. Cir. 2025) (“Hyatt II”), the Federal Circuit

Panel failed to follow controlling Supreme Court

precedents on the principles of separation of powers

that render unavailabile equitable laches defenses as

discussed in Petrella v. Metro Goldwyn Mayer, Inc.

572 U.S. 663 (2014), and SCA Hygiene Prod.

Aktiebolag v. First Quality Baby Prod., LLC, 580

U.S. 328 (2017). This case merits scrutiny for

contravening key rulings within Petrella and SCA

Hygiene: regardless of whether a timeliness

statutory “gap” exists in the Patent Act, equitable

claims of laches are unavailable to defeat the claims

in actions at law under 35 U.S.C. § 145. The Panel

clearly erred.

-7I.

The applicant has a statutory right to a

patent—not a privilege to be extinguished

by equitable power of judicial discretion

The 1952 Patent Act 2 (the “Act”) provides that

inventors may obtain patents for their inventions

“subject to the conditions and requirements of this

title.” 35 U.S.C. § 101 (emphasis added). One such

requirement is: “A person shall be entitled to a

patent unless [certain enumerated patentability

requirements are not met].” 35 U.S.C. § 102(a)

(emphasis added). This affirmatively clarifies that

the right to a patent is not a privilege but a

presumptive statutory right. Moreover, 35 U.S.C.

§ 261 provides that “patents shall have the

attributes of personal property” and “any interest

therein, shall be assignable in law by an instrument

in writing.” (Emphasis added). A patent property

right is a statutory right.

I.A

The proceeding under § 145 is a civil

action at law

The Act provides for an applicant’s civil action

against the US Patent and Trademark Office

(“PTO”) in District Court so that the “court may

adjudge that such applicant is entitled to receive a

patent for his invention, … and such adjudication

shall authorize the [PTO] to issue such patent on

compliance with the requirements of law. § 145

(emphasis added). This is a judgment at law on

patentability—not a decree in equity ordering the

PTO. See Gould v. Quigg, 822 F.2d 1074, 1079 (Fed.

2 Pub. L. No. 82-593, 66 Stat. 792 (1952).

-8Cir. 1987) (as “to the issue of whether the district

court has authority to direct the issuance of a patent,

we conclude it does not.”)

“To determine whether a statutory action is

more similar to cases that were tried in courts of law

than to suits tried in courts of equity or admiralty,

the Court must examine both the nature of the

action and of the remedy sought.” Tull v. United

States, 481 U.S. 412, 417 (1987) (emphasis added).

The “nature of the action” by the plaintiff/applicant

in a § 145 proceeding is the vindication of his legal

right to a patent; the “remedy sought” is the court’s

judgment that he “is entitled to receive a patent …”,

and an authorization of the PTO to issue such

patent. § 145.

Courts recognize that “[l]itigation of patent

validity is an action at law, separate from the

infringement cause of action.” In re Technology

Licensing Corp., 423 F.3d 1286, 1292-93 (Fed. Cir.

2005) (emphasis added; Newman, CJ., dissenting

and collecting cases). The Supreme Court confirmed

this

also

with

respect

to

patentability

determinations in prosecution of an application at

the PTO. Microsoft Corp. v. I4I Limited Partnership,

564 U.S. 91, 96-97 (2011) (“While the ultimate

question of patent validity is one of law, the same

factual questions underlying the PTO's original

examination of a patent application will also bear on

an invalidity defense in an infringement action.”)

(Cleaned up, emphasis added). An applicant’s claim

to a patent, both during prosecution at the PTO and

later in a § 145 action, is not contingent on privilege,

fairness, or judicial discretion; it is a statutory claim

to a defined statutory property right.

-9Accordingly, a § 145 proceeding is best

understood as an action at law to obtain a statutory

entitlement, not a suit invoking the district court’s

equitable powers. First, the source of the applicant’s

entitlement is purely statutory: the Patent Act

provides that the inventor “shall be entitled to a

patent unless…” § 102 (emphasis added). An

inventor meeting the statutory conditions is “entitled

to a patent,” and the PTO “shall issue a patent

therefor.” § 131 (emphasis added). Section 145 does

not create an equitable cause of action; it provides a

civil action by which an applicant may establish

entitlement to that statutory right when the agency

has denied it. The statutory language directing that

“[t]he court may adjudge that such applicant is

entitled to receive a patent … as the facts in the case

may appear,” is language characteristic of a law-side

adjudication of entitlement rather than the exercise

of discretionary equitable relief. The court does not

weigh equitable factors or fashion flexible remedies;

it determines, de novo and on the evidence, whether

the statutory requirements are satisfied. If so, the

judgment “authorize[s] the Director to issue such

patent on compliance with the requirements of law,”

making the court’s role analogous to entering

judgment establishing a legal right, with issuance of

the patent following as a ministerial consequence of

that determination.

