Petition for Writ of Certiorari — Dr. Reddy's Laboratories, Ltd., et al., Petitioners v. Eli Lilly and Company

No. ______

In the

Supreme Court of the United States

________________

DR. REDDY’S LABORATORIES, LTD.

AND DR. REDDY’S LABORATORIES, INC.,

Petitioners,

v.

ELI LILLY & COMPANY,

________________

Respondent.

On Petition for Writ of Certiorari to the

United States Court of Appeals

for the Federal Circuit

________________

PETITION FOR WRIT OF CERTIORARI

________________

JOHN C. O’QUINN

Counsel of Record

WILLIAM H. BURGESS

C. ALEX SHANK

KIRKLAND & ELLIS LLP

1301 Pennsylvania Ave. NW

Washington, DC 20004

(202) 389-5000

john.oquinn@kirkland.com

Counsel for Petitioners

February 24, 2020

QUESTION PRESENTED

Under patent law’s “doctrine of equivalents,” a

patent holder can allege infringement even when the

defendant does not literally practice every element of

a patent claim. But if the patent applicant previously

narrowed the claim during prosecution to obtain the

patent, the general rule for more than 100 years has

been that the patent holder cannot use the doctrine of

equivalents in litigation to recapture territory

between the broader pre-amendment claim and the

narrower post-amendment claim. That rule is known

as “prosecution history estoppel.”

In Festo Corp. v. Shoketsu Kinzoku Kogyo

Kabushiki Co., 535 U.S. 722 (2002), this Court held

that prosecution history estoppel does not apply if the

patentee can “show that at the time of the amendment

one skilled in the art could not reasonably be expected

to have drafted a claim that would have literally

encompassed the alleged equivalent.” Id. at 741. A

patentee can make that showing in different ways,

including by demonstrating that the “the rationale

underlying the amendment … bear[s] no more than a

tangential relation to the equivalent in question.” Id.

at 740.

The question presented is whether, under Festo’s

“tangential” exception to prosecution history estoppel,

patent owners may recapture subject matter they

could have claimed in prosecution but did not, by

arguing that they surrendered more than they needed

to during prosecution to address a rejection by the

Patent Office.

ii

PARTIES TO THE PROCEEDING

All parties are listed in the caption.

The court of appeals issued an opinion addressing

two companion appeals together (Fed. Cir. Nos. 182128 and 18-2126), though it issued separate

judgments in each appeal. This petition arises from

Appeal No. 18-2128. In Appeal No. 18-2126 (the other

companion appeal), the parties were Eli Lilly &

Company, and Hospira, Inc.

CORPORATE DISCLOSURE STATEMENT

Dr. Reddy’s Laboratories, S.A. is the parent

company of Petitioner Dr. Reddy’s Laboratories, Inc.

Petitioner Dr. Reddy’s Laboratories, Ltd. is the parent

company of Dr. Reddy’s Laboratories, S.A.

iii

STATEMENT OF RELATED PROCEEDINGS

This case arises from the following proceedings in

the U.S. District Court for the Southern District of

Indiana, and the U.S. Court of Appeals for the Federal

Circuit:

Eli Lilly & Co. v. Dr. Reddy’s Laboratories, Ltd.

and Dr. Reddy’s Laboratories, Inc., S.D. Ind. No. 1:16CV-00308-TWP-MPB (judgment entered July 27,

2018)

Eli Lilly & Co. v. Dr. Reddy’s Laboratories, Ltd.

and Dr. Reddy’s Laboratories, Inc., Fed. Cir. No. 182128 (judgment entered Aug. 9, 2019)

Although the court of appeals issued an opinion

addressing two companion appeals together (Fed. Cir.

Nos. 18-2128 and 18-2126, see App-3 & n.1), the

appeals were not consolidated, and separate

judgments were issued in each appeal. This petition

arises from Appeal No. 18-2128. In Appeal No. 182126 (the other companion appeal), the parties were

Eli Lilly & Company, and Hospira, Inc., and the

underlying district court proceeding was Eli Lilly &

Co. v. Hospira, Inc., No. 1:16-CV-3460-TWP-MPB

(judgment entered Dec. 9, 2019).

There are no other proceedings in state or federal

trial or appellate courts, or in this Court, directly

related to this case within the meaning of this Court’s

Rule 14.1(b)(iii).

iv

TABLE OF CONTENTS

QUESTION PRESENTED .......................................... i

PARTIES TO THE PROCEEDING ........................... ii

CORPORATE DISCLOSURE STATEMENT ............ ii

STATEMENT OF RELATED PROCEEDINGS ....... iii

TABLE OF AUTHORITIES ...................................... vi

PETITION FOR WRIT OF CERTIORARI ................ 1

OPINIONS BELOW ................................................... 4

JURISDICTION ......................................................... 5

STATEMENT OF THE CASE ................................... 5

A. Legal Background ........................................ 5

B. Factual Background ................................... 10

C. Proceedings Below ...................................... 13

REASONS FOR GRANTING THE PETITION....... 17

I.

The Federal Circuit Is Internally Divided On

The Meaning Of The “Tangential Exception”

To Prosecution History Estoppel. ..................... 17

II. The Decision Below Cannot Be Reconciled

With This Court’s Precedents. .......................... 24

III. The Question Presented Is Important, And

This Case Is The Ideal Vehicle To Resolve It. .. 26

CONCLUSION ......................................................... 29

v

APPENDIX CONTENTS

Appendix A

Opinion, U.S. Court of Appeals for the

Federal Circuit, Eli Lilly & Co. v. Hospira,

Inc., Nos. 18-2126 & 18-2127, Eli Lilly & Co.

v. Dr. Reddy’s Labs., Ltd., No. 18-2128, (Aug.

9, 2019)......................................................... App-1

Appendix B

Order Denying Rehearing, U.S. Court of

Appeals for the Federal Circuit, Eli Lilly &

Co. v. Dr. Reddy’s Labs., Ltd., No. 18-2128

(Nov. 8, 2019) ............................................. App-31

Appendix C

Findings of Fact and Conclusions of Law,

U.S. District Court for the Southern District

of Indiana, Eli Lilly & Co. v. Dr. Reddy’s

Labs., Ltd., No. 1:16-CV-00308-TWP-MPB

(June 22, 2018) ......................................... App-33

Appendix D

Order, U.S. District Court for the Southern

District of Indiana, Eli Lilly & Co. v. Dr.

