Court Opinion

ID: 4661814
Source: CourtListenerOpinion
Date Created: 2021-02-22 16:00:43.037686+00
Date Added: 2024-06-11T08:02:16.467349
License: Public Domain

Case: 19-1704    Document: 57    Page: 1   Filed: 02/22/2021

   United States Court of Appeals
       for the Federal Circuit
                 ______________________

                     SYNQOR, INC.,
                       Appellant

                            v.

                VICOR CORPORATION,
                        Appellee
                 ______________________

                       2019-1704
                 ______________________

     Appeal from the United States Patent and Trademark
 Office, Patent Trial and Appeal Board in No. 95/001,702.
                   ______________________

                Decided: February 22, 2021
                 ______________________

    STEVEN J. HOROWITZ, Sidley Austin LLP, Chicago, IL,
 argued for appellant. Also represented by THOMAS D. REIN;
 MICHAEL D. HATCHER, Dallas, TX.

    MATTHEW A. SMITH, Smith Baluch LLP, Menlo Park,
 CA, argued for appellee. Also represented by ELIZABETH
 LAUGHTON; ANDREW BALUCH, Washington, DC.
                 ______________________

   Before DYK, CLEVENGER, and HUGHES, Circuit Judges.
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2                          SYNQOR, INC.   v. VICOR CORPORATION

    Opinion for the court filed by Circuit Judge HUGHES.

       Dissenting opinion filed by Circuit Judge DYK.

 HUGHES, Circuit Judge.

     SynQor, Inc. appeals the inter partes reexamination
 decision of the Patent Trial and Appeal Board holding un-
 patentable as obvious original claims 1–19, 28, and 31 of
 SynQor’s patent, U.S. Patent No. 7,072,190, as well as
 newly presented claims 34–38, which were proposed during
 the reexamination proceeding. Because decisions the
 Board made in previous reexamination proceedings pre-
 clude finding claims 1–19, 28, and 31 obvious based on the
 grounds relied upon by the Board, we vacate the Board’s
 decision as to those claims. And because the expiration of
 the ’190 patent renders any appeal of the Board’s decision
 regarding claims 34–38 moot, we also vacate the Board’s
 decision as to those claims.
                               I
     The ’190 patent, entitled “High Efficiency Power Con-
 verter,” issued on July 4, 2006, with a lineage of parent ap-
 plications dating back to a January 1997 provisional
 application. The ’190 patent counts itself part of an exten-
 sive family including two other patents that have been in-
 volved in litigation reaching this court: U.S. Patent
 Nos. 7,564,702 and 8,023,290. See Appellant’s Br. vi–viii.
 These patents disclose technology for DC-DC power con-
 verters used in large computer systems and telecommuni-
 cation and data communication equipment to convert
 direct electric current from one voltage to another. See
 SynQor, Inc. v. Artesyn Techs., Inc., 709 F.3d 1365, 1372–
 73 (Fed. Cir. 2013) (SynQor I). The patents claim a tech-
 nology SynQor dubs “Intermediate Bus Architecture,”
 which SynQor claims “improve[s] prior art systems by sep-
 arating the isolation and regulation functionality of DC-DC
 converters into two steps and using a single isolation stage
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 SYNQOR, INC.   v. VICOR CORPORATION                       3

 to drive multiple regulation stages.” Vicor Corp. v. SynQor,
 Inc., 869 F.3d 1309, 1313–14, 1316–17 (Fed. Cir. 2017)
 (SynQor II).
     The ’190 patent has a lengthy litigation history with
 multiple board decisions and appeals in this court. Only
 the portions relevant to this appeal are recited here.
     In 2011, SynQor asserted the ’190 patent, the ’702 pa-
 tent, and the ’290 patent, among others, against Vicor. See
 SynQor, Inc. v. Cisco Sys., Inc., No. 2:11CV54, 2014 WL
 1338712 (E.D. Tex. Jan. 2, 2014). Vicor petitioned for reex-
 amination of the ’190, ’702, and ’290 patents, arguing that
 the claims of the ’190 patent were unpatentable over two
 references: “Steigerwald,” U.S. Patent No. 5,377,090, in-
 cluding the text and drawings of U.S. Patent No. 5,274,539
 incorporated by reference, and “Cobos,” Cobos et al., “Low
 Output Voltage DC/DC Conversion,” 20th Int’l Conf. In-
 dus. Electronics, Control and Instrumentation (Sept. 5–9,
 1994) pp. 1676–81. In response, SynQor argued that an
 artisan would not have combined Steigerwald and Cobos
 because they taught circuits that operated at incompatible
 frequencies.
     On appeals from the reexaminations of the ’702 and
 ’290 patents, the Board affirmed that the challenged claims
 of the ’702 patent were not unpatentable, finding that
 “there are incompatibilities in frequency between [Cobos
 and Steigerwald].”       Vicor Corp. v. SynQor, Inc.,
 No. APPEAL 2014-007362, 2015 WL 1871498, at *12
 (P.T.A.B. Apr. 20, 2015). The Board likewise found the
 challenged claims of the ’290 patent not unpatentable
 based on a combination of Steigerwald, Cobos, and another
 reference. Vicor Corp. v. SynQor, Inc., No. APPEAL 2015-
 004509, 2016 WL 2344380, at *6–7 (P.T.A.B. May 2, 2016).
 The Board reasoned that SynQor’s evidence that Stei-
 gerwald and Cobos operated at incompatible frequencies
 was more credible than Vicor’s evidence to the contrary. Id.
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4                         SYNQOR, INC.   v. VICOR CORPORATION

     SynQor and Vicor appealed the decisions of the Board
 in the reexaminations of the ’702 and ’290 patents to this
 court. This court affirmed the patentability of the chal-
 lenged claims of the ’290 patent, holding that substantial
 evidence supported the Board’s finding that an artisan
 would not combine Steigerwald and Cobos because of their
 frequency incompatibility. SynQor II, 869 F.3d at 1320.
 The court also affirmed the Board’s decision finding the
 ’702 patent not unpatentable but was not asked to review
 and therefore did not reach the Board’s finding that Stei-
 gerwald and Cobos were incompatible. See generally Vicor
 Corp. v. SynQor, Inc., 706 F. App’x 673 (Fed. Cir. 2017).
     But as to the patent at issue here, the ’190 patent, the
 Board found instead that Steigerwald and Cobos were not
 incompatible. In concluding that the challenged claims of
 the ’190 patent were unpatentable over Steigerwald and
 Cobos, the Board was “not persuaded that the switching
 frequency differential is sufficient to render the combina-
 tion unsuitable.” Vicor Corp. v. SynQor, Inc., No. APPEAL
 2014-001733, 2016 WL 2344371, at *6 (P.T.A.B. May 2,
 2016). It found claim 34 unpatentable based on a new
 ground of rejection, see id. at *15, and SynQor opted to re-
 open prosecution of claim 34.
     The ’190 patent expired in January 2018. A year later,
 the Board issued its decision regarding the claim in the
 ’190 reexamination. The Board again rejected SynQor’s ar-
 gument that Steigerwald and Cobos had incompatible fre-
 quencies, concluding that “the evidence points strongly to
 the lack of a frequency range discrepancy between Cobos
 and Steigerwald.”        Vicor Corp. v. SynQor, Inc.,
 No. APPEAL 2018-000038, 2019 WL 852075, at *4
 (P.T.A.B. Feb. 19, 2019).
     SynQor timely appealed the Board’s final decision in
 the ’190 patent reexamination. We have jurisdiction under
 28 U.S.C. § 1295(a)(4)(A).
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 SYNQOR, INC.   v. VICOR CORPORATION                        5

                               II
      SynQor makes four arguments on appeal. First,
 SynQor argues that common law issue preclusion arising
 from the ’702 and ’290 patent reexaminations should have
 collaterally estopped the Board from finding that an arti-
 san would be motivated to combine Steigerwald and Co-
 bos. 1 Second, SynQor argues that the Board’s findings on
 the frequency (in)compatibility in the ’190 patent reexami-
 nation exhibit inadequately explained inconsistencies with
 the ’290 patent reexamination decision and within the two
 decisions issued in the ’190 patent reexamination, requir-
 ing vacatur under principles of administrative law. Third,
 SynQor argues that an additional obviousness ground un-
 der which the Board found claims 2–4 obvious, combining
 Steigerwald, Cobos, and a third reference, lacked substan-
 tial evidence that an artisan would combine Steigerwald
 with the third reference. Finally, SynQor argues that its
 appeal of the Board’s decision on newly presented claims
 34–38 became moot through the happenstance of patent ex-
 piration, so the Board’s decisions regarding those claims
 should therefore be vacated.

