festo v. shoketsu kinzoku kogyo kabushiki 1359 - berkeley law - home

1359FESTO v. SHOKETSU KINZOKU KOGYO KABUSHIKICite as 344 F.3d 1359 (Fed. Cir. 2003)

plain that the resulting agreement, if any,did not contain the crucial governmentalpromise to permit extended amortizationof goodwill. There was consequently nobinding contractual term that was breach-ed by the enactment of FIRREA, and thusno liability. And without liability, there isno need for us to reach the parties’ conten-tion regarding David L. Paul’s forfeitureunder the Forfeiture of False Claims Act.The summary judgment granted in favorof the government was therefore appropri-ate.

VI

In light of the discussion above, we con-clude that neither the FDIC nor the Paulsons have standing to sue the governmentfor a breach of contract; their dismissalfrom the case was correct. Because thereis no contract on which David L. Paul mayrecover against the United States, the trialcourt properly granted summary judgmentin favor of the government. Consequently,the judgment of the Court of FederalClaims is affirmed.

AFFIRMED.

,

FESTO CORPORATION,Plaintiff–Appellee,

v.

SHOKETSU KINZOKU KOGYO KA-BUSHIKI CO., LTD., a/k/a SMC Cor-poration, and SMC Pneumatics, Inc.,Defendants–Appellants.

No. 95–1066.

United States Court of Appeals,Federal Circuit.

Sept. 26, 2003.

Rehearing En Banc Denied Nov. 5, 2003.

Holder of two patents relating tomagnetically coupled rodless cylinders

sued competitor for infringement. TheUnited States District Court for the Dis-trict of Massachusetts, Patti B. Saris, J.,held for plaintiff, and competitor appealed.The Court of Appeals, 72 F.3d 857, af-firmed. On grant of writ of certiorari, theSupreme Court, 520 U.S. 1111, 117 S.Ct.1240, 137 L.Ed.2d 323, vacated and re-manded. On remand, the Court of Appealsinitially affirmed in part, vacated in part,and remanded, 172 F.3d 1361, but on re-hearing en banc, 187 F.3d 1381, reversed.Certiorari was granted. The SupremeCourt, vacated and remanded, 122 S.Ct.1831. On remand, the Court of Appeals,Lourie, Circuit Judge, held that: (1) factualissues existed as to whether ordinarilyskilled artisan at time of amendmentwould have thought aluminum sleeve wasobjectively unforeseeable equivalent ofmagnetizable sleeve; (2) patent holdercould not satisfy ‘‘tangential’’ criterion foraluminum sleeve equivalent; (3) patentholder could not satisfy ‘‘some other rea-son’’ criterion for aluminum sleeve equiva-lent; (4) factual issues existed as to wheth-er ordinarily skilled artisan at time ofamendment would have thought singletwo-way sealing ring was objectively un-foreseeable equivalent of two one-waysealing rings located at each end of piston;(5) patent holder could not satisfy ‘‘tangen-tial’’ criterion for two one-way sealingrings; and (6) patent holder did not estab-lish ‘‘some other reason’’ that patenteescould not reasonably have been expectedto describe single two-way sealing ring.

Remanded.Rader, Circuit Judge, filed concurring

opinion.Newman, Circuit Judge, filed opinion

concurring in part and dissenting in part,in which, Mayer, Circuit Judge, joined.

1. Patents O168(2.1)A narrowing amendment made to

comply with any provision of the Patent

1360 344 FEDERAL REPORTER, 3d SERIES

Act, including the means or step for provi-sion, may invoke an estoppel. 35 U.S.C.A.§ 112.

2. Patents O168(2.2)

A voluntary amendment may give riseto prosecution history estoppel in a patentinfringement case.

3. Patents O312(1.6)A patentee’s failure to overcome the

Warner–Jenkinson presumption, whichtreats a narrowing amendment as havingbeen made for a substantial reason relatedto patentability when the record does notreveal the reason for the amendment,gives rise to the Festo presumption, thatan ‘‘unexplained’’ narrowing amendmentsurrendered the entire territory betweenthe original and the amended claim limita-tions, but a patentee is entitled to rebutthat presumption.

4. Patents O312(1.6)A patentee’s rebuttal of the Warner–

Jenkinson presumption, which treats anarrowing amendment as having beenmade for a substantial reason related topatentability when the record does not re-veal the reason for the amendment, isrestricted to the evidence in the prosecu-tion history record.

5. Patents O314(5)Determinations concerning whether

the presumption of surrender of all subjectmatter between an original claim limitationand the amended claim limitation has aris-en, and whether it has been rebutted, arequestions of law for the court, not a jury.

6. Patents O312(1.6)A patentee may overcome the pre-

sumption of surrender of all subject matterbetween an original claim limitation andthe amended claim limitation by demon-strating that the alleged equivalent wouldhave been unforeseeable at the time of the

narrowing amendment, that the rationaleunderlying the narrowing amendment boreno more than a tangential relation to theequivalent in question, or that there was‘‘some other reason’’ suggesting that thepatentee could not reasonably have beenexpected to have described the allegedequivalent.

7. Patents O312(1.6)In the analysis of whether a patentee

has rebutted a presumption of surrenderof all subject matter between an originalclaim limitation and the amended claimlimitation, when determining whether analleged equivalent would have been objec-tively unforeseeable to one of ordinaryskill in the art at the time of the amend-ment, a district court may hear experttestimony and consider other extrinsic evi-dence relating to the relevant factual in-quiries.

8. Patents O312(1.6)Whether a patentee has established a

merely tangential reason for a narrowingamendment, in the analysis of whether apatentee has rebutted a presumption ofsurrender of all subject matter between anoriginal claim limitation and the amendedclaim limitation, is for the court to deter-mine from the prosecution history recordwithout the introduction of additional evi-dence, except, when necessary, testimonyfrom those skilled in the art as to theinterpretation of that record; inquiry fo-cuses on the patentee’s objectively appar-ent reason for the narrowing amendment.

9. Patents O324.60Factual issues existed as to whether

ordinarily skilled artisan at time of amend-ment would have thought aluminum sleevewas objectively unforeseeable equivalent ofmagnetizable sleeve, in context of inven-tion relating to magnetically coupled rod-less cylinders, and, consequently, remandto district court was warranted, to deter-


mine whether patentee could rebut pre-sumption of surrender of all subject matterbetween original claim limitation and filingof narrowing amendment.

10. Patents O312(1.6)

Patent holder could not satisfy ‘‘tan-gential’’ criterion for aluminum sleeveequivalent, in context of invention relatingto magnetically coupled rodless cylinders,and, therefore, patent holder could notovercome presumption of surrender of allsubject matter between original claim limi-tation and filing of narrowing ‘‘magnetiza-ble’’ amendment, since prosecution historydid not reveal any reason for ‘‘magnetiza-ble’’ amendment, and patent holder did nototherwise show that rationale for ‘‘magnet-izable’’ amendment was only tangential toaccused equivalent.

11. Patents O312(1.6)

Patent holder could not satisfy ‘‘someother reason’’ criterion for aluminumsleeve equivalent, in context of inventionrelating to magnetically coupled rodlesscylinders, and, therefore, patent holdercould not overcome presumption of surren-der of all subject matter between originalclaim limitation and filing of narrowing‘‘magnetizable’’ amendment, since therewas no linguistic or ‘‘other’’ limitation thatwould have prevented patentee from de-scribing accused equivalent.

12. Patents O168(3)

Patent holder presumptively dis-claimed devices that included somethingother than two sealing rings, in patentrelating to magnetically coupled rodlesscylinders, where patent holder amendedclaim during reexamination to require ‘‘apair of resilient sealing rings’’ and thatnarrowing amendment was made for rea-son of patentability.

13. Patents O168(3)Patentee presumptively surrendered

all ‘‘sealing means’’ other than two-ringstructures, in patent relating to magneti-cally coupled rodless cylinders, where orig-inal application recited linear motor thatincluded a piston having ‘‘sealing means ateach end,’’ and patentee amended claim torecite ‘‘first sealing rings’’ and ‘‘secondsealing rings’’ in response to examiner’srejection during prosecution.

14. Patents O324.60Factual issues existed as to whether

ordinarily skilled artisan at time of amend-ment would have thought single two-waysealing ring was objectively unforeseeableequivalent of two one-way sealing ringslocated at each end of piston, in inventionrelating to magnetically coupled rodlesscylinders, and, consequently, remand todistrict court was warranted, to determinewhether patentee could rebut presumptionof surrender of all subject matter betweenoriginal claim limitation and filing of nar-rowing amendment.

15. Patents O312(1.6)Patent holder could not satisfy ‘‘tan-

gential’’ criterion for two one-way sealingrings, which were located at each end ofpiston, to competitor’s accused one two-way sealing ring, in invention relating tomagnetically coupled rodless cylinders,and, therefore, patent holder could notovercome presumption of surrender of allsubject matter between original claim limi-tation and filing of narrowing ‘‘sealingring’’ amendment, since prosecution histo-ry indicated that ‘‘sealing ring’’ amend-ment was made to distinguish prior artpatents.

16. Patents O312(1.6)Patent holder did not establish ‘‘some

other reason’’ that patentees could not rea-sonably have been expected to describesingle two-way sealing ring, in invention


relating to magnetically coupled rodlesscylinders, and, therefore, patent holdercould not overcome presumption of surren-der of all subject matter between originalclaim limitation and amendment describingtwo one-way sealing rings, which were lo-cated at each end of piston; there was nolinguistic or ‘‘other’’ limitation preventingpatentee from describing equivalent, espe-cially where difference between claimedlimitation and accused equivalent was prin-cipally a difference in quantity.

Patents O328(2)

3,779,401, 4,354,125. Cited.

Charles R. Hoffmann, Hoffmann & Bar-on LLP, of Syosset, NY, argued for plain-tiff-appellee. With him on the brief wereGlenn T. Henneberger, and Anthony E.Bennett.

Arthur I. Neustadt, Oblon, Spivak,McClelland, Maier & Neustadt, P.C., ofArlington, VA, argued for defendants-ap-pellants. With him on the brief wereCharles L. Gholz, and Robert T. Pous. Ofcounsel on the brief was James B. Lam-pert, Hale and Dorr, LLP, of Boston, MA.

Lynn E. Eccleston, Eccleston LawFirm, of Washington, DC, for amicus curi-ae Bar Association of the District of Co-lumbia, Patent, Trademark & CopyrightSection.

J. Richard Manning, President, Wash-ington State Bar Association, of Seattle,Washington, for amicus curiae, Washing-ton State Bar Association. With him onthe brief were Jerry A. Riedinger andJames P. Donohue.

Joshua R. Rich, McDonnell BoehnenHulbert & Berghoff, of Chicago, IL, foramicus curiae, The Association of Patent

Law Firms. With him on the brief werePaul S. Tully and S. Richard Carden.

Kelly L. Morron, Chadbourne & ParkeLLP, of New York, NY, for amicus curiae,The Association of the Bar of the City ofNew York.

Claire Laporte, Foley Hoag LLP, ofBoston, MA, for amicus curiae The Feder-al Circuit Bar Association. With her onthe brief was Denise W. DeFranco. Ofcounsel on the brief was George E. Hutch-inson, Executive Director, Federal CircuitBar Association, of Washington, DC.

