Petition for Writ of Certiorari — NexStep, Inc., Petitioner v. Comcast Cable Communications, LLC

No.

In the Supreme Court of the United States

NEXSTEP, INC., PETITIONER

v.

COMCAST CABLE COMMUNICATIONS, LLC

ON PETITION FOR A WRIT OF CERTIORARI

TO THE UNITED STATES COURT OF APPEALS

FOR THE FEDERAL CIRCUIT

PETITION FOR A WRIT OF CERTIORARI

PAUL J. ANDRE

LISA KOBIALKA

JAMES R. HANNAH

CHRISTINA M. FINN

KRAMER LEVIN NAFTALIS

& FRANKEL LLP

333 Twin Dolphin Drive

Suite 700

Redwood Shores, CA 94065

(650) 752-1700

AARON M. FRANKEL

CRISTINA L. MARTINEZ

CARLOS J. TIRADO

KRAMER LEVIN NAFTALIS

& FRANKEL LLP

1177 Avenue of the Americas

New York, NY 10036

(212) 715-9100

ROY T. ENGLERT, JR.

DANIEL N. LERMAN

Counsel of Record

JEFFREY C. THALHOFER

KRAMER LEVIN NAFTALIS

& FRANKEL LLP

2000 K Street NW

4th Floor

Washington, DC 20006

(202) 775-4500

dlerman@kramerlevin.com

QUESTION PRESENTED

Under the “doctrine of equivalents,” a product that

does not literally infringe the express terms of a

patent claim may nonetheless infringe if there is

equivalence between the elements of the accused

product and those of the patented invention. This

Court has long held that equivalence “is not the

prisoner of a formula” and that proof of equivalence

“can be made in any form.” Graver Tank & Mfg. Co. v.

Linde Air Prods. Co., 339 U.S. 605, 609 (1950).

In the decision below, a divided panel of the

Federal Circuit set aside a jury’s verdict of

equivalence. The majority did so on the ground that

the patentee’s expert failed to present “particularized

testimony and linking argument”—a categorical,

judicially created requirement that the Federal

Circuit imposes on all patentees seeking to prove

equivalence.

The question presented is:

Whether a patentee must in every case present

“particularized testimony and linking argument” to

establish infringement under the doctrine of

equivalents.

(I)

II

PARTIES TO THE PROCEEDING

Petitioner is NexStep, Inc., the appellant in the

court of appeals.

Respondent is Comcast Cable Communications,

LLC, the appellee in the court of appeals.

CORPORATE DISCLOSURE STATEMENT

Petitioner NexStep, Inc., has no parent

corporation, and no publicly held company holds 10%

or more of its stock.

RELATED PROCEEDINGS

United States District Court (D. Del.):

NexStep, Inc. v. Comcast Cable Communications,

LLC, No. 19-cv-1031-RGA (May 12, 2022)

United States Court of Appeals (Fed. Cir.):

NexStep, Inc. v. Comcast Cable Communications,

LLC, Nos. 2022-1815, 2022-2005, 2022-2113

(Oct. 24, 2024)

III

TABLE OF CONTENTS

Page

Opinions below ................................................................... 1

Jurisdiction ........................................................................ 1

Statement ........................................................................... 1

A. Legal background............................................... 4

B. The present controversy .................................... 7

Reasons for granting the petition .................................... 15

I.

The Federal Circuit has improperly imposed a

rigid formula for proving equivalence in all

cases ......................................................................... 16

II. This Court’s review is warranted ............................ 26

A. This Court has consistently reaffirmed

the importance of the doctrine of

equivalents ....................................................... 26

B. This Court has rejected rigid patent-law

rules like the one imposed by the Federal

Circuit here ...................................................... 28

C. The Federal Circuit’s rule invades the

jury function ..................................................... 31

Conclusion ........................................................................ 33

Appendix A — Court of appeals opinion

(Oct. 24, 2024) ......................................... 1a

Appendix B — District court opinion

(May 12, 2022) ...................................... 57a

Appendix C — Court of appeals order denying

rehearing (Jan. 2, 2025)........................ 77a

IV

TABLE OF AUTHORITIES

Cases:

Page

Amgen Inc. v. Sanofi, 598 U.S. 594 (2023) ...................... 6

AquaTex Indus., Inc. v. Techniche Sols.,

479 F.3d 1320 (Fed. Cir. 2007) ............................. 19, 20

Bonito Boats, Inc. v. Thunder Craft Boats, Inc.,

489 U.S. 141 (1989) ...................................................... 6

Coupe v. Royer, 155 U.S. 565 (1895) ................................ 6

Duff v. Sterling Pump Co., 107 U.S. 636 (1883) .............. 5

eBay Inc. v. MercExchange, L.L.C.,

547 U.S. 388 (2006) .................................................... 30

Festo Corp. v. Shoketsu Kinzoku Kogyo

Kabushiki Co.,

535 U.S. 722 (2002) ............................. 2, 5, 7, 26, 27, 31

Graver Tank & Mfg. Co. v. Linde

Air Prods. Co., 339 U.S. 605 (1950) ......... 2, 4-7, 16, 18,

19, 21, 24, 30, 31

Gray v. James,

10 F. Cas. 1015 (C.C.D. Pa. 1817) ................................ 6

Halo Elecs., Inc. v. Pulse Elecs., Inc.,

579 U.S. 93 (2016) ................................................ 29, 30

Interactive Pictures Corp. v. Infinite Pictures,

Inc., 274 F.3d 1371 (Fed. Cir. 2001) ........................... 31

Jimenez v. City of Chicago,

732 F.3d 710 (7th Cir. 2013) ...................................... 21

KSR Int’l Co. v. Teleflex Inc.,

550 U.S. 398 (2007) .................................................... 29

Lear Siegler, Inc. v. Sealy Mattress

Co. of Mich., Inc.,

873 F.2d 1422 (Fed. Cir. 1989) ..................11, 23, 28, 32

V

Cases—Continued:

Page

Malta v. Schulmerich Carillons, Inc.,

952 F.2d 1320 (Fed. Cir. 1991) ...... 18, 22, 23, 25, 28, 32

Nestier Corp. v. Menasha Corp.–Lewisystems

Div., 739 F.2d 1576 (Fed. Cir. 1984) .......................... 27

Octane Fitness, LLC v. ICON Health & Fitness,

Inc., 572 U.S. 545 (2014) ...................................... 29, 30

Reeves v. Sanderson Plumbing Prods., Inc., 530

U.S. 133 (2000) ..................................................... 24, 25

Richardson v. Marsh,

481 U.S. 200 (1987) .................................................... 22

Royal Typewriter Co. v. Remington Rand, Inc.,

168 F.2d 691 (2d Cir. 1948) ........................................ 22

Sanitary Refrigerator Co. v. Winters,

280 U.S. 30 (1929) ........................................................ 6

Shinseki v. Sanders, 556 U.S. 396 (2009) ..................... 30

Singer Mfg. Co. v. Cramer,

192 U.S. 265 (1904) ...................................................... 5

Sparf v. United States, 156 U.S. 51 (1895).................... 21

Teva Pharms. USA, Inc. v. Sandoz, Inc.,

574 U.S. 318 (2015) .............................................. 31, 32

Texas Instruments Inc. v. Cypress

Semiconductor Corp.,

90 F.3d 1558 (Fed. Cir. 1996) ....................10, 23, 26, 32

Union Paper-Bag Mach. Co. v. Murphy,

97 U.S. 120 (1877) ............................................ 2, 17, 22

VLSI Tech. LLC v. Intel Corp.,

87 F.4th 1332 (Fed. Cir. 2023) ........................ 10-12, 32

VI

Cases—Continued:

Page

Warner-Jenkinson Co. v. Hilton Davis Chem.

