US Supreme Court Briefs

No. 00-1543

In the Supreme Court of the United States

FESTO CORPORATION, PETITIONER

v.

SHOKETSU KINZOKU KOGYO KABUSHIKI CO., ET AL.

ON WRIT OF CERTIORARI
TO THE UNITED STATES COURT OF APPEALS
FOR THE FEDERAL CIRCUIT

BRIEF FOR THE UNITED STATES
AS AMICUS CURIAE SUPPORTING VACATUR
AND REMAND

THEODORE B. OLSON
Solicitor General
Counsel of Record
STUART E. SCHIFFER
Acting Assistant Attorney
General
LAWRENCE G. WALLACE
Deputy Solicitor General
JEFFREY P. MINEAR
Assistant to the Solicitor
General
VITO J. DIPIETRO
ANTHONY J. STEINMEYER
JOHN FARGO
HOWARD S. SCHER
GRACE KARAFFA
Attorneys
Department of Justice
Washington, D.C. 20530-0001
(202) 514-2217

JAMES A. TOUPIN
General Counsel
JOHN M. WHEALAN
Solicitor
LINDA MONCYS ISACSON
CYNTHIA C. LYNCH
MARK NAGUMO
Associate Solicitors
United States Patent and
Trademark Office
Arlington, VA 22215

QUESTIONS PRESENTED

The doctrine of equivalents provides that a product or process that doesnot literally infringe upon the express terms of a patent claim may neverthelessbe found to infringe if there is an "equivalence" between theelements of the accused product or process and the claimed elements of thepatented invention. Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520U.S. 17, 21 (1997). That doctrine is limited by the concept of prosecutionhistory estoppel, which recognizes that, if a patent claim is amended duringpatent prosecution, the amendment may curtail application of the doctrineof equivalents to the amended claim. See id. at 30-34. The questions presentedin this case are:

1. Whether an amendment of a patent claim that narrows the scope of theclaim for any reason related to the statutory requirements for a patentgives rise to prosecution history estoppel with respect to the amended portionof the claim.

2. Whether an amendment of a patent claim that gives rise to prosecutionhistory estoppel completely precludes invocation of the doctrine of equivalentsfor the amended portion of the claim.

In the Supreme Court of the United States

No. 00-1543

FESTO CORPORATION, PETITIONER

v.

SHOKETSU KINZOKU KOGYO KABUSHIKI CO., ET AL.

ON WRIT OF CERTIORARI
TO THE UNITED STATES COURT OF APPEALS
FOR THE FEDERAL CIRCUIT

BRIEF FOR THE UNITED STATES
AS AMICUS CURIAE SUPPORTING VACATUR
AND REMAND

INTEREST OF THE UNITED STATES

Pursuant to the Patent Clause of the Constitution, U.S. Const. Art. I,§ 8, Cl. 8, Congress has charged the United States Patent and TrademarkOffice (PTO), an agency of the Department of Commerce, with responsibilityfor examining all patent applications to ensure that they satisfy the statutoryconditions for patentability. See 35 U.S.C. 131 (1994 & Supp. V 1999).In addition, the United States is regularly engaged in litigation over thevalidity and scope of patents, as a patent holder and as a defendant ininfringement actions. The United States accordingly has a strong interest,embracing a number of perspectives, in a stable, predictable, and efficientpatent system. The United States has a particular interest in ensuring thatthe doctrine of equivalents and the related concept of prosecution historyestoppel provide both a fair scope of patent protection and sufficient certaintyof a patent's limits to protect legitimate expectations while promotingcompetition and innovation.

STATEMENT

Petitioner Festo Corporation commenced a civil action in the United StatesDistrict Court for the District of Massachusetts alleging that respondentshad infringed two United States patents that Festo owns. Festo asserted,among other theories, infringement under the doctrine of equivalents. SeePet. App. 3a. The district court concluded that respondents had infringedthe patents, id. at 208a-209a, and the United States Court of Appeals forthe Federal Circuit affirmed the district court's judgment, id. at 190a-207a.This Court vacated the court of appeals' judgment and remanded the casefor further consideration in light of its decision in Warner-Jenkinson Co.v. Hilton Davis Chemical Co., 520 U.S. 17 (1997). See Shoketsu Kinzoku KogyoKabushiki Co. v. Festo Corp., 520 U.S. 1111 (1997).

On remand, the court of appeals affirmed the district court's judgmentin part and vacated and remanded in part. Pet. App. 156a-189a. The courtof appeals then granted a petition for rehearing en banc before 12 judgesof that court on five specific issues relating to the doctrine of equivalentsand the concept of prosecution history estoppel. Festo Corp. v. ShoketsuKinzoku Kogyo Kabushiki Co., 187 F.3d 1381 (Fed. Cir. 1999). Based on itsresolution of those issues, the en banc court reversed the district court'sjudgment of infringement. Pet. App. 1a-56a. Six of the court of appealsjudges wrote separately. See id. at 56a-64a (Plager, J., concurring); id.at 64a-69a (Lourie, J., concurring); id. at 69a-111a (Michel, J., concurringin part and dissenting in part); id. at 111a-113a (Rader, J., concurringin part and dissenting in part); id. at 113a-131a (Linn, J., concurringin part and dissenting in part); id. at 131a-155a (Newman, J., concurringin part and dissenting in part).

A. The Doctrine Of Equivalents And The Concept Of Prosecution HistoryEstoppel

This Court's decision in Warner-Jenkinson sets out the central principlesthat govern the doctrine of equivalents. "Under this doctrine, a productor process that does not literally infringe upon the express terms of apatent claim may nonetheless be found to infringe if there is 'equivalence'between the elements of the accused product or process and the claimed elementsof the patented invention." 520 U.S. at 21. "What constitutesequivalency must be determined against the context of the patent, the priorart, and the particular circumstances of the case." Id. at 24 (quotingalso Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 609(1950)).