     1    Vicor argues that SynQor forfeited its issue preclu-
 sion argument by not raising it before the Board despite
 having the opportunity to do so. Appellee’s Br. 30. But
 SynQor could not have raised issue preclusion because nei-
 ther the ’702 nor ’290 patent reexaminations became final
 until after the Board’s decision regarding claims 1–19, 28,
 and 31. “[I]ssue preclusion applies even though the pre-
 cluding judgment . . . comes into existence while the case
 as to which preclusion is sought (this case) is on appeal.”
 MaxLinear, Inc. v. CF CRESPE LLC, 880 F.3d 1373, 1376
 (Fed. Cir. 2018) (quoting Soverain Software LLC v. Victo-
 ria’s Secret Direct Brand Mgmt., LLC, 778 F.3d 1311, 1315
 (Fed. Cir. 2015)).
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6                          SYNQOR, INC.   v. VICOR CORPORATION

     Because we agree with SynQor as to its first argument
 that issue preclusion compelled a finding that an artisan
 would not combine Steigerwald and Cobos—which resolves
 the parties’ dispute for claims 1–19, 28, and 31—we ad-
 dress only this argument and SynQor’s fourth argument as
 to the mootness of the Board’s decisions regarding claims
 34–38.
                               A
     “[T]he determination of a question directly involved in
 one action is conclusive as to that question in a second
 suit.” B & B Hardware, Inc. v. Hargis Indus., Inc., 575 U.S.
 138, 147 (2015) (quoting Cromwell v. County of Sac, 94 U.S.
 351, 354 (1877)). “It is well established that collateral es-
 toppel, also known as issue preclusion, applies in the ad-
 ministrative context.” MaxLinear, Inc., 880 F.3d at 1376.
 In fact, “because the principle of issue preclusion was so
 ‘well established’ at common law, in those situations in
 which Congress has authorized agencies to resolve dis-
 putes, ‘courts may take it as given that Congress has legis-
 lated with the expectation that the principle [of issue
 preclusion] will apply ‘except when a statutory purpose to
 the contrary is evident.’” B & B Hardware, 575 U.S. at 148
 (quoting Astoria Fed. Sav. & Loan Ass’n v. Solimino, 501
 U.S. 104, 108 (1991)).
      Thus, administrative decisions have preclusive effect
 “[w]hen an administrative agency is acting in a judicial ca-
 pacity and resolves disputed issues of fact properly before
 it which the parties have had an adequate opportunity to
 litigate.” B & B Hardware, 575 U.S. at 148–49 (quoting
 Univ. of Tenn. v. Elliott, 478 U.S. 788, 797–98 (1986)). “Alt-
 hough administrative estoppel is favored as a matter of
 general policy, its suitability may vary according to the spe-
 cific context of the rights at stake, the power of the agency,
 and the relative adequacy of agency procedures.” Astoria,
 501 U.S. at 109–10.
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 SYNQOR, INC.   v. VICOR CORPORATION                       7

     Applying these principles, we have already held that
 issue preclusion applies to inter partes reviews. See Papst
 Licensing GmbH & Co. KG v. Samsung Elecs. Am., Inc.,
 924 F.3d 1243, 1250–51 (Fed. Cir. 2019). Accordingly, we
 must decide “whether there is an ‘evident’ reason why Con-
 gress would not want [inter partes reexamination] deci-
 sions to receive preclusive effect, even in those cases in
 which the ordinary elements of issue preclusion are met.”
 B & B Hardware, 575 U.S. at 151. In doing so, we apply a
 “lenient presumption in favor of administrative estoppel.”
 Astoria, 501 U.S. at 112. If Congress did not foreclose the
 application of issue preclusion, we then “turn to whether
 there is a categorical reason why [inter partes reexamina-
 tion] decisions can never meet the ordinary elements of is-
 sue preclusion, e.g., those elements set out in § 27 of the
 Restatement (Second) of Judgments.” B & B Hardware,
 575 U.S. at 153. Absent any such categorical reasons, we
 turn to whether the elements of collateral estoppel are met
 in the specific factual circumstances here.
      The application of issue preclusion presents a question
 of law that we review de novo. See Shell Petroleum, Inc. v.
 United States, 319 F.3d 1334, 1338 (Fed. Cir. 2003).
                               1
     The statutory scheme governing inter partes reexami-
 nation shows no evident intent to foreclose common law es-
 toppel. 2 To the contrary, Congress enacted statutory

    2    The inter partes reexamination procedure ended
 with the passage of the America Invents Act. Pub. L.
 No. 112-29, 125 Stat. 284 (2011). As a consequence, our
 holding today is necessarily limited to remaining inter
 partes reexaminations. As of November 2020, only eight
 appeals and two requests for rehearing from inter partes
 reexaminations remained pending before the Board.
 See https://www.uspto.gov/dashboard/ptab/.
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8                         SYNQOR, INC.   v. VICOR CORPORATION

 estoppel provisions considerably more muscular than com-
 mon law collateral estoppel. In re Affinity Labs of Tex.,
 LLC, 856 F.3d 883, 890 (Fed. Cir. 2017) (“Congress enacted
 measures in the inter partes reexamination statute to ‘pre-
 vent abusive reexamination requests, including broad es-
 toppel provisions.’” (quoting 145 Cong. Rec. 26,984 (1999)
 (statement of Sen. Hatch))).
     The core estoppel provisions come from 35 U.S.C.
 §§ 315(c), 317(b) (2006). Section 315(c) prevents third-par-
 ties who successfully requested inter partes reexamina-
 tion, when sued for patent infringement under 28 U.S.C.
 § 1338, from asserting “the invalidity of any claim finally
 determined to be valid and patentable on any ground which
 the third-party requester raised or could have raised dur-
 ing the inter partes reexamination proceedings.” Sec-
 tion 317(b) provides for the converse of § 315(c), estopping
 “further validity challenges—using inter partes reexamina-
 tion—to the specific claims the validity of which had been
 previously resolved against the requester” in district court
 or in a prior inter partes reexamination. Affinity Labs,
 856 F.3d at 893. The provision implements a further codi-
 fication of common law claim preclusion principles.
     Uncodified § 4607 of the session law that enacted inter
 partes reexamination, the Optional Inter Partes Reexami-
 nation Procedure Act of 1999, provides for even more
 sweeping issue preclusion. Section 4607 estops “[a]ny
 party who requests an inter partes reexamination” from
 “challenging at a later time, in any civil action, any fact
 determined during the process of such reexamination, ex-
 cept with respect to a fact determination later proved to be
 erroneous based on information unavailable at the time of
 the inter partes reexamination decision.” Optional Inter
 Partes Reexamination Procedure Act of 1999, Pub. L.
 No. 106-113, 113 Stat. 1501A-567, 1501A-571, sec. 4607
 (emphasis added). Perhaps recognizing the breadth of this
 provision, Congress included a severability clause in this
 section. Id.
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 SYNQOR, INC.   v. VICOR CORPORATION                         9

      Admittedly, this provision does not facially establish
 the applicability of this preclusive factfinding to future in-
 ter partes reexaminations. But it is unlikely that a Con-
 gress amenable to precluding federal courts from
 considering fact questions traditionally submitted to a jury
 would object to those same conclusions binding the admin-
 istrative agency that resolved the factual questions. That
 Congress failed to expressly apply this provision to “any
 civil action or subsequent reexamination” makes no differ-
 ence when “courts may take it as given that Congress has
 legislated with the expectation that the principle [of issue
 preclusion] will apply except when a statutory purpose to
 the contrary is evident.” Astoria, 501 U.S. at 108.
     Vicor argues that Congress evinced its intent to fore-
 close common law estoppel in certain exceptions to §§ 315,
 317, and 4607 for challenges based on newly discovered
 prior art or information, and in Congress’s edict in
 35 U.S.C. § 312(a) (pre-AIA) that “[t]he existence of a sub-
 stantial new question of patentability is not precluded by
 the fact that a patent or printed publication was previously
 cited by or to the [Patent and Trademark] Office or consid-
 ered by the Office.” Vicor argues that common law estoppel
 would subsume these exceptions. But common law preclu-
 sion would not apply to newly discovered prior art, as the
 import of that prior art necessarily cannot have been “ac-
 tually litigated.” Similarly, preclusion based on prior art
 previously cited to the PTO or considered by the PTO would
 only be appropriate when “actually litigated”—in which
 case, by definition, the assertion of that prior art could not
 raise a “substantial new question of patentability.” The
 statutory scheme governing inter partes reexaminations is
 fully consonant with common law estoppel.
                               2
     That leaves the question of whether inter partes reex-
 aminations categorically fail to meet the ordinary elements
 of issue preclusion. We follow the Supreme Court in
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 10                          SYNQOR, INC.   v. VICOR CORPORATION