Co., 520 U.S. 17 (1997) ...............................2, 3, 5, 7, 16,

21, 24, 27, 30, 31

Winans v. Denmead,

56 U.S. (15 How.) 330 (1853).............................. 5, 6, 27

Zafiro v. United States,

506 U.S. 534 (1993) .................................................... 17

Statutes and rules:

35 U.S.C. § 112 .............................................................. 26

35 U.S.C. § 112(b) ............................................................ 4

Fed. R. Civ. P. 50 ........................................................... 24

Fed. R. Evid. 702 ........................................................... 14

Miscellaneous:

Dennis Crouch, Doctrine of Equivalents: Expert

Testimony Must Include Particularized Links,

Patently-0 (Oct. 25, 2024) .......................................... 20

Charles Alan Wright, The Doubtful Omniscience

of Appellate Courts, 41 Minn. L. Rev. 751

(1957) ......................................................................... 32

In the Supreme Court of the United States

NO.

NEXSTEP, INC., PETITIONER

v.

COMCAST CABLE COMMUNICATIONS, LLC

ON PETITION FOR A WRIT OF CERTIORARI

TO THE UNITED STATES COURT OF APPEALS

FOR THE FEDERAL CIRCUIT

PETITION FOR A WRIT OF CERTIORARI

OPINIONS BELOW

The decision of the court of appeals (App., infra,

1a-56a) is reported at 119 F.4th 1355. The decision of

the district court (App., infra, 57a-75a) is unreported

but available at 2022 WL 1503922.

JURISDICTION

The judgment of the court of appeals was entered

on October 24, 2024. A petition for rehearing was

denied on January 2, 2025 (App., infra, 76a-77a). On

March 4, 2025, the Chief Justice extended the time

within which to file a petition for a writ of certiorari

to and including May 2, 2025. The jurisdiction of this

Court is invoked under 28 U.S.C. § 1254(1).

STATEMENT

This case involves the standard for showing

infringement under the “doctrine of equivalents.”

This Court developed the doctrine of equivalents to

ensure that patent infringers could not escape

liability by the simple expedient of making

(1)

2

insubstantial changes to an inventor’s product or

process. Patents would provide little protection if

confined to the strict, literal terms of their claims;

“[o]utright and forthright duplication is a dull and

very rare type of infringement,” and “[t]o prohibit no

other would place the inventor at the mercy of

verbalism.” Graver Tank & Mfg. Co. v. Linde Air

Prods. Co., 339 U.S. 605, 607 (1950).

“The language in the patent claims may not

capture every nuance of the invention or describe with

complete precision the range of its novelty.” Festo

Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535

U.S. 722, 731 (2002). So, “[i]f patents were always

interpreted by their literal terms, their value would

be greatly diminished.” Ibid. Accordingly, patents

cover both their literal claim elements and—under the

doctrine of equivalents—the “substantial equivalent”

thereof. Warner-Jenkinson Co. v. Hilton Davis Chem.

Co., 520 U.S. 17, 35 (1997) (quoting Union Paper-Bag

Mach. Co. v. Murphy, 97 U.S. 120, 125 (1877)).

Different tests for equivalence may be appropriate

in different circumstances, but the inquiry, ultimately,

is whether the accused product contains elements that

are equivalent to each of the elements in the claimed

invention. See Warner-Jenkinson, 520 U.S. at 39-40.

That inquiry is flexible, and depends on the

circumstances of each case: Equivalence “is not the

prisoner of a formula and is not an absolute to be

considered in a vacuum.” Graver Tank, 339 U.S. at

609. Accordingly, “[p]roof can be made in any form:

through testimony of experts or others versed in the

technology; by documents, including texts and

3

treatises; and, of course, by the disclosures of the prior

art.” Ibid. (emphasis added).

The decision below is the culmination and

extension of several Federal Circuit decisions that

shackle this Court’s case-specific, flexible equivalence

inquiry with rigid judicially created requirements.

Instead of permitting proof of equivalence to be made

“in any form,” the court of appeals created a

formalistic rule requiring stylized testimony—what it

calls “particularized testimony”—that explains, to the

court’s satisfaction, “why” a claim element is

equivalent.

To make matters worse, though equivalence is a

question of fact that, after a jury verdict, is reviewed

for substantial evidence (see Warner-Jenkinson, 520

U.S. at 23, 38), the court of appeals also requires a

witness to provide a particular form of “linking

argument.” Without it—and even though argument is

not evidence—a patentee’s equivalence case is deemed

insufficient as a matter of law.

Most striking of all, the court of appeals imposes

these stylized requirements in even the simplest

cases. Petitioner’s is a case in point.

The critical question below—whether a short

series of button presses on an allegedly infringing

smartphone application is equivalent to “a single

action”—is readily susceptible to commonsense

determination by lay jurors. And here, a properly

instructed jury, presented with substantial evidence

of equivalence, rendered a verdict of infringement

under the doctrine of equivalents. But the district

court—now with the blessing of a split panel of the

Federal Circuit—threw out the jury’s verdict based on

4

a determination that petitioner’s technical expert did

not provide enough “particularized testimony and

linking argument” to establish that several button

presses are equivalent to a “single action.” Neither the

district court nor the majority of the Federal Circuit

panel explained why any technical testimony at all

was needed to establish that commonsense finding.

As Judge Reyna explained in his dissenting

opinion below, the majority “concoct[ed] a rigid new

rule” governing the equivalence determination in all

cases. App., infra, 53a. That procrustean rule bucks

this Court’s doctrine-of-equivalents precedents

holding that the equivalence inquiry is a flexible and

case-specific one. The majority’s holding also

undermines the jury’s factfinding role in infringement

trials, as it was based on a perception of insufficient

formal argument rather than the absence of

substantial evidence.

The Court should grant review to align Federal

Circuit law with the flexible equivalence standard

that this Court has articulated consistently over many

decades.

A. Legal Background

1. A patent must “claim” the invention covered by

that patent. 35 U.S.C. § 112(b). Thus, “[i]n

determining whether an accused device or

composition infringes a valid patent, resort must be

had in the first instance to the words of the claim.”

Graver Tank, 339 U.S. at 607. But, this Court

recognized some 75 years ago, the inquiry cannot stop

there: “[T]o permit imitation of a patented invention

which does not copy every literal detail would be to

convert the protection of the patent grant into a

5

hollow and useless thing.” Ibid. Artificially rigid

restrictions on the doctrine of equivalents, like the

absence of any such doctrine, threaten such

hollowness and uselessness.

