Amicus Curiae Brief — Harold R. Berk, Petitioner v. Wilson C. Choy, et al.

No. 24-440

IN THE

Supreme Court of the United States

_______________

HAROLD R. BERK,

Petitioner,

v.

WILSON C. CHOY, ET AL.,

_______________

Respondents.

On Writ of Certiorari to the United States

Court of Appeals for the Third Circuit

_______________

BRIEF OF PROFESSOR MICHAEL T. MORLEY

AS AMICUS CURIAE IN SUPPORT OF

RESPONDENTS

_______________

F. ANDREW HESSICK

160 Ridge Road

Chapel Hill, NC 27599

RICHARD A. SIMPSON

Counsel of Record

Wiley Rein LLP

2050 M Street, NW

Washington, DC 20036

(202) 719-7000

rsimpson@wiley.law

August 5, 2025

Counsel for Amicus Curiae

i

TABLE OF CONTENTS

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

INTEREST OF AMICUS CURIAE ............................1

SUMMARY OF ARGUMENT .....................................2

ARGUMENT ...............................................................4

I. The Rules Enabling Act authorizes procedural

rules that do not abridge, enlarge, or modify

substantive rights. ..................................................4

A. The Rules Enabling Act establishes a twostep process for determining a Rule’s validity

. ............................................................................5

B. This Court should clarify what constitutes a

“substantive right” for purposes of § 2072(b)

. ..........................................................................19

II. Applying the Federal Rules of Civil Procedure

to displace Delaware’s affidavit requirement

would abridge or modify litigants’ substantive

rights under state law. ..........................................22

CONCLUSION ..........................................................26

ii

TABLE OF AUTHORITIES

Page(s)

Cases

Amchem Products, Inc. v. Windsor,

521 U.S. 591 (1997) ............................................. 8

Babbitt v. Sweet Home Chapter of Cmtys.

for a Great Or.,

515 U.S. 687 (1995) ............................................. 7

Burlington N. R.R. Co. v. Woods,

480 U.S. 1 (1987) ..................................... 6, 20, 22

Bus. Guides, Inc. v. Chromatic Commc’ns

Enters., Inc.,

498 U.S. 533 (1991) ............................................. 6

Cohen v. Beneficial Industrial Loan Corp.,

337 U.S. 541 (1949) ..................................... 24, 26

Dick v. New York Life Ins. Co.,

359 U.S. 437 (1959) ........................................... 23

Douglas v. NCNB Tex. Nat’l Bank,

979 F.2d 1128 (5th Cir. 1992) ........................... 12

Dunn v. CFTC,

519 U.S. 465 (1997) ............................................. 7

Erie Railroad Co. v. Tompkins,

304 U.S. 64 (1938) ............................. 2, 12, 13, 18

Froio v. Du Pont Hosp. for Children,

816 A.2d 784 (Del. 2003) ................................... 24

iii

Garman v. Campbell Cnty. Sch. Dist. No. 1,

630 F.3d 977 (10th Cir. 2010) ........................... 12

Gasperini v. Ctr. for Humanities, Inc.,

518 U.S. 415 (1996) ..................... 2, 19, 20, 24, 25

Guaranty Trust Co. v. York,

326 U.S. 99 (1945) ..................................... 5, 9, 24

Hanna v. Plumer,

380 U.S. 460 (1965) ................... 3, 5, 8, 14, 18, 21

King v. Burwell,

576 U.S. 473 (2015) ............................................. 7

McCollum Aviation, Inc. v. CIM Assocs.,

438 F. Supp. 245 (S.D. Fla. 1977) ..................... 12

Miss. Publ’g Corp. v. Murphee,

326 U.S. 438 (1946) ........................................... 14

Ortiz v. Fibreboard Corp.,

527 U.S. 815 (1999) ............................................. 8

Palmer v. Hoffman,

318 U.S. 109 (1943) ........................................... 23

ReHabCare Grp. E., Inc. v. Camelot Terrace, Inc.,

No. 10 CV 02350, 2010 WL 5174369

(N.D. Ill. Dec. 15, 2010) .................................... 12

Semtek International Inc. v. Lockheed Martin Corp.,

531 U.S. 497 (2001) ................................... 7, 8, 22

Shady Grove Orthopedic Assocs. v. Allstate Ins. Co.,

559 U.S. 393 (2010) ......................... 2, 6, 9, 11, 13

iv

Sibbach v. Wilson & Co.,

312 U.S. 1 (1941) ....................................... 5, 6, 12

Slack Techs., LLC v. Pirani,

598 U.S. 759 (2023) ............................................. 7

Walker v. Armco Steel Corp.,

446 U.S. 740 (1980) ........................................... 10

Woods v. Interstate Realty,

337 U.S. 535 (1949) ........................................... 26

Statutes

28 U.S.C. § 2072 ..................................... 2, 4, 5, 7, 19

73 Cong. ch. 651, 48 Stat. 1064 (1934) .................... 4

Del. Code Ann. tit. 18, § 6853 ...................... 3, 22, 24

Other Authorities

A. Benjamin Spencer, Substance, Procedure,

and the Rules Enabling Act, 66 UCLA L.

Rev. 654, 683 (2019)

................................................................. 8, 19, 21

Allan Ides, The Standard for Measuring the

Validity of a Federal Rule of Civil

Procedure: The Shady Grove Debate

Between Justices Scalia and Stevens, 86

Notre Dame L. Rev. 1041 (2011)

........................................................... 6, 11, 13, 14

Amendments to Rules of Civil Procedure for

the United States District Courts, 31

F.R.D. 587 (1963) .............................................. 10

v

Catherine T. Struve, Institutional Practice,

Procedural Uniformity, and As-Applied

Challenges Under the Rules Enabling

Act, 86 Notre Dame L. Rev. 1181 (2011)

......................................................... 10, 11, 14, 15

19 Charles Alan Wright & Arthur R. Miller,

Federal Practice & Procedure § 4509 (3d

ed. 2025) ............................................................ 14

Donald L. Doernberg, “The Tempest”: Shady

Grove Orthopedic Associates, P.A. v.