 looking to the Restatement (Second) of Judgments for guid-
 ance to determine whether “categorical reason[s]” exist
 that inter partes reexamination cannot satisfy the ordinary
 elements of issue preclusion. B&B Hardware, 575 U.S. at
 152–53; see Power Integrations, Inc. v. Semiconductor Com-
 ponents Indus., LLC, 926 F.3d 1306, 1311–12 (Fed. Cir.
 2019) (applying the Restatement (Second) of Judgments to
 evaluate the preclusive effect of a prior IPR).
     Section 83 of the Restatement gives five non-exclusive
 factors to evaluate whether an administrative tribunal’s
 decision meets the “essential elements of adjudication.”
 See Restatement (Second) of Judgments § 83(2) (1982).
 These factors “include”
      [1] Adequate notice to persons who are to be bound
      by the adjudication . . . ;
      [2] The right on behalf of a party to present evi-
      dence and legal argument in support of the party’s
      contentions and fair opportunity to rebut evidence
      and argument by opposing parties;
      [3] A formulation of issues of law and fact in terms
      of the application of rules with respect to specified
      parties concerning a specific transaction, situation,
      or status, or a specific series thereof;
      [4] A rule of finality, specifying a point in the pro-
      ceeding when presentations are terminated and a
      final decision is rendered; [and finally, a catch-all,]
      [5] Such other procedural elements as may be nec-
      essary to constitute the proceeding a sufficient
      means of conclusively determining the matter in
      question, having regard for the magnitude and
      complexity of the matter in question, the urgency
      with which the matter must be resolved, and the
      opportunity of the parties to obtain evidence and
      formulate legal contentions.
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 SYNQOR, INC.   v. VICOR CORPORATION                       11

 Id. Inter partes reexamination indisputably meets factors
 one, three, and four.
     Vicor argues that inter partes reexamination cannot
 satisfy factor two because it is an “examinational” or “in-
 quisitorial” proceeding. Appellee’s Br. 23 (quoting Abbott
 Labs. v. Cordis Corp., 710 F.3d 1318, 1326 (Fed. Cir. 2013)
 and SAS Inst., Inc. v. Iancu, 138 S. Ct. 1348 (2018)). Vicor
 argues that, accordingly, “the examiner—not the third-
 party requester—is the person who frames the challenge
 and drives the inter partes reexamination proceeding,” in-
 hibiting Vicor’s ability to present evidence and argument
 and rebut SynQor’s evidence and argument. Appellee’s
 Br. 24.
     We disagree with Vicor’s contention that inter partes
 reexamination’s fundamental nature does not afford Vicor
 the opportunity “to present evidence and legal argument in
 support of [its] contentions and fair opportunity to rebut
 evidence and argument by [SynQor.]” Restatement (Sec-
 ond) of Judgments § 83(2)(b). “In contrast to ex parte reex-
 amination, Congress specifically provided the third party
 reexamination requester the opportunity to fully partici-
 pate in the inter partes proceeding.” Affinity Labs, 856 F.3d
 at 890.
     35 U.S.C. § 314(b)(2) (pre-AIA) provides that “[e]ach
 time that the patent owner files a response to an action on
 the merits from the [PTO], the third-party requester shall
 have one opportunity to file written comments addressing
 issues raised by the action of the Office or the patent
 owner’s response thereto.” See also 37 C.F.R. § 1.947
 (“Each time the patent owner files a response to an Office
 action on the merits pursuant to § 1.945, a third party re-
 quester may once file written comments within a period of
 30 days from the date of service of the patent owner’s re-
 sponse.”). The patent owner and requester must serve all
 papers on one another, 37 C.F.R. § 1.903, and the patent
 owner may not have an ex parte discussion of the merits of
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 12                        SYNQOR, INC.   v. VICOR CORPORATION

 the reexamination with the examiner, id. § 1.955. In addi-
 tion, a third-party may “appeal [to the Board of Patent Ap-
 peals and Interferences] . . . with respect to any final
 decision favorable to the patentability of any original or
 proposed amended or new claim of the patent” or “be a
 party to any appeal taken by the patent owner [to the
 BPAI].” 35 U.S.C. § 315(b) (pre-AIA). Through these pro-
 cesses, both parties may present and rebut one another’s
 legal arguments.
     The parties also can present and rebut evidence—even
 expert testimony. See 37 C.F.R. §§ 1.937(b) (“The inter
 partes reexamination proceeding will be conducted in ac-
 cordance with [37 C.F.R.] §§ 1.104 through 1.116 . . . [.]”),
 1.116(e)–(g) (limiting the filing of “affidavits or other evi-
 dence” only after final rejection, an action closing prosecu-
 tion, the filing of an appeal, or the like). Cf. Abbott, 710
 F.3d at 1320 (describing the submission of competing ex-
 pert affidavits in an inter partes reexamination).
     This participation of the requester to provide both ar-
 gument and evidence distinguishes the “examinational”
 nature of inter partes reexamination from the initial exam-
 ination process or ex parte reexamination. Even if this pro-
 cess is not formally adversarial in the manner of inter
 partes review, it provides adequate adversarial participa-
 tion for both the patent owner and requester, facilitating a
 reasoned judgment on the issue before a neutral factfinder.
     Vicor argues, however, that as part and parcel of inter
 partes reexaminations’ “inquisitorial” nature, parties do
 not have rights to discovery or subpoena power, depriving
 parties of the power to depose witnesses and foreclosing
 them from “submit[ting] transcribed testimony, taken un-
 der oath and subject to cross-examination.” Appellee’s
 Br. 26 (quoting B&B Hardware, 575 U.S. at 144). But Vi-
 cor presents too rigid a view of the considerations at play
 in allowing one administrative tribunal to bind itself in
 later decisions. Chiefly, the Restatement provides that the
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 SYNQOR, INC.   v. VICOR CORPORATION                         13

 opportunity to present evidence without compulsory pro-
 cess may be inadequate, “for example,” “depending on the
 nature of the matter in controversy, the legal capability
 and stature of the tribunal, and applicable constitutional
 requirements.” Restatement (Second) of Judgments § 83
 cmt. c. But compulsory process is hardly dispositive, as
 other factors may weigh for and against the preclusivity of
 an administrative decision, such as the right to obtain ju-
 dicial review. Id.; see also Banner v. United States,
 238 F.3d 1348, 1354 (Fed. Cir. 2001) (“In determining
 whether a party has had a ‘full and fair’ opportunity to lit-
 igate an issue, a court should look at [as relevant here]
 whether there were significant procedural limitations in
 the prior proceeding . . . .”); Wright & Miller, Administra-
 tive Action Precluding Judicial Decision, 18B FED. PRAC. &
 PROC. JURIS. § 4475 (2d ed.). Instead, to determine
 whether adequate procedures are present, we examine
 “whether the procedures used in the first proceeding were
 fundamentally poor, cursory, or unfair.” B & B Hardware,
 575 U.S. at 158. We must also consider “whether extrinsic
 policies indicate that the second forum should nevertheless
 examine the matter in question anew. These policies con-
 cern the relative competence and responsibility of the two
 forums . . . .” Restatement (Second) of Judgments § 6 In-
 tro. Note. Taking these broad considerations into account,
 we conclude that the procedural mechanisms used in inter
 partes reexamination are sufficient to apply collateral es-
 toppel arising from a first reexamination to a second reex-
 amination.
     First, as a matter of fairness, a party receives no differ-
 ent procedure in a second inter partes reexamination than
 in a first. “If the prior opportunity and incentive to litigate
 the claim or issue in question were substantially the same
 as would have existed had the matter been adjudicated in
 the second forum, the procedural prerequisites exist for
 normal application of the rules of res judicata.” Id. It
 makes little sense to preclude the application of collateral
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 14                        SYNQOR, INC.   v. VICOR CORPORATION

 estoppel based on a lack of procedure in the first proceeding
 to which the party objecting to collateral estoppel will not
 be entitled to in the second proceeding.
     Vicor had the same opportunity to introduce its own
 evidence and contest SynQor’s evidence in the ’702 and ’290
 patent reexaminations as it did in the ’190 patent reexam-
 ination. And Vicor had the opportunity to seek judicial re-
 view of the Board’s unfavorable decisions in these
 reexaminations, which it took advantage of with regard to
 the frequency incompatibility question for the ’290 reexam-
 ination—but declined for the same question in the ’702
 reexamination.
      Next, the magnitude, context, and regulatory scheme
 of inter partes reexamination support the application of
 collateral estoppel between reexaminations. The statutory
 estoppel provisions show that Congress provided for broad
 statutory estoppel applying inter partes reexamination de-
 cisions in district court. See 35 U.S.C. § 315(c) (pre-AIA). 3
 This statutory provision does not compel the application of
 collateral estoppel between inter partes reexaminations,
 but Congressional intent must of course inform the func-
 tioning of Article I tribunals. See Wright & Miller, supra
 n.Error! Bookmark not defined. (“Any particular [ad-
 ministrative] scheme may contemplate that administrative
 decisions are not meant to preclude independent judicial
 action, or to the contrary may contemplate that courts