The Court expressed concern in Warner-Jenkinson that the doctrine ofequivalents, as it had come to be applied before that decision, had "takenon a life of its own, unbounded by the patent claims." 520 U.S. at28-29. The Court observed that unbridled application of the doctrine conflictswith "the definitional and public-notice functions of the statutoryclaiming requirement." Id. at 29. It responded to that conflict bymaking clear that "[e]ach element contained in a patent claim is deemedmaterial to defining the scope of the patented invention, and thus the doctrineof equivalents must be applied to individual elements of the claim, notto the invention as a whole." Ibid. Furthermore, the Court emphasizedthat "[i]t is important to ensure that the application of the doctrine,even as to an individual element, is not allowed such broad play as to effectivelyeliminate that element in its entirety." Ibid.

The Court additionally recognized that the doctrine of equivalents isconstrained by "a well-established limit on nonliteral infringement,known variously as 'prosecution history estoppel' and 'file wrapper estoppel.'"Warner-Jenkinson, 520 U.S. at 30. That concept rests on the understandingthat, if a patent applicant narrows the scope of patent protection by claimamendments or other actions during the proceedings before the PTO to obtaina patent, the patent holder should not be allowed to argue, in a subsequentinfringement action, that the disclaimed subject matter is equivalent tothat which the applicant had actually claimed in its narrowing amendment.See id. at 30-34; Schriber-Schroth Co. v. Cleveland Trust Co., 311 U.S.211, 220-221 (1940).

The Court noted that prosecution history estoppel most frequently comesinto play when the applicant, in order to overcome a PTO patent examiner'srejections based on references to the prior art, narrows a portion of theapplicant's original claim and thereby effectively disavows that the subjectmatter excluded by the narrower claim is equivalent to that claim. See 520U.S. at 31 & n.5 (citing Exhibit Supply Co. v. Ace Patents Corp., 315U.S. 126 (1942), and other examples). But not every amendment gives riseto prosecution history estoppel. "Where the reason for the change wasnot related to avoiding the prior art, the change may introduce a new element,but it does not necessarily preclude infringement by equivalents of thatelement." Id. at 33. The Court "place[d] the burden on the patentholder to establish the reason for an amendment required during patent prosecution."Ibid. Where the patent holder fails to establish an explanation, a districtcourt "should presume that the patent applicant had a substantial reasonrelated to patentability for including the limiting element added by amendment"and "prosecution history estoppel would bar the application of thedoctrine of equivalents as to that element." Ibid.

B. The Relevant Facts

Festo owns the Stoll and Carroll patents, which disclose magnetic rodlesscylinder assemblies. The claimed devices employ a piston on the inside ofa cylinder, which moves in response to fluid under pressure, and a sleeveon the outside of the cylinder, which is magnetically coupled to the piston.Pet. App. 33a. The magnetic attraction between the sleeve and the pistoncauses the sleeve to follow the piston as it moves along the inside of thecylinder, thus enabling the sleeve to transport articles on a conveyingsystem. See ibid.

Claim 1 of the Stoll patent and Claim 9 of the Carroll patent describethe relevant features of the devices. See Pet. App. 31a-39a. Each of thoseclaims discloses, among other elements, a pair of sealing rings on the piston,having a lip on only one side, which contain fluid flow and exclude impurities.Id. at 34a-35a, 37a. In addition, Claim 1 of the Stoll patent disclosesa sleeve made of a magnetizable material. Id. at 34a. Respondents' accuseddevices differ in two respects. Those devices employ a single two-way sealingring, having a lip on both sides, which seals against fluid flow on bothsides of the ring. Id. at 38a. In addition, the outer portion of the sleevein respondents' accused devices is made of an aluminum alloy, a materialthat is not magnetizable. Id. at 38a-39a.

Claim 1 of the Stoll patent was amended during prosecution. Claim 1 originallyrecited "[a] linear motor for use in a conveying system" thatincluded "a piston which is slidable in said tubular part and whichhas sealing means at each end," and a piston and drive assembly "eachcarrying a drive magnet arrangement in the form of a hollow cylindricalassembly." Pet. App. 39a. The patent examiner rejected that claim,as well as the other claims contained in the Stoll application, under 35U.S.C. 112, because the "exact method of operation is unclear."Pet. App. 40a. The applicant amended its claims, reciting, among other things,the sealing ring structure and a sleeve of magnetizable material. Ibid.The applicant also stated, in accompanying remarks, that the sealing ringstructure made the amended claims distinguishable from prior art referencesthat the patent examiner had identified as possibly pertinent. Id. at 40a-41a.The patent examiner allowed the amended claims. Id. at 41a.

Claim 9 of the Carroll patent was also amended during patent prosecution,during a reexamination proceeding. Claim 1 of the original Carroll patentdid not recite sealing rings, but disclosed them in the written descriptionportion of the specification. Pet. App. 42a. The applicant thereafter submittedthe patent for reexamination in light of a German prior art reference thatdisclosed a similar device having several of the claimed features, includinga pair of sealing rings. Ibid. During the reexamination proceeding, theapplicant canceled Claim 1 and added Claim 9, which explicitly recited asealing ring structure that, according to the applicant, was distinguishablefrom the prior art. Id. at 42a-43a. The patent examiner allowed the amendedclaim. Id. at 43a.

C. The Pertinent Proceedings

The district court granted Festo summary judgment on the ground thatrespondents' devices infringed upon the Carroll patent under the doctrineof equivalents. Pet. App. 43a-44a. The district court found that respondentshad failed to come forward with material evidence rebutting Festo's experttestimony that the single two-way sealing ring that respondents employedin their devices was equivalent to the two sealing rings recited in theCarroll patent. Id. at 44a. Respondents did not argue that prosecution historyestoppel applied to the Carroll patent, id. at 53a n.8, but they did raisethat defense on summary judgment in response to Festo's argument that respondents'devices infringed upon the Stoll patent, id. at 43a-44a. The district courtrejected the defense, and Festo's assertion that respondents infringed uponthe Stoll patent was tried before a jury. Id. at 44a. The jury found, througha special verdict, that respondents' devices infringed upon the Stoll patentunder the doctrine of equivalents. Id. at 44a-45a.