Nancy J. Linck, Sr. Vice President, Gen-eral Counsel & Secretary, Guilford Phar-maceuticals Inc., of Baltimore, MD, foramicus curiae, Biotechnology Industry Or-ganization.

Lawrence F. Scinto, Fitzpatrick, Cella,Harper & Scinto, of New York, NY, foramicus curiae, American Intellectual Prop-erty Law Association. With him on thebrief was Michael P. Sandonato. Of coun-sel on the brief were Ronald E. Myrick,President, American Intellectual PropertyLaw Association, of Arlington, VA; DavidG. Conlin P.C., Edwards & Angell, LLP, ofBoston, MA; and Janice M. Mueller, JohnMarshall Law School, of Chicago, IL.

Maxim H. Waldbaum, Salans, of NewYork, NY, for amicus curiae, FederationInternationale Des Conseils En ProprieteIndustrielle. Of counsel on the brief wereR. Danny Huntington, Burns, Doane,Swecker & Mathis, L.L.P., of Alexandria,Virginia; John P. Sutton, of San Francis-co, CA; Raymond C. Stewart, Birch, Stew-art, Kolasch & Birch, LLP, of FallsChurch, VA; and Tipton Jennings IV, Fin-negan, Henderson, Farabow, Garrett &Dunner, L.L.P., of Washington, DC.

Mark S. Davies, Attorney, Civil Division,Department of Justice, of Washington, DC,argued for amicus curiae, the UnitedStates. With him on the brief were Vito J.


DiPietro, Anthony J. Steinmeyer, andJohn Fargo, Attorneys. Of counsel on thebrief were James A. Toupin, GeneralCounsel; John M. Whealan, Solicitor;Thomas W. Krause, Cynthia C. Lynch, andLinda Moncys Isacson, Associate Solici-tors, United States Patent and TrademarkOffice, Office of the Solicitor, of Arlington,VA.

Nicholas J. Seay, Quarles & Brady LLP,of Madison, Wisconsin, for amicus curiae,The Wisconsin Alumni Research Founda-tion, et al. With him on the brief wereAnthony A. Tomaselli, Kristin GrahamNoel, and Josephine K. Benkers.

James P. Leeds, Eli Lilly and Company,of Indianapolis, IN, for amicus curiae, EliLilly and Company. With him on the briefwas Robert A. Armitage.

Kenneth C. Bass III, Sterne, Kessler,Goldstein & Fox, P.L.L.C., of Washington,DC, for amicus curiae, Sterne, Kessler,Goldstein, & Fox, P.L.L.C. With him onthe brief were David K.S. Cornwell andLinda E. Alcorn.

Richard F. Ziegler, Cleary, Gottlieb,Steen & Hamilton, of New York, NY, foramicus curiae, United Technologies Corpo-ration, et al. With him on the brief wasDavid H. Herrington.

Dan L. Bagatell, Brown & Bain, P.A., ofPhoenix, AZ, for amicus curiae, Intel Cor-poration.

Joshua D. Sarnoff, Glushko–SamuelsonIntellectual Property Law Clinic, Washing-ton College of Law, American University,of Washington, DC, for amicus curiae,Consumer Project on Technology.

Before MAYER, Chief Judge,NEWMAN and MICHEL, Circuit Judges,PLAGER, Senior Circuit Judge,*LOURIE, CLEVENGER, RADER,SCHALL, BRYSON, GAJARSA, LINN,DYK, and PROST, Circuit Judges.

Opinion for the court filed by CircuitJudge LOURIE, in which Circuit JudgeMICHEL, Senior Circuit Judge PLAGER,and Circuit Judges CLEVENGER,RADER, SCHALL, BRYSON, GAJARSA,LINN, DYK, and PROST join.Concurring opinion filed by Circuit JudgeRADER. Opinion concurring in part anddissenting in part filed by Circuit JudgePAULINE NEWMAN, in which ChiefJudge MAYER joins.

LOURIE, Circuit Judge.

This case is back to this court on re-mand from the Supreme Court of theUnited States for adjudication as to wheth-er prosecution history estoppel bars Festofrom relying on the doctrine of equivalentsin this patent infringement suit. FestoCorp. v. Shoketsu Kinzoku Kogyo Kabush-iki Co., 535 U.S. 722, 122 S.Ct. 1831, 152L.Ed.2d 944 (2002) (‘‘Festo VIII ’’). Thesole issue specifically before us is whetherFesto can rebut the presumption that thefiling of narrowing amendments for thetwo patents in suit surrendered all subjectmatter between the original claim limita-tions and the amended claim limitations.Id. at 741, 122 S.Ct. 1831. For the reasonsset forth herein, we conclude that Festocannot overcome that presumption bydemonstrating that the rationale underly-ing the narrowing amendments bore nomore than a tangential relation to the ac-cused equivalents or by demonstratingthat there was ‘‘some other reason’’ suchthat the patentee could not reasonably

* See 28 U.S.C. § 46(c)(2) (allowing senior cir-cuit judges ‘‘to continue to participate in thedecision of a case or controversy that was

heard or reheard by the court at a time whensuch judge was in regular active service’’).


have been expected to have described theaccused equivalents. However, we re-mand to the district court to determinewhether Festo can rebut the presumptionof surrender by establishing that theequivalents in question would have beenunforeseeable to one of ordinary skill inthe art at the time of the amendments.

BACKGROUND

Enough has been written about the factsand prior decisions in this case that weneed not provide more than a brief sum-mary here. This litigation began in 1988when Festo filed suit against ShoketsuKinzoku Kogyo Kabushiki Co. and SMCPneumatics, Inc. (collectively, ‘‘SMC’’) forinfringement of United States Patents4,354,125 (the ‘‘Stoll patent’’) and B13,779,401 (the ‘‘Carroll patent’’), which re-late to magnetically coupled rodless cylin-ders. The United States District Courtfor the District of Massachusetts grantedpartial summary judgment that SMC’s ac-cused device infringed claims 5, 6, and 9 ofthe Carroll patent under the doctrine ofequivalents, and a jury found that SMC’saccused device infringed claim 1 of theStoll patent under the doctrine of equiva-lents. Festo Corp. v. Shoketsu KinzokuKogyo Kabushiki Co., No. 88–1814–PBS(D.Mass. Oct. 27, 1994) (‘‘Festo I ’’).

After initially affirming the districtcourt’s judgment, Festo Corp. v. ShoketsuKinzoku Kogyo Kabushiki Co., 72 F.3d857 (Fed.Cir.1995) (‘‘Festo II ’’), vacatedand remanded, 520 U.S. 1111, 117 S.Ct.1240, 137 L.Ed.2d 323 (1997) (‘‘FestoIII ’’),1 we eventually took the case en bancto address certain issues relating to prose-cution history estoppel and the doctrine of

equivalents that ‘‘remained in the wake of’’the Supreme Court’s decision in Warner–Jenkinson Co. v. Hilton Davis ChemicalCo., 520 U.S. 17, 117 S.Ct. 1040, 137L.Ed.2d 146 (1997). Festo Corp. v. Shok-etsu Kinzoku Kogyo Kabushiki Co., 234F.3d 558, 563 (Fed.Cir.2000) (en banc)(‘‘Festo VI ’’). In our en banc decision, weheld that: (1) a ‘‘substantial reason relatedto patentability’’ that may give rise to anestoppel is not limited to overcoming priorart under 35 U.S.C. § 102 or § 103, butencompasses other reasons relating to thestatutory requirements for a patent, in-cluding compliance with 35 U.S.C. § 112,id. at 566; (2) a ‘‘voluntary’’ claim amend-ment—i.e., one neither required by a pat-ent examiner nor made in response to arejection by an examiner for a stated rea-son—may give rise to prosecution historyestoppel, id. at 568; (3) no range of equiva-lents is available for an amended claimlimitation when prosecution history estop-pel applies, id. at 569; and (4) ‘‘unex-plained’’ amendments are not entitled toany range of equivalents, id. at 578 (citingWarner–Jenkinson, 520 U.S. at 33, 117S.Ct. 1040). Applying those principles tothe facts of this case, we concluded thatthe limitations at issue in the Stoll andCarroll patents had been narrowed byamendments made during prosecution andreexamination, respectively, and that Fes-to had failed to establish reasons unrelatedto patentability for those amendments.Id. at 587–91. We therefore held that norange of equivalents was available for theamended claim limitations and reversedthe district court’s judgment of infringe-ment with respect to both patents. Id. at588–91.

1. On a first remand from the Supreme Court,a panel of this court again affirmed the dis-trict court’s judgment of infringement underthe doctrine of equivalents. Festo Corp. v.Shoketsu Kinzoku Kogyo Kabushiki Co., 172

F.3d 1361 (Fed.Cir.1999) (‘‘Festo IV ’’). Wethen granted SMC’s petition for rehearing enbanc. Festo Corp. v. Shoketsu Kinzoku KogyoKabushiki Co., 187 F.3d 1381 (Fed.Cir.1999)(‘‘Festo V ’’).


The Supreme Court then granted certio-rari to review our en banc decision. FestoCorp. v. Shoketsu Kinzoku Kogyo Kabush-iki Co., 533 U.S. 915, 121 S.Ct. 2519, 150L.Ed.2d 692 (2001) (‘‘Festo VII ’’). First,the Court agreed with our holding that ‘‘anarrowing amendment made to satisfy anyrequirement of the Patent Act may giverise to an estoppel.’’ Festo VIII, 535 U.S.at 736, 122 S.Ct. 1831. Second, however,the Court disagreed with our adoption of acomplete bar to the doctrine of equivalentswhen prosecution history estoppel arises.Id. at 737, 122 S.Ct. 1831. The Courtinstead established a presumption that anarrowing amendment made for a reasonof patentability surrenders the entire terri-tory between the original claim limitationand the amended claim limitation, and ex-plained that a patentee may overcome thatpresumption by showing that ‘‘at the timeof the amendment one skilled in the artcould not reasonably be expected to havedrafted a claim that would have literallyencompassed the alleged equivalent.’’ Id.at 741, 122 S.Ct. 1831. Specifically, theCourt enumerated the three ways in whichthe patentee may overcome the presump-tion—i.e., by demonstrating that ‘‘theequivalent [would] have been unforesee-able at the time of the [amendment],’’ 2

that ‘‘the rationale underlying the amend-ment [bore] no more than a tangentialrelation to the equivalent in question,’’ orthat ‘‘there [was] some other reason sug-gesting that the patentee could not reason-ably be expected to have described theinsubstantial substitute in question.’’ Id.at 740–41, 122 S.Ct. 1831. Observing thatthe narrowing amendments at issue in this

case were made for reasons of patentabili-ty, the Court remanded for this court orthe district court to determine in the firstinstance whether Festo can demonstratethat those narrowing amendments did notsurrender the particular equivalents inquestion. Id. The Court accordingly va-cated and remanded the judgment of ouren banc court. Id. at 742, 122 S.Ct. 1831.

On remand, we asked the parties tobrief the following issues:

1. Whether rebuttal of the presump-tion of surrender, including issuesof foreseeability, tangentialness,or reasonable expectations ofthose skilled in the art, is a ques-tion of law or one of fact; andwhat role a jury should play indetermining whether a patentowner can rebut the presumption.