      3  When Congress provides for statutory estoppel, the
 administrative proceeding “need do no more than satisfy
 the minimum procedural requirements of the Fourteenth
 Amendment’s Due Process Clause.” See Kremer v. Chem.
 Constr. Corp., 456 U.S. 461, 481–83 (1982). In prior cases,
 this court has found that “excluding compulsory production
 of testimony in inter partes reexamination proceedings”
 does not cause a due process violation. See, e.g., Abbott,
 710 F.3d at 1328.
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 SYNQOR, INC.   v. VICOR CORPORATION                         15

 extend special deference to an agency.”). Furthermore, the
 decisions of the Patent and Trademark Office, and the
 members of the Board, represent the “considered judgment
 of an expert agency.” See Microsoft Corp. v. i4i Ltd., 564
 U.S. 91, 112 (2011). Factual determinations made by the
 expert agency entrusted by Congress to make those deter-
 minations—and to make them finally—need not be end-
 lessly reexamined. Cf. Safir v. Gibson, 432 F.2d 137, 143
 (2d Cir. 1970) (Friendly, J.) (holding that a Federal Mari-
 time Commission decision was entitled to preclusive effect,
 noting the FMC’s expertise and that the issues “were fully
 litigated before the agency designated to determine them”),
 cert. denied, 400 U.S. 942 (1970).
     Vicor’s fundamental objection to the procedure used in
 inter partes reexamination appears to center on the lack of
 opportunity to cross-examine SynQor’s experts under
 oath. 4 But inter partes reexamination provides “full and
 fair opportunity to litigate,” even without cross-examina-
 tion. While we recognize the importance of cross-examina-
 tion in judicial proceedings, it is not the only means of
 evaluating the credibility of testimony. “Vigorous cross-ex-
 amination, presentation of contrary evidence, and careful
 instruction on the burden of proof are the traditional and
 appropriate means of attacking shaky but admissible evi-
 dence.” Daubert v. Merrell Dow Pharms., Inc., 509 U.S.
 579, 596 (1993).
     In an inter partes reexamination, a party has the op-
 portunity to respond directly to the other party’s evidence,
 challenge an expert’s credibility or the basis for the expert’s
 conclusions, and to submit the opinions of its own expert

     4   We note that expert testimony submitted in reex-
 aminations must be submitted in the form of an affidavit
 or declaration as sworn testimony, rendering it also “under
 oath.” See, e.g., 37 C.F.R. § 1.132; MPEP § 716.02(g);
 MPEP § 717.01(c).
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 16                         SYNQOR, INC.   v. VICOR CORPORATION

 supporting these arguments and offering evidence to the
 contrary. This testing of the opposition’s evidence will not
 come in the form of confrontation during oral testimony,
 but it serves a similar purpose. And this form of challeng-
 ing opposing testimony more suitably supplants cross-ex-
 amination when the matter in question is the scientific
 opinion of technical experts, being evaluated by factfinders
 with technical expertise themselves. Cf. Belden Inc. v.
 Berk-Tek LLC, 805 F.3d 1064, 1079 (Fed. Cir. 2015)
 (“[Board] members, because of [their] expertise, may more
 often find it easier to understand and soundly explain the
 teachings and suggestions of prior art without expert assis-
 tance.”). The need for cross-examination to address credi-
 bility is further obviated, at least partially, by the adoption
 of the requirements for candor and disclosure used to safe-
 guard ex parte patent prosecution for inter partes reexam-
 ination. See 37 C.F.R. § 1.933.
     Courts and commentators 5 have advocated for the ne-
 cessity of live testimony and cross-examination within an
 administrative proceeding before collateral estoppel may
 apply. See, e.g., Nasem v. Brown, 595 F.2d 801, 807
 (D.C. Cir. 1979) (holding that collateral estoppel did not ap-
 ply from an agency proceeding because of a lack of live tes-
 timony and cross-examination); David A. Brown, Note,
 Collateral Estoppel Effects of Administrative Agency Deter-
 minations: Where Should Federal Courts Draw the Line?,
 73 CORNELL L. REV. 817, 831–34 (1988) (discussing proce-
 dural requirements for collateral estoppel to apply). But
 this court, in applying collateral estoppel to inter partes re-
 views in MaxLinear, 880 F.3d at 1376, has already recog-
 nized that live testimony is not a prerequisite for collateral
 estoppel to arise from an administrative proceeding. Other

      5 3 Wigmore, EVIDENCE § 1367, p. 27 (2d ed. 1923)
 (famously deeming cross-examination “the greatest legal
 engine ever invented for the discovery of truth”).
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 SYNQOR, INC.   v. VICOR CORPORATION                        17

 courts have also recognized the lack of bright-line proce-
 dural requirements. See, e.g., Johnson v. Dep’t of Agric.,
 833 F.3d 948, 956–57 (8th Cir. 2016) (explaining that
 “[t]here is no litmus test for deciding whether agency pro-
 cedures are extensive enough to warrant granting them
 preclusive effect[,]” but denying collateral estoppel for lack
 of discovery, cross-examination, ability to object to evi-
 dence, and judicial review); Chauffeur’s Training Sch., Inc.
 v. Spellings, 478 F.3d 117, 132 (2d Cir. 2007) (rejecting ar-
 gument that collateral estoppel should not apply because
 the school was “not permitted to cross-examine the Depart-
 ment’s statistical expert” where the school had the oppor-
 tunity to submit competing evidence and argue how the
 statistical evidence was defective); Herrera v. Churchill
 McGee, LLC, 680 F.3d 539, 547–50 (6th Cir. 2012) (holding
 that the decisions of a state human rights commission were
 rendered in a judicial capacity and applying administrative
 preclusion where evidence was developed by an agency in-
 vestigator and no hearing was held but claimant could re-
 spond to evidence submitted by the agency and seek
 judicial review).
     In inter partes reexaminations—where the finders of
 fact are administrative judges with relevant expertise—
 cross-examination may provide rhetorical effectiveness but
 is not necessary for full and fair opportunity to contest ev-
 idence. Given the statutory estoppel scheme for inter
 partes reexaminations, the informal procedural safe-
 guards, the nature of the tribunal, and the overall magni-
 tude and complexity of the proceedings, we are
 unpersuaded that inter partes reexamination procedures
 are so “fundamentally poor, cursory, or unfair,” B & B
 Hardware, 575 U.S. at 158, that the resolution of a factual
 dispute in a first inter partes reexamination should not col-
 laterally estop the contrary resolution of that dispute in a
 second reexamination.
     The dissent contends that we rely on Chauffer’s—a
 case it describes as an outlier—“for the proposition that
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 18                          SYNQOR, INC.   v. VICOR CORPORATION

 cross-examination is not required for collateral estoppel.”
 See Dissenting Op. 6. We do not cite Chauffer’s for the cat-
 egorical rule that cross-examination is not required. Ra-
 ther, we cite Chauffer’s—among others—as an example to
 show the lack of bright-line rules when it comes to deter-
 mining whether collateral estoppel applies to an adminis-
 trative decision. Indeed, it is not the majority but the
 dissent that calls for such a categorical rule regarding what
 is or is not required for collateral estoppel to apply. This is
 inconsistent with our application of collateral estoppel to
 inter partes reviews, which like inter partes reexamina-
 tions do not require live testimony, and with the decisions
 of our sister circuits. See Herrera, 680 F.3d at 547 (“[A] full
 and fair opportunity to litigate does not require any ‘single
 model of procedural fairness, let alone a particular form of
 procedure.’” (quoting Kremer, 456 U.S. at 483)).
                                3
     Given that common law collateral estoppel applies to
 inter partes reexaminations, we next evaluate whether the
 facts here support issue preclusion. They do.
     “Issue preclusion is appropriate only if: (1) the issue is
 identical to one decided in the first action; (2) the issue was
 actually litigated in the first action; (3) resolution of the is-
 sue was essential to a final judgment in the first action;
 and (4) plaintiff had a full and fair opportunity to litigate
 the issue in the first action.” In re Freeman, 30 F.3d 1459,
 1465 (Fed. Cir. 1994).
     Here, the issues are identical between the ’190 patent
 reexamination and the ’290 and ’702 patent reexamina-
 tions. “Our precedent does not limit collateral estoppel to
 patent claims that are identical. Rather, it is the identity
 of the issues that were litigated that determines whether
 collateral estoppel should apply.” Ohio Willow Wood Co. v.
 Alps S., LLC, 735 F.3d 1333, 1342 (Fed. Cir. 2013); see also
 B & B Hardware, 575 U.S. at 157 (citing the Restatement
 (Second) of Judgments § 27 cmt. c, at 252–53, that an
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 SYNQOR, INC.   v. VICOR CORPORATION                       19