Allstate Insurance Co.: The Rules

Enabling Act Decision that Added to the

Confusion, But Should Not Have, 44

Akron L. Rev. 1147 (2011) .......................... 20, 21

Fed. R. Civ. P. 1 .................................................. 3, 20

Fed R. Civ. P. 4 ....................................................... 11

Fed R. Civ. P. 64 ..................................................... 11

Fed. R. Civ. P. 69 .................................................... 11

Jean Macchiaroli Eggen, Medical

Malpractice Screening Panels: Proposed

Model Legislation To Cure Judicial Ills,

58 Geo. Wash. L. Rev. 181 (1990) ..................... 22

Jeffrey A. Parness, Amy M. Leonetti &

Austin W. Bartlett, The Substantive

Elements in the New Special Pleading

Laws, 78 Neb. L. Rev. 412 (1999) ..................... 22

vi

John H. Ely, The Irrepressible Myth of Erie,

87 Harv. L. Rev. 693 (1974)

..................................................... 6, 10, 13, 18, 20

Leslie M. Kelleher, Taking “Substantive

Rights” (in the Rules Enabling Act) More

Seriously, 74 Notre Dame L. Rev. 47

(1998) ..................................................... 11, 18, 21

Max Minzner, The Criminal Rules Enabling

Act, 46 U. Rich. L. Rev. 1047 (2012) ................. 21

Merriam Webster’s Collegiate Dictionary

(10th ed. 1997)..................................................... 7

Paul D. Carrington, “Substance” and

“Procedure” in the Rules Enabling Act,

1989 Duke L.J. 281 (1989) ............................ 3, 21

Stephen B. Burbank, The Rules Enabling

Act of 1934, 130 U. Pa. L. Rev. 1015,

(1982) ......................................... 14, 15, 16, 17, 20

Stephen C. Yeazell, Judging Rules, Ruling

Judges, 61 L. & Contemp. Probs. 229

(1998) ................................................................. 11

Thomas D. Rowe, Jr., Not Bad for

Government Work: Does Anyone Else

Think the Supreme Court Is Doing a

Halfway Decent Job in Its Erie-Hanna

Jurisprudence?, 73 Notre Dame L. Rev.

963, 983 (1998) .................................................. 10

1

INTEREST OF AMICUS CURIAE 1

Professor Michael T. Morley is Sheila M. McDevitt

Professor of Law at the Florida State University

College of Law and Faculty Director of the FSU

Election Law Center established by the Florida

Legislature, Fla. Stat. § 1004.421 (2025). He teaches

and writes in the areas of federal courts, remedies,

and election law, and he has an interest in the sound

development of these fields. His work was cited by

this Court in Trump v. CASA, Inc., 145 S. Ct. 2540

(2025).

1 No counsel for a party authored this brief in whole or in part,

and no counsel or party other than amicus or his counsel made a

monetary contribution intended to fund the preparation or

submission of this brief.

2

SUMMARY OF ARGUMENT

The Federal Rules of Civil Procedure do not

displace the Delaware affidavit requirement. Under

28 U.S.C. § 2072(a) the Court has the authority to

promulgate procedural rules. At the same time,

§ 2072(b) limits that authority by prohibiting rules

that “abridge, enlarge or modify any substantive

rights.” Section 2072 thus establishes two distinct

requirements. Even if a rule is procedural, or

rationally capable of being classified as such,

§ 2072(b) mandates that it may not change a

substantive right.

Whether a procedural rule changes another

substantive right is necessarily case specific and

depends on the nature of the other substantive right

that may be affected. See Shady Grove Orthopedic

Assocs. v. Allstate Ins. Co., 559 U.S. 393, 412 (2010)

(plurality opinion) (“[I]t is hard to understand how it

can be determined whether a Federal Rule ‘abridges’

or ‘modifies’ substantive rights without knowing what

state-created rights would obtain if the Federal Rule

did not exist”). A procedural rule that validly applies

in one case because it does not change a substantive

right cannot be applied in other cases where its

application would affect substantive rights.

There are various potential tests to resolve that

question.

One possibility is to incorporate the

standard for substantive rights under Erie Railroad

Co. v. Tompkins, 304 U.S. 64, 78-79 (1938), deeming a

law substantive if its application “significantly

affects” the outcome of the litigation. Gasperini v. Ctr.

for Humanities, Inc., 518 U.S. 415, 416 (1996).

Another is to evaluate the law under Federal Rule of

3

Civil Procedure 1, treating a right as procedural if it

is aimed at securing “the just, speedy, and inexpensive

determination” of federal cases, Fed. R. Civ. P. 1, and

substantive if it furthers other, unrelated goals.

A third approach is to deem a rule substantive if it

“substantially affect[s] . . . primary decisions” made

outside the litigation context. Hanna v. Plumer, 380

U.S. 460, 476 (1965) (Harlan, J., concurring). A fourth

option is to ask whether the rule at issue is generally

applicable to civil actions, in which case it is

procedural, or instead “specially” affects “a group of

litigants or prospective litigants,” in which case it is

substantive. Paul D. Carrington, “Substance” and

“Procedure” in the Rules Enabling Act, 1989 Duke L.J.

281, 308 (1989).

Under any of these tests, Delaware’s affidavit of

merit requirement creates substantive rights. The

requirement—which obliges a plaintiff to submit with

a complaint alleging a medical malpractice claim an

expert affidavit attesting to the merit of the claim,

Del. Code Ann. tit. 18, § 6853(a)—determines whether

a person is entitled to sue at all, not merely how a

person must initiate a lawsuit. The rule substantially

affects the outcome of litigation, since failure to

comply with it results in dismissal. The rule is not

generally applicable to civil actions; it applies only to

medical malpractice claims. The requirement is not

aimed solely at resolving cases justly and

inexpensively; its function is to protect medical

providers by precluding some medical malpractice

claims. Those additional protections affect conduct

outside the courtroom by allowing medical providers

to act with less fear of litigation.