Second, the structure of the remedy confirms the

law-side character of the proceeding. The applicant

seeks a determination of entitlement to a

government-conferred statutory right, not an

injunction against unlawful conduct, specific

performance, or other traditionally equitable relief.

The statute does not speak in equitable terms—no

- 10 reference to equity, discretion, balancing, or

irreparable injury—but instead contemplates

adjudication of facts and application of law to

determine whether the applicant is “entitled.” This

mirrors traditional actions at law used to establish

an entitlement at law, after which the operative

consequence follows by force of the judgment. The

directive that the court “adjudge” entitlement

reinforces that the court is entering a judgment

declaring a right, not exercising equitable discretion

by decree. The following other aspects of the statute

support this conclusion.

Mutually-exclusive alternative to appeal

The fact that § 145’s “unless appeal has been

taken” clause makes it an express mutually-exclusive

alternative to an appeal under § 141, strongly

supports treating it as a law-side proceeding. Both

mechanisms review the same agency determination

and address the same alleged wrong: the PTO’s

denial of a patent. Section 141 provides a

conventional appellate path—indisputably a lawside adjudication determining entitlement under

statutory criteria. Section 145 does not alter the

nature of the right asserted; it merely changes the

mode of adjudication from appellate review on the

record to a de novo civil action with optionally

additional evidence. Where Congress provides two

mutually-exclusive procedural avenues to vindicate

the same statutory entitlement, it is implausible

that one path invokes equitable discretion while the

other applies legal standards. Nothing in § 145

authorizes the court to grant or deny relief based on

equitable considerations; instead, the court “may

adjudge” entitlement “as the facts in the case may

- 11 appear,” paralleling a law-side determination of

right. The structural symmetry—same parties, same

agency decision, same statutory entitlement, and

mutually-exclusive routes—indicate that § 145 is not

an equitable substitute but a law-side alternative

procedure for obtaining the same statutory right.

Mandatory expenses of the proceedings

The mandatory-expenses provision is also

difficult to reconcile with an equitable proceeding.

Section 145 states: “All the expenses of the

proceedings shall be paid by the applicant.” This

applies even when the applicant prevails and the

court adjudges entitlement to the patent. That

provision is fundamentally inconsistent with

traditional equitable principles. Equity acts in

personam and is guided by fairness; courts

exercising equitable jurisdiction historically retain

discretion over costs and tailor relief to avoid unjust

outcomes. A regime requiring a fully successful

plaintiff to bear all expenses—including those

incurred by the opposing party—does not reflect

equitable tailoring but instead a fixed statutory

consequence attached to invoking a particular legal

remedy.

The rigidity of § 145 contrasts with equity’s

hallmark completeness for flexibly achieving justice.

As the maxim goes, “equity delights to do justice and

not by halves.” 3 A court exercising equitable

discretion would not ordinarily vindicate a party’s

right yet impose the entire financial burden of

3 See e.g., Caddington v. United States, 178 F. Supp. 604, 607

(Ct. Cl. 1959).

- 12 litigation on that same party. Congress’s decision to

impose all expenses categorically—without regard to

outcome, fairness, or equitable considerations—

evidences that § 145 is a statutorily defined action at

law, not a proceeding governed by equitable

principles.

I.B

Equitable defenses cannot be interposed

in a § 145 proceeding as it is an action at

law

The action-at-law nature of the proceeding

controls. A civil action under § 145 to obtain a

statutory right is an action at law in which an

equitable

defense

is

unavailable,

including

prosecution laches. Therefore, equitable judgments

cannot be the basis upon which the District Court in

a § 145 civil action “must … state its conclusions of

law.” Fed. R. Civ. Proc. § 52(a)(1) (emphasis added).