 “issue” must be understood broadly enough “to prevent rep-
 etitious litigation of what is essentially the same dispute”
 (emphasis added)). In the ’190 patent reexamination here,
 as in the ’702 and the ’290 patent reexaminations, the rel-
 evant issue was whether “Cobos’ and Steigerwald’s circuits
 are mutually incompatible because of their switching fre-
 quency.” Vicor, 2016 WL 2344371, at *6. Compare id. with
 Vicor, 2015 WL 1871498, at *11 (addressing whether an
 artisan would have failed to combine Steigerwald and Co-
 bos “due to the incompatible switching frequencies of the
 two circuits”) and Vicor, 2016 WL 2344380, at *6 (deciding
 the issue of whether an artisan would have “overcome” “the
 frequency incompatibility of Cobos and Steigerwald” to
 combine the two references).
      This issue was litigated and decided in both the ’290
 and ’702 patent reeexaminations. In the ’702 patent reex-
 amination, the Board noted that SynQor argued “that the
 topologies of [Steigerwald and Cobos] are constrained to
 distinctly different and incompatible particular frequency
 ranges.” Vicor, 2015 WL 1871498, at *11. The Board ex-
 plained that Vicor disputed this, asserting “that SynQor’s
 arguments regarding switching frequencies are spurious”
 because Steigerwald “does not limit itself to any particular
 frequency.” Id. at *12. The Board, acting as the trier of
 fact, decided this issue, holding that “there are incompati-
 bilities in frequency between” Steigerwald and Cobos and
 that “[t]he Examiner and [Vicor] do not address how one of
 ordinary skill would have dealt with these incompatibili-
 ties sufficiently, instead principally arguing that they are
 nonexistent or spurious,” and that this incompatibility
 “lessen[s] the strength of the case for a conclusion of obvi-
 ousness.” Id.. Likewise, in the ’290 patent reexamination,
 “[t]he Board found that a person skilled in the art would
 not have been motivated to combine Steigerwald . . . and
 Cobos because of operating frequency incompatibilities be-
 tween the references’ circuits.” SynQor II, 869 F.3d at
 1320. This court rejected Vicor’s argument that the
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 20                         SYNQOR, INC.   v. VICOR CORPORATION

 Board’s finding was not supported by substantial evidence
 and affirmed the Board’s decision to decline to adopt the
 proposed rejections. Id.
      The Board’s findings that an artisan would not com-
 bine Steigerwald and Cobos because of their operating fre-
 quency incompatibilities were essential to the judgments
 holding the ’290 and ’702 patents not obvious. “In order to
 give preclusive effect to a particular finding in a prior case,
 that finding must have been necessary to the judgment
 rendered in the previous action.” Freeman, 30 F.3d
 at 1466. This court’s resolution of Vicor’s appeal of the
 Board’s decision in the ’290 patent reexamination illus-
 trates that the question of frequency incompatibility of
 Steigerwald and Cobos was essential to the judgment. The
 court noted that the Board rejected Vicor’s argument that
 an artisan would be motivated to combine Steigerwald and
 Cobos because of the references’ frequency incompatibili-
 ties. See SynQor II, 869 F.3d at 1320. Having found that
 substantial evidence supported the frequency incompati-
 bilities, the court affirmed the Board’s decision finding the
 ’290 patent not obvious based on a combination including
 Cobos and Steigerwald. Id. And, for the reasons described
 in the prior section, Vicor had a full and fair opportunity to
 litigate the issue.
     The dissent states that the Board reached the opposite
 frequency compatibility conclusion regarding the ’190 pa-
 tent because Vicor presented new evidence in a subsequent
 inter partes reexamination: the deposition of Dr. Stei-
 gerwald obtained during district court litigation. See Dis-
 senting Op. 8. As an initial matter, Vicor argued and
 presented evidence to support that Steigerwald and Cobos
 did not operate on incompatible frequencies in each of the
 three inter partes reexaminations. Even more, Vicor pre-
 sented Dr. Steigerwald’s deposition to support compatibil-
 ity in the 2016 inter partes reexamination of the
 ’290 patent, but in that decision the Board did not credit
 that testimony over the testimony of SynQor’s witness. See
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 SYNQOR, INC.   v. VICOR CORPORATION                         21

 Vicor, 2016 WL 2344380, at *6–7. It is therefore not clear
 that the Board reached its contrary conclusion in 2016 and
 again in 2019 based on any new and previously unavailable
 evidence. Nonetheless, assuming that it did, collateral es-
 toppel applies “even if new evidence exists.” Black v. Off.
 of Pers. Mgmt., 641 F. App’x 1007, 1009 (Fed. Cir. 2016). A
 losing party does not get a second bite at the apple simply
 because they can find a new and arguably more persuasive
 witness to present their evidence; this is precisely the type
 of rematch that collateral estoppel is intended to foreclose
 to serve the interests of repose and finality. See Astoria,
 501 U.S. at 107 (“[A] losing litigant deserves no rematch
 after a defeat fairly suffered, in adversarial proceedings, on
 an issue identical in substance to the one he subsequently
 seeks to raise.”); Allen v. McCurry, 449 U.S. 90, 94 (1980)
 (“[C]ollateral estoppel relieve[s] parties of the cost and vex-
 ation of multiple lawsuits, conserve[s] judicial resources,
 and, by preventing inconsistent decisions, encourage[s] re-
 liance on adjudication.”).
      Thus, because the Board was precluded from finding
 that an artisan would combine Steigerwald and Cobos, we
 vacate the Board’s decision on claims 1–19, 28, and 31, and
 remand for further proceedings consistent with this opin-
 ion.
                               B
     We turn our attention to the Board’s decision on claims
 34–38. Because SynQor added these claims during reex-
 amination, the claims would not go into effect unless and
 until the Director issued a reexamination certificate incor-
 porating them after the Patent and Trademark Office
 found them patentable. See 35 U.S.C. §§ 314 (pre-AIA),
 316(a) (pre-AIA). Since the ’190 patent expired before the
 appeals of the patentability of claims 34–38 terminated,
 the claims will never issue. See 37 C.F.R. § 1.530(j) (“[N]o
 amendment, other than the cancellation of claims, will be
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 22                       SYNQOR, INC.   v. VICOR CORPORATION

 incorporated into the patent by a [reexamination] certifi-
 cate issued after the expiration of the patent.”).
     SynQor argues that the inability of these claims to ever
 be included in an issued patent forecloses any relief from
 the Board’s decisions as to those claims, making any review
 of those decisions “moot through the happenstance of pa-
 tent expiration.” Appellant’s Br. 60. SynQor asserts that
 the mootness of any review dictates that we should follow
 “established practice” and vacate the Board’s decision re-
 garding those claims. Id. (quoting United States v. Mun-
 singwear, Inc., 340 U.S. 36, 39–40 (1950)).
     We agree with SynQor that we lack jurisdiction to con-
 sider the Board’s decisions on claims 34–38 because the ex-
 piration of the ’190 patent rendered the patentability of
 those claims moot. We are further persuaded that
 SynQor’s opportunity to seek review of the Board’s adverse
 decision on these claims was “frustrated by the vagaries of
 circumstance.” U.S. Bancorp Mortg. Co. v. Bonner Mall
 P’ship., 513 U.S. 18, 25 (1994). In such circumstances, va-
 catur is available so that “those who have been prevented
 from obtaining the review to which they are entitled [are]
 not . . . treated as if there had been a review.” Mun-
 singwear, 340 U. S. at 39. This “prevent[s] an unreviewa-
 ble decision ‘from spawning any legal consequences.’”
 Camreta v. Greene, 563 U.S. 692, 713 (2011) (quoting Mun-
 singwear, 340 U.S. at 40–41). Because SynQor has not had
 the opportunity to seek review of the Board’s decisions on
 claims 34–38, we vacate the Board’s decisions as to those
 claims.
                             III
     We have considered the parties’ remaining arguments
 and find them unpersuasive. Because collateral estoppel
 properly applies to the Board’s decision on claims 1–19, 28,
 and 31, we vacate its decision and remand for the Board to
 apply collateral estoppel. Because the Board’s decisions on
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 SYNQOR, INC.   v. VICOR CORPORATION                      23

 claims 34–38 are moot, we vacate the Board’s dispositions
 of claims 34–38.
                VACATED AND REMANDED
                               COSTS
 Costs to SynQor.
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    United States Court of Appeals
        for the Federal Circuit
                   ______________________

                      SYNQOR, INC.,
                        Appellant

                              v.