4

Accordingly, the Federal Rules should not be read

to displace the Delaware affidavit requirement.

ARGUMENT

The Rules Enabling Act authorizes this Court to

promulgate rules regulating “practice and procedure”

in federal court, 28 U.S.C. § 2072(a), but those rules

cannot “abridge, enlarge or modify any substantive

right.” id. § 2072(b). Applying the Federal Rules of

Civil Procedure to displace the Delaware affidavit

requirement

would

violate

that

limitation.

Accordingly, the Court should affirm.

I. The

Rules

Enabling

Act

authorizes

procedural rules that do not abridge,

enlarge, or modify substantive rights.

The Rules Enabling Act (the “Act”) confers on this

Court the power to prescribe rules of practice and

procedure for the federal courts. 73 Cong. ch. 651, 48

Stat. 1064 (1934). The Act, now codified at 28 U.S.C.

§ 2072, has been amended several times since its

enactment in 1934, but its substance has not changed.

It authorizes the promulgation of procedural rules,

but those procedural rules may not abridge, enlarge,

or modify substantive rights.

The Court’s approach to § 2072 has not been

entirely consistent. This case presents an ideal

opportunity to clarify that the Rules Enabling Act’s

text, structure, and purpose, as well as this Court’s

precedents, require courts to engage in a two-step

process to determine whether a Federal Rule of Civil

Procedure may be applied in a particular case. First,

the court must confirm that the Rule at issue is

5

authorized by § 2072(a) because it is “rationally

capable” of being classified as procedural. Hanna, 380

U.S. at 472. Second, the court must determine

whether applying the Rule in the particular context

abridges, enlarges, or modifies substantive rights in

violation of § 2072(b).

This Part begins by demonstrating that § 2072(b)

establishes an independent, enforceable constraint on

this Court’s authority to promulgate procedural rules.

It then identifies potential standards the Court may

apply in doing so.

A. The Rules Enabling Act establishes a

two-step process for determining a

Rule’s validity.

1. The Constitution grants Congress authority to

adopt rules of practice and procedure in federal courts.

Sibbach v. Wilson & Co., 312 U.S. 1, 9 (1941).

Pursuant to this power, Congress may adopt rules to

“regulate matters which, though falling within the

uncertain area between substance and procedure, are

rationally capable of classification as either.” Hanna,

380 U.S. at 472.

Congress has chosen to delegate part of this power

to the judiciary. The Rules Enabling Act begins by

empowering the Court “to prescribe general rules of

practice and procedure . . . for cases in” the federal

courts. 28 U.S.C. § 2072(a). This grant of authority

reflects the full scope of Congress’s constitutional

power. Rules promulgated under this provision must

regulate “the manner [or] the means by which a right

to recover . . . is enforced.” Guaranty Trust Co. v.

York, 326 U.S. 99, 109 (1945).

6

Congress, however, has not delegated to the

judiciary its full authority to regulate federal judicial

procedure. John H. Ely, The Irrepressible Myth of

Erie, 87 Harv. L. Rev. 693, 707 n.77 (1974). Section

2072(b) limits the scope of the procedural rules the

Court may promulgate under § 2072(a) by imposing

the “additional requirement” that such rules “must

not ‘abridge, enlarge or modify any substantive

right.’” Burlington N. R.R. Co. v. Woods, 480 U.S. 1, 5

(1987) (quoting 28 U.S.C. § 2072(b)); see also Sibbach,

312 U.S. at 10 (characterizing § 2072(b) as a “proviso[]

or caveat[]” on § 2072(a)).

Section 2072(b)’s “text . . . in plain and

understandable terms[] imposes a substantive-rights

limit” on the scope of Congress’s delegation of

rulemaking authority to the Court. Allan Ides, The

Standard for Measuring the Validity of a Federal Rule

of Civil Procedure: The Shady Grove Debate Between

Justices Scalia and Stevens, 86 Notre Dame L. Rev.

1041, 1061 (2011). Under § 2072(b), a procedural rule

that has a greater than “incidental” effect on

“litigants’ substantive rights” violates § 2072(b).

Burlington N. R.R. Co., 480 U.S. at 5; accord Bus.

Guides, Inc. v. Chromatic Commc’ns Enters., Inc., 498

U.S. 533, 554 (1991); cf. Shady Grove Orthopedic

Assocs., 559 U.S. at 407-08 (plurality opinion) (holding

a rule is valid if it “regulate[s] only the process for

enforcing . . . rights,” without “alter[ing] the rights

themselves, the available remedies, or the rules of

decision” (emphasis added)).

The text of § 2072(b) makes clear that this

limitation restricts the scope of the procedural rules

that otherwise would be permitted under § 2072(a).

7

Section 2072(b) provides that “[s]uch rules shall not

abridge, enlarge or modify any substantive right.” 28

U.S.C. § 2072(b) (emphasis added). Used in this way,

the word “such” is defined to be “of the character [or]

quality . . . previously indicated.” Merriam Webster’s

Collegiate Dictionary 1172 (10th ed. 1997).

Accordingly, the phrase “such rules” in § 2072(b)

indicates that its restrictions apply to the procedural

rules permitted by § 2072(a). See King v. Burwell, 576

U.S. 473, 487 (2015) (“By using the phrase ‘such

Exchange,’ Section 18041 instructs the Secretary to

establish and operate the same Exchange that the

State was directed to establish under Section 18031.”);

see also Slack Techs., LLC v. Pirani, 598 U.S. 759, 767

(2023) (“[T]he statute repeatedly uses the word ‘such’

to narrow the law’s focus”).

The rule against surplusage confirms this

understanding of § 2072(b). See Dunn v. CFTC, 519

U.S. 465, 472 (1997) (reading a statute “consonant

with the doctrine that legislative enactments should

not be construed to render their provisions mere

surplusage”); see also Babbitt v. Sweet Home Chapter

of Cmtys. for a Great Or., 515 U.S. 687, 698 (1995).

Reading § 2072(b) to be satisfied whenever a rule is

arguably procedural as required by § 2072(a) would

impermissibly render § 2072(b) redundant.