The Supreme Court has long recognized that, “in

actions at law[,] … equitable defenses are not

permitted.” Lantry v. Wallace, 182 U.S. 536, 549-550

(1901) (emphasis added); County of Oneida v. Oneida

Indian Nation of N.Y., 470 U.S. 226, 244, n.16 (1985)

(“[A]pplication of the equitable defense of laches in an

action at law would be novel indeed.”). This is not a mere

semantic separation of forms, but a substantive

functional and jurisdictional separation that

prevents courts from converting statutory rights into

mere privileges that can be refused as a matter of

judicial discretion or equity. The Supreme Court has

held “equitable principles [as] applicable only

against one who affirmatively has sought equitable

relief.” Manufacturers’ Finance Co. v. McKey, 294

U.S. 442, 453 (1935) (emphasis added). Therefore,

statutory rights are not “subject to denial or

- 13 curtailment in virtue of equitable principles.” Id.;

Deweese v. Reinhard, 165 U.S. 386, 390 (1897) (“A

court of equity acts only when and as conscience

commands; and, if the conduct of the plaintiff be

offensive to the dictates of natural justice, then,

whatever may be the rights he possesses, and

whatever use he may make of them in a court of law,

he will be held remediless in a court of equity.”)

(Emphasis added).

The Federal Rules of Civil Procedure merged the

procedures of law and equity in 1938 to create a

single “civil action.” Fed. R. Civ. Proc. § 2. However,

that procedural merger “[did] not abolish the

distinction between law and equity” as a substantive

matter. Coca-Cola Co. v. Dixi-Cola Labs., 155 F.2d

59, 63 (4th Cir. 1946); see Stainback v. Mo Hock Ke

Lok Po, 336 U.S. 368, 382 n.26 (1949) (“substantive

principles … remain[ed] unaffected”); Grupo

Mexicano de Desarrollo, S.A. v. All. Bond Fund, Inc.,

527 U.S. 308, 322 (1999) (The “merger did not alter

substantive rights”). Federal courts remain

constrained to “apply equitable principles to

equitable rights and legal principles to legal rights.”

Sun Oil Co. v. Burford, 130 F.2d 10, 17 (5th Cir.

1942), rev’d on other grounds, 319 U.S. 315 (1943).

Indeed, the Supreme Court has recognized that, “a

major departure from the long tradition of equity

practice should not be lightly implied.” Weinberger v.

Romero-Barcelo, 456 U.S. 305, 320 (1982). It later

acknowledged that the “substantive and remedial

principles [applicable] prior to … the federal rules

[have] not changed.” Petrella, 572 U.S. at 679

(cleaned up, brackets in original). Honoring the

substantive distinction between law and equity, the

Supreme Court held that in an action at law for

- 14 money damages, a United States District Court has

no equitable power to enjoin the defendant from

transferring assets in which no equitable interest is

claimed. Grupo Mexicano de Desarrollo, 527 U.S. at

333 (1999).

Later decisions on laches were no different in

effect. First, in Petrella, the Supreme Court held

that the equitable defense of laches could be applied

only to equitable claims. 572 U.S. at 678 (“[L]aches

is a defense developed by courts of equity; its

principal application was, and remains, to claims of

an equitable cast.”) (Emphasis added). The Court

reasoned that the 1938 adoption of the Federal Rules

of Civil Procedure did not alter “the substantive and

remedial principles” of the federal courts. Id. at 679.

Accordingly, the Court entirely rejected the argument

that a “federal civil action is subject to both

equitable and legal defenses” because “since 1938,

federal courts have frequently allowed defendants to

assert what were formerly equitable defenses—

including laches—in what were formerly legal

actions.” Petrella, 572 U.S. at 699 (Breyer J.,

dissenting). Second, the Supreme Court was to

decide “whether Petrella's reasoning applies to a

similar provision of the Patent Act” and held “that it

does.” SCA Hygiene, 580 U.S. at 332 (Laches “cannot

be invoked to bar legal relief”).

Nothing about the equitable defense of laches

suggests any different treatment in a civil action

under § 145 or during prosecution at the PTO to

obtain the statutory right to a patent. Broadening

the application of laches defense to claims at law

would “clash with the purpose for which the defense

developed in the equity courts.” SCA Hygiene, 580

U.S. at 335.