After all, a competitor might pirate an invention

by making minor and insubstantial changes to the

claimed invention. Whether or not the competitor

acted in bad faith, confining claims to their precise

words or blinkering actual equivalence would “place

the inventor at the mercy of verbalism,” thus

“depriv[ing] him of the benefit of his invention

and * * * foster[ing]

concealment

rather

than

disclosure of inventions.” Graver Tank, 339 U.S. at

607; see Festo, 535 U.S. at 731.

The doctrine of equivalents solves those problems.

“Under this doctrine, a product or process that does

not literally infringe upon the express terms of a

patent claim may nonetheless be found to infringe if

there is ‘equivalence’ between the elements of the

accused product or process and the claimed elements

of the patented invention.” Warner-Jenkinson, 520

U.S. at 21. The doctrine “grow[s] out of a legally

implied term in each patent claim that ‘the claim

extends to the thing patented, however its form or

proportions may be varied.’” Id. at 35 (quoting Winans

v. Denmead, 56 U.S. (15 How.) 330, 343 (1853)). To

escape infringement, the differences between an

accused product and the subject patent must be

“substantial,” not merely “colorable.” Singer Mfg. Co.

v. Cramer, 192 U.S. 265, 286 (1904); Duff v. Sterling

Pump Co., 107 U.S. 636, 639 (1883).

One way to demonstrate equivalence is by showing

that the differences between the claimed invention

and the accused device are “insubstantial.” See

6

Warner-Jenkinson, 520 U.S. at 39-40. Another way, at

issue in this case, is by showing that an accused

product “performs substantially the same function in

substantially the same way to obtain the same result”

as the claimed invention. Graver Tank, 339 U.S. at

608 (quoting Sanitary Refrigerator Co. v. Winters, 280

U.S. 30, 42 (1929)); see also Gray v. James, 10 F. Cas.

1015, 1016 (C.C.D. Pa. 1817) (Washington, J.) (“where

the machines are substantially the same, and operate

in the same manner, to produce the same result, they

must be in principle the same”).

Like the literal-infringement inquiry, equivalence

is a question of fact to be decided by the jury, not the

trial court. Graver Tank, 339 U.S. at 609. “[M]inor

differences may not be relied on as, of themselves,

taking the defendants’ machine out of the reach of the

plaintiffs’ patent, but they are the subject of

legitimate consideration by the jury, as part of the

evidence upon which they must pass in determining

the question of infringement.” Coupe v. Royer, 155

U.S. 565, 580 (1895) (emphasis added).

2. This Court has time and again affirmed the

importance and continuing vitality of the doctrine of

equivalents. Indeed, the doctrine is critical to the

patent bargain, in which inventors “bring[ ] ‘new

designs and technologies into the public domain

through disclosure,’ so they may benefit all”—and in

turn receive “a limited term of ‘protection from

competitive exploitation.’” Amgen Inc. v. Sanofi, 598

U.S. 594, 604 (2023) (quoting Bonito Boats, Inc. v.

Thunder Craft Boats, Inc., 489 U.S. 141, 151 (1989)).

Without protection from a mere insubstantial “change

of form,” “the property of inventors would be

valueless.” Winans, 56 U.S. at 342-343.

7

“Unimportant and insubstantial substitutes for

certain elements could defeat the patent, and its value

to inventors could be destroyed by simple acts of

copying.” Festo, 535 U.S. at 731. Thus, when asked to

eliminate the doctrine in Warner-Jenkinson, this

Court declined to do so and instead clarified “that the

doctrine of equivalents * * * [is] settled law.” Id. at

739.

3. This Court has emphasized that the doctrine of

equivalents is flexible, not rigid and formulaic. That

makes sense—the doctrine of equivalents exists in the

first place because forbidding only literal

infringement would destroy the patent bargain by

“subordinating substance to form.” Graver Tank, 339

U.S. at 607. Equivalence, thus, “is not the prisoner of

a formula and is not an absolute to be considered in a

vacuum”; rather, it must be assessed “against the

context of the patent, the prior art, and the particular

circumstances of the case.” Warner-Jenkinson, 520

U.S. at 24-25 (quoting Graver Tank, 339 U.S. at 609).

At bottom, the question is always whether the accused

product contains elements “equivalent to each claimed

element of the patented invention.” Id. at 40.

B. The Present Controversy

1. Petitioner is a startup company that develops

technologies to improve consumers’ interaction with

electronics. It owns U.S. Patent No. 8,280,009 (“the

’009 Patent”), which is directed to an electronic

“concierge device” that initiates streamlined and

improved technical support for household devices

“responsive to a single action performed by a user.”

App., infra, 17a (emphasis added).

8

Petitioner sued respondent for infringement based

on respondent’s “My Account App” smartphone

application, which likewise initiates requests for

technical support without the need to perform

intermediate steps like identifying the malfunctioning

device’s serial number and determining an

appropriate support center for the device. App., infra,

16a, 18a-19a. Petitioner alleged that the My Account

App infringed the ’009 Patent literally and under the

doctrine of equivalents. Id. at 19a.

The case proceeded to trial, where the main issue

was whether the short series of button presses

required by the My Account App to trigger customer

service constitutes a “single action”—either literally

or under the doctrine of equivalents. App., infra, 19a.

Petitioner’s technical expert gave detailed literalinfringement testimony, identifying, describing, and

demonstrating to the jury the exact sequence of

button presses at issue in the accused product and the

downstream troubleshooting actions that they trigger.

Id. at 34a-35a. The expert concluded that the short

sequence of button presses in the My Account App is

a “single action”—just as throwing a baseball is a

single action, despite requiring constituent steps

including picking up, orienting, and propelling the

baseball. Id. at 34a.

Then, when providing testimony on infringement

under the doctrine of equivalents, petitioner’s expert

referred back to his detailed literal-infringement

testimony. He explained that the same short series of

button presses that he had previously discussed in

detail for literal infringement is, at minimum,

equivalent to a single action because it performs

9

substantially the same function in the same way to

obtain the same result. App., infra, 25a-26a.

Petitioner’s expert echoed and built on many of the

points that he had made with respect to literal

infringement. Thus, he explained that, “to the extent

the action to start the troubleshooting process[ ] is not

literally a single action, it is at least equivalent to a

single action because a single stream-like action

starts the process to begin troubleshooting.” App.,

infra, 35a. The expert explained that the “several

button presses” in the My Account App are equivalent

to the “single action” claimed in petitioner’s patent

and perform the “same function” of starting a multifaceted troubleshooting process. Id. at 25a-26a.

The jury found that the My Account App did not

literally infringe the ’009 Patent but did infringe it

under the doctrine of equivalents. App., infra, 19a.

Eight months later, the district court set aside the

jury’s verdict. Id. at 19a-20a, 57a-75a.

The district court observed that the “Federal

Circuit has held, ‘a patentee must . . . provide

particularized testimony and linking argument as to

the “insubstantiality of the differences” between the

claimed invention and the accused device or process.’”