Reddy’s Labs., Ltd., No. 1:16-CV-00308-TWPMPB (Dec. 14, 2017) .................................. App-50

vi

TABLE OF AUTHORITIES

Cases

Ajinomoto Co. v. ITC,

932 F.3d 1342 (Fed. Cir. 2019) ...................... passim

Amgen Inc. v. Hoechst Marion Roussel, Inc.,

457 F.3d 1293 (Fed. Cir. 2006) .............................. 18

Biagro W. Sales, Inc. v. Grow More Inc.,

423 F.3d 1296 (Fed. Cir. 2005) .............................. 19

Cross Med. Prods., Inc. v. Medtronic Sofamor

Danek, Inc., 480 F.3d 1335 (Fed. Cir. 2007) ......... 17

Exhibit Supply Co. v. Ace Patents Corp.,

315 U.S. 126 (1942) .................................................. 7

Felix v. Am. Honda Motor Co.,

562 F.3d 1167 (Fed. Cir. 2009) .............................. 18

Festo Corp. v. Shoketsu Kinzoku Kogyo

Kabushiki Co.,

234 F.3d 558 (Fed. Cir. 2000) .................................. 8

Festo Corp. v. Shoketsu Kinzoku Kogyo

Kabushiki Co.,

344 F.3d 1359 (Fed. Cir. 2003) ............ 10, 17, 19, 23

Festo Corp. v. Shoketsu Kinzoku Kogyo

Kabushiki Co., 535 U.S. 722 (2002) .............. passim

Graver Tank & Mfg. Co. v. Linde Air Prods.

Co., 339 U.S. 605 (1950) .......................................... 6

Honeywell Int’l, Inc. v. Hamilton Sundstrand

Corp., 523 F.3d 1304 (Fed. Cir. 2008) ....... 18, 19, 23

Insituform Techs., Inc. v. CAT Contracting,

Inc., 385 F.3d 1360 (Fed. Cir. 2004) ...................... 20

Int’l Rectifier Corp. v. IXYS Corp.,

515 F.3d 1353 (Fed. Cir. 2008) .............................. 19

vii

Litton Sys., Inc. v. Honeywell, Inc.,

145 F.3d 1472 (Fed. Cir. 1998) .............................. 27

Lucent Techs., Inc. v. Gateway, Inc.,

525 F.3d 1200 (Fed. Cir. 2008) ........................ 10, 19

Merrill v. Yeomans, 94 U.S. 568 (1876) ................... 28

Morgan Envelope Co. v. Albany Perforated

Wrapping Paper Co., 152 U.S. 425 (1894) .............. 7

Nautilus, Inc. v. Biosig Instruments, Inc.,

572 U.S. 898 (2014) .................................................. 5

Norian Corp. v. Stryker Corp.,

432 F.3d 1356 (Fed. Cir. 2005) ........................ 20, 28

Primos, Inc. v. Hunter’s Specialties, Inc.,

451 F.3d 841 (Fed. Cir. 2006) .......................... 20, 21

Regents of Univ. of Cal. v.

Dakocytomation Cal., Inc.,

517 F.3d 1364 (Fed. Cir. 2008) .................. 17, 21, 22

Schriber-Schroth Co. v. Cleveland Trust Co.,

311 U.S. 211 (1940). ................................................. 7

Schwarz Pharma, Inc. v. Paddock Labs., Inc.,

504 F.3d 1371 (Fed. Cir. 2007) .............................. 19

Shepard v. Carrigan, 116 U.S. 593 (1886) ................ 7

Smith v. Magic City Kennel Club,

282 U.S. 784 (1931) .................................................. 7

Teva Pharm. USA, Inc. v. Sandoz, Inc.,

135 S. Ct. 831 (2015)................................................ 5

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

520 U.S. 17 (1997) .............................................. 6, 28

Weber Elec. Co. v. E.H. Freeman Elec. Co.,

256 U.S. 668 (1921) .................................................. 7

viii

Winans v. Denmead,

56 U.S. (15 How.) 330 (1854) ................................... 5

Statutes

28 U.S.C. §1254 .......................................................... 5

35 U.S.C. §102 ............................................................ 1

35 U.S.C. §103 ............................................................ 1

35 U.S.C. §112 ............................................................ 1

35 U.S.C. §154 ............................................................ 5

Other Authorities

Br. for U.S. as Amicus Curiae, Festo Corp. v.

Shoketsu Kinzoku Kogyo Kabushiki Co.,

2001 WL 1025650 (U.S. Aug. 31, 2001) .............. 8, 9

FTC, EMERGING HEALTH CARE ISSUES (June

2009), https://tinyurl.com/voe5myd....................... 27

MICHAELA D. PLATZER & JOHN F. SARGENT,

JR., CONG. RESEARCH SERVICE: U.S.

SEMICONDUCTOR MANUFACTURING (June

2016), https://tinyurl.com/tyhlptk ......................... 27

PETITION FOR WRIT OF CERTIORARI

During the application process for a patent, the

Patent Office often rejects claims in applications,

frequently because the claims are too broad in a way

that renders them invalid under 35 U.S.C. §§102, 103

or 112. Faced with a rejection from the Patent Office,

the applicant has a choice:

(1) abandon the

application, (2) dispute the rejection, or (3) amend the

claims to address the rejection. When the applicant

chooses the third option, and narrows the claims to

obtain a patent, the general rule for more than 100

years—known as prosecution history estoppel—has

been that the patent owner cannot later use the

doctrine of equivalents in litigation to recapture

territory between the broader pre-amendment claims

and the narrower post-amendment claims. Were it

otherwise, patent owners could accomplish a bait-andswitch by narrowing their claims to get a patent, and

then effectively broadening those claims in litigation

through the doctrine of equivalents.

In Festo Corp. v. Shoketsu Kinzoku Kogyo

Kabushiki Co., 535 U.S. 722, 740-41 (2002), this Court

held that the rule of prosecution history estoppel is not

absolute. A patentee will not be estopped if it can

“show that at the time of the amendment one skilled

in the art could not reasonably be expected to have

drafted a claim that would have literally encompassed

the alleged equivalent.” Id. at 741 (emphasis added).

One way a patentee can make that showing is to

demonstrate

“the

rationale

underlying

the

amendment … bear[s] no more than a tangential

relation to the equivalent in question.” Id. at 740.

2

For the past eighteen years, over dozens of

decisions, the Federal Circuit has puzzled over what

this Court meant by that “tangential relation”

language, and has given two irreconcilable answers.

This case is the ideal vehicle to clarify Festo because

the Federal Circuit’s choice between its two answers

dictated the outcome.

In this case, the Patent Office rejected

Respondent Eli Lilly’s claims as overbroad, and Eli

Lilly responded by drafting narrower claims. It is

undisputed that Respondent could easily have drafted

a claim that literally encompassed Petitioners’

product. Respondent had done just that in other

patents and applications by claiming groups of

chemical compounds. Instead, for the patent in this

case, Respondent chose to narrow its claims to recite

only one specific chemical compound—“pemetrexed

disodium.”

Pemetrexed disodium is the active

ingredient in Respondent’s product, but not

Petitioners’ product. After obtaining its patent with

claims only to “pemetrexed disodium,” Respondent

sued Petitioners, alleging infringement under the

doctrine of equivalents.