Decisions of this Court also recognize the

restriction § 2072(b) imposes on procedural rules. For

example, in Semtek International Inc. v. Lockheed

Martin Corp., 531 U.S. 497, 503–04 (2001), the Court

held that Fed. R. Civ. P. 41(b) does not determine the

preclusive effect of federal court judgments in

diversity cases. Even though Rule 41(b) “govern[ed]

8

the internal procedures of the rendering court,” this

Court recognized that interpreting it as controlling

claim preclusion would “arguably violate” § 2072(b) by

changing substantive rights established by state law.

Id. This Court applied a similar analysis in Amchem

Products, Inc. v. Windsor, 521 U.S. 591 (1997). There,

the Court interpreted Rule 23 “in keeping . . . with the

Rules Enabling Act, which instructs that rules of

procedure ‘shall not abridge, enlarge or modify any

substantive right.’” Id. at 612-13 (citing 28 U.S.C.

§ 2072(b)); see also, e.g., Ortiz v. Fibreboard Corp., 527

U.S. 815, 845 (1999) (noting the “need for caution” in

interpreting the federal rules to avoid violating

§ 2072(b)).

Thus, § 2072 establishes a two-part inquiry. First,

§ 2072(a) authorizes the Court to promulgate only

procedural rules. Second, even if a rule is procedural,

or rationally capable of being classified as such, see

Hanna, 380 U.S. at 472, § 2072(b) mandates that it

may not change a substantive right. See A. Benjamin

Spencer, Substance, Procedure, and the Rules

Enabling Act, 66 UCLA L. Rev. 654, 683 (2019)

(“Supreme Court precedent . . . makes clear that the

Court has embraced an understanding of the [Rules

Enabling Act] that gives its ‘abridge, enlarge or

modify’ language independent weight apart from the

directive to confine rules to the procedural realm”).

2. The two-step inquiry mandated by the Rules

Enabling Act is necessarily case-specific. Whether a

federal rule is procedural within the meaning of

§ 2072(a) can be assessed by analyzing the rule itself.

But the § 2072(b) inquiry as to whether a federal

procedural rule changes another substantive right

9

cannot be determined in a vacuum. Rather, that

analysis necessarily depends on the nature of the

other substantive right that may be affected. See

Shady Grove, 559 U.S. at 412 (plurality opinion) (“[I]t

is hard to understand how it can be determined

whether a Federal Rule ‘abridges’ or ‘modifies’

substantive rights without knowing what statecreated rights would obtain if the Federal Rule did not

exist”).

A procedural rule that validly applies in cases

where its application does not curtail a substantive

right may not properly be applied in another case

where its application would have such an effect. By

the same token, a determination that applying a

procedural rule in a particular case would affect a

substantive right does not render the rule facially

invalid or categorically unenforceable; rather, it

means only that the rule cannot be applied in

circumstances where it changes the substantive right.

See id. at 423 (Stevens, J., concurring in part and

concurring in the judgment) (“A federal rule,

therefore, cannot govern a particular case in which

the rule would displace a state law that is procedural

in the ordinary use of the term but is so intertwined

with a state right or remedy that it functions to define

the scope of the state-created right.” (emphasis

added)).

For example, although a federal rule imposing a

two-year statute of limitations in all actions brought

in federal court could rationally be classified as a

procedural rule permitted by § 2072(a), see Guaranty

Trust, 326 U.S. at 109, that rule could not be applied

to shorten the limitations period when state law

10

establishes a longer timeframe because to do so would

abridge substantive rights. See Walker v. Armco Steel

Corp., 446 U.S. 740, 750 n.10 (1980) (noting concerns

about “whether it is competent for the Supreme Court,

exercising the power to make rules of procedure

without affecting substantive rights, to vary the

operation of statutes of limitations”); see also

Amendments to Rules of Civil Procedure for the

United States District Courts, 31 F.R.D. 587, 620

(1963) (Black & Douglas, JJ., dissenting) (explaining

that transferring responsibility for certain aspects of

the federal rulemaking process from the Court to the

Judicial Conference of the United States “would

relieve us of the embarrassment of having to sit in

judgment on the constitutionality of rules which we

have approved and which as applied in given

situations might have to be declared invalid”

(emphasis added)). 2

2 Scholars of all stripes have likewise concluded that § 2072(b)

must be assessed on as-applied basis. See Catherine T. Struve,

Institutional Practice, Procedural Uniformity, and As-Applied

Challenges Under the Rules Enabling Act, 86 Notre Dame L. Rev.

1181, 1184 (2011) (“[S]tate-specific as-applied invalidation of a

federal rule should be permissible . . . .”); Thomas D. Rowe, Jr.,

Not Bad for Government Work: Does Anyone Else Think the

Supreme Court Is Doing a Halfway Decent Job in Its Erie-Hanna

Jurisprudence?, 73 Notre Dame L. Rev. 963, 983 (1998)

(“[I]nvalidity of a Federal Rule for violating the substantiverights proviso might be no more than as applied where a

substantive, state provision collided directly with the Federal

Rule; the Rule would remain fully valid in other states lacking

similar provisions.”); Ely, supra at 722 (explaining § 2072(b)

establishes a “significant, enclave-type proviso” that may

prohibit a procedural rule from being applied in certain cases

depending on the “character of the state provision that

enforcement of the Federal Rule in question will supplant”);

11

Restricting the application of a federal rule on an

as-applied basis may sometimes result in the rule

being treated differently among district courts

because of differences in state law. In a state where

no substantive law is affected by the application of a

particular Federal Rule of Civil Procedure, a district

court may apply the Rule in all cases. In contrast, the

substantive law of another state may prevent a

district court there from applying that Rule in certain

circumstances. See Shady Grove, 559 U.S. at 416.