The court of appeals initially affirmed the district court judgment.Pet. App. 190a-211a. On remand following this Court's decision in Warner-Jenkinson,the court of appeals affirmed in part. Id. at 156a-189a. The en banc courtultimately reversed the district court's decision in its entirety. Id. at1a-56a. The court decided the appeal by addressing five questions "relatingto the doctrine of equivalents that remained in the wake of" WarnerJenkinson, see id. at 2a-4a, 8a-32a, and then applying its legal determinationsto the relevant facts, id. at 4a, 45a-56a.

The court concluded in response to Question 1 that an amendment of apatent claim that narrows the scope of a claim for any reason related tothe statutory requirements for a patent will give rise to prosecution historyestoppel with respect to the amended portion of the claim. Pet. App. 3a,8a-11a. The court determined in response to Question 2 that a "voluntary"claim amendment can trigger prosecution history estoppel and should be treatedthe same as claim amendments made in response to a patent examiner's rejection.Id. at 3a-4a, 11a-13a. In response to Question 3, the court concluded that,when a claim amendment gives rise to prosecution history estoppel, the amendmentacts as a "complete bar" and precludes any invocation of the doctrineof equivalents for the amended portion of the claim. Id. at 4a, 13a-30a.In response to Question 4, the court ruled that "unexplained"amendments likewise are not entitled to any range of equivalents. Id. at4a, 31a. The court declined to decide Question 5, which asked whether ajudgment of infringement in this case would violate the "all elements"rule established in Warner-Jenkinson, because its resolution of the priorquestions, when applied to the facts of this case, rendered the questionmoot. Id. at 4a, 31a-32a.

The court of appeals applied its legal determinations to the facts ofthis case and concluded that those determinations mandated reversal of thedistrict court's decision. See Pet. App. 45a-56a. The court ruled that,because the relevant claim elements of the Stoll and Carroll patents werethe product of amendments that narrowed the claims, and because Festo didnot establish explanations for those amendments unrelated to patentability,the amendments gave rise to prosecution history estoppel, which completelybars the application of the doctrine of equivalents to the amended portionsof those claims. Id. at 56a. Four judges dissented in part from that ruling,objecting principally to the court's application of prosecution historyestoppel as a "complete" bar to invocation of the doctrine ofequivalents. See id. at 69a-70a (Michel, J.); id. at 111a-113a (Rader, J.);id. at 113a-114a (Linn, J.); id. at 131a-133a (Newman, J.).

SUMMARY OF ARGUMENT

This Court's decision in Warner-Jenkinson Co. v. Hilton Davis ChemicalCo., 520 U.S. 17 (1997), describes the interplay between the doctrine ofequivalents and prosecution history estoppel. That decision makes clearthat the doctrine of equivalents plays a carefully circumscribed role indetermining the scope of patent claims and that prosecution history estoppelremains an important limitation on the role of that doctrine. This casepresents two important questions respecting prosecution history estoppelthat Warner-Jenkinson did not expressly answer. They should be resolvedby reference to that decision and its recognition of the central balancethat must be struck between the public's need for clarity of patent coverageand the patent holder's need for fair protection from infringement.

A. The court of appeals correctly ruled that an amendment of a patentclaim that narrows the scope of the claim for reasons of patentability givesrise to prosecution history estoppel with respect to the amended portionof that claim. That result follows from this Court's decision in Warner-Jenkinson,which reaffirmed the longstanding principle that a patent applicant whonarrows the initial claims and effectively surrenders subject matter asa condition for obtaining a patent implicitly disclaims any right to a patentfor the subject matter that was surrendered. Nevertheless, a court mustcarefully analyze the claim amendment in the context of the alleged infringementto ensure that the amendment does indeed manifest a narrowing of the claimthat surrenders relevant subject matter. A court should apply prosecutionhistory estoppel only if the particular terms of the amendment narrow therelevant claim in that manner.

B. The court of appeals erred in ruling that a patent claim amendmentthat gives rise to prosecution history estoppel completely bars invocationof the doctrine of equivalents for the amended portion of the claim. Thecourt concluded that its prior approach to prosecution history estoppel,which applied a "flexible bar," was unworkable because it didnot provide certainty with respect to the scope of patent protection. Whilethat prior approach was unsatisfactory, the court's "complete bar"does not comport with this Court's measured perspective in Warner-Jenkinsonand fails to strike a sound balance between certainty of patent scope andfair protection of patent rights. In keeping with its approach in Warner-Jenkinson,this Court should hold the patent holder subject to a presumption that narrowingamendments preserved no range of equivalents. The patent holder could overcomethat presumption by showing a concrete basis, based on the patent prosecutionrecord and relevant to the specific context of the infringement suit, forextending the amended portion of the claim beyond its literal terms to encompassequivalent elements. That approach would substantially diminish the unacceptablyhigh level of uncertainty that presently inheres in the application of prosecutionhistory estoppel while fairly protecting the interests of patent holders.

C. Because the court of appeals erred in ruling that prosecution historyestoppel completely bars the doctrine of equivalents for amended claims,the court's judgment should be vacated and the case remanded for furtherproceedings. The court of appeals should remand the case to the districtcourt for a determination of whether the patent claims were narrowed ina way that would lead to prosecution history estoppel. If so, the courtshould place the burden on the patent holder to overcome the presumptionthat the literal terms of the relevant claim elements describe the fullscope of the patents.