                 VICOR CORPORATION,
                         Appellee
                  ______________________

                         2019-1704
                   ______________________

     Appeal from the United States Patent and Trademark
 Office, Patent Trial and Appeal Board in No. 95/001,702.
                   ______________________

 DYK, Circuit Judge, dissenting.
     The majority holds that collateral estoppel (or issue
 preclusion) applies to inter partes reexamination proceed-
 ings at the United States Patent and Trademark Office
 (USPTO). The majority’s holding is incorrect because these
 proceedings are examinational (or inquisitorial) rather
 than adjudicatory, do not include court-like adjudicatory
 procedures, and do not satisfy the requirements of B & B
 Hardware, Inc. v. Hargis Industries, Inc., 575 U.S. 138
 (2015), for application of collateral estoppel. The majority’s
 decision conflicts with decisions of the Supreme Court and
 our sister circuits. I respectfully dissent.
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 2                         SYNQOR, INC.   v. VICOR CORPORATION

                               I
      In B & B Hardware, the Supreme Court ruled that col-
 lateral estoppel applies to adjudicatory proceedings be-
 cause, in an adjudicatory proceeding, “an administrative
 agency is acting in a judicial capacity and resolves disputed
 issues of fact properly before it which the parties have had
 an adequate opportunity to litigate.” 575 U.S. at 148 (quot-
 ing Univ. of Tenn. v. Elliott, 478 U.S. 788, 797–98 (1986)).
 There is no presumption of collateral estoppel when these
 requirements are not met. See Astoria Fed. Sav. & Loan
 Ass’n v. Solimino, 501 U.S. 104, 108–09 (1991). As the Su-
 preme Court has explained, inter partes reexaminations
 are not adjudicatory. They “follow[] a more or less inquisi-
 torial course led by the Patent Office” that is only a
 “slightly more adversarial process” than ex parte reexami-
 nations, which “follow[] essentially the same inquisitorial
 process between patent owner and examiner as the initial
 Patent Office examination.” SAS Inst., Inc. v. Iancu, 138
 S. Ct. 1348, 1353 (2018). And as we have concluded, at
 their core, inter partes reexaminations are not adjudica-
 tory but “examinational.” Abbott Labs. v. Cordis Corp., 710
 F.3d 1318, 1326 (Fed. Cir. 2013) (stating that the purpose
 of replacing inter partes reexamination with inter partes
 review was to “convert[] inter partes reexamination from
 an examinational to an adjudicative proceeding” (citation
 omitted)). Collateral estoppel simply does not apply to in-
 quisitorial proceedings such as inter partes reexamina-
 tions. The panel majority’s contrary holding here is not
 consistent with Supreme Court authority.
                              II
     A survey of inter partes reexamination procedures at a
 more granular level confirms this conclusion. In B & B
 Hardware, the Supreme Court looked to the Restatement
 (Second) of Judgments for guidance on whether adminis-
 trative decisions could “meet the ordinary elements of issue
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 SYNQOR, INC.   v. VICOR CORPORATION                          3

 preclusion.” 575 U.S. at 153–54 (pointing to the Restate-
 ment (Second) of Judgments § 27). The Restatement limits
 collateral estoppel to those situations in which “[an] agency
 is in substance engaged in adjudication,” that is, “[w]here
 an administrative agency is engaged in deciding specific le-
 gal claims or issues through a procedure substantially sim-
 ilar to those employed by the courts.” Restatement
 (Second) of Judgments § 83 cmt. b. Thus, “[w]here an ad-
 ministrative forum has the essential procedural character-
 istics of a court, . . . its determinations should be accorded
 the same finality that is accorded the judgment of a court.”
 Id.
      The procedures governing inter partes reexamination
 are not similar to court proceedings and do not meet the
 requirements of the Restatement for the application of col-
 lateral estoppel. In an inter partes reexamination, the ex-
 aminer controls the course of the proceeding—not the
 third-party requester. The examiner decides which claims
 to reexamine and on which grounds, searches for additional
 prior art references, can formulate new rejections not ad-
 vanced by the third-party requester, and initiates chal-
 lenges to additional claims. 1

     1      See 37 C.F.R. § 1.104(a)(1) (“On taking up an appli-
 cation for examination or a patent in a reexamination pro-
 ceeding, the examiner shall make a thorough study thereof
 and shall make a thorough investigation of the available
 prior art relating to the subject matter of the claimed in-
 vention.”); MPEP § 2656 (8th ed. Rev. 7 2008) (“[T]he ex-
 aminer must also consider patents and printed
 publications . . . discovered by the examiner in search-
 ing . . . .”); id. § 2643 (“If the Office chooses to reexamine
 any claim for which reexamination has not been requested,
 it is permitted to do so, since the Office may always initiate
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 4                         SYNQOR, INC.   v. VICOR CORPORATION

     The examiner has no obligation to adopt and proceed
 on the arguments set out by the third-party requester. In-
 stead, the examiner must only explain why he or she views
 the third-party requester’s proposed arguments as not ap-
 propriate. 2 The process generally followed is the same as
 that followed for the examiner-led initial patent applica-
 tion examination. 37 C.F.R. § 1.937(b) (“The inter partes
 reexamination proceeding will be conducted in accordance
 with §§ 1.104 through 1.116, the sections governing the ap-
 plication examination process . . . .”). The requester has no
 right to compulsory process or cross-examination, making
 inter partes reexaminations unlike the procedures em-
 ployed by the courts and limiting the requester’s ability to
 gather, present, and test important evidence. As the
 USPTO has pointed out, “[i]n reexaminations, the [Patent
 Trial and Appeal Board] is reviewing a record developed by
 the examiner, not conducting a trial and developing a fac-
 tual record.” Brief for Intervenor USPTO 18, BioDelivery
 Scis. Int’l, Inc. v. Monosol Rx, LLC, Nos. 17-1265, -1266,
 -1268 (filed June 9, 2017), 2017 WL 2666499, at *18 [here-
 inafter “USPTO Brief”]. 3

 a reexamination on its own initiative of the non-requested
 claim (35 U.S.C. 303(a)).”).
      2   See MPEP § 2660(III) (“Reasons why the rejection
 proposed by the third party requester is not appropriate
 (i.e., why the claim cannot be rejected under the ground
 proposed by the third party requester) must be clearly
 stated for each rejection proposed by the third party re-
 quester that the examiner refuses to adopt.”).
      3   The majority points out that there are few inter
 partes reexamination proceedings that remain pending at
 the USPTO, Maj. Op. 7 n.2, but the majority decision will
 govern the future effect of all past inter partes
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 SYNQOR, INC.   v. VICOR CORPORATION                          5

     In discussing whether inter partes reexamination
 meets the requirements for collateral estoppel, commenta-
 tors have also noted that “features traditionally found [in]
 judicial determinations, such as the ability to take discov-
 ery and present evidence,” “are difficult to find in reexami-
 nation proceedings before the USPTO.” 5 R. Carl Moy,
 Moy’s Walker on Patents § 16:127 (4th ed. Dec. 2020) (dis-
 cussing Restatement (Second) of Judgments § 83).
                               III
     Of critical importance is the absence of the third-party
 requester’s ability to cross-examine witnesses. The Su-
 preme Court has described the right of cross examination
 as “a right traditionally relied upon expansively to test
 credibility as well as to seek the truth.” Pillsbury Co. v.
 Conboy, 459 U.S. 248, 259 (1983). And it has adopted the
 view that cross-examination is “the ‘greatest legal engine
 ever invented for the discovery of the truth’” because it
 “aid[es] the jury in assessing [a witness’s] credibility.” Cal-
 ifornia v. Green, 399 U.S. 149, 158 (1970); see also 1 Wein-
 stein’s Evidence Manual § 14.01 (2020) (noting that cross-
 examination “has the potential of shedding light on all the
 elements of credibility—the witness’s perception, memory,
 accuracy in narration[,] and sincerity” and that “[i]t can ex-
 pose inconsistencies, incompleteness, and inaccuracies in
 the testimony”).
     Given the importance of cross-examination, our sister
 circuits have refused to find issue preclusion in

 reexamination decisions by the Board. According to the
 USPTO, it has granted 1865 requests for inter partes reex-
 amination proceedings. USPTO, Inter Partes Reexamina-
 tion     Filing       Data      (Sept.       30,     2017),
 https://www.uspto.gov/sites/default/files/documents/in-
 ter_parte_historical_stats_roll_up.pdf.
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 6                         SYNQOR, INC.   v. VICOR CORPORATION

 administrative proceedings when the ability to cross-exam-
 ine was unavailable. For example, in Nasem v. Brown, 595
 F.2d 801 (D.C. Cir. 1979), the District of Columbia Circuit
 held that an administrative proceeding by the Office of
 Federal Equal Employment Opportunity did not meet the
 standard for collateral estoppel. Id. at 807. The court
 stressed that there was “no opportunity to cross-examine
 opposing witnesses,” concluding that cross-examination
 “cannot be underestimated” because it “creates incentives
 for witnesses to tell the truth and allows exposure of mis-
 taken perception or memory.” Id. at 807 & n.13. Similarly,
 in Johnson v. Vilsack, 833 F.3d 948 (8th Cir. 2016), the
 Eighth Circuit, while eschewing bright-line rules, refused
 to find collateral estoppel from a Department of Agricul-
 ture internal anti-discrimination investigation, relying, to-
 gether with other factors, on the unavailability of cross-
 examination. See id. at 957. The Eleventh Circuit also has
 concluded that the opportunity “to cross-examine opposing
 witnesses” in an agency proceeding is a critical fact to
 weigh when deciding whether parties “were afforded a full
 opportunity to litigate” for preclusive effect. City of Pom-
 pano Beach v. FAA, 774 F.2d 1529, 1539 n.10 (11th Cir.
 1985) (citing Nasem, 595 F.2d at 807) (discussing the re-
 lated doctrine of res judicata).
     The majority cites a single outlier case, Chauffer’s
 Training School, Inc. v. Spellings, 478 F.3d 117 (2d Cir.
 2007), for the proposition that cross-examination is not re-
 quired for collateral estoppel. See Maj. Op. 17–18 (citing
 id. at 132). 4 Chauffer’s established no such categorical