2. What factors are encompassed bythe criteria set forth by the Su-preme Court.

3. If a rebuttal determination re-quires factual findings, thenwhether, in this case, remand tothe district court is necessary todetermine whether Festo can re-but the presumption that any nar-rowing amendment surrenderedthe equivalent now asserted, orwhether the record as it nowstands is sufficient to make thosedeterminations.

4. If remand to the district court isnot necessary, then whether Festocan rebut the presumption thatany narrowing amendment sur-

2. The Supreme Court referred to unforesee-ability both at the ‘‘time of the amendment’’and at the ‘‘time of the application.’’ FestoVIII, 535 U.S. at 738, 741, 122 S.Ct. 1831.We clarify that the time when the narrowingamendment was made, and not when theapplication was filed, is the relevant time for

evaluating unforeseeability, for that is whenthe patentee presumptively surrendered thesubject matter in question and it is at thattime that foreseeability is relevant. See Pio-neer Magnetics, Inc. v. Micro Linear Corp., 330F.3d 1352, 1357 (Fed.Cir.2003).


rendered the equivalent now as-serted.

Festo Corp. v. Shoketsu Kinzoku KogyoKabushiki Co., 304 F.3d 1289, 1290–91(Fed.Cir.2002) (order). We received briefsfrom the parties and fifteen amici curiae,and we heard oral argument on these is-sues.

DISCUSSION

A. Reinstatement of Our UndisturbedEn Banc Holdings

[1] Before addressing the four issuesbriefed by the parties, we first take thisopportunity to tie up the loose ends con-cerning our now-vacated holdings on thesubject of prosecution history estoppel.Although, as a technical matter, our earlieren banc decision was vacated and we arefree to revisit our prior conclusions, wereinstate those holdings of Festo VI thatwere not disturbed by the Supreme Court.To begin with, we recognize that the Courtexpressly endorsed our holding that a nar-rowing amendment made to comply withany provision of the Patent Act, including§ 112, may invoke an estoppel. FestoVIII, 535 U.S. at 736, 122 S.Ct. 1831; seealso Festo VI, 234 F.3d at 566.

[2] We next reinstate our holding thata ‘‘voluntary’’ amendment may give rise toprosecution history estoppel. Festo VI,234 F.3d at 568. That separate holdingwas not considered, and certainly was notrejected, by the Supreme Court. See Fes-to VIII, 535 U.S. at 727–28, 122 S.Ct. 1831.Moreover, it is consistent with the Court’sremand, and its reinstatement confirmswhat we have already determined by anoverwhelming 11–1 majority.

[3] In addition, we clarify that the Su-preme Court’s Warner–Jenkinson pre-sumption, which treats a narrowingamendment as having been made for a‘‘substantial reason related to patentabili-

ty’’ when the record does not reveal thereason for the amendment, 520 U.S. at 33,117 S.Ct. 1040, remains intact after theCourt’s Festo decision, although the conse-quences of failing to overcome that pre-sumption have been altered. In Festo VI,we held that such an ‘‘unexplained’’amendment completely estops a patenteefrom relying on the doctrine of equivalentsfor the narrowed claim limitation. 234F.3d at 578. Although the Supreme Courtrejected that ‘‘complete bar’’ approach, itconfirmed that a patentee’s failure to over-come the Warner–Jenkinson presumptiongives rise to the new Festo presumption ofsurrender. Festo VIII, 535 U.S. at 740,122 S.Ct. 1831 (‘‘[W]hen the court is unableto determine the purpose underlying anarrowing amendment—and hence a ratio-nale for limiting the estoppel to the sur-render of particular equivalents—the courtshould presume that the patentee surren-dered all subject matter between thebroader and the narrower language.’’). Apatentee is now entitled to rebut the pre-sumption that an ‘‘unexplained’’ narrowingamendment surrendered the entire territo-ry between the original and the amendedclaim limitations.

[4] Thus, the Warner–Jenkinson andFesto presumptions operate together inthe following manner: The first questionin a prosecution history estoppel inquiry iswhether an amendment filed in the Patentand Trademark Office (‘‘PTO’’) has nar-rowed the literal scope of a claim. Pio-neer Magnetics, Inc. v. Micro LinearCorp., 330 F.3d 1352, 1356 (Fed.Cir.2003).If the amendment was not narrowing, thenprosecution history estoppel does not ap-ply. But if the accused infringer estab-lishes that the amendment was a narrow-ing one, then the second question iswhether the reason for that amendmentwas a substantial one relating to patenta-bility. See id. When the prosecution his-


tory record reveals no reason for the nar-rowing amendment, Warner–Jenkinsonpresumes that the patentee had a substan-tial reason relating to patentability; conse-quently, the patentee must show that thereason for the amendment was not onerelating to patentability if it is to rebutthat presumption. See id. (citing Warner–Jenkinson, 520 U.S. at 33, 117 S.Ct. 1040).In this regard, we reinstate our earlierholding that a patentee’s rebuttal of theWarner–Jenkinson presumption is re-stricted to the evidence in the prosecutionhistory record. Festo VI, 234 F.3d at 586& n. 6; see also Pioneer Magnetics, 330F.3d at 1356 (stating that only the prose-cution history record may be considered indetermining whether a patentee has over-come the Warner–Jenkinson presumption,so as not to undermine the public noticefunction served by that record). If thepatentee successfully establishes that theamendment was not for a reason of patent-ability, then prosecution history estoppeldoes not apply.

If, however, the court determines that anarrowing amendment has been made fora substantial reason relating to patentabili-ty—whether based on a reason reflected inthe prosecution history record or on thepatentee’s failure to overcome the War-ner–Jenkinson presumption—then thethird question in a prosecution history es-toppel analysis addresses the scope of thesubject matter surrendered by the narrow-ing amendment. See Pioneer Magnetics,330 F.3d at 1357. At that point Festo VIIIimposes the presumption that the patenteehas surrendered all territory between theoriginal claim limitation and the amendedclaim limitation. See Festo VIII, 535 U.S.at 740, 122 S.Ct. 1831. The patentee mayrebut that presumption of total surrenderby demonstrating that it did not surrenderthe particular equivalent in question ac-cording to the criteria discussed below.Finally, if the patentee fails to rebut the

Festo presumption, then prosecution histo-ry estoppel bars the patentee from relyingon the doctrine of equivalents for the ac-cused element. If the patentee successful-ly rebuts the presumption, then prosecu-tion history estoppel does not apply andthe question whether the accused elementis in fact equivalent to the limitation atissue is reached on the merits.

B. The Roles of the Judge and Jury

We turn now to resolution of the fourissues that we asked the parties to briefafter the Supreme Court’s remand. Inresponse to our first question regardingthe proper roles of the judge and jury,Festo submits that, although the ultimatequestion whether prosecution history es-toppel applies may be a question of law,rebuttal of the presumption of surrender isa question of fact with underlying factualissues that should be determined by ajury. In contrast, SMC posits that rebut-tal of the presumption of surrender is aquestion of law for the court to decide andone in which a jury has no role to play.

[5] We agree with SMC that rebuttalof the presumption of surrender is a ques-tion of law to be determined by the court,not a jury. Prosecution history estoppelhas traditionally been viewed as equitablein nature, its application being ‘‘guided byequitable and public policy principles.’’Loctite Corp. v. Ultraseal Ltd., 781 F.2d861, 871 n. 7 (Fed.Cir.1985), overruled onother grounds by Nobelpharma AB v. Im-plant Innovations, Inc., 141 F.3d 1059,1068 (Fed.Cir.1998); see Black & Decker,Inc. v. Hoover Serv. Ctr., 886 F.2d 1285,1295 (Fed.Cir.1989); Builders Concrete,Inc. v. Bremerton Concrete Prods. Co., 757F.2d 255, 258 (Fed.Cir.1985). We havestated on numerous occasions that whetherprosecution history estoppel applies, andhence whether the doctrine of equivalents


may be available for a particular claimlimitation, presents a question of law.E.g., Bai v. L & L Wings, Inc., 160 F.3d1350, 1354 (Fed.Cir.1998); Cybor Corp. v.FAS Techs., Inc., 138 F.3d 1448, 1460(Fed.Cir.1998) (en banc). The SupremeCourt has recognized that, as a legal limi-tation on the application of the doctrine ofequivalents, prosecution history estoppel isa matter to be determined by the court.Warner–Jenkinson, 520 U.S. at 39 n. 8,117 S.Ct. 1040; see also Multiform Desic-cants, Inc. v. Medzam, Ltd., 133 F.3d 1473,1480 (Fed.Cir.1998) (‘‘The court deter-mines TTT whether there is any estoppelderived from the prosecution history thatbars remedy even when there is technolog-ic equivalencyTTTT’’). Questions relatingto the application and scope of prosecutionhistory estoppel thus fall within the exclu-sive province of the court. Accordingly,the determinations concerning whether thepresumption of surrender has arisen andwhether it has been rebutted are questionsof law for the court, not a jury, to decide.3

C. Rebuttal of the Festo Presumption

In response to our second question, theparties and several amici propose a vari-ety of factors that they argue ought to beencompassed by the Supreme Court’s testfor rebuttal; other amici, including theUnited States, suggest that we should re-frain from identifying such factors at thistime and instead should address the rele-vant factors as they arise in future cases.In addition, the parties offer divergentviews as to what evidence a court shouldconsider in determining whether a paten-tee has rebutted the presumption of sur-render. On the one hand, Festo submitsthat the district court should be permitted

to consider any relevant evidence, whetherdocumentary or testimonial, in evaluatingrebuttal of the presumption. On the otherhand, SMC argues that the court’s evalua-tion of a patentee’s rebuttal should bebased on the prosecution history record.

[6] In discussing its newly establishedpresumption, the Supreme Court madeclear that the patentee bears the burden ofshowing that a narrowing amendment didnot surrender a particular equivalent andexplained that a patentee may rebut thepresumption of surrender by showing that‘‘at the time of the amendment one skilledin the art could not reasonably be expectedto have drafted a claim that would haveliterally encompassed the alleged equiva-lent.’’ Festo VIII, 535 U.S. at 741, 122S.Ct. 1831. As indicated above, the Courtidentified the three ways in which the pat-entee may overcome the presumption.Specifically, the patentee must demon-strate that the alleged equivalent wouldhave been unforeseeable at the time of thenarrowing amendment, that the rationaleunderlying the narrowing amendment boreno more than a tangential relation to theequivalent in question, or that there was‘‘some other reason’’ suggesting that thepatentee could not reasonably have beenexpected to have described the allegedequivalent. Id. at 740–41, 122 S.Ct. 1831.Because we cannot anticipate all of thecircumstances in which a patentee mightrebut the presumption of surrender, webelieve that discussion of the relevant fac-tors encompassed by each of the rebuttalcriteria is best left to development on acase-by-case basis. However, we providethe following general guidance, which weapply to the patents in suit below, regard-

3. We recognize that rebuttal of the presump-tion may be subject to underlying facts, whichwe discuss in more detail below. Nonethe-less, the resolution of factual issues underly-ing a legal question may properly be decided

by the court. See, e.g., Markman v. WestviewInstruments, Inc., 52 F.3d 967, 980–81 (Fed.Cir.1995) (en banc), aff’d, 517 U.S. 370, 390,116 S.Ct. 1384, 134 L.Ed.2d 577 (1996)(claim construction).


ing the application of the three rebuttalcriteria.