App., infra, 68a. Applying that rule, the district court

concluded that the “fatal flaw in [petitioner’s expert’s]

testimony” was his “failure to provide a linking

argument.” Ibid. (emphasis added); see id. at 73a. The

district court therefore granted respondent’s motion

for judgment of noninfringement as a matter of law.

Id. at 73a; see id. at 3a.

10

2. A divided panel of the court of appeals affirmed.

App., infra, 1a-45a.

The majority began by explaining that, as “most

relevant to this appeal, ‘we have long demanded

specificity and completeness of proof as crucial to

enforcing the limits on the doctrine [of equivalents]:

The patentee must provide particularized testimony

and linking argument as to the insubstantiality of the

differences between the claimed invention and the

accused device.’” App., infra, 23a (emphasis added)

(quoting VLSI Tech. LLC v. Intel Corp., 87 F.4th 1332,

1343 (Fed. Cir. 2023)). According to the Federal

Circuit, those formal requirements “assure that the

fact-finder does not, under the guise of applying the

doctrine of equivalents, erase a plethora of

meaningful structural and functional limitations of

the claim.” Id. at 23a-24a (quoting Texas Instruments

Inc. v. Cypress Semiconductor Corp., 90 F.3d 1558,

1567 (Fed. Cir. 1996)).

The majority held that petitioner’s expert failed to

satisfy its “particularized testimony and linking

argument” requirement. It first concluded that,

during the portion of his testimony specifically

directed to the doctrine of equivalents, the expert

“never identified a particular element or elements in

the My Account App as being equivalent to the ‘single

action’ limitation” in the claimed invention. App.,

infra, 27a.

As noted above, petitioner’s expert specifically

identified and demonstrated the exact sequence of

button presses at issue during his literal-infringement

testimony and then referred back to that sequence as

the critical function in respondent’s device. He

11

testified that, in his view, those “several button

presses” perform the “same function” as the “single

action element” in the claimed invention—and do so

in the “same way” to achieve the “same result.” App.,

infra, 25a-26a. According to the majority, however,

that testimony did not sufficiently “guide the jury to

focus on what theory or what button presses are

allegedly equivalent.” Id. at 28a. Thus, the majority

held, the expert failed to “include a particularized

identification of what elements in the accused device

are equivalent to the claimed limitation.” Ibid.

The majority stated that the expert’s testimony

was also “deficient because [he] failed to provide a

‘meaningful explanation of why’ the element or

elements from the accused product or process are

equivalent to the claimed limitation for each part of

the function-way-result test.” App., infra, 28a

(quoting VLSI, 87 F.4th at 1344). But, in addition to

testifying that several button presses operate “in the

same way” as a single button press under the doctrine

of equivalents, the expert had previously explained in

the context of literal infringement that “multiple steps

might be contained in a single action.” Id. at 50a-51a

(Reyna, J., concurring-in-part and dissenting-in-part).

Under Federal Circuit precedent, however, “even if

there ‘was evidence and argument on literal

infringement[ ] that may also bear on equivalence,’

that ‘does not satisfy’ the requirements of the doctrine

of equivalents in the absence of particularized

testimony and linking argument.” App., infra, 38a

(quoting Lear Siegler, Inc. v. Sealy Mattress Co. of

Mich., Inc., 873 F.2d 1422, 1425 (Fed. Cir. 1989)). The

majority thus concluded that the expert’s direct-

12

infringement testimony failed to provide the requisite

particularized testimony and linking argument. Ibid.

The majority did not dispute that the infringement

question was a simple, non-technical, and “easily

understandable” one: whether multiple button

presses can be substantially equivalent to a single

action. App., infra, 39a. But, the majority explained,

the Federal Circuit has “never recognized a

technology-specific exception to the evidentiary rules”

that it requires to demonstrate infringement under

the doctrine of equivalents. Id. at 40a (emphasis

added). Rather, its “precedent requires particularized

testimony and linking argument, regardless of the

complexity or the simplicity of the underlying

technology.” Ibid.

The majority opined that it is not enough for the

“jury [to] understand[] the underlying technology.”

App., infra, 42a. Instead, “the doctrine of equivalents

itself introduces a distinct and complex inquiry that

requires appropriate guidance” in the form of

“particularized testimony and linking argument to

ensure that the jury does not misapply the doctrine

and thereby stray beyond the doctrine’s ‘properly

limited’ role.” Ibid. (emphasis added) (quoting VLSI,

87 F.4th at 1342).

3. Judge Reyna dissented in relevant part. App.,

infra, 46a-56a.

Judge Reyna stated that the majority committed

two legal errors. First, the majority analyzed

petitioner’s “evidence of infringement under the

doctrine of equivalents in a vacuum” and flouted the

substantial-evidence standard for reviewing jury

verdicts. App., infra, 48a (Reyna, J., concurring-in-

13

part and dissenting-in-part). Petitioner “NexStep

presented its doctrine of equivalents evidence in the

context of its literal infringement evidence,” and the

court must presume that the jury “considered all of

NexStep’s evidence when rendering its verdict, rather

than only a subset of the evidence.” Id. at 49a. Yet the

majority discounted testimony on literal infringement

that filled the purported gaps in petitioner’s case for

equivalence. For example, petitioner’s expert provided

a detailed analysis of the exact button presses that

were at issue when he provided his literalinfringement analysis. Thus, when the expert “later

referred to ‘several button presses’ when addressing

infringement under the doctrine of equivalents, the

jury could reasonably conclude that [he] was referring

them to [the same] specific elements he identified

during his literal infringement testimony.” Id. at 50a.

But the majority’s rigid “evidentiary rule[ ],” to which

it refused to make an “exception” (id. at 40a (majority

opinion)), allowed it to discount the substantial

evidence in the record clearly supporting the jury’s

verdict.

As for the supposedly missing “why” testimony,

petitioner’s expert “testified that several button

presses are a single action because single actions have

multiple steps, such as throwing a baseball.” App.,

infra, 51a (Reyna, J., concurring-in-part and

dissenting-in-part) (emphasis added). And there was

plenty of testimony as to “the ‘way’ that the accused

product or the claim limitation operates.” Id. at 51a52a. In short, the panel affirmed the negation of the

jury’s verdict through judgment as a matter of law—

which is appropriate only in “extraordinary

14

circumstances,” id. at 56a—by “disregard[ing] the

totality of the evidence presented” and taking a “nontechnical non-complex factual issue” away from the

jury. Id. at 47a-48a.

Second, Judge Reyna explained, “[t]he majority

concoct[ed] a rigid new rule” requiring “expert opinion

testimony to prove infringement under the doctrine of

equivalents” in every case, no matter how simple.

App., infra, 53a. While Federal Circuit precedent “at

least requires the evidence” to show equivalence,

expert testimony is but one form such evidence may

take. Ibid. And expert testimony is unnecessary in

cases like this one—where “the technology or the

specific doctrine of equivalents issue is so simple that

evidence other than expert testimony is more than

adequate for a jury to understand the issues.” Id. at

54a.

Judge Reyna noted that the majority was

concerned that “the doctrine of equivalents itself is

‘conceptually difficult,’” and so its “new rule is

necessary so that experts may ease the jury’s burden

of understanding the complexity of a legal doctrine.”