In Respondent’s view,

Petitioners’ pemetrexed ditromethamine product is

equivalent to Respondents’ “pemetrexed disodium”

claims, and Petitioners were thus liable for

infringement.

On a straightforward application of Festo, this

should have been an easy case.

Indisputably,

Respondent could “reasonably be expected to have

drafted a claim that would have literally encompassed

the alleged equivalent,” 535 U.S. at 741, when it was

amending its claims to respond to the Patent Office’s

3

rejection. Respondent had drafted precisely such

claims that in other patents. And under one line of

Federal Circuit precedent interpreting Festo, this case

should have been easier still: several cases addressing

this recurring fact pattern hold that a patent owner

cannot invoke the tangential exception by arguing

that, in hindsight, it surrendered more than it needed

to address the Patent Office’s invalidity rejection.

The panel in this case, however, followed a

different line of Federal Circuit precedent, under

which patent owner can invoke the tangential

exception by arguing that, in hindsight, it surrendered

more than it needed to address the Patent Office’s

invalidity rejection.

In effect, the “tangential”

exception is a prosecution remorse exception.

Applying that approach here, the panel held that

Respondent was entitled to invoke the tangential

exception to prosecution history estoppel because it

surrendered more than it needed to address the

Patent Office’s rejection.

Although Respondent

unambiguously surrendered Petitioners’ product in

prosecution (i.e., its pre-amendment claims covered

Petitioners’ product; its post-amendment claims did

not), at a time when it knew how to capture that

product, the Federal Circuit panel found that

Respondent’s claim amendment was “inartful” and

that Respondent “did not need or intend to cede”

Petitioners’ product.

In other words, the court

considered only Respondent’s “reason” for amending

its claims at all rather than Respondent’s “reason” for

making the specific amendment it made. As a result,

Petitioners were penalized for relying on the

prosecution history of Respondent’s patent, and were

4

held liable for infringement based on a compound

Respondent had unquestionably surrendered.

The Federal Circuit’s confusion over the meaning

of Festo’s “tangential” exception warrants this Court’s

review. It is a recurring question whose answer this

Court should not leave in its current panel-dependent

state. Both of the Federal Circuit’s approaches cannot

be right, and the approach taken here and in other

cases is wrong. In its cases that treat the “tangential”

exception as a prosecution-remorse exception, the

Federal Circuit undermines an important legal limit

on the doctrine of equivalents and threatens the

public-notice function of patent claims. If it is to

remain true that “a patent holder should know what

he owns, and the public should know what he does

not,” Festo, 535 U.S. at 731, the Court should grant

certiorari and reverse.

OPINIONS BELOW

The Federal Circuit’s opinion is reported at 933

F.3d 1320 and reproduced at App-1-30. The order

denying rehearing en banc is reproduced at App-3132.

Although the court of appeals’ opinion addressed

two companion appeals together (Fed. Cir. Nos. 182128 and 18-2126), the appeals were not consolidated,

and separate judgments were issued in each one. This

petition arises from Appeal No. 18-2128. Relevant

underlying district court opinions are the opinion

following the bench trial—reported at 323 F. Supp. 3d

1042 and reproduced at App-33-49—and the

unreported order denying summary judgment of

noninfringement, available at 2017 WL 6387316 and

reproduced at App-50-74.

5

JURISDICTION

The Federal Circuit issued its opinion on August

9, 2019.

Petitioners filed a timely petition for

rehearing en banc, which the court denied on

November 8, 2019.

On January 24, 2020, the Chief Justice extended

the time for filing a petition for certiorari to and

including February 24, 2020.

This Court has

jurisdiction under 28 U.S.C. §1254(1).

STATEMENT OF THE CASE

A. Legal Background

Every patent application must include “claims,”

where the applicant “particularly point[s] out and

distinctly claim[s] the subject matter which the

inventor … regards as the invention.” 35 U.S.C.

§112(b). A patent grants its owner the right to exclude

others from making, using, or selling the claimed

invention. 35 U.S.C. §154(a)(1). Claims define the

scope of those rights and provide notice to the public.

Teva Pharm. USA, Inc. v. Sandoz, Inc., 135 S. Ct. 831,

835 (2015); Nautilus, Inc. v. Biosig Instruments, Inc.,

572 U.S. 898, 909-10 (2014).

The judicially-created “doctrine of equivalents”

expands a patent owner’s ability to sue others “beyond

the literal terms in a patent.” Festo, 535 U.S. at 727.

For example, a patent owner may assert that claims

to “cone” shaped railcars are infringed by octagonalpyramid shaped railcars. Winans v. Denmead, 56 U.S.

(15 How.) 330, 342-44 (1854). Or “alkaline earth metal

silicate” claims may be infringed by magnesium

silicate (magnesium is not an alkaline earth metal).

Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339

6

U.S. 605, 610-12 (1950). The underlying “premise” of

the doctrine is “language’s inability to capture the

essence of innovation.” Festo, 535 U.S. at 734. If

patent owners were strictly limited to the literal scope

of their claims, competitors could easily circumvent

patents by making insubstantial modifications that

the patentee could not reasonably have anticipated

during the drafting and application process. Id. at

733-34.

Because the doctrine of equivalents permits

infringement theories that reach beyond the text of

the claims, it necessarily “renders the scope of patents

less certain.” Festo, 535 U.S. at 732. This Court has

said that the public must tolerate some uncertainty as

“the price of ensuring the appropriate incentives for

innovation.” Id. at 732. But that price is not

unlimited. “There can be no denying that the doctrine

of equivalents, when applied broadly, conflicts with

the definitional and public-notice functions of the

statutory claiming requirement.” Warner-Jenkinson

v. Hilton Davis Chem. Co., 520 U.S. 17, 29 (1997).

Even with the doctrine of equivalents, “[a] patent

holder should know what he owns, and the public

should know what he does not.” Festo, 535 U.S. at 731.

An important limit on the doctrine of equivalents

is prosecution history estoppel. Id. at 727. If the

Patent Office rejects claims in an application as

invalid, and the patent applicant responds by

narrowing the claims, “this prosecution history estops

him from later arguing that the subject matter covered

by the original, broader claim was nothing more than

an equivalent.” Id. “Competitors may rely on the

estoppel to ensure that their own devices will not be

7

found to infringe by equivalence.” Id. That has been

the general rule for more than 100 years. See, e.g.,

Schriber-Schroth Co. v. Cleveland Trust Co., 311 U.S.