ARGUMENT

THE COURT OF APPEALS CORRECTLY RULED THAT A PATENT CLAIM AMENDMENT THATNARROWS THE SCOPE OF A CLAIM GIVES RISE TO PROSECUTION HISTORY ESTOPPEL,BUT THE COURT ERRED IN HOLDING THAT PROSECUTION HISTORY ESTOPPEL COMPLETELYPRECLUDES APPLICATION OF THE DOCTRINE OF EQUIVALENTS

This Court's decision in Warner-Jenkinson Co. v. Hilton Davis ChemicalCo., 520 U.S. 17 (1997), has greatly clarified the role of the doctrineof equivalents in patent infringement suits. The Court has made clear thatthe scope of a patent is controlled primarily by the "statutory claimingrequirement" of the patent laws, see 35 U.S.C. 112, which requiresthe patent applicant to set out with precision the claim limitations thatdefine the scope of the invention. See 520 U.S. at 28-30. The patent claims,which serve both "definitional and public-notice" functions, id.at 29, establish the critical dimensions of a patent's protection. The doctrineof equivalents plays a strictly confined role in ascertaining those dimensionsin response to a claim of infringement. The doctrine-which takes into accountthat the limits of language may result in unavoidably imprecise patent claimsand that the patent owner is entitled to protection from infringement byproducts that differ only through insubstantial deviations from the patent'sverbal formulation-provides the patent holder with a limited measure ofprotection beyond the patent's literal terms. See id. at 28-29, 40.

Warner-Jenkinson has also clarified the relationship between the doctrineof equivalents and the concept of prosecution history estoppel. Prosecutionhistory estoppel, a judge-made principle that recognizes that patent claimamendments frequently result in a diminishment of the patent's scope, remainsan important limitation on the doctrine of equivalents. 520 U.S. at 30,33-34. But the Court made clear that the reason for the amendment is centralto the estoppel analysis. Id. at 30-31, 32. "Mindful that claims doindeed serve both a definitional and a notice function," the Court"place[d] the burden on the patent holder to establish the reason foran amendment required during patent prosecution." Id. at 33. If thepatent holder fails to come forward with a reason for amending an elementof the claim, then the district court "should presume that the patentapplicant had a substantial reason related to patentability for includingthe limiting element" and "prosecution history estoppel wouldbar the application of the doctrine of equivalents as to that element."Ibid.

This case presents two questions that Warner-Jenkinson did not explicitlydecide: (1) whether an amendment of a patent claim that narrows the scopeof the claim for any reason related to the statutory requirements for apatent gives rise to prosecution history estoppel with respect to the amendedportion of the claim; and (2) whether a patent claim amendment that givesrise to prosecution history estoppel completely precludes invocation ofthe doctrine of equivalents for the amended portion of the claim. The enbanc court of appeals answered each of those questions affirmatively.

We submit that the starting point of the analysis should be Warner-Jenkinson,which marks this Court's baseline for ascertaining the relationship betweenthe doctrine of equivalents and prosecution history estoppel. That decisionrecognizes the continued vitality of a properly limited doctrine of equivalents,520 U.S. at 21, but emphasizes the "definitional and public-noticefunctions of the statutory claiming requirement," id. at 29, and theimportant role that the PTO's patent prosecution process plays in ensuringthat the patent claims are stated with precision and limited to properlypatentable subject matter, id. at 33-34. The analysis should take accountof the central tension in patent law between the public's need for clarityof patent coverage, both to avoid trespassing on patent holders' rightsand to spur innovations, and the patent holder's need for fair protectionfrom infringement by products that differ only insubstantially from thepatented invention. See, e.g., Donald Chisum, The Scope Of Protection ForPatents After The Supreme Court's Warner-Jenkinson Decision: The Fair Protection-CertaintyConundrum, 14 Santa Clara Computer & High Tech. L.J. 1 (1998).

A. An Amendment Of A Patent Claim That Narrows The Scope Of A Claim ForReasons Related To The Statutory Requirements For A Patent Gives Rise ToProsecution History Estoppel With Respect To The Amended Portion Of TheClaim

The court of appeals correctly concluded that "a narrowing amendmentmade for any reason related to the statutory requirements for a patent willgive rise to prosecution history estoppel with respect to the amended claimelement." Pet. App. 9a. The court's ruling is consistent with Warner-Jenkinsonand rests on familiar principles of patent law.

1. Warner-Jenkinson rejected the argument that "any surrender ofsubject matter during patent prosecution, regardless of the reason for suchsurrender, precludes recapturing any part of that subject matter, even ifit is equivalent to the matter expressly claimed." 520 U.S. at 30.Rather, a district court faced with an assertion of prosecution historyestoppel in an infringement suit must examine "the reason for an amendment."Ibid. The Court indicated that prosecution history estoppel most commonlyarises as a result of "amendments made to avoid the prior art,"ibid., a reason that invariably gives rise to prosecution history estoppel.See, e.g., Exhibit Supply Co. v. Ace Patents Corp., 315 U.S. 126, 136 (1942);Keystone Driller Co. v. Northwest Eng'g Corp., 294 U.S. 42, 48 (1935); Smithv. Magic City Kennel Club, Inc., 282 U.S. 784, 789-790 (1931). The Courtfurther noted that prosecution history estoppel also arises from amendmentsmade to address a specific concern "that arguably would have renderedthe claimed subject matter unpatentable." Warner-Jenkinson, 520 U.S.at 30-31. See Crawford v. Heysinger, 123 U.S. 589, 606 (1887) (applyingprosecution history estoppel to amendments made in response to operabilityrejections).1

That conclusion has compelling force. A patent applicant who narrowsthe initial claims and effectively surrenders subject matter as a conditionfor obtaining a patent implicitly disclaims any right to a patent for thesubject matter that was surrendered. See, e.g., Exhibit Supply, 315 U.S.at 136; Cybor Corp. v. FAS Techs., Inc., 138 F.3d 1448, 1460 (Fed. Cir.1998) (en banc). As the court of appeals explained, it should not matterwhether the impetus was a prior art rejection or some other patent law requirement.Pet. App. 9a-11a. In either situation, the patent applicant, who presumablyseeks the broadest patent possible, has effectively made a public disclaimerof the surrendered subject matter in exchange for the patent. Prosecutionhistory estoppel simply implements the predictable consequence that theapplicant's patent rights are commensurately limited. The court of appealswas accordingly correct in concluding that a claim amendment gives riseto prosecution history estoppel whenever "the patent applicant hada substantial reason related to patentability for including the limitingelement added by amendment." Warner-Jenkinson, 520 U.S. at 33.