App., infra, 55a. But the “law does not require, and in

fact it chastises, witnesses who testify as to the

meaning of legal doctrines themselves.” Ibid. (citing

Fed. R. Evid. 702). “Instead, the proper way to remedy

the complexity of legal doctrines is for the district

court to instruct the jury on the law,” as was done in

this case. Id. at 55a-56a. The majority, in contrast,

“invade[d] the province of the jury” by requiring

formal linking argument from an expert and

“impos[ed] an unnecessary new rule in all future

doctrine of equivalents cases to come.” Id. at 56a.

15

REASONS FOR GRANTING THE PETITION

The decision below imposes a rigid formula for

proving equivalence that is contrary to this Court’s

precedents. By requiring formulaic “particularized

testimony and linking argument,” the Federal

Circuit’s rule improperly confines an inquiry that this

Court has held to be flexible and case-specific. In

contradiction to this Court’s instruction that evidence

of equivalence may take “any form,” the Federal

Circuit requires a specific form of evidence, and

effectively imposes a requirement of expert testimony.

The Federal Circuit’s “particularized testimony and

linking argument” formula applies to even the

simplest cases, taking commonsense decisions away

from juries. And it leads courts to disregard evidence

of equivalence that is not presented within the

Federal Circuit’s preferred rubric.

The question presented is recurring and

important. This Court has repeatedly affirmed the

critical importance of the doctrine of equivalents to

protecting the inventor’s end of the patent bargain.

But the Federal Circuit has, in a series of decisions

culminating in the decision below, gutted that

protection by imposing rigid, formulaic requirements

to prove infringement under the doctrine—an all-toofamiliar error by the Federal Circuit that this Court

has granted review to correct in other contexts. In

doing so, the Federal Circuit’s rule usurps the jury’s

role and takes courts far astray from the “general

principles of appellate review” contemplated by

Graver Tank. This Court’s review is warranted.

16

I.

The Federal Circuit Has Improperly Imposed A

Rigid Formula For Proving Equivalence In All

Cases

“Equivalence, in the patent law, is not the prisoner

of a formula and is not an absolute to be considered in

a vacuum.” Graver Tank & Mfg. Co. v. Linde Air

Prods. Co., 339 U.S. 605, 609 (1950). Evidence can

take “any form,” including “testimony of experts or

others versed in the technology; * * * documents,

including texts and treatises; and, of course, * * * the

disclosures of the prior art.” Ibid. The factfinder’s

decision controls and, under “general principles of

appellate review,” should “not be disturbed unless

clearly erroneous.” Id. at 610. The key question for the

jury is ultimately a simple one: whether the accused

product or process contains elements that are

“equivalent” to the elements in the claimed invention.

Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520

U.S. 17, 40 (1997). The decision below is contrary to

that rule.

1. To begin with, the Federal Circuit’s

“particularized testimony and linking argument”

requirement improperly confines the flexible

equivalence inquiry. Particularized “testimony” is a

specific type of evidence, whereas this Court has held

that “any form” of evidence can suffice. Graver Tank,

339 U.S. at 609. The Federal Circuit’s rigid

requirement cannot be squared with this Court’s

prescription that equivalence may be demonstrated

“by documents, including texts and treatises; and, of

course, by the disclosures of the prior art.” Ibid.

Moreover, requiring “particularized” testimony—that

is, testimony that explains equivalence of function,

way, and result in a formulaic, check-list manner—

17

licenses courts to decide equivalence as a matter of

law even when substantial evidence supports a

properly instructed jury’s verdict on the question of

equivalence.

As for the Federal Circuit’s requirement for

“linking argument” (the principal basis for the

decision below): That is not evidence at all. See, e.g.,

Zafiro v. United States, 506 U.S. 534, 541 (1993). So it

is hard to see how the majority can defend the “linking

argument” prong of its formula as an “evidentiary

requirement[ ]” or “evidentiary rule[ ].” App., infra,

23a-24a, 40a.

In Union Paper-Bag Machine Co. v. Murphy, 97

U.S. 120 (1877), this Court long ago emphasized the

case-dependent nature of equivalence. Where the

technology and equivalence question are extremely

simple and a matter of common sense, “[a]rgument to

show” equivalence may be “quite unnecessary, as that

is proved to a demonstration by a comparison of the

two devices.” Id. at 124. After discussing the expert

testimony showing that a knife and a cutter perform

the exact same task in two similar machines for

making paper bags, the Court added that, even if “the

explanation last given is too theoretical for practical

application, still we are all of the opinion that the

knife and the striker employed by the respondents

perform substantially the same function as the cutter

in the complainants’ machine.” Id. at 124-125.

Applying its own common sense, the Court “remanded

with directions to enter a decree in favor of the

complainants.” Id. at 126. Yet the modern Federal

Circuit could have come out the other way on the same

18

facts—depending solely on the form of expert

testimony.

Thus, as Judge Michel has recognized, the Federal

Circuit’s rule has erroneously “added gloss” to this

Court’s precedents by requiring “‘testimony’ (as

opposed to other forms of evidence) and ‘linking

argument’ (which, being only attorney assertions, is of

course not evidence at all).” Malta v. Schulmerich

Carillons, Inc., 952 F.2d 1320, 1331 (Fed. Cir. 1991)

(Michel, J., concurring). And the court of appeals has

added far more than just “gloss” to Graver Tank; it has

upended this Court’s pronouncement that proof of

equivalence “can be made in any form.” Graver Tank,

339 U.S. at 609. Put simply, by requiring

“particularized testimony and linking argument” in

all cases, the court of appeals has made equivalence

the very “prisoner of a formula” that this Court

rejected. Ibid.

That error led the majority to jettison the jury’s

infringement verdict in this case. The majority stated

that petitioner’s expert flunked the “particularized

testimony and linking argument” requirement

because he failed to “identify what element or

elements in the accused device are equivalent to the

claimed limitation.” App., infra, 27a. But, as the

majority and dissent both recognized, the expert

expressly identified “several button presses” as the

critical function in respondent’s device and testified

that, in his view, those “several button presses”

perform the “same function” as the “single action

element” in the claimed invention—and do so in the

“same way” to achieve the “same result.” Id. at 25a26a, 50a.

19

What else could the expert have said to make it

any clearer “what element” was equivalent? The

majority’s answer: The expert needed to provide

“particularized testimony and linking argument” that

would “guide the jury to focus on what theory or what

button presses are allegedly equivalent.” App., infra,

28a. But the expert did tell the jury what button

presses were equivalent: He “identified the distinct

‘series of button presses’” at issue. Id. at 50a (Reyna,

J., concurring-in-part and dissenting-in-part). He just

did not do so in the formulaic fashion required by the

majority as a matter of law.

2. As Judge Reyna explained, moreover, the

decision below further expands the Federal Circuit’s

ill-founded rule by effectively requiring a patentee to

“present expert opinion testimony to prove

infringement under the doctrine of equivalents.”