- 15 I.C

All cases the Federal Circuit relied upon

adjudicated underlying equitable claims

by the patent holder

The cases relied upon by the Federal Circuit in

Symbol Technologies 4 and now by the PTO, are

consistent with the proposition that laches may be

applied only against equitable claims, because they

all involved underlying assertions of injunction and

equitable claims:

(a) Webster Electric Co. v. Splitdorf Electrical Co.,

264 U.S. 463 (1924), involved the underlying

District Court “bills in equity” on patent

infringement and seeking to prevent unfair

competition, which is an equitable claim. See

Webster Electric Co. v. Podlesak, 255 F. 907, 908

(D. Ill. 1919);

(b) Woodbridge v. United States, 263 U.S. 50 (1923),

involved an underlying proceeding in the Court of

Claims “to hear and determine, … to what extent

the United States had used [the patent] and the

amount of compensation which was due in equity

and justice therefor.” Id. at 51 (emphasis added);

(c) Crown Cork & Seal Co. v. Ferdinand Gutmann

Co., 304 U.S. 159 (1938), involved an underlying

suit “to enjoin infringements of patents, two of

which are here involved.” Id. at 160 (emphasis

added);

(d) General Talking Pictures Corp. v. Western

Electric Co., 304 U.S. 175 (1938), involved three

underlying suits “brought … to restrain [enjoin]

4 Symbol Technologies, Inc. v. Lemelson Med, 277 F.3d 1361

(Fed. Cir. 2002).

- 16 infringements.” Id. at 176 (emphasis added); and

(e) Overland Motor Co. v. Packard Motor Co., 274

U.S. 417 (1927), involved an underlying suit “in

which the Packard Motor Car Company and the

Wire Wheel Corporation seek to enjoin an alleged

infringement by the Overland Motor Company of

the Cowles Patent.” Id. at 418 (emphasis added).

There appears to be no case prior to the 1952

Patent Act upon which the Federal Circuit relies

where courts have permitted the equitable defense of

prosecution laches other than when patentee sought

relief that included equitable relief.

II. Argument that the 1952 Patent Act

codified the equitable defense of

prosecution laches is unavailing

The Federal Circuit Panel maintained that “in

enacting the 1952 Patent Act, Congress intended the

prosecution laches defense to remain available.” 5 .

The relevant provision is 35 U.S.C. § 282(b), which

provides: “The following shall be defenses in any

action involving the validity or infringement of a

patent and shall be pleaded: (1) Noninfringement,

absence

of

liability

for

infringement

or

unenforceability.” (Emphasis added). The argument

is that the “unenforceability” defense includes the

equitable defense of prosecution laches. This

argument is wrong on two levels:

First, § 282 does not apply to patent

applications. The reference to “any action involving

the validity or infringement of a patent” cannot

5 Hyatt I, 998 F.3d at 1360.

- 17 pertain to the patentability of an application that is

not a patent; an action under § 145 is not an “action

involving the validity or infringement of a patent.”

An application in prosecution cannot be infringed,

nor could it require a defense against infringement.

The Supreme Court recognized for the predecessor of

§ 145 that “the proceeding is, in fact and necessarily,

a part of the application for the patent.”6 Therefore,

nothing in § 282 changed the law-equity distinction

in prosecution at the PTO, nor in § 145 proceeding,

which only involve patent applications. Nothing in

§ 145 permits insertion of any equitable factors when

rendering a judgment at law in the case.

Second, the “unenforceability” in § 282(b)(1) at

most may include equitable defenses that are only

applicable to patent holders’ claims for equitable

relief such as injunctive relief—not claims at law.

The Supreme Court has already rejected the notion

that § 282 makes all equitable defenses available

against relief at law, holding that the equitable

defense of laches is not available to defeat a claim at

law for damages. SCA Hygiene, 580 U.S. at 338-39.

That defies any view that § 282 makes all equitable

defenses applicable against all claims at law,

traditional boundaries notwithstanding.

Finally, for the proposition that § 282(b)(1)’s

“unenforceability” defense to claims at law includes

laches, the Panel (at 1361) refers to P.J. Federico,

Commentary on the New Patent Act, 35 U.S.C.A. 1

(West 1954; reprinted in 75 J. Pat. & Trademark

Off. Soc'y 161 (March 1993)), where Federico

6 Gandy v. Marble, 122 U.S. 432, 439 (1887) (emphasis added,

describing RS § 4915, the predecessor of § 145).