211, 220-21 (1940).; Exhibit Supply Co. v. Ace Patents

Corp., 315 U.S. 126, 136-37 (1942); Smith v. Magic

City Kennel Club, 282 U.S. 784, 790 (1931); Weber

Elec. Co. v. E.H. Freeman Elec. Co., 256 U.S. 668, 67778 (1921); Morgan Envelope Co. v. Albany Perforated

Wrapping Paper Co., 152 U.S. 425, 429 (1894);

Shepard v. Carrigan, 116 U.S. 593, 598 (1886). A

narrowing amendment for patentability reasons

“undercuts [the] premise” of the doctrine of

equivalents, which is that the applicant somehow

“lacked the words” to include the defendant’s product

in its claims. Festo, 535 U.S. at 734. Instead, it

suggests that the applicant focused on a particular

claim element and made a deliberate choice to narrow

it. Id. Without prosecution history estoppel, “the

inventor might avoid the [Patent Office’s] gatekeeping

role and seek to recapture in an infringement action

the very subject matter surrendered as a condition of

receiving the patent.” Id.

In Festo, this Court refined the rule of prosecution

history estoppel. The general rule is still that when a

patentee narrows claims in prosecution to comply with

any provision of the Patent Act, the amendment “may

be presumed to be a general disclaimer of the territory

between the original claim and the amended claim.”

535 U.S. at 740 (citing Exhibit Supply, 315 U.S. at

136-37); id. at 737 (“We must regard the patentee as

having conceded an inability to claim the broader

subject matter or at least as having abandoned his

right to appeal a rejection.”).

8

The patentee can rebut the presumption of

estoppel by showing that when the amendment was

made, “one skilled in the art could not reasonably be

expected to have drafted a claim that would have

literally encompassed the alleged equivalent.” Id. at

741. Festo stated three ways the patentee might make

that showing:

[1] The equivalent may have been

unforeseeable at the time of the application;

[2] the rationale underlying the amendment

may bear no more than a tangential relation

to the equivalent in question; or [3] there may

be some other reason suggesting that the

patentee could not reasonably be expected to

have described the insubstantial substitute in

question.

Id. at 740-41 (emphasis and numbers added).

The first and third parts of that passage—

“unforeseeable” and “some other reason … the

patentee could not reasonably be expected to have

described” the equivalent—appear to have been

proposed in the Solicitor General’s amicus brief. See

Br. for U.S. as Amicus Curiae *25-26, Festo Corp. v.

Shoketsu Kinzoku Kogyo Kabushiki Co., 2001 WL

1025650 (U.S. Aug. 31, 2001). The “unforeseeable”

part is readily understandable: patent applicants

cannot reasonably be expected to account for

equivalents that do not yet exist and are not

foreseeable. Festo, 535 U.S. at 738; see also Festo

Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 234

F.3d 558, 619 (Fed. Cir. 2000) (Rader, J., concurring

and dissenting) (“A primary justification for the

doctrine of equivalents is to accommodate after-

9

arising technology. … A claim using the terms ‘anode’

and ‘cathode’ from tube technology would lack the

‘collectors’ and ‘emitters’ of transistor technology that

emerged in 1948. Thus, without a doctrine of

equivalents, infringers in 1949 would have unfettered

license to appropriate all patented technology using

the out-dated terms ‘cathode’ and ‘anode’.”) (cited in

Br. for U.S., 2001 WL 1025650, at *25-26).

The “some other reason” language, see Br. for

U.S., 2001 WL 1025650 at *26, simply reiterates the

broader principle: prosecution history estoppel should

not apply if, at the time the amendment was made, the

patent applicant could not reasonably have been

expected to literally claim the alleged equivalent—

whether due to the limits of language or some other

obstacle akin to unforeseeability.

Indeed, Festo

reiterated several times that the unifying principle is

that prosecution history estoppel should not apply if,

at the time of amendment, the applicant “could not

reasonably be expected” to have drafted a claim

literally covering the alleged equivalent or “lacked the

words” to claim the alleged equivalent. 535 U.S. at

734, 740, 741.

The “tangential” passage, however, was not

suggested in any brief in Festo. The Court’s opinion

did not explain the “tangential” passage at length or

derive it from precedent. The Court simply said that

there is no “call to foreclose claims of equivalence for

aspects of the invention that have only a peripheral

relation to the reason the amendment was submitted,”

535 U.S. at 738, announced the test for rebutting the

presumption of prosecution history estoppel, and left

10

the Federal Circuit and the district courts to apply it

going forward.

The Federal Circuit has treated Festo as

announcing three exceptions to prosecution history

estoppel—including the “tangential” exception—and

has developed distinct precedent for each exception.

See, e.g., Festo Corp. v. Shoketsu Kinzoku Kogyo

Kabushiki Co., 344 F.3d 1359, 1369 (Fed. Cir. 2003)

(en banc) (“three rebuttal criteria,” “[t]he second

criterion” being the tangential exception); Lucent

Techs., Inc. v. Gateway, Inc., 525 F.3d 1200, 1217-18

(Fed. Cir. 2008) (rejecting patentee’s argument for

applying “the tangential exception”).

B. Factual Background

Respondent Lilly markets and sells an anti-cancer

drug under the brand name ALIMTA.1 ALIMTA’s

active ingredient is the chemical compound

pemetrexed disodium. Pemetrexed disodium is in a

class of chemicals called antifolates. It is also a

“salt”—a compound formed by bonding positive ions

with negative ions (one negative pemetrexed ion with

two positive sodium ions).

Lilly owns or licenses several patents that cover

ALIMTA’s active ingredient, some of which expired

before this litigation began. Two of Lilly’s licensed

patents claimed groups of chemicals (pyrrolopyrimidine derivatives) using chemical formulas with

variables. See, e.g., Dr. Reddy’s Opening Br. at 15, No.

18-2128 (Fed. Cir. Feb. 7, 2019), ECF#62. Another

Lilly patent claimed “pemetrexed,” and stated that

1 “CA-Appx” refers to the joint appendix filed with the court of

appeals, Fed. Cir. No. 18-2128, ECF#53 (filed Jan. 30, 2019).

11

“[a]s used herein, the term ‘pemetrexed’ refers to the

stable salts, acids, and free bases thereof.” CAAppx7977(3:10-20); CA-Appx7978(5:19-6:39). The

patent in this case, however, claims only the specific

compound pemetrexed disodium—not all stable salts

of pemetrexed. See, e.g., CA-Appx53 (11:25-12:4

(claim 12)).

When Lilly was applying for its patent, its claims

initially covered the entire class of antifolates,

including all pemetrexed salts. An exemplary claim in

the application recited “administration of an

antifolate” to a patient. CA-Appx7860 (claim 2). The

examiner rejected Lilly’s claims as invalid in light of

prior art. Among other things, a 1978 publication

(Arsenyan) disclosed similar treatments using

methotrexate, which is an antifolate. CA-Appx7868. In

response, Lilly specifically narrowed its claims from

all “antifolate[s]” to the “pemetrexed disodium”

ingredient in its ALIMTA product. Lilly deleted every

instance of “antifolate” in every claim, and substituted

“pemetrexed disodium” each time. See, e.g., CAAppx7877 (claim 2).