App., infra, 53a. The majority took issue with Judge

Reyna’s assertion that it was creating a “new rule,”

noting that its “discussion of the use of expert

testimony in proving infringement under the doctrine

of equivalents is limited to quoting the standard

articulated in AquaTex Industries, Inc. v. Techniche

Solutions.” Id. at 43a. There, the court of appeals

stated that “[b]oth the Supreme Court and this court

have made clear that the evidence of equivalents must

be from the perspective of someone skilled in the art,

for example ‘through testimony of experts or others

versed in the technology; by documents, including

texts and treatises; and, of course, by the disclosures

of the prior art.’” AquaTex Indus., Inc. v. Techniche

Sols., 479 F.3d 1320, 1329 (Fed. Cir. 2007) (quoting

Graver Tank, 339 U.S. at 609).

20

But, as the majority acknowledged (App., infra,

44a), AquaTex further stated that such a witness will

“typically [be] a qualified expert.” 479 F.3d at 1329.

And, even if the majority did not expressly require

expert testimony in all cases, it effectively did so: It is

difficult to imagine “any way that a mere fact-witness

could provide this particularized testimony absent

some smoking-gun document involving the accused

infringer making admissions about how its product

was attempting to mimic the patented invention.”

Dennis Crouch, Doctrine of Equivalents: Expert

Testimony Must Include Particularized Links,

Patently-0 (Oct. 25, 2024), https://perma.cc/76ZCMZYJ (discussing the decision below).

Indeed, the majority faulted petitioner’s expert for

failing to “guide the jury to focus on what theory or

what button presses are allegedly equivalent,” App.,

infra, 28a (emphasis added), or provide the requisite

“linking argument,” id. at 32a. But a fact witness’s job

is to present evidence—not legal “theories” or “linking

argument.” In addition to expert testimony, moreover,

petitioner introduced source code and technical

documents at trial, and pointed to cross-examination

testimony by respondents’ own witnesses, all of which

supported equivalence. See Pet. C.A. Br. 41-46. But

the majority focused solely on the testimony of

petitioner’s expert—and his failure to provide

sufficiently “particularized testimony and linking

argument”—to the exclusion of the other evidence at

trial. Thus, the majority’s rule in effect requires

formulaic direct expert testimony for a patentee to

win an equivalence case.

21

3. To make matters even worse, the majority

extended its rigid “particularized testimony and

linking argument” rule to apply to even the simplest

of cases. Some complex, technical cases may require

extensive expert testimony to establish equivalence—

even as simple cases require none. As this Court

explained, the equivalence inquiry is not “the prisoner

of a formula,” Graver Tank, 339 U.S. at 609, and

different “frameworks may be more suitable to

different cases,” Warner-Jenkinson, 520 U.S. at 40.

Yet the majority reasoned that “particularized

testimony and linking argument” are needed “in every

case,” regardless of the simplicity or complexity of the

technology, because “the difficulties and complexities

of the doctrine require it.” App., infra, 42a (cleaned

up). Those requirements, according to the majority,

are necessary “to ensure that the jury does not

misapply the doctrine and thereby stray beyond the

doctrine’s properly limited role.” Ibid. (internal

quotation marks omitted).

But it is the court’s job, not a witness’s, to explain

legal doctrine to the jury. Indeed, the law “chastises[ ]

witnesses who testify as to the meaning of legal

doctrines.” App., infra, 55a (Reyna, J., concurring-inpart and dissenting-in-part). That goes for experts as

well as lay witnesses. See Jimenez v. City of Chicago,

732 F.3d 710, 721 (7th Cir. 2013) (“It is the role of the

judge, not an expert witness, to instruct the jury on

the applicable principles of law, and it is the role of the

jury to apply those principles of law to the facts in

evidence.”); Sparf v. United States, 156 U.S. 51, 84

(1895). In short, proper instructions from the trial

court—instructions that juries are presumed to

22

follow—are the remedy for any doctrinal complexity.

See, e.g., Richardson v. Marsh, 481 U.S. 200, 211

(1987).

The central question in this case was a simple one

that the jury could answer without “particularized

testimony and linking argument”: whether several

button presses on a smartphone to initiate technical

support are equivalent to a “single action” to initiate

that support. That is scarcely rocket science. Cf. Royal

Typewriter Co. v. Remington Rand, Inc., 168 F.2d 691,

693 (2d Cir. 1948) (Hand, J.) (“courts have with

curious unanimity held that it does not avoid

infringement to combine into one member that which

the patent discloses as two, if the single member

performs the duties of both in the same way”). Indeed,

it is no different from asking a jury to decide if

pushing several buttons to dial a phone number is

equivalent to a single action. No technical testimony

is needed to answer that commonsense question.

Rather, a simple “comparison” is enough to show that

the button presses and claimed single action are

“substantially the same.” Union Paper-Bag Mach. Co.,

97 U.S. at 124.

Petitioner’s expert testified that several button

presses are the same as or equivalent to a “single

action” for the same reason that “throw[ing] a

baseball” constitutes a single action, despite requiring

multiple steps: “you pick it up, you orient it, you get it

in your palm, you throw it.” App., infra, 51a (Reyna,

J., concurring-in-part and dissenting-in-part). Armed

with that testimony, a properly instructed jury could

reasonably make the equivalence determination by

resorting to common sense, alone. See Malta, 952 F.2d

23

at 1334 (Newman, J., dissenting) (criticizing the fact

that the court of appeals’ “particularized testimony

and linking argument” requirement “must be fulfilled

no matter how simple the invention”).

If the Federal Circuit’s rule cannot be justified by

the need to resolve complexities of fact or law for the

jury—and if a purportedly “evidentiary” rule cannot

explain a demand for “argument”—then what is really

going on? Usurpation of the jury’s factfinding role. The

“particularized testimony and linking argument”

requirement “appl[ies] solely to jury trials.” Malta,

952 F.2d at 1333 (Newman, J., dissenting).

Indeed, it was expressly designed to limit the jury’s

factfinding role. It is “a prophylactic rule of general

applicability” meant to “minimize the risk that a jury

will find infringement under the doctrine of

equivalents” based on equivalence of only one or two

of function, way, and result. Malta, 952 F.2d at 13301331 (Michel, J., concurring); see also Texas

Instruments Inc. v. Cypress Semiconductor Corp., 90

F.3d 1558, 1567 (Fed. Cir. 1996) (“without these

requirements, the fact-finder has no analytical

framework for making its decision”). Thus, although

the majority insisted that it does “not doubt the ability

of a jury to decide the factual issue of equivalence,”

App., infra, 24a (quoting Lear Siegler, Inc. v. Sealy

Mattress Co. of Mich., Inc., 873 F.2d 1422, 1426 (Fed.

Cir. 1989)), its “particularized testimony and linking

argument” requirement says otherwise. Worse still, it

is a one-way ratchet: It protects against erroneous

findings of equivalence while doing nothing to avoid

erroneous findings of nonequivalence.

24

To be sure, this Court has counseled “a special

vigilance against allowing the concept of equivalence

to eliminate completely” the necessary focus on the

equivalence of claim elements, so that a patent is not

improperly enlarged beyond the scope of its claims.