- 18 explains that defenses in § 282 would include

“equitable defenses such as laches, estoppel and

unclean hands.” Federico commentary, however, was

made two years after the Patent Act was enacted. It

is well settled that “[p]ost-enactment legislative

history (a contradiction in terms) is not a legitimate

tool of statutory interpretation.” Bruesewitz v. Wyeth

LLC, 562 U.S. 223, 242 (2011).

Where Congress intends equitable principles

to govern adjudication, it does so expressly, as it did

in the 1946 Lanham Act for trademarks. 7 See 15

U.S.C. § 1115(b)(9) (expressly providing for

“equitable principles, including laches, estoppel, and

acquiescence”

as

defenses

to

trademark

infringement); 15 U.S.C. § 1116(a) (Courts “shall

have power to grant injunctions, according to the

principles of equity…”); 15 U.S.C. § 1117(a)

(“plaintiff shall be entitled, subject to the principles

of equity, to recover… (1) defendant’s profits, (2) any

damages sustained by the plaintiff, and (3) the costs

of the action.”) It even expressly authorized the PTO,

an agency normally lacking inherent equitable

authority, that in the limited area of “inter partes

proceedings, equitable principles of laches, estoppel,

and acquiescence, where applicable may be

considered and applied.” 15 U.S.C. § 1069. When it

enacted the 1952 Patent Act only a few years later,

Congress saw the need and knew how to authorize

application of equity, but declined to do so. There is

no indication that by enacting § 282, Congress

intended to override centuries of equity tradition

7 Pub. L. No. 79-489, 60 Stat. 427 (1946)

- 19 that precludes equitable claims from defeating

claims at law.

Conversely, reading § 282 as codifying equitable

doctrines in claims at law means that persons no

longer have statutory “rights,” but instead only

“privileges” judges may deny based on their own

assessments of fairness and the equities. At no time

did Congress authorize that kind of radical revision

to obtaining and enforcing property rights. Whatever

grounds might exist to deny petitioner his patents,

those grounds cannot rightfully include the equitable

defense of prosecution laches.

III. The compelling reasons for granting

certiorari

The Federal Circuit decisions below have created

an unprecedented dark cloud over the enforceability

of the statutory patent right. If left standing, this

cloud threatens more broadly any statutory right by

establishing the availability of equitable claims for

defeating claims in actions at law. Moreover, these

Federal Circuit decisions with the prosecution laches

presumption they establish were made precedential8

and final because the Petitioner’s timely request for

rehearing en banc was denied. Pet.App. 213-14.

The decisions below raise an important federal

question in a way that conflicts with decisions by

this Court and by sanctioning such a departure by

8

Hyatt I

is

classified

as

“precedential”

at

www.cafc.uscourts.gov/10-12-2021-20-2321-hyatt-v-hirshfeldopinion-20-2321-opinion-10-12-2021_1847303/ and Hyatt II is

classified “precedential” at www.cafc.uscourts.gov/08-29-202518-2390-hyatt-v-stewart-opinion-18-2390-opinion-8-292025_2565719/ .

- 20 lower courts and the PTO. As the single appellate

court dealing with patent law, 28 U.S.C. § 1295, the

Federal Circuit decision constitutes a singular

appellate decision, because there can be no “circuitsplit” competition on such issues. Given the

entrenched position of the Federal Circuit that is

now binding on all its future panels as well as lower

tribunals, the matter is extremely unlikely to come

before this Court again for many years. The result

will be irreversible harm not only to applicants

prosecuting patent applications at the PTO, but also

for all holders of issued patents in force.

The compelling reason for this Court’s review is

that the Federal Circuit has decided an important

federal question in a way that conflicts with relevant

decisions of this Court—a question that has never

been, but should be, settled by this Court.

CONCLUSION

For the foregoing reasons, the Court should

grant the petition for certiorari.

Respectfully submitted,

ROBERT P. GREENSPOON

DUNLAP BENNETT & LUDWIG PLLC

333 North Michigan Avenue, Suite 2700

Chicago, Illinois 60601

(312) 551-9500

Counsel for Amici Curiae

APRIL 3, 2026