Lilly then argued to the Patent Office that its

amended claims were valid because Lilly had

narrowed them from “an antifolate” to only

“pemetrexed disodium.” Lilly’s submission with its

amended claims repeated sixteen times that it claimed

only “pemetrexed disodium,” and its submission never

suggested that its amended claims included anything

else. See, e.g., CA-Appx7880 (“There is no disclosure

in Arsenyan … of the invention as presently claimed.

In particular, Arsenyan … does not disclose

pemetrexed disodium …”); id. (prior art does not

12

disclose “pemetrexed disodium, or for that matter any

other antifolate.”). Lilly successfully obtained a

patent, with claims limited to “pemetrexed disodium.”

Undisputedly,

Lilly’s

amendment

from

“antifolate” to “pemetrexed disodium” narrowed the

claims in the application further than Lilly necessarily

needed to go to address the Patent Office’s rejection.

As illustrated below, Lilly might have claimed a

subset of “antifolates” that did not include

methotrexate (“pyrrolo-pyrimidine derivatives,” for

example), as Lilly had done in other patents. Or Lilly

might have claimed “pemetrexed” as it had done in

other patents.

"Antifolate"

"Pyrrolopyrimidine

derivative"

"Pemetrexed"

"Pemetrexed

disodium"

Instead, Lilly chose to claim only the “pemetrexed

disodium” compound.

Relying on this Court’s precedent, Lilly’s

competitors—including Petitioners and others—

designed around Lilly’s claims by creating products

that did not use pemetrexed disodium. Petitioners’

product uses a different compound, pemetrexed

ditromethamine. Pemetrexed ditromethamine is an

13

antifolate and a pemetrexed salt, and was covered by

Lilly’s original claims to “an antifolate.” But it is

undisputedly not pemetrexed disodium and thus not

within the literal scope of Lilly’s claims to “pemetrexed

disodium.”

Lilly nonetheless sued Petitioners and others,

asserting infringement under the doctrine of

equivalents.

C. Proceedings Below

In this case, Lilly prevailed in district court, and

the Federal Circuit affirmed. The district court and

court of appeals decisions both turned on whether

Lilly’s narrowing amendment (from “antifolate” to

“pemetrexed disodium”) fit within Festo’s “tangential

exception.”

All agreed that (1) Lilly made the amendment to

secure its patent, (2) Petitioners’ pemetrexed

ditromethamine fell within the surrendered territory,

and (3) Lilly bore the burden to rebut the presumption

of prosecution history estoppel. Lilly contended that

Festo’s “tangential exception” applied, i.e., that the

reason for Lilly’s narrowing amendment bore only a

tangential relation to Petitioners’ product.

Lilly’s argument was based on remorse at having

surrendered more than it needed to in prosecution. It

argued that the “tangential exception” applied

because it did not need to surrender Petitioners’

product to answer the Patent Office’s rejection and

because Petitioners’ product fell within the

unnecessarily-surrendered territory. In other words,

Lilly characterized the “reason” for its amendment as

distinguishing a particular piece of prior art, and

contended that unnecessarily-surrendered scope was

14

therefore “tangential” to that reason. See, e.g., Lilly

Br. Opposing Summ. J. at 26, No. 16-CV-308, (S.D.

Ind. Sept. 21, 2007), ECF #171 (“[T]he claims were

narrowed to avoid a certain prior art species (the

antifolate methotrexate), and the narrowing excluded

other species (pemetrexed salts) that were unrelated

to the prior art and did not need to be excluded in order

to avoid it.”); Lilly Response Br. at 8, 46, No. 18-2128,

(Fed. Cir. Dec. 3, 2018), ECF#43 (“[T]he purpose of the

amendment was to avoid the Arsenyan reference .… If

a patentee was making an amendment for one reason,

and in so doing excludes an equivalent that is

unrelated to the reason for the amendment, the

tangentiality exception excuses the patentee’s failure

to claim that equivalent.”).

Lilly never contended that it lacked the words to

draft a claim covering Petitioners’ product.

In

response to Petitioners’ arguments that Lilly could

easily have claimed Petitioners’ product (e.g., by

claiming

“pemetrexed”

or

pyrrolo-pyrimidine

derivatives as it had done in other patents, or any

number of options readily available to a sophisticated

pharmaceutical company), Lilly contended that such

arguments “collapsed the tangentiality exception”

with the “separate” unforeseeability exception. Lilly

Response Br. at 45-47, No. 18-2128, (Fed. Cir. Dec. 3,

2018), ECF#43. Lilly contended that it was irrelevant

whether it could have made “other hypothetical

amendments” to its claims. Id. at 43-44; Lilly Opp’n

to Rehearing at 9, No. 18-2128, (Fed. Cir. Oct. 23,

2019), ECF#97.

The district court and the court of appeals both

accepted Lilly’s arguments. On appeal, Petitioners

15

argued that Lilly’s remorse at having surrendered

more than it needed to in prosecution cannot fit Festo’s

“tangential” exception as a matter of law. Actavis—

another generic who had relied on Lilly’s prosecution

history to design around Lilly’s claims, but had been

found to infringe under the doctrine of equivalents—

filed a supportive amicus brief.

A panel of the Federal Circuit affirmed, reasoning

that the tangential exception applied because

Petitioners’ product was part of the claim scope Lilly

surrendered in prosecution but “did not need or

intend” to surrender to avoid the Patent Office’s

rejection:

[T]he particular type of salt to which

pemetrexed is complexed relates only

tenuously to the reason for the narrowing

amendment, which was to avoid Arsenyan.…

[T]he reason for the amendment was not to

cede other, functionally identical pemetrexed

salts.

* * *

The prosecution record implies that Lilly’s

amendment, inartful though it might have

been, was prudential in nature and did not

need or intend to cede other pemetrexed salts.

App-20 (emphasis added). Much as Lilly had done in

its briefs, the panel cast Lilly’s “reason” for its

amendment as surrendering only the scope it needed

to surrender to answer the Patent Office’s rejection.

In other words, the panel inquired into the reason why

Lilly amended its claims at all, not the reason why

Lilly amended its claims in the way it did. The panel

then reasoned that the unnecessarily-surrendered

16

scope that included Petitioners’ product was

“tangential” to Lilly’s reason for amending its claims.

App-24-25 (“implausible that the reason for Lilly’s

amendment was to surrender other pemetrexed salts”;

“the prosecution history strongly indicates a less

sweeping and more sensible reason for Lilly’s

amendment: to surrender antifolates other than

pemetrexed.

Thus, we conclude … that Lilly’s

amendment was merely tangential to pemetrexed

ditromethamine.”).