Warner-Jenkinson, 520 U.S. at 40. But that is what

well-crafted jury instructions are for. And respondents

do not dispute that the jury was correctly instructed

here. If the jury makes an equivalence finding

unsupported by substantial evidence, “general

principles of appellate review” provide the remedy.

Graver Tank, 339 U.S. at 610. The Federal Circuit’s

rule goes beyond those guardrails—taking from the

jury commonsense, factual equivalence determinations that are well within the jury’s ken.

4. Finally, the majority “disregard[ed]” the literalinfringement testimony at trial because that

testimony was not presented in the particular form

required by the Federal Circuit to show equivalence.

App., infra, 48a (Reyna, J., concurring-in-part and

dissenting-in-part).

In considering a motion for judgment as a matter

of law, “the court should review all of the evidence in

the record,” and “must draw all reasonable inferences

in favor of the nonmoving party.” Reeves v. Sanderson

Plumbing Prods., Inc., 530 U.S. 133, 150 (2000)

(emphasis added); see Fed. R. Civ. P. 50. And here,

petitioner “presented its doctrine of equivalents

evidence in the context of its literal infringement

evidence.” App., infra, 49a (Reyna, J., concurring-inpart and dissenting-in-part). Its expert “testified that

several button presses are a single action because

single actions have multiple steps, such as throwing a

25

baseball,” and because “the steps a user takes to

perform one button press are the same regardless of

whether more than one press is taken.” Id. at 51a.

The majority did not dispute that petitioner’s

expert presented literal-infringement testimony that

may “bear on equivalence.” App., infra, 38a. But the

majority discounted that evidence because it “fell

short of providing particularized testimony and

linking argument.” Ibid. In other words, the majority’s

rule requires courts (and juries) to turn a blind eye to

evidence of literal infringement that, in substance,

establishes equivalence, if that evidence is not

presented in the precise form preferred by the Federal

Circuit.

In addition to discounting the literal-infringement

testimony because of its form, the majority “invoked a

new requirement of proof of equivalency: proof of not

only the three Graver Tank ‘prongs’ of ‘function, way,

and result’, but also a fourth prong of ‘why.’” Malta,

952 F.2d at 1334 (Newman, J., dissenting); see App.,

infra, 38a (faulting petitioner’s expert for failing to

explain “why those functions, ways, and results are

substantially the same”). That new requirement is

contrary to the flexible inquiry set forth by this Court

in Graver Tank (and its non-exclusive function-wayresult inquiry); contrary to the rule that witnesses

present evidence, not argument; and contrary to the

rule that, on a motion for judgment as a matter of law,

courts must consider “all of the evidence” and “draw

all reasonable inferences” in favor of the jury verdict,

Reeves, 530 U.S. at 150—without requiring that

evidence to be presented in a particular way that is

mentioned nowhere in the Federal Rules of Evidence.

26

In sum, the majority held that petitioner’s

“infringement theory under the doctrine of

equivalents was * * * legally insufficient because it

failed to comply with ‘the specific evidentiary

requirements necessary to prove infringement under

the doctrine’ of equivalents.” App., infra, 32a (quoting

Texas Instruments, 90 F.3d at 1566). As explained

above, those “specific evidentiary requirements” are

contrary to this Court’s precedent. And they allow the

Federal Circuit to second-guess jury verdicts that, like

the one here, are supported by substantial evidence. A

jury can, and should be permitted to, decide for itself

whether several button presses are a “single action” in

the same way that the single action of throwing a

baseball includes several steps.

II. This Court’s Review Is Warranted

A. This Court Has Consistently Reaffirmed The

Importance Of The Doctrine Of Equivalents

1. The patent laws embody a bargain “between

inventors, who rely on the promise of the law to bring

the invention forth, and the public, which should be

encouraged to pursue innovations, creations, and new

ideas beyond the inventor’s exclusive rights.” Festo

Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535

U.S. 722, 731 (2002). Patent protection is critical to

encourage the public disclosure of valuable

inventions. The Patent Act thus requires inventors to

“describe their work in ‘full, clear, concise, and exact

terms.’” Ibid. (quoting 35 U.S.C. § 112).

But “the nature of language makes it impossible to

capture the essence of a thing in a patent application,”

and “[t]he inventor who chooses to patent an invention

and disclose it to the public, rather than exploit it in

27

secret, bears the risk that others will devote their

efforts toward exploiting the limits of the patent’s

language.” Festo, 535 U.S. at 731. The doctrine of

equivalents is thus necessary to ensure that imitators

cannot end-run patent protection by making

insubstantial changes to an inventor’s device. “[T]he

property of inventors would be valueless, if it were

enough for the defendant to say, your improvement

consisted in a change of form; you describe and claim

but one form; I have not taken that, and so have not

infringed.” Winans v. Denmead, 56 U.S. (15 How.) 330,

342-343 (1853).

This Court addressed the concern that the doctrine

can be taken too far by requiring that “the doctrine of

equivalents * * * be applied to individual elements of

the claim, not to the invention as a whole” and that

equivalency “not [be] allowed such broad play as to

effectively eliminate [an] element in its entirety.”

Warner-Jenkinson, 520 U.S. at 29. With those

limitations in place, there is no need to cabin the

doctrine with one-size-fits-all evidentiary requirements—particularly in cases, like this one, where

common sense shows the relevant differences to be

insubstantial.

2. The decision below is the culmination and

extension of a series of Federal Circuit cases that,

despite this Court’s admonitions, unduly restrict the

doctrine of equivalents. First, the Federal Circuit

crafted a new rule—applicable only when a jury is the

factfinder—that otherwise-sufficient evidence of

equivalence is insufficient as a matter of law if the

“means” by which the elements achieve a result are

not placed in “context for [the] jury.” Nestier Corp. v.

28

Menasha Corp.–Lewisystems Div., 739 F.2d 1576,

1579 (Fed. Cir. 1984).

The court of appeals built on that rigid rule in Lear

Siegler. There, while purporting “not [to] doubt the

ability of a jury to decide the factual issue of

equivalence,” the Federal Circuit, in order “to enable

the jury to use its ability,” imposed a requirement

“that the three Graver Tank elements must be

presented in the form of particularized testimony and

linking argument.” Lear Siegler, 873 F.2d at 1426.

And the stylized evidence required went beyond the

function, way, and result factors that Graver Tank

considered; the court of appeals requires “evidence” as

to “why those functions, ways, and results are

substantially the same.” Malta, 952 F.2d at 1327 n.5

(emphasis removed); see id. at 1334 (Newman, J.,

dissenting) (explaining that the court of appeals,

“applying Lear Siegler to remove this case from the

jury, has invoked a new requirement of proof of

equivalency”).

Now, in the decision below, the majority has gone

even further. It has made clear that the Federal

Circuit’s rigid “particularized testimony and linking

argument” rule effectively requires expert testimony,

even in the simplest cases. This Court should grant

review to halt the Federal Circuit’s continuing erosion

of the doctrine of equivalents—and of innovators’

patent rights.