This kind of substantial variation of rules already

exists in district courts sitting in different states. See

Struve, supra note 2, at 1221 n.156-57. Several rules,

for example, already incorporate state law. See, e.g.,

Fed R. Civ. P. 4(e)(1) (authorizing service of process by

“following state law”); Fed R. Civ. P. 64(a)

(authorizing remedies for collecting a judgment that

are “available . . . under the law of the state where the

court is located”); Fed. R. Civ. P. 69(a)(1) (providing

Stephen C. Yeazell, Judging Rules, Ruling Judges, 61 L. &

Contemp. Probs. 229, 246 (1998) (explaining this Court must

“decid[e] whether a Rule, on its face or as applied, violates the

Rules Enabling Act, with its prohibition against Rules that

‘abridge, enlarge or modify any substantive right.’” (emphasis

added) (quoting 28 U.S.C. § 2072)); Leslie M. Kelleher, Taking

“Substantive Rights” (in the Rules Enabling Act) More Seriously,

74 Notre Dame L. Rev. 47, 93 (1998) (“There are matters falling

within state competence that are rationally capable of

classification as procedural, but are so ‘substantive’ as to be

beyond the scope of authority delegated to the Court under the

[Rules Enabling Act].”); Ides, supra at 1062 (“[I]t is difficult . . .

to read the phrase ‘really regulates procedure’” in Sibbach “as

proclaiming the irrelevance of state law and eliminating all asapplied challenges to the Federal Rules.”).

12

that the “procedure on execution” of money judgments

“must accord with the procedure of the state where

the court is located”). The disuniformity resulting

from application of § 2072(b)—inconsistency from

state to state because of differences substantive state

law—is a core feature of federalism. It is precisely the

kind of inconsistency envisioned by Erie Railroad Co.,

304 U.S. at 78-79. 3

3. None of this Court’s precedents precludes

interpreting § 2072(b) as imposing an independent

restriction on the Court’s rulemaking power. In

Sibbach, 312 U.S. at 10, the Court held that “[t]he

test” for determining whether a rule is valid under the

Rules Enabling Act “must be whether [the rule] really

regulates procedure.” Id. at 14. A plurality of the

Court in Shady Grove read this statement as

Several lower courts have enforced § 2072(b) as an

independent, enforceable limit on the judiciary’s rulemaking

authority under § 2072(a). See, e.g., Douglas v. NCNB Tex. Nat’l

Bank, 979 F.2d 1128, 1130 (5th Cir. 1992) (applying state law

because enforcing Fed. R. Civ. P. 13(a) “in the instant case would

abridge the lender’s substantive rights and enlarge the debtor’s

substantive rights”); Garman v. Campbell Cnty. Sch. Dist. No. 1,

630 F.3d 977 (10th Cir. 2010) (applying state law requirements

for filing a complaint against government defendants because

“[p]ermitting the federal rules to trump substantive [state] law

would ‘abridge, enlarge, or modify’ the litigants’ rights in

violation of the Rules Enabling Act”); McCollum Aviation, Inc. v.

CIM Assocs., 438 F. Supp. 245, 248 (S.D. Fla. 1977) (holding a

state’s registration requirement for foreign corporations “is

clearly substantive and as such, it must be given precedence over

Rule 17(b) because under the Rules Enabling Act, as developed

by Hanna, a Federal Rule cannot abridge an existing substantive

right”); accord ReHabCare Grp. E., Inc. v. Camelot Terrace, Inc.,

No. 10 CV 02350, 2010 WL 5174369, at *5 (N.D. Ill. Dec. 15,

2010).

3

13

establishing a “single criterion” for determining a

Federal Rule’s validity under the Rules Enabling Act:

whether the Rule “really regulates procedure.” Shady

Grove, 559 U.S. at 411.

That understanding of Sibbach is unwarranted.

The petitioner in Sibbach “conceded that both the

Federal Rule and the state law with which it

conflicted were procedural,” and “made no admissible

argument that the rule—either on its face or as

applied—abridged, enlarged, or modified a statecreated ‘substantive right.’” Ides, supra at 1054, 1063.

Instead, the petitioner argued that § 2072(b) prohibits

courts from applying Federal Rules to “otherwise nonsubstantive rights that are deemed ‘important’ or

‘substantial.’” Id. at 1061-62; see also id. at 1054

(explaining Sibbach’s holding that § 2072(b)’s

reference to “substantive right[s] does not embrace

concededly procedural rights merely because they

might be deemed to be ‘important’ or ‘substantial’”). 4

To the extent Sibbach holds that § 2072 authorizes the

application of Federal Rules even when they would alter or

nullify substantive rights, it should be reconsidered. See Ely,

supra, at 719-20 (criticizing Sibbach for ignoring § 2072(b)); see

also Shady Grove, 559 U.S. at 413 (plurality opinion) (“Sibbach’s

exclusive focus on the challenged Federal Rule . . . is hard to

square with § 2072(b)’s terms.”).

Although stare decisis

generally precludes this Court from reinterpreting statutes, that

has not been the case with the Rules Enabling Act due to the

important constitutional issues it implicates. See Erie, 304 U.S.

at 77-78 (reinterpreting the Rules Enabling Act because the

Court’s previous interpretation raised constitutional concerns).

Moreover, Congress’s “failure legislatively to overrule the Court’s

decisions construing the Act should not be regarded as

ratifications of the Court’s interpretations of the scope of its

4

14

In rejecting that argument, the Court “did not in fact

rule out the possibility of as-applied Enabling Act

challenges” under § 2072(b). Struve, supra note 2, at

1191.

Nor does Hanna, 380 U.S. 460, suggest that

procedural rules automatically satisfy § 2072(b). The

“right invoked in Hanna was a classically procedural

right—specifically, the right to a particular method of

service.” Ides, supra at 1062. As a result the Court

“had no occasion to consider whether [a Rule] . . .

abridged, enlarged, or modified a substantive right.”

Id.

Hanna further noted that for a court to conclude

that a Rule violates the Rules Enabling Act, it must

determine that the Advisory Committee, the Court,

and Congress “erred in their prima facie judgment” on

the issue. 380 U.S. at 471. But “[t]he fact that this

Court promulgated the rules as formulated and

recommended by the Advisory Committee does not

foreclose consideration of their validity, meaning or

consistency.” Miss. Publ’g Corp. v. Murphee, 326 U.S.