2. This Court's decision in Warner-Jenkinson indicates that discerninganalysis is nevertheless necessary when applying the court of appeals' ruling.An amendment, even one related to patentability, "does not necessarilypreclude infringement by equivalents of that element." 520 U.S. at33. As the court of appeals' post-Festo decisions emphasize, a claim amendmentdoes not give rise to prosecution history estoppel unless it manifests anarrowing of the patent claim that surrenders relevant subject matter. See,e.g., Turbocare Div. v. General Elec. Co., No. 00-1349 (Fed. Cir. Aug. 29,2001), slip op. 24-25; Lockheed Martin Corp. v. Space Sys./Loral, Inc.,249 F.3d 1314, 1326 (Fed. Cir. 2001); Litton Sys., Inc. v. Honeywell Inc.,238 F.3d 1376, 1380 (Fed. Cir.), petition for cert. pending, No. 00-1617(filed Apr. 23, 2001).2

Patent applicants may amend their patent claims for reasons of patentability-suchas to clarify an ambiguous term-that do not result in narrowing the claimsand surrendering subject matter. Rather, the amendments may state the same-orbroader-patent claims in more precise terms. For example, an applicant mayamend by rewriting a dependent claim as an independent claim. See HoneywellInt'l Inc. v. Hamilton Sundstrand Corp., No. Civ. A. 99-309 GMS, 2001 WL66348, at *6 (D. Del. Jan. 8, 2001) (citing Festo). Such amendments do notgive rise to prosecution history estoppel, which has as its core functions"preserving the notice function of the claims and preventing patentholders from recapturing under the doctrine of equivalents subject matterthat was surrendered before the Patent Office." Pet. App. 11a. Patentapplicants should not be deterred by the specter of prosecution historyestoppel from making amendments that preserve the claimed subject matterbut state their claims more precisely and thereby enhance the notice functionof the patent claims. Thus, even if a patent claim is amended for reasonsof patentability, a court should apply prosecution history estoppel onlyif the particular terms of the amendment narrow the relevant claim.3

B. An Amendment Of A Patent Claim That Gives Rise To Prosecution HistoryEstoppel Presumptively Precludes Invocation Of The Doctrine Of EquivalentsFor The Amended Portion Of The Claim

The court of appeals' conclusion that a narrowing amendment related topatentability gives rise to prosecution history estoppel leads directlyto the question of what effect the estoppel has in the infringement proceeding.The court of appeals concluded, as to that question, that "[w]hen aclaim amendment creates prosecution history estoppel with regard to a claimelement, there is no range of equivalents available for the amended claimelement." Pet. App. 13a-14a. Under the court's ruling, "[a]pplicationof the doctrine of equivalents to the claim element is completely barred."Id. at 14a. In this respect, it is our view that the court's ruling goestoo far.

1. The court of appeals based its decision to impose a "completebar" largely on "its special expertise" in resolving judiciallycreated rules of patent law and reconciling conflicts among its own decisions.Pet. App. 19a, 24a. The court detected two lines of authority among itsprecedents. In its view, decisions such as Hughes Aircraft Co. v. UnitedStates, 717 F.2d 1351 (Fed. Cir. 1983), treated prosecution history estoppelas imposing a "flexible bar" on the range of equivalents "withina spectrum ranging from great to small to zero," id. at 1363. Pet.App. 19a. But, according to the court, decisions such as Kinzenbaw v. Deere& Co., 741 F.2d 383 (Fed. Cir. 1984), cert. denied, 470 U.S. 1004 (1985),treated prosecution history estoppel as a "complete bar" thatprecluded the "speculative inquiry" of whether a narrowing amendmenthas preserved a range of equivalents beyond its literal terms, id. at 389.Pet. App. 20a-21a. See id. at 21a-24a (discussing commentary on the allegedlycontradictory lines of authority); but see id. at 91a-93a (Michel, J., dissentingin part) (disputing whether there are contradictory lines of authority);id. at 129a (Linn, J., dissenting in part) (same).

The court of appeals concluded that the flexible bar had proved "unworkable"because it does not provide "certainty as to the scope of patent protection."Pet. App. 24a-25a. According to that court, a flexible bar leaves the public,the patent holder, and competitors unable to predict until completion ofthe infringement suit "where the line of surrender is drawn,"id. at 25a, and fails "to enforce the disclaimer effect of a narrowingclaim amendment," id. at 26a. A complete bar, by contrast, "providesthe public and the patentee with definite notice as to the scope of theclaimed invention," id. at 28a, and allows competitors to improve and"design around" the claimed invention "without being inhibitedby the threat of a lawsuit" from developing new innovations, id. at30a. The court additionally noted that a complete bar "reins in thedoctrine of equivalents" and "reduces the conflict and tensionbetween the patent protection afforded by the doctrine of equivalents andthe public's ability to ascertain the scope of a patent." Ibid.

2. The policy concerns that led the court of appeals to adopt its "completebar" are substantial. The United States unsuccessfully petitioned fora writ of certiorari in Hughes Aircraft Co. v. United States, 140 F.3d 1470,reh'g denied over dissents, 148 F.3d 1384 (Fed. Cir. 1998), cert. denied,525 U.S. 1177 (1999), after a divided court of appeals subjected the governmentto an infringement judgment of more than $100 million based on that court'spre-Festo conception of prosecution history estoppel. As explained in thatpetition, the court's estoppel analysis "failed to recognize what [theapplicant] had surrendered when amending his patent claim in response toprior art." See Pet. at 16, United States v. Hughes Aircraft Co., cert.denied, 525 U.S. 1177 (1999) (No. 98-871).

While the court's pre-Festo practice did not sufficiently confine thedoctrine of equivalents, the court's adoption of a complete-bar rule failsto strike the right balance between the public interest in certainty ofpatent scope and the patent holder's interest in the fair protection ofthe patent right. This Court's conclusion in Warner-Jenkinson that the doctrineof equivalents retains vitality necessarily requires that the courts makean accommodation between those competing interests. That decision counselsin favor of imposing estoppel more rigorously, but it counsels against applyingprosecution history estoppel as a rigid and potentially unfair rule thatwould completely preclude resort to the doctrine of equivalents for amendedpatent claims.