[7] The first criterion requires a paten-tee to show that an alleged equivalentwould have been ‘‘unforeseeable at thetime of the amendment and thus beyond afair interpretation of what was surren-dered.’’ Id. at 738, 122 S.Ct. 1831. Thiscriterion presents an objective inquiry,asking whether the alleged equivalentwould have been unforeseeable to one ofordinary skill in the art at the time of theamendment. Usually, if the alleged equiv-alent represents later-developed technolo-gy (e.g., transistors in relation to vacuumtubes, or Velcrob in relation to fasteners)or technology that was not known in therelevant art, then it would not have beenforeseeable. In contrast, old technology,while not always foreseeable, would morelikely have been foreseeable. Indeed, ifthe alleged equivalent were known in theprior art in the field of the invention, itcertainly should have been foreseeable atthe time of the amendment. See PioneerMagnetics, 330 F.3d at 1357. By its verynature, objective unforeseeability dependson underlying factual issues relating to, forexample, the state of the art and the un-derstanding of a hypothetical person ofordinary skill in the art at the time of theamendment. Therefore, in determiningwhether an alleged equivalent would havebeen unforeseeable, a district court mayhear expert testimony and consider otherextrinsic evidence relating to the relevantfactual inquiries.

[8] The second criterion requires apatentee to demonstrate that ‘‘the ratio-nale underlying the narrowing amendment[bore] no more than a tangential relationto the equivalent in question.’’ Festo VIII,535 U.S. at 740, 122 S.Ct. 1831. In otherwords, this criterion asks whether the rea-son for the narrowing amendment was pe-ripheral, or not directly relevant, to the

alleged equivalent. See The AmericanHeritage College Dictionary 1385 (3ded.1997) (defining ‘‘tangential’’ as ‘‘[m]ere-ly touching or slightly connected’’ or‘‘[o]nly superficially relevant; divergent’’);2 The New Shorter Oxford English Dictio-nary 3215–16 (1993) (defining ‘‘tangential’’as ‘‘merely touch[ing] a subject or matter;peripheral’’). Although we cannot antici-pate the instances of mere tangentialnessthat may arise, we can say that an amend-ment made to avoid prior art that containsthe equivalent in question is not tangential;it is central to allowance of the claim. SeePioneer Magnetics, 330 F.3d at 1357.Moreover, much like the inquiry intowhether a patentee can rebut the Warner–Jenkinson presumption that a narrowingamendment was made for a reason of pat-entability, the inquiry into whether a pat-entee can rebut the Festo presumptionunder the ‘‘tangential’’ criterion focuses onthe patentee’s objectively apparent reasonfor the narrowing amendment. As wehave held in the Warner–Jenkinson con-text, that reason should be discerniblefrom the prosecution history record, if thepublic notice function of a patent and itsprosecution history is to have significance.See id. at 1356 (‘‘Only the public record ofthe patent prosecution, the prosecutionhistory, can be a basis for [the reason forthe amendment to the claim]. Otherwise,the public notice function of the patentrecord would be undermined.’’); Festo VI,234 F.3d at 586 (‘‘In order to give duedeference to public notice considerationsunder the Warner–Jenkinson framework,a patent holder seeking to establish thereason for an amendment must base hisarguments solely upon the public record ofthe patent’s prosecution, i.e., the patent’sprosecution history. To hold otherwise—that is, to allow a patent holder to rely onevidence not in the public record to estab-lish a reason for an amendment—would


undermine the public notice function of thepatent record.’’). Moreover, whether anamendment was merely tangential to analleged equivalent necessarily requires fo-cus on the context in which the amend-ment was made; hence the resort to theprosecution history. Thus, whether thepatentee has established a merely tangen-tial reason for a narrowing amendment isfor the court to determine from the prose-cution history record without the introduc-tion of additional evidence, except, whennecessary, testimony from those skilled inthe art as to the interpretation of thatrecord.

The third criterion requires a patenteeto establish ‘‘some other reason suggestingthat the patentee could not reasonably beexpected to have described the insubstan-tial substitute in question.’’ Festo VIII,535 U.S. at 741, 122 S.Ct. 1831. Thiscategory, while vague, must be a narrowone; it is available in order not to totallyforeclose a patentee from relying on rea-sons, other than unforeseeability and tan-gentialness, to show that it did not surren-der the alleged equivalent. Thus, thethird criterion may be satisfied when therewas some reason, such as the shortcomingsof language, why the patentee was pre-vented from describing the alleged equiva-lent when it narrowed the claim. When atall possible, determination of the third re-buttal criterion should also be limited tothe prosecution history record. For exam-ple, as we recently held in Pioneer Mag-netics, Inc. v. Micro Linear Corp., 330F.3d 1352 (Fed.Cir.2003), a patentee maynot rely on the third rebuttal criterion if

the alleged equivalent is in the prior art,for then ‘‘there can be no other reason thepatentee could not have described the sub-stitute in question.’’ Id. at 1357. We neednot decide now what evidence outside theprosecution history record, if any, shouldbe considered in determining if a patenteehas met its burden under this third rebut-tal criterion.4

D. The Patents in Suit

[9] Having set forth the general legalstandards that govern rebuttal of the pre-sumption of surrender, we turn now toFesto’s attempt to overcome that pre-sumption with respect to the Stoll andCarroll patents. In response to our thirdand fourth questions, Festo argues thatremand to the district court is necessary inthis case so that it may develop the recordaccording to the Supreme Court’s newlycreated rebuttal criteria. Festo maintainsthat it will present documentary and testi-monial evidence to demonstrate that thenarrowing amendments to the Stoll andCarroll patents did not surrender the twoequivalents in question. In contrast, SMCargues that further remand is not neces-sary because, as a matter of law, Festocannot rebut the presumption of surrenderwith respect to either accused equivalent.

Based on the parties’ arguments and theprosecution history record, we concludethat Festo cannot show that the ‘‘magnet-izable’’ and ‘‘sealing ring’’ amendments tothe Stoll and Carroll patents were ‘‘tan-gential’’ or were made for ‘‘some otherreason.’’ However, because there existfactual issues relating to the objective un-

4. Consistent with Supreme Court precedent,the holdings of that Court and our own re-garding the Festo presumption of surrenderand its rebuttal apply to all granted patentsand to all pending litigation that has not beenconcluded with a final judgment, includingappeals. See Harper v. Va. Dep’t of Taxation,509 U.S. 86, 97, 113 S.Ct. 2510, 125 L.Ed.2d

74 (1993) (‘‘When this Court applies a rule offederal law to the parties before it, that rule isthe controlling interpretation of federal lawand must be given full retroactive effect in allcases still open on direct review and as to allevents, regardless of whether such events pre-date or postdate our announcement of therule.’’).


foreseeability of the two accused equiva-lents, we remand to the district court todetermine whether Festo can rebut thepresumption of surrender by demonstrat-ing that the accused device’s aluminumsleeve and sealing ring elements wouldhave been unforeseeable to a person ofordinary skill in the art at the time of theamendments.

1. SMC’s Aluminum Sleeve

Claim 1 of the application that issued asthe Stoll patent originally recited a linearmotor having a piston, a driven assembly,and a magnet arrangement. Stoll amend-ed that claim during prosecution by, interalia, adding the limitation that the drivenmember include ‘‘a cylindrical sleeve madeof a magnetizable material.’’ 8125 patent,col. 6, ll. 2–3 (emphasis added). Becausethat narrowing amendment was made for areason of patentability, see Festo VIII, 535U.S. at 741, 122 S.Ct. 1831, Stoll presump-tively disclaimed the entire territory be-tween the original limitation and theamended limitation, i.e., any driven mem-ber that does not have ‘‘a cylindrical sleevemade of a magnetizable material.’’ SMC’saccused device includes a sleeve made ofaluminum, a nonmagnetizable material.Thus, the question before us is whetherFesto can show that the ‘‘magnetizable’’amendment did not surrender an alumi-num sleeve.5

First, we are unable to determinewhether Festo can satisfy the first rebuttalcriterion on the current record. Althoughit seems unlikely that an aluminum sleeve

would have been unforeseeable, as it wasmade of a commonly available metal, Festoargues that one skilled in the art at thetime of the ‘‘magnetizable’’ amendmentwould not have foreseen the interchangea-bility of an aluminum alloy sleeve and amagnetizable alloy sleeve in Stoll’s smallgap design involving rare earth magnets.Factual issues thus exist as to whether anordinarily skilled artisan would havethought an aluminum sleeve to be an un-foreseeable equivalent of a magnetizablesleeve in the context of the invention. Ac-cordingly, we remand to the district courton the question of unforeseeability to allowthe parties to introduce evidence on thisissue.

[10] Second, however, we concludethat Festo has failed to show that thereason for the ‘‘magnetizable’’ amendmentwas only tangentially related to SMC’s al-uminum sleeve. Festo argues that theoriginal claims in the Stoll patent were re-written as a single independent claim inresponse to a § 112, ¶ 1 rejection, in whichthe examiner questioned whether the in-vention was a motor or a clutch, and thatthe ‘‘magnetizable’’ limitation was unneces-sary to answer that question. Festo thusargues that the amendment was unneces-sary to respond to (and thus only tangen-tial to) the § 112 rejection; however, itfails to explain how the patentee’s ratio-nale for adding the term ‘‘magnetizable’’was only tangential, or peripheral, to theaccused equivalent of a nonmagnetizablealuminum sleeve. Because the prosecu-tion history reveals no reason for the

5. SMC argues that Festo is completely barredfrom relying on the doctrine of equivalents forthe ‘‘magnetizable’’ amendment because thatamendment was ‘‘unexplained.’’ However,as discussed above, an ‘‘unexplained’’ amend-ment—just like a narrowing amendmentmade for a reason of patentability—triggers arebuttable presumption that the patentee hassurrendered the entire territory between the

original and the amended limitations. SeeFesto VIII, 535 U.S. at 740, 122 S.Ct. 1831.Festo is thus entitled to attempt to rebut thepresumption of surrender for the ‘‘magnetiza-ble’’ amendment. In any event, the SupremeCourt made clear that the ‘‘magnetizable’’amendment gives rise to the Festo presump-tion of surrender. See id. at 741, 122 S.Ct.1831.


‘‘magnetizable’’ amendment, Festo VI, 234F.3d at 588, and because Festo still identi-fies no such reason, Festo has not shownthat the rationale for the ‘‘magnetizable’’amendment was only tangential to the ac-cused equivalent. We therefore concludethat Festo cannot satisfy the ‘‘tangential’’criterion for the aluminum sleeve equiva-lent.