438, 444 (1946). Furthermore, as the Wright & Miller

treatise explains, the “intended scope of a rule [may

be] uncertain,” or a Rule may “be applied in unusual

situations that might not have been anticipated by the

Advisory Committee, the Judicial Conference, or the

Supreme Court during the Rule’s formulation.” 19

Charles Alan Wright & Arthur R. Miller, Federal

rulemaking power . . . .” Stephen B. Burbank, The Rules

Enabling Act of 1934, 130 U. Pa. L. Rev. 1015, 1102 (1982).

15

Practice & Procedure § 4509 (3d ed. 2025); see also

Struve, supra note 2, at 1209-10 (discussing various

reasons why a rule’s effects on substantive rights

might become apparent only after the rulemaking

process concludes).

4. The Rules Enabling Act’s legislative history

bolsters this plain-meaning interpretation of

§ 2072(b) limiting the scope of rules allowable under

§ 2072(a).

As Professor Stephen B. Burbank’s

comprehensive analysis of that history demonstrates,

Congress’s

primary

consideration

was

the

“allocat[ion] [of] power between the Supreme Court as

rulemaker and Congress.” Burbank, supra note 4, at

1025. “Nothing could be clearer from the pre-1934

history of the Rules Enabling Act than that the

procedure/substance dichotomy in the first two

sentences was intended to allocate lawmaking power

between the Supreme Court as rulemaker and

Congress.” Id. at 1106; see also id. at 1101-02

(explaining that the Act’s “statutory limitations . . .

were intended to confine the power of the Court itself,

a fact that requires the Court ever be open to the

reconsideration of past interpretations”).

The

“protection of state law” was a “probable effect” of this

limitation. Id. at 1106.

Chief Justice Taft, one of the Rules Enabling Act’s

longstanding supporters, had recommended that

Congress grant the Court “the same power to make

rules at law as it had in equity.” Id. at 1070. A bill

was developed by Senator Cummins to implement this

proposal, providing that “the rules for actions at law

be prepared by a commission such as Taft had

recommended.” Id. at 1072. He sent a copy to Chief

16

Justice Taft and Justice Sutherland, explaining that

its prohibition on abridging, enlarging, or modifying

litigants’ “substantive rights” was “designed to

emphasize the fact that ‘Congress could not if it

wanted to, confer upon the Supreme Court, legislative

power.’” Id. at 1073 (quoting Letter from the Hon.

Albert B. Cummins to the Hon. George Sutherland

(Dec. 17, 1923) (on file with Iowa State Historical

Department)). The Rules Enabling Act as enacted

was “essentially unchanged” from the version drafted

in 1924. Id. at 1099.

The 1926 Senate Judiciary Committee report

explained that the language that would become

§ 2072(b) prevents the Court from using the power the

bill granted to develop procedural rules to “affect

substantive rights or remedies.” Id. at 1086 (quoting

S. Rpt. No. 69-1174, at 9 (1926)). The report

emphasized that the bill did not allow courts to change

“substantive legal and remedial rights affected by the

considerations of public policy.” Id. It cautioned “that

an expansive interpretation of the first sentence [now

§ 2072(a)] would ignore the second [now § 2072(b)].”

Id. at 1108 (quoting S. Rpt. No. 69-1174, at 9, 11

(1926)). 5

5 Admittedly, Professor Burbank contends § 2072(b) lacks any

“independent meaning” and does not impose any separate

“limitations” on § 2072(a). Burbank, supra note 4, at 1107. But

that conclusion is premised on a narrow interpretation of

§ 2072(a). That is, Burbank argues that § 2072(a) does not

delegate to the judiciary all of Congress’ authority to regulate

federal judicial procedure. Rather, the term contains “inherent”

restrictions that already prevent violations of substantive rights.

17

Accordingly, reading § 2072(a) to authorize any

procedural rule while failing to accept any limitations

on that power pursuant to § 2072(b) is inconsistent

with congressional intent and runs contrary to the

separation of powers considerations motivating the

Rules Enabling Act. “As might be expected in a

statute designed to allocate lawmaking power,”

decisions that “affect ‘rights’ already recognized by the

‘substantive law’” are “for Congress, or in the absence

of congressional action, for the states.” Id. at 1124-25

(footnote omitted).

5. As the Rules Enabling Act’s legislative history

demonstrates, compelling separation-of-powers and

policy considerations require independently enforcing

Id. at 1108 (“[T]he first sentence itself [now § 2072(a)] was

thought to impose significant restrictions on court rulemaking.”).

Rather than reinterpreting § 2072(a) to define the term

“procedure” more narrowly, this Court may instead rectify the

problem Professor Burbank identifies by instead recognizing—as

several of its precedents already appear to do, see supra p. 8—

that § 2072(b) prevents application of procedural rules where

they would materially impact a litigant’s substantive rights.

Either way, the Rules Enabling Act’s legislative history does not

support the notion that this Court may both claim the full extent

of Congress’s rulemaking authority while simultaneously

recognizing no safeguards to prevent material infringements of

substantive rights.

Burbank, supra note 4, at 1108

(demonstrating that construing the Rules Enabling Act as

delegating the full scope of Congress’s rulemaking authority to

the judiciary “neglect[s] restrictions sought to be imposed by

Congress”).

18

§ 2072(b) to ensure the Federal Rules do not

materially impact litigants’ substantive rights.

Declining to enforce independent protection for

substantive rights under § 2072(b) in diversity cases

also undermines federalism by allowing procedural

rules effectively to nullify state policies that may have

been crafted to promote important substantive policy

objectives. Kelleher, supra note 2, at 69, 92 (“A legal

rule can have both procedural and substantive

purposes, and even if the animating policies of a rule

ostensibly are procedural, it may have significant

substantive implications, whether intended or not.”).

The Erie Doctrine teaches that federal courts are

presumptively required to apply state substantive law

in diversity cases and other matters arising under

state law. Erie, 304 U.S. at 78 (holding that, except

where the Constitution or federal law otherwise

require, “the law to be applied in any case is the law

of the [S]tate”).