First, Warner-Jenkinson indicates that a primary constraint on the doctrineof equivalents should involve analytic discipline by the courts when conductingthe fact-specific inquiry into whether two products or processes are equivalent.See 520 U.S. at 28-29. The Court adopted the all-elements test for preciselythat reason, id. at 29, and it further emphasized that the "focus onindividual elements and a special vigilance against allowing the conceptof equivalence to eliminate completely any such elements" are the appropriatemeans for confining the doctrine to its proper sphere, id. at 40. In effect,Warner-Jenkinson directs lower courts to construe equivalents as narrowlyas necessary, on a case-by-case basis, to preserve "the definitionaland public-notice functions of the statutory claiming requirement."Id. at 29; see also id. at 29-30.

Second, Warner-Jenkinson refused to adopt a similarly "rigid"rule for assessing prosecution history estoppel, notwithstanding the claritysuch a rule might impart, because it would have the effect of substantiallyundermining the stability of the PTO's patent prosecution process. See 520U.S. at 32 & n.6. The "complete bar" rule would have a similareffect. The holders of the "numerous patents which have not yet expired,"id. at 32 n.6-most of which contain amended claims-are properly chargedwith knowledge that narrowing amendments would give rise to prosecutionhistory estoppel, but they could not have anticipated that those amendmentswould necessarily result in an absolute bar to any range of equivalents.See Pet. App. 110a (Michel, J., dissenting in part); id. at 113a (Linn,J., dissenting in part). At the same time, current and future applicantscould be rendered reluctant to amend claims in pending applications forfear of eliminating protection against equivalents. That consequence wouldnot only discourage the give-and-take between the PTO patent examiners andapplicants that leads to more refined claims, see In re Zletz, 893 F.2d319, 322 (Fed. Cir. 1989), but it would also substantially diminish thefuture effectiveness of the court's complete bar in "rein[ing] in thedoctrine of equivalents," Pet. App. 30a. See id. at 108a-110a (Michel,J., dissenting in part); id. at 120a-121a (Linn, J., dissenting in part).Hence, the disadvantages that the Court in Warner-Jenkinson discerned witha "rigid rule" are also present here. There is, in short, a logicallimit to how much baggage the question whether or not there has been anamendment can be expected to carry in preventing the doctrine of equivalentsfrom "tak[ing] on a life of its own." Warner-Jenkinson, 520 U.S.at 28-29.

Third, Warner-Jenkinson makes clear that the concept of prosecution historyestoppel, even when applied in the most common context of determining theeffect of amendments designed to avoid prior art, may require some inquiryinto the record to determine what range of equivalents is precluded. TheCourt specifically pointed out that, in the case of such amendments, a courtmay permissibly consider "the manner in which the amendment addressedand avoided the objection." 520 U.S. at 33 n.7. This Court's past decisionslikewise acknowledge the relevance of such an inquiry. See Pet. App. 78a-84a(Michel, J., dissenting in part) (discussing Goodyear Dental Vulcanite Co.v. Davis, 102 U.S. 222 (1880), and Hurlbut v. Schillinger, 130 U.S. 456(1889)). The court of appeals' holding that a narrowing amendment relatedto patentability completely bars any equivalents would make that inquiryunnecessary.

3. This Court's decision in Warner-Jenkinson provides guidance on howto resolve the basic tension, common to the doctrine of equivalents andprosecution history estoppel, between the public's interest in certaintyand the patent holder's interest in a fair scope of protection. That decisionrecognized the value of regulating the use of prosecution history estoppelthrough burdens of proof and presumptions that accurately reflect the consequencesthat patent holders and competitors should reasonably expect to result fromclaim amendment. See 520 U.S. at 33. The Court can likewise use those constructsto formulate a proper role for prosecution history estoppel that promotesthe patent law's goal of providing certainty, without imposing an undulyrigid, and potentially draconian, rule.

In Warner-Jenkinson, the Court concluded that the patent holder bearsthe burden of "establish[ing] the reason for an amendment requiredduring patent prosecution." 520 U.S. at 33. If the patent holder failsto establish the reason, the district court "should presume that thepatent applicant had a substantial reason related to patentability"that "would bar the application of the doctrine of equivalents."Ibid. In this case, the Court can place a comparable burden on the patentholder to demonstrate that the applicant's narrowing amendments preserveda range of equivalents that provide a basis for asserting infringement.In the absence of a concrete showing, based on the patent prosecution recordand relevant to the specific context of the infringement suit, the districtcourt should presume that, when the applicant narrowed its claims to obtaina patent, it limited those claims to their literal terms.4

The patent holder rightly should bear the burden of demonstrating thatthe claim amendments preserve the type of equivalents at issue because thepatent laws themselves require the patent applicant to define claims withspecificity, 35 U.S.C. 112, "not only to secure to him all to whichhe is entitled, but to apprise the public of what is still open to them."McClain v. Ortmayer, 141 U.S. 419, 424 (1891). It is "just and fair,both to the patentee and to the public," to expect that the patenteewill "understand, and correctly describe, just what he has invented,and for what he claims a patent." Merrill v. Yeomans, 94 U.S. 568,573-574 (1877). When a patent applicant is faced with a rejection, the conscientiousapplicant will focus attention on the precise consequences of a narrowingamendment. In that situation, the applicant, who "is master of hisclaims," Pet. App. 67a (Lourie, J., concurring), can be expected togive especially fastidious attention to carefully defining the scope ofthe amended claim. It is accordingly "just and fair" to placethe burden on the patent holder to demonstrate that the claim amendmentspreserve the type of equivalents at issue in the infringement suit.