The same week as the decision in this case, a

divided panel of the Federal Circuit decided Ajinomoto

Co. v. ITC, 932 F.3d 1342 (Fed. Cir. 2019), where the

majority and dissent disagreed over whether the

“tangential exception” to prosecution history estoppel

applied. Like the panel in this case, the Ajinomoto

panel majority based its analysis on a post hoc

assessment of whether the patentee needed to

surrender as much as it did to address an examiner’s

rejection. Id. at 1355. The dissent responded that the

majority’s analysis was inconsistent with precedent

and that “[t]he problem with the majority’s analysis is

that it ignores how the patentee deliberately elected to

narrow the claims.” Id. at 1363 (Dyk, J., dissenting).

In this case, Petitioners sought rehearing,

supported by an amicus curiae. After requesting a

response from Lilly, the court of appeals denied

rehearing. App-31-32.

17

REASONS FOR GRANTING THE PETITION

I.

The Federal Circuit Is Internally Divided On

The Meaning Of The “Tangential Exception”

To Prosecution History Estoppel.

This Court first announced the “tangential

exception” to prosecution history estoppel in Festo in

2002, stating that prosecution history estoppel will not

apply if “the rationale underlying the amendment …

bear[s] no more than a tangential relation to the

equivalent in question.” 535 U.S. at 740. That passage

does not appear to have antecedents in this Court’s

prior precedent, nor was it suggested in any brief in

that case. For the past eighteen years, in dozens upon

dozens of appeals raising the issue, the Federal Circuit

has struggled to figure out what that language means,

and has developed a body of precedent around the

“tangential exception” to prosecution history estoppel.

Beginning with the remand in Festo itself, the

meaning of the “tangential exception” has divided

panels, provoked separate opinions disagreeing with

earlier decisions, and generally led to confusion. See,

e.g., Festo, 344 F.3d at 1369 (consulting dictionaries

for meaning of “tangential”); id. at 1384 (Newman, J.,

dissenting), (disagreeing with majority’s treatment of

“tangential” exception); Cross Med. Prods., Inc. v.

Medtronic Sofamor Danek, Inc., 480 F.3d 1335, 134648 (Fed. Cir. 2007) (Rader, J., concurring) (“[F]rankly,

this court might well have justifiably reached a

different result in both” earlier decisions applying the

tangential exception); Regents of Univ. of Cal. v.

Dakocytomation Cal., Inc., 517 F.3d 1364, 1380-82

(Fed. Cir. 2008) (Prost, C.J., dissenting); Honeywell

Int’l, Inc. v. Hamilton Sundstrand Corp., 523 F.3d

18

1304, 1321-22 (Fed. Cir. 2008) (Newman, J.,

dissenting); Ajinomoto, 932 F.3d at 1361-64 (Dyk, J.,

dissenting).

Federal Circuit precedent has crystallized around

two irreconcilable approaches.

1. Under one approach, the court asks why the

patentee made the specific narrowing amendment it

chose to make. See, e.g, Felix v. Am. Honda Motor Co.,

562 F.3d 1167, 1184 (Fed. Cir. 2009) (“If Felix had

intended only to add a channel and not add a gasket,

he could easily have simply amended original claim 1

to add limitation (e) and not limitation (f).”); Amgen

Inc. v. Hoechst Marion Roussel, Inc., 457 F.3d 1293,

1315 (Fed. Cir. 2006) (“if the patentee had wished only

to limit the claims to human EPO, the patentee could

have done so by continuing to use the adjective

‘human’ … in the third preliminary amendment;

instead the patentee chose to further narrow the

claims …”).

Under that approach, the “tangential exception”

applies when an amendment adds multiple

limitations to a claim at the same time, and not all

relate to an examiner’s rejection. The limitations

unrelated to the examiner’s rejection may fit the

tangential exception. Judge Dyk’s dissenting opinion

in Ajinomoto applies that approach. 932 F.3d at 136164. By the same token, the “tangential exception”

generally does not apply where the alleged equivalent

and the reason for the amendment both concern the

same claim element. Where, as here, the patentee

focused on a particular claim element, and responded

to an examiner’s rejection by narrowing in a way that

excludes a defendant’s allegedly equivalent product,

19

the rationale for the narrowing amendment cannot be

“tangential” to the alleged equivalent. Honeywell, 523

F.3d at 1316 (“Because the alleged equivalent focuses

on the IGV limitation, the amendment bore a direct,

not merely tangential, relation to the equivalent.”);

Biagro W. Sales, Inc. v. Grow More Inc., 423 F.3d 1296,

1306 (Fed. Cir. 2005) (“Because both the reason for the

amendment and the asserted equivalent relate to the

concentration of the fertilizer,” the tangential

exception does not apply.).

Decisions in that line further hold that patent

owners cannot invoke the “tangential exception” by

arguing that, in retrospect, they narrowed their claims

more than they needed to in response to an examiner’s

rejection. See, e.g., Ajinomoto, 932 F.3d at 1362-63

(collecting cases); Int’l Rectifier Corp. v. IXYS Corp.,

515 F.3d 1353, 1359 (Fed. Cir. 2008) (“IR’s decision to

claim that structure using the limiting term

‘adjoining,’ whether or not required to overcome the

rejection, cannot be described as only tangentially

related …”) (emphasis added); Lucent, 525 F.3d at

1218; Schwarz Pharma, Inc. v. Paddock Labs., Inc.,

504 F.3d 1371, 1377 (Fed. Cir. 2007) (“[T]hat the

inventors may have thought after the fact that they

could have relied on other distinctions in order to

defend their claims is irrelevant and speculative ....”);

Festo, 344 F.3d at 1371. To accept such an argument

would turn the “tangential” exception into a buyer’s

remorse exception, by ignoring how the patent

applicant chose to amend its claims in response to a

rejection and focusing instead on what the applicant

wished it had done.

20

Judge Bryson’s opinion in Norian Corp. v. Stryker

Corp., 432 F.3d 1356 (Fed. Cir. 2005)—often cited by

decisions in this line of cases—explains that patentees

frequently make such surrendered-more-than-Ineeded-to arguments, but that “there is no principle of

patent law that the scope of a surrender of subject

matter during prosecution is limited to what is

absolutely necessary to avoid a prior art reference that

was the basis for an examiner’s rejection.” Id. at 1361

(rejecting buyer’s-remorse argument in the context of

claim construction); id. at 1363 (applying prosecution

history estoppel for similar reasons).