     4   The majority also relies on Herrera v. Churchill
 McGee, LLC, 680 F.3d 539 (6th Cir. 2012), which holds
 that, in the context of a probable cause determination be-
 fore a state human rights commission, a formal hearing
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 SYNQOR, INC.   v. VICOR CORPORATION                         7

 rule. The Second Circuit noted that “denial of cross-exam-
 ination of expert testimony might in some circumstances
 justify denial of collateral estoppel effect to an award based
 on such expert testimony,” but it held that the denial of
 cross-examination in the circumstances of the case was not
 prejudicial. Chauffer’s, 478 F.3d at 132.
     The case involved whether a school was collaterally es-
 topped from contesting a damages calculation made by an
 administrative law judge (ALJ) at the Department of Edu-
 cation in an earlier proceeding. Id. at 123–24, 131–32. The
 school argued that collateral estoppel should not apply be-
 cause it was not permitted to cross-examine the Depart-
 ment’s statistical expert who testified to the amount due.
 See id. at 132. The Second Circuit observed that the
 agency’s hearing focused on the methodology of calculating
 the assessment and that, during the hearing, the Depart-
 ment’s evidence “revealed and explained” “[t]he assump-
 tions underlying the Department’s statistical analysis and
 the calculations upon which it depended” and the school did
 not offer competing statistical evidence. Id. In the Second
 Circuit’s view, “[t]he School’s argument [came] down to
 nothing more than a claim that arguments rebutting the

 was not required for preclusive effect. Id. at 550–51. Her-
 rera appears to be inconsistent with the Second Circuit’s
 decision in Kosakow v. New Rochelle Radiology Associates,
 274 F.3d 706, 735–36 (2d Cir. 2001) (finding no collateral
 estoppel after a state human rights commission probable
 cause investigation because, among other reasons, the em-
 ployee did not have access to discovery). Whether or not
 Herrera was correctly decided, it involved the determina-
 tion of probable cause, which entails the application of a
 lower burden of proof. Reduced requirements for a full and
 fair opportunity to litigate may be appropriate in that con-
 text.
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 8                         SYNQOR, INC.   v. VICOR CORPORATION

 Department’s analysis would have been more rhetorically
 effective in the form of cross-examination than in the form
 of written submissions of contrary evidence or argument.”
 Id.
      Even if Chauffer’s was correctly decided on its particu-
 lar facts, the present case is unlike Chauffer’s, the factual
 circumstances being quite different. The issue is not a sta-
 tistical calculation of a monetary amount but a complex de-
 termination as to whether two references could be
 combined to challenge a patent as obvious.
     SynQor, Inc.’s patent-at-issue, U.S. Patent No.
 7,072,190 (“the ’190 patent”), is directed toward a power
 architecture for telecommunications and computer sys-
 tems that allows power converters to take up less space on
 circuit boards. Vicor Corp. proposed rejection of the ’190
 patent as obvious based on the combination of Steigerwald
 U.S. Patent No. 5,377,090 (“Steigerwald patent”) 5 and an
 article by Cobos. In an earlier proceeding involving a dif-
 ferent patent, the Board concluded that the references
 could not be combined to render the patent obvious because
 the circuits in the Steigerwald patent and Cobos article op-
 erated at different and incompatible frequencies, explain-
 ing that “there are incompatibilities in frequency between
 the references” and it was unclear “how one of ordinary
 skill would have dealt with these incompatibilities suffi-
 ciently.” J.A. 36,189. These conclusions were based on a
 declaration from Dr. Schlecht, the inventor of the ’190 pa-
 tent, who was also used as an expert by the patentee, that

     5   We have previously held that the Steigerwald ’090
 patent incorporates certain aspects of the Steigerwald U.S.
 Patent No. 5,274,539, and the two should be read together
 as a combined reference. Vicor Corp. v. SynQor, Inc., 603
 F. App’x 969, 974–75 (Fed. Cir. 2015).
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 SYNQOR, INC.   v. VICOR CORPORATION                          9

 supposedly showed that the Steigerwald patent operated
 at frequencies in the range of 3.6 MHz and higher.
      Here, however, the Board reached the opposite conclu-
 sion with the benefit of deposition testimony from Dr. Stei-
 gerwald, the inventor of the Steigerwald patent.
 Dr. Steigerwald was deposed by Vicor (the requester here)
 on October 28, 2013, in related district court litigation.
 During examination by counsel for Vicor, Dr. Steigerwald
 contradicted Dr. Schlecht and testified that the circuit of
 the Steigerwald patent operated at a frequency of either
 0.5 or 1 MHz, within the frequency range of the other ref-
 erence (Cobos). Dr. Steigerwald’s deposition was not avail-
 able to Vicor in the earlier proceeding, but Vicor submitted
 it to the Board in the later proceeding.
      Given this new information, the Board concluded that
 the circuits were compatible and thus the references could
 be combined. The additional evidence gained from compul-
 sory process changed the Board’s outcome on this complex
 technical issue. The unavailability of compulsory process
 and the inability to cross-examine Dr. Schlecht in the ear-
 lier proceeding was clearly prejudicial because it deprived
 Vicor of the opportunity to develop critical facts for the ear-
 lier proceeding. Even under Chauffer’s, which turned on
 the lack of prejudicial effect, collateral estoppel would not
 apply.
      In response, the majority makes two arguments:
 (1) that it is not clear that the Board’s change in interpre-
 tation resulted from the new district court deposition testi-
 mony from Dr. Steigerwald and (2) that, even if there was
 new testimony, collateral estoppel still applies. See Maj.
 Op. 20–21. The majority misses the point. The point is
 that compulsory process and cross-examination allow for
 the development of potentially significant evidence that
 would otherwise be unavailable. Dr. Steigerwald’s district
 court deposition testimony is an example of such
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 10                         SYNQOR, INC.   v. VICOR CORPORATION

 potentially relevant evidence. The absence of compulsory
 process and cross-examination in inter partes reexamina-
 tions—and the resulting inability to discover relevant evi-
 dence—demonstrates the inappropriateness of applying
 collateral estoppel to decisions in inter partes reexamina-
 tions.
                               IV
      Disregarding the importance of cross-examination, the
 majority claims that “inter partes reexamination provides
 ‘full and fair opportunity to litigate,’ even without cross-ex-
 amination.” Maj. Op. 15. In the majority’s view, the “form
 of challenging opposing testimony” adopted by the USPTO
 “more suitably supplants cross-examination when the mat-
 ter in question is the scientific opinion of technical experts,
 being evaluated by factfinders with technical expertise
 themselves.” Id. at 16. The majority also claims that “[i]n
 inter partes reexaminations—where the finders of fact are
 administrative judges with relevant expertise—cross-ex-
 amination may provide rhetorical effectiveness but is not
 necessary for [a] fulsome and fair opportunity to contest
 evidence.” Id. at 17. No case support is cited, and insofar
 as I am aware, there are no such cases to cite.
     Cross-examination is especially important for technical
 witnesses, as the Supreme Court and our sister circuits
 have agreed. For example, the Supreme Court has ex-
 plained that cross-examination of an expert is important
 “in testing [the expert’s] honesty, proficiency, and method-
 ology.” Melendez-Diaz v. Massachusetts, 557 U.S. 305, 321
 (2009). Cross-examination of an expert witness can illus-
 trate the witness’s “lack of proper training or deficiency in
 judgment” and cross-examination may explore the expert’s
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 SYNQOR, INC.   v. VICOR CORPORATION                        11

 “methodology,” which “requires the exercise of judgment
 and presents a risk of error.” Id. at 320. 6
     The experience of cross-examination in inter partes re-
 view proceedings further shows the importance of cross-ex-
 amination as to technical matters even where the
 adjudicators have their own technical expertise. In inter
 partes review proceedings, the Board regularly bases its
 conclusions on a witness’s cross-examination testimony. 7