More broadly, the Erie Doctrine is about fairness:

a person’s material rights in a case should not differ

depending on whether the case is filed in state court

or the federal court across the street. Id. at 76-77

(condemning the “injustice and confusion” that arises

when a case’s outcome depends on whether it is filed

in federal or state court); see also Hanna, 380 U.S.

at 467 (“The Erie rule is rooted in part in a realization

that it would be unfair for the character or [sic] result

of a litigation materially to differ because the suit had

been brought in a federal court.”); Ely, supra at 714

n.123.

Automatically enforcing any arguably

procedural rule without regard to the impact it has on

19

a litigant’s entitlement to sue or ability to prevail

fosters such unjust arbitrary disparities.

* * *

In sum, the Rules Enabling Act authorizes this

Court to make “general rules of practice and

procedure and rules of evidence” for the federal courts.

28 U.S.C. § 2072(a)

But those rules, even if

procedural, may not be applied when doing so would

“abridge, enlarge or modify any substantive right.”

Id. § 2072(b). This Court should faithfully and

vigorously enforce both parts of the statute.

B. This Court should clarify what

constitutes a “substantive right” for

purposes of § 2072(b).

Determining what constitutes a “substantive

right” under § 2072(b) can be a “challenging

endeavor.” Gasperini, 518 U.S. at 427. There are

several approaches the Court may choose to adopt for

that purpose. An important theme underlying all of

these alternatives is that “[t]he determination of

whether a rule abridges, enlarges, or modifies

substantive rights cannot be made without taking

state—and federal—substantive rights into account.”

Spencer, supra at 680 (footnote omitted).

One possibility would be to incorporate the

standard for substantive rights already built into the

Erie Doctrine by Hanna v. Plumer. Under this

approach, a state measure should be treated as

substantive when declining to apply it in federal court

would “significantly affect” the outcome of the

litigation. Gasperini, 518 U.S. at 416; see also

20

Burlington N. R.R. Co., 480 U.S. at 5 (holding that a

Rule violates § 2072(b) is if it more than “incidentally

affect[s] litigants’ substantive rights”). The Court has

cautioned, however, that this test cannot be “applied

mechanically” but instead must be guided by the two

considerations laid out in Erie—discouraging forum

shopping and avoiding inequitable administration of

the law. Gasperini, 518 U.S. at 416.

Dean Ely suggested an alternate approach. He

proposes that a substantive right under § 2072(b) is

one tailored toward achieving some policy objective

“not having to do with the fairness or efficiency of the

litigation process.”

Ely, supra at 725.

This

understanding is consistent with Rule 1, which

specifies that procedural rules are adopted to “secure

the just, speedy, and inexpensive determination” of

federal cases. Fed. R. Civ. P. 1. Laws and other

measures concerning other, unrelated policy

objectives are substantive. While Congress may have

constitutional authority to override them through its

legislative powers, the Rules Enabling Act should not

be read to delegate such blanket authority to the

federal judiciary. Burbank, supra note 4, at 1102.

Dean Ely’s standard also appears to underlie this

Court’s implication in Burlington Northern Railroad

Co., 480 U.S. at 5, that the Rules Enabling Act does

not allow courts to enforce procedural rules that have

a greater-than-incidental effect on substantive rights.

A third potential interpretation is that a rule

involves substantive rights if it would lead a rational

party to order its conduct “outside of the courthouse

and before commencement of litigation” in accordance

with it. Donald L. Doernberg, “The Tempest”: Shady

21

Grove Orthopedic Associates, P.A. v. Allstate

Insurance Co.: The Rules Enabling Act Decision that

Added to the Confusion, But Should Not Have, 44

Akron L. Rev. 1147, 1186, 1206 (2011); see also

Spencer, supra at 659 (“[S]ubstantive rights pertain

to our primary interactions with one another and with

governments”); Max Minzner, The Criminal Rules

Enabling Act, 46 U. Rich. L. Rev. 1047, 1060 (2012).

Rules impacting a party’s “decision to commence

litigation” qualify as substantive under this standard.

Doernberg, supra at 1186-87, 1191-92.

Justice

Harlan’s Hanna concurrence embraced this position.

A rule impacts substantive rights when it would

“substantially affect those primary decisions

respecting human conduct which our constitutional

system leaves to state regulation.” Hanna, 380 U.S.

at 475 (Harlan, J., concurring).

A fourth option focuses on whether a particular

provision is trans-substantive. A rule is procedural if

it governs federal courts’ resolution of cases and is

“generally applicable to all civil actions.” Carrington,

supra at 308. Such procedural requirements have no

connection to any substantive policy beyond the

operation of the courts. Id. In contrast, a rule affects

substantive rights if it “specially” affects “a group of

litigants or prospective litigants” (beyond just

plaintiffs or defendants as a class). Id. Requirements

in statutes that create particular rights or relate to

specific claims “can be more readily characterized as

substantive” because they are “dimension[s]” or

“condition[s]” of that right or claim. Id. at 290-91; cf.

Kelleher, supra note 2, at 108-21 (proposing a multifactor test to identify substantive rights).

22

Any of these interpretations would faithfully

enforce the text, structure, and legislative intent

underlying the Rules Enabling Act, and more

effectively flesh out this Court’s holdings in cases such

as Semtek International, 531 U.S. at 503–04, and

Burlington Northern Railroad Co., 480 U.S. at 5.

II. Applying the Federal Rules of Civil

Procedure to displace Delaware’s affidavit

requirement would abridge or modify

litigants’ substantive rights under state law.

Under any of the standards set forth above,

Delaware’s affidavit of merit requirement creates

substantive rights. Accordingly, a court may not

interpret or apply a Federal Rule of Civil Procedure in

a manner that suspends or circumvents this

requirement.

Delaware’s affidavit requirement obliges a

plaintiff suing for medical negligence to submit an

expert affidavit attesting to the merit of the claim

with the complaint. Del. Code Ann. tit. 18, § 6853(a).