2. The Federal Circuit’s other approach is

diametrically opposite to the first. Some panels accept

precisely the type of buyer’s-remorse arguments that

other panels reject and base the tangential-exception

inquiry on a post hoc assessment of what the patent

applicant needed to surrender to avoid an examiner’s

rejection. Those panels begin by phrasing the “reason”

for the disputed narrowing amendment as

surrendering only what was necessary to avoid a

specific rejection—often to distinguish a particular

piece of invalidating prior art. See, e.g, Insituform

Techs., Inc. v. CAT Contracting, Inc., 385 F.3d 1360,

1370 (Fed. Cir. 2004) (“the narrowing amendment in

this case was for the purpose of distinguishing the

invention over Everson.”); Primos, Inc. v. Hunter’s

Specialties, Inc., 451 F.3d 841, 849 (Fed. Cir. 2006)

(“The patentee added the ‘differentially spaced’

limitation to distinguish the diaphragm mouth call

from a prior art device that consisted of a shelf-like

structure positioned on top of the membrane without

any spacing.”).

21

It generally follows, in those panels’ view, that

unnecessarily surrendered claim scope is “tangential”

to that reason—without regard to the applicant’s

choice of how far to go in avoiding the examiner’s

rejection. See, e.g., App-19-20; Ajinomoto, 932 F.3d at

1355; Regents, 517 F.3d at 1378; Primos, 451 F.3d at

849 (Unlike the prior art, “[t]he accused device, …

includes a dome that is spaced above the membrane.

Because the accused device's dome includes the

spacing, the amendment was merely tangential…”).

The panel in this case took that approach. It

considered why Lilly amended its claims at all, not

why Lilly chose to amend its claims by narrowing from

“an antifolate” to “pemetrexed disodium.” Thus, the

panel concluded that “the reason for the narrowing

amendment … was to avoid Arsenyan,” and “not to

cede other, functionally identical, pemetrexed salts.”

App-20. From there, the panel reasoned that “Lilly’s

amendment, inartful though it might have been, was

prudential in nature and did not need or intend to cede

other pemetrexed salts.” Id. (emphasis added). In the

panel’s view, it was irrelevant that Lilly chose to give

Arsenyan a wide berth and literally did “cede other

pemetrexed salts” by narrowing its claims from

“antifolate” to the specific “pemetrexed disodium”

compound in its product, even though Lilly knew how

to claim more broadly.

The Ajinomoto majority’s analysis likewise asked

why the patentee amended its claims at all, and relied

on a post hoc assessment of what scope the patent

owner needed to surrender to avoid the examiner’s

rejection—while largely ignoring what the patent

owner actually did surrender, 932 F.3d at 1355

22

(reason was to amend the claims to “no longer

include[] the prior-art E. coli YfiK protein”), and

finding that the tangential exception did not apply

where the alleged equivalent was not part of the scope

the patent owner needed to surrender (without regard

for the fact that the patent owner did surrender that

scope). Id. Ajinomoto and this case both cited earlier

Federal Circuit decisions as supporting their

approach, including the Regents case, where the

dissent contended that the majority had erroneously

accepted

a

surrendered-more-than-I-needed-to

argument from the patent owner. 517 F.3d at 138081. (Prost, C.J., dissenting). App-23-24.

3. The two approaches are fundamentally

irreconcilable. Under the first approach, the patent

owner’s reasons for making the particular amendment

it made drive the analysis. And the result is usually

that the patent owner cannot escape prosecution

history estoppel by arguing that it surrendered more

than it needed to. Under the second approach, the

patent owner’s reasons for amending the claim at all

drive the analysis. And there, the same argument

produces the opposite result: the patent owner can

escape prosecution history estoppel by arguing that it

surrendered more than it needed to. This difference

in approaches has split Federal Circuit panels.

Ajinomoto, 932 F.3d at 1363 (Dyk, J., dissenting) (“The

majority adopts a slightly different version of

Ajinomoto’s

untenable

[surrendered-more-thannecessary] argument” and “ignores how the patentee

deliberately elected to narrow the claims.” (emphasis

added)); Regents, 517 F.3d at 1380-82 (Prost, C.J.,

dissenting). To be sure, if the patentee did need to

surrender what it did— if the patentee amended its

23

claims to distinguish prior art that contains the

defendant’s alleged equivalent—then the patentee

will lose under both approaches. Festo, 344 F.3d at

1369 (“Although we cannot anticipate the instances of

mere tangentialness that may arise, we can say that

an amendment made to avoid prior art that contains

the equivalent in question is not tangential; it is

central to allowance of the claim.”). But where, as

here and in many other cases, the defendant’s product

was not within the prior art the Patent Office cited,

but within the scope the patentee surrendered to avoid

that prior art, the applicability of the “tangential”

exception will depend on which panel the parties draw

on appeal.

So it was here: the choice of approach dictated the

outcome in this case. Had the first approach been

taken, prosecution history estoppel would have

applied. The court would have asked why Lilly chose

the amendment it did, not just why Lilly amended the

claims at all. Here, Lilly chose to narrow an element

of its claims from “antifolate” to “pemetrexed

disodium.”

Petitioners’

product

(pemetrexed

ditromethamine) is equivalent to that same narrowed

element.2 Lilly’s reason for the particular amendment

it made—i.e., its choice of how far to go in narrowing

the “antifolate” term to avoid prior art—“bore a direct,

not merely tangential, relation to the equivalent.”

Honeywell, 523 F.3d at 1316.

2 It is undisputed that “pemetrexed disodium” is one element,

not two. See Lilly Br. on Appeal at 61, No. 18-2126, (Fed. Cir.

Nov. 13, 2018), ECF#28; Dr. Reddy’s Reply Br. at 19, No. 18-2128,

at 19 (Fed. Cir. Jan. 16, 2019), ECF#46 (citing id.).

24

But because the panel took the second approach,

it focused on Lilly’s reasons for amending the claims

at all and on what Lilly wished it had done in

hindsight. Thus, the panel held that prosecution

history estoppel would not apply based on the view

that Lilly’s amendment, “inartful though it might

have been, was prudential in nature and did not need

or intend to cede other pemetrexed salts.” App-20

(emphasis added). Absent this Court’s review, the

applicability of the “tangential exception” will

continue to depend—as it did here—on which panel

the parties draw on appeal.

II. The Decision Below Cannot Be Reconciled

With This Court’s Precedents.

Both approaches cannot be right, and the

approach applied here is plainly wrong.

Festo reiterated several times that the

“exceptions” to prosecution history estoppel—

including the “tangential” exception—are all instances

where the patentee could not reasonably be expected to

have described the insubstantial substitute in question.

See 535 U.S. at 741 (the third exception is “some other

reason suggesting that the patentee could not

reasonably be expected to have described the

insubstantial substitute in question.”) (emphasis

added); id. (To avoid prosecution history estoppel,

“[t]he patentee must show that at the time of the

amendment one skilled in the art could not reasonably

be expected to have drafted a claim that would have

literally encompassed the alleged equivalent.”). That

is because the doctrine of equivalents is “premised on”

the inherent limits of language, 535 U.S. at 734, and

recognition that inventors cannot be expected to

25

anticipate every insubstantial change a competitor

might make. Id. at 731-32. A narrowing amendment

to a particular element, however, “undercuts that

premise” as to that element, and shows “that the

inventor turned his attention to the subject matter in

question, knew the words for both the broader and

narrower claim, and affirmatively chose the latter.”