It is also "just and fair" to establish a presumption thatthe narrowing amendment states the exact limits of the patent claim. Whena patent applicant is faced with a rejection, the applicant has a particularlypowerful incentive to frame its narrowing amendment as expansively as possibleand to avoid surrendering any more subject matter than necessary to securethe patent. Indeed, the Court has stated that, when a patent applicant submitsa narrowing amendment to avoid prior art, the applicant by necessary implicationdisclaims the range of equivalents that falls between the original and theamended claims. See, e.g., Exhibit Supply, 315 U.S. at 136. Thus, patentholders have long been on notice that they cannot assume, without considerablerisk, that a narrowing amendment, made to overcome a patentability rejection,will embrace more than its literal terms. They must correspondingly drafttheir amendments with care.

The proposed presumption would preserve the full literal scope of theamended claim. A patent applicant who has made a narrowing amendment relatedto patentability can continue to claim infringement by a device that includes,for the amended element, a new element that falls outside of what the amendmentsurrendered. As this Court recognized in Exhibit Supply, a patent applicantthat narrows claims in response to a prior art rejection "recognize[s]and emphasize[s] the difference between the [original language and the amendedlanguage] and proclaim[s] his abandonment of all that is embraced in thatdifference." 315 U.S. at 136 (emphasis added). Hence, an applicantwho wishes to describe a means for joining two pieces of wood, but wishesto avoid prior art disclosing glue and wooden pegs, might use the term "metalfasteners"-rather than "screws" or "nails"-to ensureliteral coverage of the full range of metal fastening devices. An applicantdoes not surrender subject matter, including alternative means for accomplishingthe same result, that careful drafting has preserved. See, e.g., ACLARABiosciences, Inc. v. Caliper Techs. Corp., 125 F. Supp. 2d 391, 400-403(N.D. Cal. 2000).

But the presumption would require the patent holder to show a concretebasis, based on the patent prosecution record and relevant to the specificcontext of the infringement suit, for a non-literal extension of a claimelement that was narrowed to obtain a patent. This approach would have theadvantage of promoting the certainty of scope that the court of appealsfound lacking under its "flexible bar" jurisprudence. See Pet.App. 28a-30a. At the same time, it would prevent the injustice that couldresult from imposing a complete bar in certain exceptional situations wherethe preclusion of all equivalents would deny a patent holder a fair scopeof protection. Two such situations are apparent.

First, a patent holder should be allowed to assert that an accused deviceinfringes under the doctrine of equivalents if the court finds that theassertedly equivalent element is itself an innovation that was not knownto persons of ordinary skill in the art at the time the applicant amendedthe claim. Prosecution history estoppel rests on the rationale that theapplicant's claim amendment manifests a surrender of subject matter. Butthe applicant should not be charged with such a surrender if the equivalentsupposedly surrendered did not exist and was not reasonably within the contemplationof the PTO and the applicant at the time of the claim amendment. Rather,the patent holder should have the opportunity to establish that use of aninnovation satisfies the conditions for equivalence. See Pet. App. 111a-113a(Rader, J., dissenting in part); cf. Warner-Jenkinson, 520 U.S. at 37 ("theproper time for evaluating equivalency-and thus knowledge of interchangeabilitybetween elements-is at the time of infringement, not at the time the patentwas issued").

Second, a patent holder should be entitled to assert that an accuseddevice infringes under the doctrine of equivalents if the court concludesthat, owing to the nature of the subject matter at issue, it was not possiblefor one of ordinary skill in the art to draft a claim amendment that literallyencompassed the allegedly equivalent element while disclaiming the surrenderedsubject matter. The doctrine of equivalents arose from concerns that the"unsparing logic" of literalism can deny the patent holder fairpatent protection. Royal Typewriter Co. v. Remington Rand, Inc., 168 F.2d691, 692 (2d Cir.) (L. Hand, J.), cert. denied, 335 U.S. 825 (1948). Thecourts can properly insist that prosecution history estoppel requires applicantsto draft claim amendments to encompass literally all the equivalents theywish to include. But there may be some instances in which the literal termscannot reasonably describe all of the insubstantial substitutes that mightbe conceived for a particular element. In those instances, the doctrineof equivalents should be available to protect the patent holder from trivialor manifestly insubstantial changes that unambiguously deny the inventor"the benefit of his invention." Graver Tank & Mfg. Co. v.Linde Air Prods. Co., 339 U.S. 605, 607 (1950).

The courts should exercise discipline in assessing assertions from patentholders that claim amendments could not have been crafted with greater precision,lest they invite wholesale return to the court of appeals' "flexiblebar approach," which that court properly concluded is "unworkable."Pet. App. 25a. That inquiry should proceed as a matter of law. See Markmanv. Westview Instruments, Inc., 517 U.S. 370 (1996) (courts, rather thanjuries, construe patent claims). It is not likely to be burdensome becausethe courts have a ready benchmark for evaluating such claims. A court cancompare the actual claim amendment against the alternative claim formulationsthat a person of ordinary skill in the art could have adopted to provideliteral coverage of the alleged equivalent. Given the versatility of language,patent holders will face a substantial obstacle in overcoming the presumptionthat their narrowed claims encompass no more than they literally embrace.But that challenge would not be insurmountable if the technology is complexor the alleged distinctions are trivial. See Pet. App. 107a-108a (Michel,J., dissenting in part) (noting that certain fields, such as biotechnology,place particular demands on literalism in describing the scope of a claim).

Creating a presumption, rather than a complete bar, would not provideabsolute certainty respecting the scope of an amended patent claim. Buteven strictly literal interpretations of claims give rise to questions ofconstruction and, hence, even the court of appeals' complete bar cannotprovide absolute certainty. The position that we urge can substantiallydiminish the unacceptably high level of uncertainty that presently inheresin the application of prosecution history estoppel but still fairly protectthe interests of patent holders. Like the application of the doctrine ofequivalents itself, the application of the presumption would require courtsto exercise judgment and discipline to ensure that the patent claims remainthe primary source for determining the scope of patent protection. But thatexercise of judgment is unavoidable under a system of patent laws that seeksto balance the public's need for clarity of patent coverage against thepatent holder's need for fair protection from infringement.