[11] Third, we conclude that Festo haspointed to no ‘‘other’’ reason why the pat-entee could not reasonably have been ex-pected to have described an aluminumsleeve. Festo argues that it can satisfythe third rebuttal criterion by showingthat Stoll could not reasonably have beenexpected to have drafted a claim to coverwhat was thought to be an inferior andunacceptable design. That argument doesnot help Festo in satisfying the ‘‘other’’criterion; indeed, it suggests that Stollcould have described an aluminum sleevebut chose not to do so because that ‘‘inferi-or’’ element was not a part of his invention.In any event, it seems clear that there wasno linguistic or ‘‘other’’ limitation to pre-vent Stoll from describing the accusedequivalent. Although Stoll chose to claima ‘‘magnetizable’’ sleeve, he reasonablycould have been expected to have de-scribed a sleeve made of a common non-magnetizable material, such as aluminum,if that were what he intended to claim.For example, Stoll could have describedthe accused equivalent at various levels ofspecificity by using a common descriptiveterm such as ‘‘aluminum’’ or ‘‘metal.’’ Wetherefore conclude that Festo cannot satis-fy the third rebuttal criterion for the alu-minum sleeve equivalent.

2. SMC’s Sealing Ring

[12, 13] Both the Stoll patent and theCarroll patent include ‘‘sealing ring’’ limi-tations that were added by amendmentsmade in the PTO. With respect to the Stoll

patent, claim 1 of the original applicationrecited a linear motor that included a pis-ton having ‘‘sealing means at each end.’’In response to an examiner’s rejection dur-ing prosecution, Stoll amended claim 1 torecite ‘‘first sealing rings’’ and ‘‘secondsealing rings.’’ 8125 patent, col. 5, l. 37 &col. 6, l. 11. It must therefore be pre-sumed that Stoll surrendered all ‘‘sealingmeans’’ other than two-ring structures.With respect to the Carroll patent, claim 1of the original application made no refer-ence to sealing rings. During reexamina-tion, however, Festo (as assignee of theCarroll patent) amended claim 1 (as newclaim 9) to require ‘‘a pair of resilientsealing rings.’’ 8401 patent, col. 2, l. 14.Because that narrowing amendment wasmade for a reason of patentability, seeFesto VIII, 535 U.S. at 741, 122 S.Ct. 1831,Festo presumptively disclaimed devicesthat include other than two sealing rings.SMC’s accused device includes a singletwo-way sealing ring. Thus, the questionbefore us is whether Festo can demon-strate that the two ‘‘sealing ring’’ amend-ments did not surrender a single two-waysealing ring.

[14] First, we cannot determine fromthe current record whether the accusedsealing ring element would have been ob-jectively unforeseeable at the time of theamendments. Festo argues that SMC’stwo-way sealing ring was an inferior andunforeseeable equivalent of the one-waysealing rings located at each end of thepiston in the claimed invention. Factualissues thus exist as to whether a person ofordinary skill in the art would have consid-ered the accused two-way sealing ring tobe an unforeseeable equivalent of the recit-ed pair of sealing rings. We thereforeremand to the district court to determine,with the presentation of evidence as thecourt sees fit, the objective unforeseeabili-ty of a single two-way sealing ring.


[15] Second, however, we conclude thatFesto has not shown that the rationalesunderlying the ‘‘sealing ring’’ amendmentswere only tangentially related to a singletwo-way sealing ring. Festo argues thatthe ‘‘sealing ring’’ amendment in the Stollpatent was made to clarify the invention inresponse to a § 112 rejection, and that theamendment in the Carroll patent could nothave distinguished the prior art based onthe relevant aspect of the invention be-cause the prior art disclosed a pair ofsealing rings. Looking to the prosecutionhistory, however, we earlier concluded thatthe ‘‘sealing ring’’ amendments in both theStoll patent and the Carroll patent weremade to distinguish prior art patents.With respect to the Stoll patent, we deter-mined that the ‘‘sealing ring’’ amendmentwas made to distinguish two prior art pat-ents that did not disclose sealing rings.Festo VI, 234 F.3d at 589 (‘‘[N]either of[the two prior art patents] discloses theuse of structure preventing the interfer-ence by impurities located inside the tubeand on the outside of the tube while thearrangement is moved along the tube.’’).Similarly, with respect to the Carroll pat-ent, we stated that, even though a prior artpatent disclosed a piston with sealingrings, Festo distinguished that referenceby claiming a combination of features thatincluded a pair of sealing rings. Id. at591. Thus, we have already determinedthat the two ‘‘sealing ring’’ amendmentswere made to distinguish prior art patentsbased, at least in part, on the ‘‘sealingring’’ aspect of the invention. Nothing inthe prosecution history or the SupremeCourt’s opinion has changed the soundnessof those determinations. We thereforeconclude that Festo cannot establish thatthe rationales underlying the ‘‘sealingring’’ amendments were only tangentiallyrelated to SMC’s accused sealing ring.

[16] Third, we conclude that Festo hasnot established some ‘‘other’’ reason thatthe patentees could not reasonably havebeen expected to have described a singletwo-way sealing ring. Festo again arguesthat it can satisfy the third rebuttal crite-rion by showing that the patentees couldnot reasonably have been expected to havedrafted claims to cover an inferior andunacceptable design. We again rejectthat argument as unpersuasive because, ifthe patentees knew of an inferior designand chose not to include it within theclaims, then it cannot be said that theycould not have been expected to have de-scribed that design. Festo also arguesthat it would have been unreasonable tohave expected Stoll to have broadened theoriginal claim to cover the accused equiva-lent. Festo’s premise—that the originalclaim did not encompass an equivalenttwo-way sealing ring—is in error, howev-er. It overlooks our earlier conclusion,which we ratify here, that the original‘‘sealing means’’ limitation literally encom-passed structural equivalents under § 112,¶ 6. Id. at 589. Therefore, SMC’s singletwo-way sealing ring, if in fact equivalent,would have fallen within the literal scopeof the original claim, and Festo’s argu-ment cannot succeed. More to the point,it cannot be said that there was a linguis-tic or ‘‘other’’ limitation preventing Stolland Festo from describing the equivalentin question, especially where, as here, thedifference between the claimed limitationand the accused equivalent is principally adifference in quantity. Instead of reciting‘‘first sealing means TTT and second seal-ing means’’ or ‘‘a pair of TTT sealingrings,’’ the patentees easily could have en-compassed SMC’s sealing ring by claim-ing, for example, ‘‘at least one sealingring.’’ We therefore conclude that Festocannot rebut the presumption that Stolland Festo surrendered a single two-way


sealing ring under the third rebuttal crite-rion.

E. Remand

On remand, both parties may introduceevidence relating to the unforeseeability ofthe equivalents in question, as the trialcourt deems appropriate. If the court de-termines that Festo has failed to rebut thepresumption of surrender, then prosecu-tion history estoppel bars Festo from rely-ing on the doctrine of equivalents. If,however, the court determines that Festohas successfully rebutted the presumptionwith respect to either of the two accusedequivalents, then the court may reinstateits and the jury’s findings regarding equiv-alency in fact, as appropriate.

CONCLUSION

For the foregoing reasons, we concludethat Festo cannot overcome the presump-tion of surrender by showing that the nar-rowing amendments to the ‘‘magnetizable’’and ‘‘sealing ring’’ limitations of the Stolland Carroll patents were only ‘‘tangential’’or were made for ‘‘some other reason.’’However, we remand to the district courtto consider whether Festo can rebut thepresumption by demonstrating that thetwo accused equivalents would have beenunforeseeable to a person of ordinary skillin the art at the time of the amendments.

REMANDED.

RADER, Circuit Judge, concurring.

For a third (or perhaps a fourth) time,this court revisits some exceptions to anexception to an exception to the standardrule of infringement.1 These many pro-nouncements on such a fine point beg thequestion of why this court and the Su-preme Court have repeatedly returned tosuch a detail. A part of the answer is thatthese exceptions, like many facets of pat-ent law, do not affect solely infringementprinciples. Like the proverbial balloon, apinch on this backside of the law disruptssymmetry on the front side. In this case,the pinch to rein in the doctrine of equiva-lents disrupts a fundamental practice ofpatent acquisition, namely that nearly ev-ery patent faces amendment during prose-cution. While I concur in this court’s mostrecent pronouncement, I write separatelyto highlight the difficulty of preservingexpectations when frequently revisingstandards affecting the scope of patentcoverage. The principle of foreseeability,I conclude, focuses on the correct inquiriesto preserve expectations for patent hold-ers.

Before the Supreme Court ventured tocreate new presumptions for the exceptionto the exception to the standard rule forinfringement, claim amendments without afulsome explanation of purpose did not‘‘bar the application of the doctrine ofequivalents.’’ 2 Warner–Jenkinson Co. v.Hilton Davis Chem. Co., 520 U.S. 17, 33,117 S.Ct. 1040, 137 L.Ed.2d 146 (1997).

1. See Hilton Davis Chem. Co. v. Warner–Jen-kinson Co., 114 F.3d 1161 (Fed.Cir.1997) (enbanc ); Festo Corp. v. Shoketsu Kinzoku KogyoKabushiki Co., 234 F.3d 558 (Fed.Cir.2000)(en banc ) (Festo VI ); Johnson & JohnstonAssocs. Inc. v. R.E. Serv. Co., 285 F.3d 1046(Fed.Cir.2002) (en banc ). Counting the Su-preme Court’s opinions, this opinion is thefifth or sixth visit to these exceptions to theexception to the doctrine of equivalents. Fes-to Corp. v. Shoketsu Kinzoku Kogyo KabushikiCo., 535 U.S. 722, 122 S.Ct. 1831, 152L.Ed.2d 944 (2002) (Festo VIII ); Warner–Jen-

kinson Co. v. Hilton Davis Chem. Co., 520 U.S.17, 117 S.Ct. 1040, 137 L.Ed.2d 146 (1997).Of course, by counting Federal Circuit panelopinions on this topic, the number couldquickly rise into the dozens.

2. Moreover, due to the pressure to keep upwith rising patent filings, the prosecution pro-cess most often produces amendments with-out that fulsome explanation. According toUnited States Patent and Trademark Officestatistics, about 67,000 applications were filedin 1950, about 103,000 in 1970, about 165,-


Instead, a flexible rule permitted courts totailor the application of the doctrine ofequivalents to the intent and breadth ofthe amendment. Thus, under the flexiblerule, the courts genuinely sought to deter-mine the scope of the surrendered subjectmatter and to estop any recapture of thatscope under the doctrine of equivalents.3

An amendment during prosecution did notwork an entire forfeiture of equivalentsbeyond the scope of surrender. Of course,as documented by this court in Festo Corp.v. Shoketsu Kinzoku Kogyo Kabushiki Co.,234 F.3d 558 (Fed.Cir.2000) (en banc )(Festo VI ), this court’s first Festo en banc,that flexible rule engendered some impre-cision.4 Nonetheless that rule—now dis-carded—sought to preserve expectationsof patent applicants.

In response to the demise of the flexiblerule and the rise of new rules, an applicantmust now avoid amendments, file moreand increasingly specific claims (at the riskof prolonging the backlogged prosecutionprocess), resort to less precise functionalclaims to preserve a statutory equivalent,5

or perhaps even use continuation strate-gies 6 to protect claim scope. This court

and the Supreme Court necessarily dis-turbed some settled expectations in theprosecution process, Warner–Jenkinson,520 U.S. at 41, 117 S.Ct. 1040 (Ginsburg,J., concurring), to achieve more certaintyin the enforcement process. Doctrinalchanges in enforcement rules almost invar-iably affect as well the patent acquisitionprocess.