535 U.S. at 734-35.

Here, it is beyond dispute that Lilly could

“reasonably be expected to have” claimed Petitioners’

product when it made its narrowing amendment. 535

U.S. at 741. Lilly did precisely that in other patents,

claiming

“pemetrexed”

or

pyrrolo-pyrimidine

derivatives. Lilly did not “lack[] the words,” id. at

735—it had used them before. The premise of the

doctrine of equivalents, and the unifying principle

behind the exceptions to prosecution history estoppel,

is thus conspicuously absent here. Lilly’s choice to

claim “pemetrexed disodium” rather than some

broader set of compounds is just that—a choice. To

relieve Lilly of the consequences of that choice because

it was “inartful” or “not need[ed] or intend[ed]” is thus

directly contrary to Festo.

More fundamentally, the approach the panel took

undermines prosecution history estoppel as a limit on

the doctrine of equivalents and threatens the publicnotice function of patent claims. Even with the

doctrine of equivalents, “[a] patent holder should know

what he owns, and the public should know what he

does not.” Festo, 535 U.S. at 731. For more than 100

years, prosecution history estoppel has allowed a

patent owner’s competitors to “rely on … the public

record of the patent proceedings” to know ex ante

26

whether “their own devices will … be found to infringe

by equivalence.” Id. at 726; see also Statement of the

Case §A, supra.

Under the approach the panel applied here, the

public cannot objectively rely on narrowing

amendments in prosecution to learn what a patent

holder does not own. Patent owners will be able to

argue—as Lilly did here—that the “reason” for any

narrowing amendment was to avoid a particular

rejection, and that any surrender of scope that was not

necessary to that reason is “tangential.” This invites

precisely the sort of circumvention of the examination

process that prosecution history estoppel is designed

to prevent, where “the inventor might avoid the

[Patent Office’s] gatekeeping role and seek to

recapture in an infringement action the very subject

matter surrendered as a condition of receiving the

patent.” Festo, 535 U.S. at 734. The approach taken

to the tangential exception in cases like Honeywell,

Biagro, and Judge Dyk’s Ajinomoto dissent is faithful

to this Court’s precedent. The approach taken here

and in similar cases is not.

III. The Question Presented Is Important, And

This Case Is The Ideal Vehicle To Resolve It.

Only this Court can explain what it meant when

it announced the “tangential” exception in Festo. The

Federal Circuit has debated that question for eighteen

years, over dozens of decisions, and given two

irreconcilable answers.

There is no reasonable

prospect that further percolation would improve the

situation. Nor, given the Federal Circuit’s exclusive

jurisdiction and the doctrine of equivalents’ character

as judge-made law, is there any role for another court

27

or Congress to clarify the meaning of the tangential

exception. “There is perhaps no question more

important to the health of patents than the scope and

application of the judicially-created doctrine of

equivalents.” Litton Sys., Inc. v. Honeywell, Inc., 145

F.3d 1472, 1472 (Fed. Cir. 1998) (Plager, J., dissenting

from denial of rehearing en banc). The Federal

Circuit’s confused treatment of the “tangential”

exception throws the scope and application of the

doctrine of equivalents into disarray.

As the amicus briefing below confirms, the

meaning of the “tangential exception” is important

because it affects the ability of productive companies

to determine their potential liability ex ante, before

making substantial investments in competing

products. Developing and securing FDA approval of a

generic drug product, for example, typically costs

millions of dollars. See, e.g., FTC, EMERGING HEALTH

CARE

ISSUES

14

(June

2009),

https://tinyurl.com/voe5myd.

Analogous costs for

follow-on biologic manufacturers are hundreds of

millions of dollars or more. Id. A new semiconductor

plant costs billions of dollars. MICHAELA D. PLATZER

& JOHN F. SARGENT, JR., CONG. RESEARCH SERVICE:

U.S. SEMICONDUCTOR MANUFACTURING 9 (June 2016),

https://tinyurl.com/tyhlptk. Too much uncertainty in

the scope of patents chills beneficial investments in

legitimate products.

This Court’s precedent

recognizes the same point: “If competitors cannot be

certain about a patent’s extent, they may be deterred

from engaging in legitimate manufactures outside its

limits, or they may invest by mistake in competing

products that the patent secures.” Festo, 535 U.S. at

732; see also, e.g., Merrill v. Yeomans, 94 U.S. 568,

28

573-74 (1876) (“The public should not be deprived of

rights supposed to belong to it, without being clearly

told what it is that limits these rights.”). Although the

doctrine of equivalents requires the public to tolerate

some uncertainty, “[t]here can be no denying that the

doctrine of equivalents, when applied broadly,

conflicts with the definitional and public-notice

functions of the statutory claiming requirement.”

Warner-Jenkinson, 520 U.S. at 29. Even with the

doctrine of equivalents, “[a] patent holder should [still]

know what he owns, and the public should know what

he does not.” Festo, 535 U.S. at 731.

This case is an ideal vehicle to resolve the

meaning of the tangential exception. For one thing,

the applicability of the tangential exception decides

the entire case. It is undisputed that the predicates

for prosecution history estoppel apply—i.e., that Lilly

made a narrowing amendment that triggers

prosecution history estoppel unless an exception

applies. Lilly has not argued that either of Festo’s

other two exceptions apply; it has relied entirely on

the tangential exception. If Lilly can invoke the

tangential exception, its infringement claims succeed;

if not, its infringement claims fail.

For another, this case cleanly exemplifies a

recurring fact pattern in patent litigation: a patent

applicant surrenders more than necessary to avoid a

rejection in prosecution, then tries to recapture some

of that claim scope in litigation. See Norian, 432 F.3d

at 1361 (“[I]t frequently happens that patentees

surrender more through amendment than may have

been absolutely necessary to avoid particular prior

art.”). And it is uniquely clear here that when Lilly

29

amended its claims, it did not lack the words to cover

Petitioners’ product:

it could have claimed

“pemetrexed,” as it did in other patents, but instead

chose to claim “pemetrexed disodium.” To resolve this

case would require little more than reaffirming the

principle articulated in Festo that all three

exceptions—including the “tangential” exception—

apply only where “the patentee could not reasonably

be expected to have described the insubstantial

substitute in question.” See 535 U.S. at 741.

CONCLUSION

For the foregoing reasons, this Court should grant

the petition for certiorari.

Respectfully submitted,

JOHN C. O’QUINN

Counsel of Record

WILLIAM H. BURGESS

C. ALEX SHANK

KIRKLAND & ELLIS LLP

1301 Pennsylvania Ave. NW

Washington, DC 20004

(202) 389-5000

john.oquinn@kirkland.com

Counsel for Petitioners

February 24, 2020