     6    See also Howard v. Walker, 406 F.3d 114, 127 (2d
 Cir. 2005) (“On cross-examination, an attorney is free to
 challenge an expert’s methodology, her conclusions, and
 the bases for her conclusions. To the extent that the relia-
 bility of certain facts accepted by an expert is questionable,
 the exercise and process of cross-examination allow a de-
 fendant to bring any such factual disputes to the attention
 of the jury.”); Westberry v. Gislaved Gummi AB, 178 F.3d
 257, 261 (4th Cir. 1999) (explaining that “expert witnesses
 have the potential to ‘be both powerful and quite mislead-
 ing’” and that while “the court need not determine that the
 expert testimony a litigant seeks to offer into evidence is
 irrefutable or certainly correct,” “[v]igorous cross-examina-
 tion” is an important tool to test the expert’s testimony (ci-
 tation omitted)); Bunker Hill Co. v. EPA, 572 F.2d 1286,
 1305 (9th Cir. 1977) (emphasizing that when an issue “is of
 a highly complex and technical nature” “cross-examination
 will help crystalize the varying contentions of the experts
 and help guarantee that both parties’ experts are respon-
 sive to criticisms and counterarguments” and that “[c]ross-
 examination of the witnesses will also aid [the] court in re-
 viewing” issues on a potential appeal).
      7   E.g., Cellco P’ship v. Bridge & Post, Inc., No.
 IPR2018-00054, 2019 WL 1749296, at *11 (P.T.A.B. Apr.
 15, 2019) (patent owner’s expert’s concession during cross-
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 12                        SYNQOR, INC.   v. VICOR CORPORATION

 The need for and importance of cross-examination in inter
 partes review proceedings can hardly be said to differ in
 inter partes reexaminations.
     Significantly, the USPTO, which is intimately involved
 with and knowledgeable about inter partes reexamina-
 tions, has previously urged that there should be no preclu-
 sive effect stemming from issues previously litigated in an
 inter partes reexamination because there is no cross-exam-
 ination and cross-examination is frequently outcome-deter-
 minative. USPTO Brief, 2017 WL 2666499, at *18–19.
                               V
     The majority relies on various statutory estoppel pro-
 visions to support its view that “[t]he statutory scheme . . .

 examination); Hamamatsu Photonics K.K. v. SEMICAPS
 Pte Ltd., No. IPR2017-02110 , 2019 WL 1292463, at *10
 (P.T.A.B. Mar. 18, 2019) (petitioner’s expert’s testimony
 “was undercut by his testimony under cross-examination”);
 Seabery N. Am. Inc. v. Lincoln Global, Inc., No. IPR 2016-
 00840, 2017 Pat. App. LEXIS 11685, at *25–26 (P.T.A.B.
 Oct. 2, 2017) (crediting an expert witness’s testimony on
 cross-examination that further supported his conclusions);
 Ericsson Inc. v. Intell. Ventures I LLC, No. IPR2014-00527,
 2015 Pat. App. LEXIS 6161, at *25–30 (P.T.A.B. May 18,
 2015) (patent owner’s expert made concession on cross-ex-
 amination and failed to explain how a reference differed
 from a patent during cross-examination); see also FLIR
 Sys., Inc. v. Leak Surveys, Inc., Nos. IPR2014-00411, -
 00434, -00608, -00609, 2014 Pat. App. LEXIS 6178, at *36
 (P.T.A.B. Sept. 5, 2014) (institution decision) (noting that
 arguments “are best addressed in a trial phase where both
 parties have an opportunity to cross-examine witnesses
 and where the Board can evaluate credibility of wit-
 nesses”).
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 SYNQOR, INC.   v. VICOR CORPORATION                          13

 is fully consonant with common law estoppel,” Maj. Op 9.
 Far from supporting the majority, these provisions contra-
 dict its reasoning. First, the majority relies on 35 U.S.C.
 §§ 315(c) and 317(b) (2006). Section 315(c) prohibits an un-
 successful third-party requester from challenging the va-
 lidity of a patent claim in district court if the claim has been
 “finally determined to be valid and patentable on any
 ground which the third-party requester raised or could
 have raised during the inter partes reexamination proceed-
 ings.” Id. § 315(c). Section 317(b) prohibits the converse,
 estopping a party from requesting an inter partes reexam-
 ination of claims “actually challenged and for which the re-
 questing party received an adverse final decision in [a]
 district court proceeding.” In re Affinity Labs of Tex., LLC,
 856 F.3d 883, 893 (Fed. Cir. 2017) (interpreting § 317(b)).
 The statute also bars subsequent reexamination of the
 same claims on the same grounds in an inter partes reex-
 amination proceeding. 35 U.S.C. § 317(b). As we held in
 Affinity Labs, these provisions are claim specific and in the
 nature of a claim preclusion bar rather than issue preclu-
 sion (collateral estoppel). See 856 F.3d at 892. These pro-
 visions (barring relitigation of the same claims) are
 entirely irrelevant to the present situation where the
 claims of a different patent are involved.
     Second, the majority also relies on uncodified section
 4607. That provision is similar to collateral estoppel. It
 states that
     [a]ny party who requests an inter partes reexami-
     nation under section 311 of title 35, United States
     Code, is estopped from challenging at a later time,
     in any civil action, any fact determined during the
     process of such reexamination, except with respect
     to a fact determination later proved to be erroneous
     based on information unavailable at the time of the
     inter partes reexamination decision.
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 14                         SYNQOR, INC.   v. VICOR CORPORATION

 Optional Inter Partes Reexamination Procedure Act of
 1999, Pub. L. No. 06-113, 113 Stat. 1501A-567, 1501A-567,
 sec. 4607. But section 4607 does not apply by its own terms
 to facts determined in the first proceeding that, in a later
 proceeding, are challenged on the basis of “information un-
 available” in the first proceeding. That is the situation
 here. New information developed as a result of compulsory
 process and cross-examination would not bar reconsidera-
 tion in a later civil action. And, as the majority admits,
 section 4607 facially only applies to later district court pro-
 ceedings and not to inter partes reexamination proceed-
 ings. See Maj. Op. 9.
     Congress’s decision to depart from the usual rules of
 collateral estoppel only in “civil action[s]” in district court
 and only when there is no previously unavailable evidence
 demonstrates a deliberate choice and strongly suggests
 that Congress did not wish to depart from the usual rule of
 collateral estoppel with respect to later USPTO proceed-
 ings or proceedings with new evidence. 8 Jama v. Immigr.
 & Customs Enf’t, 543 U.S. 335, 341 (“We do not lightly as-
 sume that Congress has omitted from its adopted text re-
 quirements that it nonetheless intends to apply . . . .”);
 United States v. Texas, 507 U.S. 529, 534 (1993) (“[S]tat-
 utes which invade the common law . . . are to be read with
 a presumption of favoring the retention of long-established
 and familiar principles, except when a statutory purpose to
 the contrary is evident. . . . In order to abrogate a common-
 law principle, the statute must ‘speak directly’ to the ques-
 tion addressed by the common law.” (citations omitted));
 Monessen Sw. Ry. Co. v. Morgan, 486 U.S. 330, 337 (1988)
 (holding that, in passing the Federal Employers’ Liability

      8 Congress may well have considered that a second
 reexamination proceeding provided far less opportunity to
 develop new evidence than a district court proceeding.
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 SYNQOR, INC.   v. VICOR CORPORATION                        15

 Act, “Congress expressly dispensed with [certain] common-
 law doctrines of that era” but being “unpersuaded that
 Congress intended to abrogate [other] doctrine[s] sub silen-
 tio”).
                               VI
      To be sure, we have applied collateral estoppel to inter
 partes review proceedings at the USPTO, but that is be-
 cause those proceedings, which include compulsory process
 and cross-examination, are essentially adjudicatory. See
 MaxLinear, Inc. v. CF CRESPE LLC, 880 F.3d 1373,
 1376–77 (Fed. Cir. 2018). Congress intentionally reformed
 inter partes reexamination and created inter partes review
 to “convert[] inter reexamination from an examinational to
 an adjudicative proceeding.” Abbott, 710 F.3d at 1326 (al-
 teration in original) (quoting H.R. Rep. No. 112-98, pt. 1, at
 46–47 (2011)). Indeed, the Supreme Court has recognized
 that Congress created inter partes review to be “a party-
 directed, adversarial process.” SAS, 138 S. Ct. at 1355.
                          CONCLUSION
     In sum, inter partes reexamination proceedings are ex-
 aminational and not adjudicatory and do not satisfy the re-
 quirements for collateral estoppel. The majority’s decision
 is without support and contrary to governing Supreme
 Court authority. 9

     9    I do not disagree with the majority’s decision re-
 garding the mootness of claims 34 through 38, and the de-
 cision to vacate the Board’s decision as to those claims. See
 Maj. Op. Section II.B.