Without belaboring the point, I ventureto suggest that, at the pace of thesechanges in fundamental patent law, thenoble objective of bringing more certaintyto the doctrine of equivalents nonethelessexacts a price in unintended consequences.For instance, the Supreme Court’s strin-gent estoppel presumptions also entail con-siderable unanticipated arbitrariness be-cause examiners differ. Some examinersaggressively seek to narrow and defineclaims. Others demand far fewer amend-ments. Thus the application of the forfei-ture presumption often depends on theluck of the examiner draw. In any event,the new certainty rules for equivalents (arebuttable presumption that narrowingamendments erect a complete bar), at least

000 in 1990, and about 327,000 in 2001. U.S.Patent Activity, at http://www.uspto.gov/web/offices/ac/ido/oeip/taf/h counts.htm.

3. Litton Sys., Inc. v. Honeywell, Inc., 140 F.3d1449, 1462–64 (Fed.Cir.1998) (an amendmentbarred some equivalents but not others, andJenkinson Co. v. Hilton Davis Chem. Co., 520U.S. 17, 117 S.Ct. 1040, 137 L.Ed.2d 146(1997). Of course, by counting Federal Cir-cuit panel opinions on this topic, the numbercould quickly rise into the dozens.

Moreover, due to the pressure to keep upwith rising patent filings, the prosecution pro-cess most often produces amendments with-out that fulsome explanation. According toUnited States Patent and Trademark Officestatistics, about 67,000 applications were filedin 1950, about 103,000 in 1970, about 165,-000 in 1990, and about 327,000 in 2001.U.S. Patent Activity, athttp://www.uppto.gov/web/offices/ac/ido/oeip/taf/ counts.htm, remanding for factual deter-mination underlying prosectution history es-toppel); Dixie USA, Inc. v. Infab Corp., 927F.2d 584, 588 (Fed.Cir.1991)(an applicant

may ‘‘obtain some degree of equivalence evenin the face of prosecution history estoppel, TTT

a total preclusion of equivalence should notapply’’); Hughes Aircraft Co. v. U.S., 717 F.2d1351, 1362 (Fed.Cir.1983) (rejecting as a‘‘wooden application of estoppel’’ the viewthat vitually any amendment of the claimsbars all resort to the doctrine of equivalents).

4. The problem is defining the scope of thesurrender when an amendment literally aban-dons more subject matter than perhaps neces-sary to escape prior art or otherwise traversethe examiner’s rejection.

5. 35 U.S.C. § 112, paragraph 6 (2000), in-cludes a statutory equivalent as part of theliteral infringement inquiry.

6. See, e.g., Johnson & Johnston Assocs. Inc. v.R.E. Serv. Co., 285 F.3d 1046, 1055 (Fed.Cir.2002) (en banc ) (stating that while the doc-trine of equivalents does not extend to dis-closed but unclaimed subject matter, the ap-plicant may claim such subject matter in acontinuation).


for a period of time, may disrupt as muchcertainty as they provide. In particular,these new rules are likely to influence boththe patent acquisition and enforcementprocesses in unpredictable ways.

To make my point clearer, much of theunpredictability of these changes lies inthe pace of change. By common law stan-dards, this court’s jurisprudence moves ata lightning pace. This pace can engenderuncertainty about the consequences ofeach new rule. This court met en banc tocabin the doctrine of equivalents in 1995.A scarce few years later, the doctrine iscertainly more confined, but patent lawalso has numerous new rules affecting thescope of claims, the strategy of prosecut-ing a patent, and other aspects of inventionlaw. Trial courts and practitioners havelittle time to assess the full impact of onerule before hit with another or an excep-tion to the first. With exception added toexception, and presumptions rebutted bystill newer presumptions, a practitionercan scarcely predict the scope of claimsyears in the future, when they are likely tobe enforced, let alone the scope of claimsdrafted a few years ago when amendmentsdid not potentially forfeit claim scope. Inother words, the pace of the creation ofnew rules is itself disrupting the funda-mental principle of certainty in the scopeof patent claims.

With that word of caution about the paceand consequences of doctrinal shifts, Iwish to emphasize that the principle offoreseeability, adopted by the Supreme

Court, promises to bring the enforcementof the doctrine of equivalents together withthe expectations of the claim drafting pro-cess. With some period of stability anduniform application, the foreseeabilityprinciple promises to ease the pace anduncertainties inherent in this transition tonew rules. Ultimately, as this court hasnoted in the past, Sage Prods., Inc. v.Devon Indus., Inc., 126 F.3d 1420, 1425(Fed.Cir.1997), foreseeability is the over-arching principle that reconciles the noticefunction of claims with the protective func-tion of the doctrine of equivalents.

This reconciling principle is simple: thedoctrine of equivalents does not embracesubject matter that the patent draftercould have foreseen during the applicationprocess and thus could have included inthe claims. Thus, the literal scope of theclaims alone defines invention scope in anyforeseeable circumstances. At the sametime, the doctrine of equivalents protectsagainst insubstantial and unforeseeablecircumstances. The Supreme Court hasembraced that principle by stressing thatthis court must not apply ‘‘the completebar by another name.’’ Festo Corp. v.Shoketsu Kinzoku Kogyo Kabushiki Co.,535 U.S. 722, 741, 122 S.Ct. 1831, 152L.Ed.2d 944 (2002) (Festo VIII ). Becauseit continues to embrace the other aspectsof the ‘‘complete bar’’ it created in War-ner–Jenkinson, the Supreme Court positsforeseeability as an important way 7 to ren-

7. The tangentiality and ‘‘some other reason’’grounds for rebutting the complete surrenderpresumption are also important ways to ac-knowledge the drafter’s expectations whenapplying an estoppel. Tangentiality, in par-ticular, should permit courts to honor theobjective intent of amendments when seekingthe scope of the surrender of subject matter.In the facts of the Warner–Jenkinson case, forexample, the applicant amended the claim toescape prior art on the top end of the claimedpH range. The alleged infringer sought touse prosecution history estoppel to foreclose

use of the doctrine of equivalents to captureits product that used a pH below the claimedrange. In that case, the amendment’s surren-der of subject matter above the claimed rangemay diverge from or only bear a peripheralrelation to an equivalent beneath the claimedrange. Similarly, by its terms, the ‘‘someother reason’’ rebuttal grounds requirescourts to consider reasons, including as thiscourt notes ‘‘the shortcomings of language,’’that ‘‘the patentee could not reasonably beexpected to have described the insubstantialsubstitute in question.’’ Maj. op. at 1370 (cit-


der its complete bar estoppel presump-tions more sensitive to the patent drafter’s(and amender’s) expectations.

Upon reflection, foreseeability will con-tinue to emerge as the unifying principlethat justifies the doctrine of equivalentseven beyond the confines of rebutting es-toppel presumptions. Because the fore-seeability principle incorporates a realisticvision of what the applicant intended toachieve by claim drafting and amend-ments, this principle pledges to uphold,rather than disrupt, drafting expectations.The foreseeability principle has the virtueof placing the judicial enforcer at the tableof the patent drafter at the time of claim-ing or amending. From that vantagepoint and with knowledge of the prior art,the judge (guided by experts) can deducesomething close to the bounds that a care-ful drafter would have drawn to define theinvention.

Under the foreseeability principle, thedoctrine of equivalents will not encompassany accessible prior art because this sub-ject matter could have been included in theclaims. On the other hand, any after-arising technology or later developmentsor advances would not fall within the scopeof what the drafter should have foreseenand claimed. After all, a skilled patentdrafter is a legal technician, not an inven-tor.

This enterprise depends on the intenselyfactual considerations of the state of theart at the time of drafting. In applyingthe foreseeability exception, the trial courtmust assess the factual record of eventsduring prosecution, the factual contents ofcustom and usage of terms in the relevantart, the factual level of ordinary skill in theart, the factual bounds of the prior art, andthe factual understanding of a person ofordinary skill in the art at the time of

invention. A trial judge, who can freelyelicit evidence as needed and can directlyinteract with technical experts, is thus in abetter position to apply the foreseeabilityexception. By the same token, the trialjudge’s findings deserve deference fromthis court.

At this point the Supreme Court hasonly applied foreseeability to identify thescope of surrendered subject matter for anestoppel. But applying the foreseeabilityprinciple directly to bar foreseeable equiv-alents outside an amendment and estoppelcontext is very consistent with the Su-preme Court’s holding. This principle inoperation promises to preserve draftingexpectations while honoring the noticefunction of claims.

PAULINE NEWMAN, Circuit Judge,concurring in part, dissenting in part, inwhich MAYER, Chief Judge, joins.

Technology has come to dominate mod-ern industry and culture, and patent prin-ciples have evolved as a primary economicincentive for innovation. Our strength asa nation is grounded in our technologicleadership and entrepreneurial energy,and in our competitive vigor. The properbalance among invention, innovation, andcompetition is a matter of national con-cern. The doctrine of equivalents is partof that balance. The importance of theissue led the Federal Circuit and the Su-preme Court to reconsider this body oflong-established judge-made law.

The doctrine of equivalents was judicial-ly created in order to preserve the value ofpatents as against imitators, described inGraver Tank as the ‘‘unscrupulous copy-ist.’’ 339 U.S. 605, 607, 70 S.Ct. 854, 94L.Ed. 1097 (1950). The Court reaffirmedin Festo:

ing Festo VIII, 535 U.S. at 741, 122 S.Ct. 1831).


If patents were always interpreted bytheir literal terms, their value would begreatly diminished. Unimportant andinsubstantial substitutes for certain ele-ments could defeat the patent, and itsvalue to inventors could be destroyed bysimple acts of copying.

Festo Corp. v. Shoketsu Kinzoku KogyoKabushiki Co., 535 U.S. 722, 731, 122 S.Ct.1831, 152 L.Ed.2d 944 (2002). The Courtrecognized that ‘‘the doctrine of equiva-lents renders the scope of patents lesscertain,’’ id. at 732, 122 S.Ct. 1831, andthat ‘‘this uncertainty [is] the price of en-suring the appropriate incentives for inno-vation.’’ Id. In this context the Court,while rejecting the Federal Circuit’s impo-sition of an absolute bar to equivalency ofamended claim elements, did not return tothe status quo ante. Instead, in Festo theCourt brought increased rigor to the es-toppels generated during patent examina-tion.

A patentee’s access to infringement rem-edy under the doctrine of equivalents haslong been subordinate to the estoppels thatarise during examination. The patenteecannot reach, through equivalency, thatwhich was disclaimed in order to obtainthe patent. This requires judicial determi-nation of what was yielded during exami-nation, and its effect on particular allegedequivalents. The uncertainties of such de-termination has led to increasing con-straints on application of the doctrine. InFesto the Court acted to limit access toequivalency in the circumstance when aclaim, as initially presented by the appli-cant, had literally encompassed the devicelater alleged to be equivalent; when suchclaim was amended so that it no longerencompassed the alleged equivalent, theCourt held that estoppel presumptively ap-plies to the entire territory between thescope of the original proposed claim andthe claim as amended. This presumptioncan be rebutted, but only on grounds

‘‘where the amendment cannot reasonablybe viewed as surrendering a particularequivalent.’’ 535 U.S. at 740, 122 S.Ct.1831.