This requirement furthers several important

substantive state policy objectives apart from the fair

and efficient operation of the court system. These

goals include discouraging strike suits, minimizing

the overall costs to the insurance system, and

controlling health care costs. See Jeffrey A. Parness,

Amy M. Leonetti & Austin W. Bartlett, The

Substantive Elements in the New Special Pleading

Laws, 78 Neb. L. Rev. 412, 416–20 (1999); Jean

Macchiaroli Eggen, Medical Malpractice Screening

Panels: Proposed Model Legislation To Cure Judicial

Ills, 58 Geo. Wash. L. Rev. 181, 181–85 (1990).

23

The affidavit requirement is substantive because

it determines whether a person is entitled to sue at

all, not merely how a person must initiate a lawsuit.

A person must have actual evidence of medical

malpractice to open the courthouse doors and subject

a defendant to the burdens, costs, inconvenience, and

risks of litigation. This Court has already held that

requiring a particular party to adduce evidence of

particular facts in order to win a case is a substantive

requirement controlled by state law. See Dick v. New

York Life Ins. Co., 359 U.S. 437, 446 (1959)

(“[B]urden[s] of proof are ‘substantive.’”); Palmer v.

Hoffman, 318 U.S. 109, 117 (1943) (“The question of

the burden of establishing contributory negligence is

a question of local law which federal courts in

diversity of citizenship cases must apply.” (citation

omitted)). For the same reasons, a statute requiring

a particular party to provide evidence in order to

commence a case should be deemed substantive, as

well.

A state should have the ability to limit the

circumstances under which potential defendants are

haled into court under its laws; those limits are

undermined if they can be circumvented in federal

court.

Indeed, dispensing with the affidavit

requirement is likely to affect a plaintiff’s decision

whether to file suit in state or federal court,

particularly when the plaintiff has a weak claim and

lacks expert evidentiary support.

To be sure, Delaware law also prescribes the

procedure a plaintiff must follow to satisfy this

substantive requirement: the plaintiff must file its

affidavit with the court. But the inclusion of a

24

“procedural instruction” does not convert a

substantive provision into a procedural one when “the

State’s objective is manifestly substantive.”

Gasperini, 518 U.S. at 429. This Court has recognized

that state substantive rights may be embedded in

procedural rules, such as a pre-filing bond

requirement, see Cohen v. Beneficial Industrial Loan

Corp., 337 U.S. 541, 555 (1949), or a statute of

limitation, see Guaranty Trust, 326 U.S. at 110.

Of course, even if this Court held that Delaware’s

affidavit of merit requirement was inapplicable in

federal court, a plaintiff in a medical malpractice case

would eventually be required to obtain an expert

opinion to support his case. See Del. Code Ann. tit. 18,

§ 6853(e) (“No liability shall be based upon asserted

negligence unless expert medical testimony is

presented as to the alleged deviation from the

applicable standard of care . . . .”). But that obligation

would not arise until after considerable litigation had

taken place. Froio v. Du Pont Hosp. for Children, 816

A.2d 784, 786 (Del. 2003) (explaining that “expert

medical testimony” is an “essential element” of a

Delaware medical malpractice claim and must be

presented once there has been an “adequate time for

discovery”).

Refusing

to

apply

Delaware’s

affidavit

requirement in federal court would allow a plaintiff to

sue there without incurring thousands of dollars in

up-front expert fees. By subjecting the defendant to

the cost and burdens of litigation, including discovery,

the plaintiff could pressure the defendant to settle,

notwithstanding that he or she would have been

unable to sue in state court at all. Indeed, the

25

incentive to file in federal court would be particularly

high among plaintiffs with weak or meritless claims

who hope to make easy money by forcing defendants

into settlements solely to avoid the cost and

disruption of prolonged litigation.

As this analysis demonstrates, dispensing with the

affidavit requirement would also cause “substantial

variations” in the outcomes of similar suits filed in

federal and state courts. Gasperini, 518 U.S. at 430

(internal quotation marks omitted) (quoting Hanna,

380 U.S. at 467–68).

Weak, unsupported, and

meritless claims would continue to be weeded out in

state court, while federal dockets would remain

clogged with them.

In short, the Delaware affidavit requirement is

substantive because it is intended to provide, and in

fact provides, real protection for medical providers by

preventing plaintiffs from pursuing malpractice

claims without making a threshold showing that their

claims have merit.

That protection extends to

insurers providing malpractice coverage and

ultimately to the public at large by holding down the

overall cost of medical care.

Because Delaware’s affidavit requirement is

substantive, § 2072(b) prohibits applying the Federal

Rules of Civil Procedure in a way that abridges,

enlarges, or modifies that requirement. See supra

Part I. Accordingly, to the extent that any Federal

Rule of Civil Procedure conflicts with the Delaware

affidavit requirement, 6 federal courts should apply

Of course, this Court could opt not to construe Rule 8 as

conflicting with Delaware law in the first place. This Court has

6

26

the Delaware affidavit requirement instead of

following the Federal Rule.

CONCLUSION

The Court should affirm the judgment of the

United States Court of Appeals for the Third Circuit.

Respectfully Submitted.

F. ANDREW HESSICK

160 Ridge Road

Chapel Hill, NC 27599

RICHARD A. SIMPSON

Counsel of Record

Wiley Rein LLP

2050 M Street, NW

Washington, DC 20036

(202) 719-7000

rsimpson@wiley.law

August 5, 2025

Counsel for Amicus Curiae

never held that the Federal Rules preclude enforcement of statelaw requirements for initiating a lawsuit that promote

substantive state policy objectives. See Cohen, 337 U.S.at 543,

556 (enforcing, in a diversity case, a state law requiring a

plaintiff to post security in order to commence a derivative suit,

even though the plaintiff had filed a complaint which compiled

with the Federal Rules); Woods v. Interstate Realty, 337 U.S. 535,

536 & n.1, 538 (1949) (enforcing, in a diversity case, a state law

requiring a foreign corporation to file a “written power of

attorney” to be eligible to sue, even though the plaintiff

corporation had filed a complaint which compiled with the

Federal Rules).