B. This Court Has Rejected Rigid Patent-Law

Rules Like The One Imposed By The Federal

Circuit Here

This Court has frequently granted review to

abolish rigid doctrinal rules imposed by the Federal

29

Circuit. For example, this Court’s obviousness cases

had long “set forth an expansive and flexible

approach.” KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398,

415 (2007). The Federal Circuit nevertheless

“transform[ed] the general principle” governing

obviousness “into a rigid rule that limit[ed] the

obviousness inquiry” by requiring a specific “teaching,

suggestion, or motivation” to combine prior art

references. Id. at 419. This Court rejected that

inflexible rule, explaining that the court of appeals

had improperly allowed a “[h]elpful insight[ ]” to

become a “rigid and mandatory formula[ ].” Id. at 418419.

This Court has twice stepped in to correct

inflexible Federal Circuit rules in the related areas of

attorneys’ fees and enhanced damages in patent cases.

First, the court of appeals replaced a “holistic,

equitable approach” for determining whether a case is

“exceptional” for purposes of awarding attorneys’ fees

with “a more rigid and mechanical formulation.”

Octane Fitness, LLC v. ICON Health & Fitness, Inc.,

572 U.S. 545, 549-550 (2014). Explaining that “there

is no precise rule or formula for making these

determinations,” this Court rejected the Federal

Circuit’s “overly rigid” and “inflexible” formulation.

Id. at 554-555 (cleaned up).

Then, two years later, the Court rejected a

similarly wooden rule that required the application of

a “two-part test” in “every case before district courts

may award enhanced damages” for infringement.

Halo Elecs., Inc. v. Pulse Elecs., Inc., 579 U.S. 93, 104

(2016). This Court “eschew[ed] that “rigid formula,”

which insulated some egregious infringers and unduly

30

restricted trial-court discretion. Id. at 107; see also

Shinseki v. Sanders, 556 U.S. 396, 407 (2009)

(rejecting the Federal Circuit’s harmless-error

framework, which required the use of “rigid rules”

rather than “case-specific application of judgment,

based upon examination of the record”); eBay Inc. v.

MercExchange, L.L.C., 547 U.S. 388, 393 (2006)

(rejecting the Federal Circuit’s “categorical rule” for

injunctive relief in patent cases).

Now, the Federal Circuit has yet again erected a

“rigid formula”—in contravention of this Court’s

precedents. Halo Elecs., 579 U.S. at 107. This Court

has long maintained that equivalence “is not the

prisoner of a formula” and that proof of equivalence

“can be made in any form.” Graver Tank, 339 U.S. at

609. The court of appeals has nevertheless

transformed that flexible, case-specific equivalence

inquiry into a “rigid and mechanical formulation,”

Octane Fitness, 572 U.S. at 550, by requiring

patentees to present “particularized testimony and

linking argument” in every case. This Court has also

cautioned that “the particular linguistic framework

used is less important than whether the test is

probative of the essential inquiry,” Warner-Jenkinson,

520 U.S. at 40, but the decision below “prevent[s] the

reviewing court from directly asking” the essential

question, Sanders, 556 U.S. at 408—whether there is

substantial evidence that the differences between a

“single action” and a series of button presses are

insubstantial. The Federal Circuit has calcified a

particular linguistic and evidentiary framework for

all equivalence cases.

31

In Warner-Jenkinson, this Court assumed that

“the Federal Circuit will refine the formulation of the

test for equivalence in the orderly course of case-bycase determinations.” 520 U.S. at 40. But, instead of

refining the standard in an orderly, case-by-case

fashion, the Federal Circuit has done just the

opposite—imposing a strict, one-size-fits-all formulaic

rule that pretermits case-specific judgment. This

Court previously stepped in to remind the court of

appeals, in the closely related area of prosecution

history estoppel, that it has “consistently applied the

doctrine in a flexible way, not a rigid one.” Festo, 535

U.S. at 738. It should do so here, too.

C. The Federal Circuit’s Rule Invades The Jury

Function

Review is also warranted because the majority’s

approach to review usurps the jury’s role, contrary to

this

Court’s

admonition

that

equivalence

determinations be subject to “general principles of

appellate review.” Graver Tank, 339 U.S. at 610.

Again, the Federal Circuit is having trouble breaking

a bad habit that this Court has had to correct before.

See Teva Pharms. USA, Inc. v. Sandoz, Inc., 574 U.S.

318, 321-322 (2015) (reversing the Federal Circuit for

usurping the factfinder’s role by reviewing the

evidentiary underpinnings of a district court’s claim

construction de novo rather than for clear error).

Here, rather than ask whether respondent showed

that the jury’s findings were “not supported by

substantial evidence,” as required to overturn a jury

verdict, Interactive Pictures Corp. v. Infinite Pictures,

Inc., 274 F.3d 1371, 1376 (Fed. Cir. 2001) (emphasis

added), the majority decided whether petitioner’s

32

expert faithfully adhered to its “particularized

testimony and linking argument” requirement. That

move took from the jury a simple, factual question of

equivalence—whether a short sequence of button

presses is equivalent to a single action—and

transformed it into a legal question governed by the

court’s rigid rule.

The cost of that error extends beyond this case. By

erasing jury verdicts and deciding this and similar

cases for itself, the court of appeals “impairs the

confidence of litigants and the public in the decisions

of the trial courts, and it multiplies the number of

appeals.” Malta, 952 F.2d at 1332 (Newman, J.,

dissenting) (quoting Charles Alan Wright, The

Doubtful Omniscience of Appellate Courts, 41 Minn. L.

Rev. 751, 779 (1957)). Indeed, this Court has

admonished the Federal Circuit to “have in mind that

[its] function is not to decide factual issues de novo.”

Teva, 574 U.S. at 324. It should grant review here to

reinforce that instruction.

The decision below is no outlier. The court of

appeals has repeatedly overturned (or affirmed

decisions overturning) jury verdicts finding

infringement under the doctrine of equivalents

because the patentee failed to present evidence in the

form of “particularized testimony and linking

argument.” See VLSI Tech. LLC v. Intel Corp., 87

F.4th 1332, 1345 (Fed. Cir. 2023); Texas Instruments,

90 F.3d at 1568; Malta, 952 F.2d at 1327; Lear Siegler,

873 F.2d at 1426. The erosion of the jury-trial right in

doctrine-of-equivalents cases—which has reached its

apex in this case—calls out for review.

33

CONCLUSION

The petition for a writ of certiorari should be

granted.

Respectfully submitted.

PAUL J. ANDRE

LISA KOBIALKA

JAMES R. HANNAH

CHRISTINA M. FINN

KRAMER LEVIN NAFTALIS

& FRANKEL LLP

333 Twin Dolphin Drive

Suite 700

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AARON M. FRANKEL

CRISTINA L. MARTINEZ

CARLOS J. TIRADO

KRAMER LEVIN NAFTALIS

& FRANKEL LLP

1177 Avenue of the Americas

New York, NY 10036

(212) 715-9100

MAY 2025

ROY T. ENGLERT, JR.

DANIEL N. LERMAN

Counsel of Record

JEFFREY C. THALHOFER

KRAMER LEVIN NAFTALIS

& FRANKEL LLP

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dlerman@kramerlevin.com