Thus the Court tightened access to thedoctrine of equivalents, for this presump-tion of surrender may arise even when theparticular equivalent was not described inprior art, and even when the alleged equiv-alent was not a ground of rejection andwas not disclaimed. When this presump-tion arises, rigorous criteria must be metfor rebuttal. These criteria reflect theadditional constraints that flow when theapplicant had initially presented claimsthat included the now-alleged equivalent.My concern with the actions of this courton remand is with its interpretation andapplication of this new presumption andthe Court’s rebuttal criteria.

The Court remanded, to this court andthe district court, for application of theseprinciples to Festo’s Carroll and Stoll pat-ents, and specifically for determination of‘‘what territory the amendments surren-dered’’ and ‘‘whether petitioner can dem-onstrate that the narrowing amendmentsdid not surrender the particular equiva-lents at issue.’’ Festo, 535 U.S. at 741, 122S.Ct. 1831. My colleagues now implementthe presumption of surrender in ways thatenlarge the surrendered territory, and im-plement the rebuttal analysis by convert-ing two of the Court’s three rebuttal crite-ria into questions of law and then decidingthem, sua sponte, without trial or record.My colleagues deny Festo’s request topresent evidence as to these issues despitetheir status as questions of first impres-sion.

From this flawed implementation of theCourt’s decision, I respectfully dissent.

I concur in the court’s ruling that de-termination of the presumption of surren-der and its rebuttal is for the court and


is decided without a jury, by analogy tothe decision in Markman v. Westview In-struments, Inc., 517 U.S. 370, 116 S.Ct.1384, 134 L.Ed.2d 577 (1996). I also con-cur in the remand to the district court fordetermination of the rebuttal issue of un-foreseeability, although I object to theprejudgments with which the remand isencumbered. I do not agree with thetreatment of the factual criteria of ‘‘tan-gentialness’’ and ‘‘other reasons’’ as ques-tions of law, or with the adjudication ofthese new issues without permitting evi-dence and argument in accordance withthe procedures of trial.

I

The doctrine of equivalents is not an endin itself. No patentee plans to rely onprotection outside of the patent’s claims, assupport for invention and investment.Disputed issues of equivalency generallyarise only after an innovative advance hasbeen successfully commercialized, and oth-ers appropriate the benefit thereof whileskirting the claims. Thus the doctrine ofequivalents is a tool of a technology-basedeconomy; it is an indicator of the policybalance between creativity and imitation.

A national economic policy that weighson the side of fostering development andinvestment in new technology will have adifferent approach to the law of equiva-lency than an economic policy aimed at fa-cilitating competition by minor change inexisting products. Any tightening or loo-sening of access to the doctrine of equiva-lents shifts the balance between inventorand copier. The high public interest inthis case reflects these fundamentals, for

the administration of this law affects ma-jor commercial and societal interests.The number and diversity of the amicuscuriae 1 briefs reflect the complexity ofthese concerns and the variety of view-points among technology-based enterpris-es. The public interest here is not in thefate of these litigants and these long-ex-pired patents; the interest is in the waythis judge made law affects technologicinnovation and competition.

II

The Supreme Court remanded with in-structions to determine, first, ‘‘what terri-tory the amendments surrendered,’’ Festo,535 U.S. at 741, 122 S.Ct. 1831, implement-ing the presumption of surrender thatarises when a claim as originally filed cov-ered the alleged equivalent, and was sub-sequently narrowed by amendment. Thefacts of the Carroll and Stoll patents raiseseveral issues of first impression, ques-tions whose resolution is fundamental toapplication of the Court’s new presump-tion.

For the Carroll reexamination patent,the only element for which equivalency isat issue is the claimed pair of sealing rings.The SMC devices use a single two-waysealing ring. The original Carroll patentclaims, as filed and prosecuted and grant-ed, did not include sealing rings or anyother sealing element. The broadest claimof the original patent was:

1. A device for moving articles com-prising a cylinder of non-ferrous materi-al, a piston including a permanent mag-

1. Briefs were filed by the American Councilon Education et al.; American IntellectualProperty Law Ass’n; Association of the Bar ofthe City of New York; Association of PatentLaw Firms; Bar Ass’n of the District of Co-lumbia; Biotechnology Industry Org.; Car-gill, Inc. et al.; Consumer Project on Technol-

ogy; Eli Lilly & Co.; Federal Circuit BarAss’n; Federation Internationale Des Conseilsen Propriete Industrielle; Intel Corp.; Sterne,Kessler, Goldstein, & Fox, P.L.L.C.; the Unit-ed States; and the Washington State BarAss’n.


net having a pole-piece on each axialside thereof, a body disposed outsideand adjacent to said cylinder, said bodyincluding a permanent magnet whichsubstantially surrounds the cylinder,there being a pole piece on each axialside of the permanent magnet includedin said body, and means for controllingthe admission of pressure fluid into thecylinder and exhaust of fluid from thecylinder for moving the piston in thecylinder, the attractive forces betweenthe permanent magnets being such thatmovement of the piston causes corre-sponding movement of the body below apredetermined load on the body andsuch that above said predetermined loadmovement of the piston does not causecorresponding movement of the body.

Festo requested reexamination in light ofpreviously uncited German references, un-related to the sealing rings element. Withthe reexamination application Festo pre-sented new claim 9, that contained all thelimitations of original patent claims 1, 2, 7,and 8, plus a clause to a pair of sealingrings:

a pair of resilient sealing rings situatednear opposite axial ends of the centralmounting member and engaging the cyl-inder to effect a fluid-tight seal there-with

During prosecution no rejection and noargument was directed to the sealingrings, although other elements of theclaims were mentioned by the applicantand the examiner. No amendment wasmade to the sealing rings in the reexami-nation application.

The Court’s new presumption of estop-pel is founded on the premise that thepatentee, by narrowing amendment, ‘‘dis-claimed’’ a ‘‘material difference’’ betweenthe claims before and after amendment.Festo, 535 U.S. at 734, 122 S.Ct. 1831,quoting Exhibit Supply Co. v. Ace Patents

Corp., 315 U.S. 126, 136–137, 62 S.Ct. 513,86 L.Ed. 736 (1942). The presumption ofsurrender requires that the claims as orig-inally presented covered the alleged equiv-alent and that the entire intervening terri-tory was presumptively yielded by theamendment.

Festo argues that no territory with re-spect to the sealing rings was surrenderedduring prosecution. Festo points out thatthe sealing rings could not have beenclaimed more broadly because the onlystructure disclosed in the specification isthe pair of sealing rings. Festo stressesthe Court’s statement that ‘‘What isclaimed by the patent application must bethe same as what is disclosed in the speci-fication; otherwise the patent should notissue.’’ 535 U.S. at 736, 122 S.Ct. 1831.The parties and the amici curiae recog-nized that there is a significant differencebetween claims that were initially of ascope that included the alleged equivalentand were narrowed by amendment thatexcluded the equivalent, and claims thatdid not include the equivalent and werenot narrowed by amendment.

My colleagues hypothesize that Festocould have presented a claim to ‘‘at leastone sealing ring,’’ and thus rule that thesurrendered territory includes the accusedSMC single sealing ring, although no suchclaim was requested. Festo points outthat if such a claim had been presented forreexamination it would have been subjectto rejection as new matter or for enlargedclaim scope prohibited by 35 U.S.C. § 305.Judicial hindsight is not a basis for rewrit-ing the prosecution record, and the pointsraised by Festo should not be ignored.The question of the scope of the presump-tively surrendered territory is material tothis remand, and to guide further applica-tion of the Court’s decision.

Related questions are present for theStoll patent. The elements for which


equivalency is at issue are the pair ofsealing rings and the sleeve of magnetiza-ble material. In the Stoll application bothof these elements were initially claimed,and the issue is the scope of the surren-dered territory. Like the Carroll patent,these aspects are not adequately consid-ered in the majority opinion.

The Stoll patent is the United Statescounterpart of a patent initially filed inGermany, and was filed as a translation ofthe German application. It containedclaims in a dependent form that did notconform to United States practice. Therelevant claims as initially filed follow, withemphases added to the elements for whichequivalency is at issue:

1. A linear motor for use in a con-veying system, said motor being opera-ble by a pressure medium and compris-ing a tubular part connectible to asource of the pressure medium, a pistonwhich is slidable in said tubular part andwhich has sealing means at each end forwiping engagement with an internalsurface of the tubular part and so as toform a seal for the pressure medium,and a driven assembly which is slidableon the tubular part and which has meansat each end for wiping engagement withan external surface of the tubular part,the piston and the driven assembly eachcarrying a drive magnet arrangement inthe form of a hollow cylindrical assem-bly, each magnet arrangement havingradial play relative to the adjacent sur-face of the tubular part, and surfaces ofthe magnet arrangements which face thetubular part being closely adjacent tothe respective surfaces of the tubularpart.

4. A linear motor according to any ofclaims 1 to 3, wherein the sealing meansof the piston comprise sealing rings andthe piston is provided with sliding guiderings near the sealing rings.

8. A linear motor according to any ofthe preceding claims wherein the drivenassembly is provided with a sleeve madeof magnetizable material, which encir-cles the hollow cylindrical assembly ofthe magnet arrangement.

The Examiner rejected all of the claimsunder § 112 ¶ 1, on the ground: ‘‘Exactmethod of operation unclear. Is device atrue motor or magnetic clutch?’’ The Ex-aminer also rejected claims 4–12 under§ 112 ¶ 2 for improper multiple dependentform. No other rejection was made. Inresponse Stoll changed ‘‘linear motor’’ to‘‘an arrangement,’’ and rewrote the claims.Stoll cancelled claim 1 and added claim 13that included, inter alia, the elements oforiginal claims 4 and 8:

13. In an arrangement having a hollowcylindrical tube and driving and drivenmembers movable thereon for conveyingarticles, the improvement comprising

wherein said tube is made of a non-magnetic material,

wherein said driving member is a pis-ton movably mounted on the inside ofsaid tube, said piston having a pistonbody and plural axially spaced, first per-manent annular magnets encircling saidpiston body,

said piston further including firstmeans spacing said first permanentmagnets in said axial spaced relation,the radially peripheral surface of saidmagnets being oriented close to the in-ternal wall surface of said tube,

said piston further including pluralguide ring means encircling said pistonbody and slidingly engaging said inter-nal wall and

first sealing rings located axially out-side said guide rings for wiping saidinternal wall as said piston moves alongsaid tube to thereby cause any impuri-ties that may be present in said tube tobe pushed along said tube so that said


first annular magnets will be free ofinterference from said impurities,

wherein said driven member includesa cylindrical sleeve made of a magnetiz-able material and encircles said tube,

said sleeve having plural axiallyspaced second permanent annular mag-nets affixed thereto and in magneticallyattracting relation to said first perma-nent annular magnets

and second means spacing said secondpermanent annular magnets in said axi-ally spaced relation, the radially innersurface of said magnets being orientedclose to the external surface of saidtube,

said sleeve having end face meanswith second sealing rings located axiallyoutside said second permanent annularmagnets for wiping the external wallsurface of said tube as said driven mem-ber is moved along said tube in responseto a driving movement of said piston tothereby cause any impurities that maybe present on said tube to be pushedalong said tube so that said second per-manent annular magnets will be free ofinterference from said impurities.

(Emphases added.) Claim 13 was allowedwithout rejection.