C. The Court Of Appeals' Judgment Should Be Vacated And The Case ShouldBe Remanded To The District Court For Further Proceedings

The court of appeals concluded that, because the relevant claim elementsof the Stoll and Carroll patents were the product of amendments that narrowedthe claims, and because Festo did not establish explanations for those amendmentsunrelated to patentability, the amendments gave rise to prosecution historyestoppel, which had the effect of completely barring application of thedoctrine of equivalents to the amended portions of those claims. Pet. App.56a. If the Court concludes that the court of appeals erred in categoricallyimposing a complete bar, that court's judgment should be vacated and thecase should be remanded for further proceedings to determine what role,if any, the doctrine of equivalents should play in this infringement action.

Because the patent law landscape has changed considerably since the districtcourt initially entered its judgment in 1994, and because further assessmentof the facts may be necessary, the court of appeals should remand the caseto the district court for reconsideration in the first instance. The initialinquiry on remand should be whether the relevant claims of the Stoll andCarroll patents were narrowed by amendment, in a respect relevant to thealleged infringement, for reasons related to patentability. If so, thenprosecution history estoppel applies and the district court should placethe burden on Festo to show, from the patent prosecution record and thecharacteristics of the claimed infringement, that the presumption that theliteral terms of the relevant claim elements describe the full scope ofthe patents is unwarranted. Festo may make such a showing, for example,by demonstrating that the allegedly equivalent elements are later-developedtechnologies that were not known to persons of ordinary skill in the artand were therefore not surrendered through the claim amendments. Or Festomay make such a showing by demonstrating that persons of ordinary skillin the art could not reasonably have drafted a patent claim that literallyencompassed the allegedly equivalent elements.

CONCLUSION

The judgment of the court of appeals should be vacated and the case shouldbe remanded for further proceedings consistent with the foregoing analysis.

Respectfully submitted.

THEODORE B. OLSON
Solicitor General
STUART E. SCHIFFER
Acting Assistant Attorney
General
LAWRENCE G. WALLACE
Deputy Solicitor General
JEFFREY P. MINEAR
Assistant to the Solicitor
General
VITO J. DIPIETRO
ANTHONY J. STEINMEYER
JOHN FARGO
HOWARD S. SCHER
GRACE KARAFFA
Attorneys

JAMES A. TOUPIN
General Counsel
JOHN M. WHEALAN
Solicitor
LINDA MONCYS ISACSON
CYNTHIA C. LYNCH
MARK NAGUMO
Associate Solicitors
United States Patent and
Trademark Office

AUGUST 2001

1 The Court relied primarily on its own precedent to reject the argumentthat prosecution history estoppel applies without regard to the reason foran amendment. See Warner-Jenkinson, 520 U.S. at 30-31 & n.5. But theCourt also noted that the focus on patentability is appropriate in lightof patent policy and practice. The Court stated that there is "no substantialcause for requiring a more rigid rule," id. at 32, noting that thePTO may have relied upon a more "flexible" approach and that alteringcurrent practice "could very well subvert the various balances thePTO sought to strike when issuing the numerous patents which have not yetexpired," id. at 32 n.6.

2 See also Graco Children's Prods., Inc. v. Regalo Int'l, LLC, No. 97-CV-6885,2001 WL 392886, at *3-*4 (E.D. Pa. Apr. 17, 2001) (adding language to aclaim that merely restated a limitation that was already present did notgive rise to prosecution history estoppel because it did not narrow thescope of the claim); SRAM Corp. v. AD-II Eng'g, Inc., No. 00 C 6675, 2001WL 817857, at *10 (N.D. Ill. July 9, 2001) (an amendment to the patent specification,but not the patent claims, that overcame a rejection for indefinitenessby supplying the antecedent basis for a claim limitation did not triggerprosecution history estoppel because it did not narrow the scope of thepatent claim); see also TM Patents, LLP v. IBM Corp., 136 F. Supp. 2d 209,217 (S.D.N.Y. 2001) ("Festo, by its terms, applies only to amendmentsthat narrow the scope of patent claims."); Pickholtz v. Rainbow Techs.,Inc., 125 F. Supp. 2d 1156, 1161 (N.D. Cal. 2000) ("the court mustconsider whether the amendments 'narrowed the literal scope of the claim'").

3 Patent law requires a similar inquiry when a patent holder seeks reissuanceof a patent. See 35 U.S.C. 252 para. 1 (1994 & Supp. V 1999); see alsoPet. App. 76a-77a (Michel, J., dissenting in part). In that situation, theissue is whether a modification of claim language in the reissuance applicationactually changes the substantive scope of a claim limitation so as to "recapture"subject matter surrendered at the time of the original issuance. See Leggettv. Avery, 101 U.S. 256, 260 (1880). The recapture inquiry and the questionwhether a claim amendment gives rise to prosecution history estoppel areanalogous in that both look to and depend upon the same basic inquiry-whethera patentee surrendered subject matter during patent prosecution. See, e.g.,Hester Indus., Inc. v. Stein, Inc., 142 F.3d 1472, 1480-1483 (Fed. Cir.)(comparing the breadth and scope of original and amended claim limitations),cert. denied, 525 U.S. 947 (1998); see also Seattle Box Co. v. IndustrialCrating & Packing, Inc., 731 F.2d 818, 827-828 (Fed. Cir. 1984) (determiningwhether reissue claims have the same substantive scope as original claimsso that there is liability for pre-reissue activities).

4 This showing should focus on specific facts drawn from the intrinsicevidence reflected in the patent prosecution or the specific technologyinvolved that would lead one of ordinary skill in the art at the time ofthe amendment to conclude that the asserted equivalent was not fairly withinthe subject matter surrendered. Extrinsic evidence, such as expert testimony,might be used to explain but not to contradict such intrinsic evidence.Cf. Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582-1583 (Fed.Cir. 1996) (recognizing that extrinsic evidence may not be used to derogatefrom public record in construing patent claims).

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