For the sealing rings, original claim 1recited ‘‘sealing means’’ for the internalsurface, original claim 4 claimed ‘‘sealingrings,’’ and new claim 13 claimed ‘‘firstsealing rings.’’ Festo argues that the orig-inal claims, construed in light of the speci-fication, do not include the SMC singletwo-way sealing ring. Festo also arguesthat since ‘‘sealing rings’’ were claimed inoriginal claim 4, the territory surrenderedbetween claim 4 and claim 9 does not

include the single two-way sealing ring.The issue of the role of subordinate claimsin determining the surrendered territory israised by the parties, for although claim 1is broader than claim 4, both were originalclaims. Resolution is necessary to thiscase.

For the sleeve of magnetizable material,a further variation arises. The sleeve ofmagnetizable material was claimed in orig-inal claim 8; its scope was not changed.Festo argues that since this element wasoriginally claimed, and was never nar-rowed by amendment, no territory wassurrendered. SMC argues that Stoll’soriginal claim 1 did not mention a sleeve ofany material, and therefore that this scopewas unlimited, and was narrowed whenclaim 1 was cancelled, despite the presenceof original claim 8. Again, the question ofthe role of subordinate claims in determin-ing the territory of surrender is squarelyraised, and requires resolution.

It is improper simply to assume that allpotential equivalents were surrendered inall cases, whatever the nature and scope ofthe original claims and whatever the rela-tion of the amendment to the originalclaims. These aspects have wide implica-tions, as the amici curiae recognized,2 andshould not be decided by indirection andwithout discussion.

III

The Court held that to rebut the pre-sumption of surrender the ‘‘patentee mustshow that at the time of the amendmentone skilled in the art could not reasonablybe expected to have drafted a claim thatwould have literally encompassed the al-

2. Various amicus briefs pointed out the com-plex implications for patent prosecution, for itis customary to present broad and successive-ly narrow claims, to rewrite or cancel claims,and to move elements between dependent and

independent claims. The amici pointed outthat such routine actions may now have un-foreseeable consequences, and impose newpitfalls, costs, and burdens on inventors.


leged equivalent.’’ 535 U.S. at 741, 122S.Ct. 1831. The Court identified threegeneral classes of rebuttal criteria: (1)unforeseeability of the equivalent; (2)whether the reason for the amendmenthad only a tangential relation to the equiv-alent; and (3) some other reason why thepatentee could not reasonably be expectedto have retained literal coverage of theequivalent. Id. at 740–741, 122 S.Ct. 1831.

The patentee must establish that al-though the entire intervening territory waspresumptively surrendered, the particularalleged equivalent was not surrendered.Festo states that it can meet the Court’srebuttal criteria, and has proffered evi-dence as to all three criteria. This courtnow denies Festo the opportunity to pres-ent evidence as to the two criteria of tan-gentialness and some other reason, estab-lishing these criteria as questions of law,not fact, and decides these questions offirst impression without development andwithout evidence. As to these criteria,Festo has been deprived of both trial andappeal.

1. Unforeseeability

I concur in the remand for trial of theissue of unforeseeability, although Istrongly object to the court’s inappropriateprejudgments of the facts on remand. Forexample, for the magnetizable sleeve, Fes-to states that it will present evidence that‘‘one skilled in the art at that time of theapplication would not have foreseen theinterchangeability of an aluminum alloysleeve with the sleeve of magnetizable ma-terial in the STOL small gap design.’’

Festo proffers evidence of the technologiccomplexity and state of understanding ofthe subject matter, the context in whichthe amendments were presented, the con-tent of the prior art, and the nature of theSMC equivalent material. My colleaguesannounce that it is ‘‘unlikely’’ that Festocan establish unforeseeability, because alu-minum is a ‘‘commonly available metal.’’However, the evidence on remand is enti-tled to be weighed at trial without thiscourt’s thumb on the scale.

The court also rules that known equiva-lents cannot be unforeseeable, stating thatany ‘‘alleged equivalent known in the priorart in the field of the invention, certainlyshould have been foreseeable at the timeof the amendment.’’ This is not the hold-ing of Pioneer Magnetics, Inc. v. MicroLinear Corp., 330 F.3d 1352 (Fed.Cir.2003), which the court cites as authority.In Pioneer Magnetics the court held thatwhen the alleged equivalent was describedin a reference that was cited during prose-cution, and the narrowing amendment‘‘was made to avoid the very prior art thatcontained the equivalent,’’ the equivalentthereby distinguished cannot have beenunforeseeable. The Pioneer rationale wasnot that the equivalent technology wasforeseeable because it was known, but thatit was foreseeable because it had beenspecifically cited and disclaimed duringprosecution. Those are not the facts ofthis case, for the amendments to the Car-roll and Stoll patents were not made toavoid the SMC equivalents or to distin-guish prior art that disclosed these equiva-lents.3

3. Several amici curiae pointed out the incon-gruity whereby equivalency in fact followsfrom known (foreseeable) interchangeability,see Warner–Jenkinson Co. v. Hilton DavisChemical Co., 520 U.S. 17, 25, 117 S.Ct. 1040,137 L.Ed.2d 146 (1997) (‘‘ ‘An important fac-tor is whether persons reasonably skilled inthe art would have known of the interchange-

ability of an ingredient not contained in thepatent with one that was.’ ’’) (quoting GraverTank & Mfg. Co. v. Linde Air Products Co., 339U.S. 605, 609, 70 S.Ct. 854, 94 L.Ed. 1097(1950)), yet the patentee must now prove un-foreseeability in order to gain access to thedoctrine of equivalents.


This question of first impression shouldbe remanded to the district court withoutencumbrance and without prejudgment,for appropriate exploration of the facts,and application of law to found facts. Theparties are entitled to the opportunity topresent evidence of this and the othercriteria of rebuttal, in the context and withthe safeguards of trial. See Icicle Sea-foods, Inc. v. Worthington, 475 U.S. 709,714, 106 S.Ct. 1527, 89 L.Ed.2d 739 (1986)(for ‘‘findings of fact essential to a properresolution of the legal question [the Courtof Appeals] should have remanded to theDistrict Court to make those findings’’);Pullman–Standard v. Swint, 456 U.S. 273,291–92, 102 S.Ct. 1781, 72 L.Ed.2d 66(1982) (‘‘[Factfinding] is the basic responsi-bility of district courts, rather than appel-late courts, and TTT the Court of Appealsshould not have resolved in the first in-stance this factual dispute which had notbeen considered by the District Court.’’)(quoting DeMarco v. United States, 415U.S. 449, 450, 94 S.Ct. 1185, 39 L.Ed.2d501 (1974)). (All alterations in original.)

2. Tangential Relation to the Reasonfor the Amendment

The Court ruled that there is no ‘‘call toforeclose claims of equivalence for aspectsof the invention that have only a peripher-al relation to the reason the amendmentwas submitted.’’ 535 U.S. at 738, 122 S.Ct.1831. Rebuttal on this ground may arise,for example, when a claim was amended todistinguish a specific reference, and theamendment also excluded subject matterthat was unrelated to the reference. Thusthe reason why a claim was amended maybe evidence of whether the alleged equiva-lent is sufficiently unrelated to the prose-cution rationale as to rebut the presump-tive surrender.

The court limits the evidence of thiscriterion to the prosecution record. How-

ever, the factors relevant to determinationof tangential relation are unlikely to residein the prosecution record, for unrelatedsubject matter or unknown equivalents areunlikely to have been discussed by eitherthe examiner or the applicant. The issueof ‘‘tangentialness’’ may require consider-ation of how the reason for an amendmentaffected the patentee’s view that certaintechnology was extraneous. The prosecu-tion record rarely discusses devices thatare not prior art.

Festo and amici curiae have describedvarious factors that may be relevant to thequestion of tangential or peripheral rela-tion, such as the nature of the prosecutionaction, the content of any references thatled to a narrowing amendment, and thedifferences between the claimed subjectmatter and the alleged equivalent. Theexample is offered that if the reason for anamendment were compliance with an en-ablement rejection, then it may be relevantwhether the later-arising equivalent couldbe practiced without undue experimenta-tion. Such evidence would not reside inthe prosecution record.

Festo had not been informed that itsevidence is limited to the prosecution rec-ord, upon which this court now decides theissue without Festo having had the oppor-tunity to prove its case. At the trial pros-ecution history estoppel was not at issue;SMC told the district court that ‘‘this isnot really a prosecution history estoppelcase.’’ Festo Corp. v. Shoketsu KinzokuKogyo Kabushiki Co., 72 F.3d 857, 863(Fed.Cir.1995). Now that it is such a case,Festo is surely entitled to develop an evi-dentiary record. The court’s refusal toremand on this ground of rebuttal, rulingthat evidence outside the prosecution rec-ord is not admissible, renders this rebuttalcriterion unlikely ever to be met.


3. Some Other Reason

The Court’s third rebuttal criterion of‘‘some other reason suggesting that thepatentee could not reasonably be expectedto have described the insubstantial substi-tute in question’’ avoids foreclosing theopportunity of rebuttal in unanticipatedsituations. It is unnecessary to rule inadvance that ‘‘some other reason’’ is nar-rowly limited to ‘‘shortcomings of lan-guage’’ and generally to the prosecutionrecord. Like tangentialness, if some otherreason arises that relates to the allegedequivalent, evidence would be more likelyto reside outside of the prosecution recordthan within it.

The Court’s concern with language ap-pears to be directed not to the simplemeaning of words, but to the prescience ofinventors as they explore new technology.Festo raises the argument that it ‘‘couldnot be expected to draft a claim to coverall insubstantial modifications an infringermay dream up;’’ indeed, this is a policyquestion of consequential impact on thecontent of patent specifications. Insofaras the ‘‘inadequacy of language’’ is consid-ered as a ground of rebuttal, the subjectengaged Judge Hand in Philip A. HuntCo. v. Mallinckrodt Chemical Works, 177F.2d 583 (2d Cir.1949), who observed that‘‘obviously it is impossible to enumerate allpossible variants. Indeed, some degree ofpermissible latitude would seem to followfrom the doctrine of equivalents, whichwas devised to eke out verbal insufficien-cies of claims.’’ Id. at 585.

This court, however, approaches the cri-terion of ‘‘some other reason’’ from theopposite direction, ruling that it is neces-

sary for Festo to show some reason that‘‘prevent[ed] Stoll from describing the ac-cused [aluminum] equivalent.’’ The courtimposes the requirement that the inventorwas actually prevented from describing anunknown equivalent, in order to rebut thepresumption of surrender—and that thereason was contained in the prosecutionhistory—a virtual impossibility.

All three classes of rebuttal raise ques-tions of fact and all raise questions of firstimpression, requiring full and fair explora-tion of the issues with benefit of the proce-dures of trial. The court’s limitation of thepresentation of evidence that may serve torebut the presumption of surrender con-stricts judicial ability to render a just deci-sion.

CONCLUSION

The Supreme Court in its Festo decisionbalanced the needs of patentees for ade-quate protection of their inventions, andthe needs of would-be competitors for ade-quate notice of the scope of that protec-tion. This court’s application of theCourt’s decision in Festo places new andcostly burdens on inventors, and reducesthe incentive value of patents. By adopt-ing a generous interpretation of the scopeof surrender, and stinginess toward itsrebuttal, the ensuing framework is onethat few patentees can survive.

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