Court Opinion

ID: 4665959
Source: CourtListenerOpinion
Date Created: 2021-03-09 16:01:11.833531+00
Date Added: 2024-06-11T09:11:06.708079
License: Public Domain

Case: 19-1688    Document: 72           Page: 1       Filed: 03/09/2021

    United States Court of Appeals
       for the Federal Circuit
                  ______________________

                    UNILOC 2017 LLC,
                        Appellant

                                  v.

         FACEBOOK INC., WHATSAPP, INC.,
                     Appellees
              ______________________

                        2019-1688
                  ______________________

     Appeal from the United States Patent and Trademark
 Office, Patent Trial and Appeal Board in Nos. IPR2017-
 01427, IPR2017-02087.

           -------------------------------------------------

                    UNILOC 2017 LLC,
                        Appellant

                                  v.

         FACEBOOK INC., WHATSAPP, INC.,
                     Appellees
              ______________________

                        2019-1689
                  ______________________
Case: 19-1688    Document: 72      Page: 2    Filed: 03/09/2021

 2                          UNILOC 2017 LLC   v. FACEBOOK INC.

     Appeal from the United States Patent and Trademark
 Office, Patent Trial and Appeal Board in Nos. IPR2017-
 01428, IPR2017-02088.
                  ______________________

                  Decided: March 9, 2021
                  ______________________

     JEFFREY A. STEPHENS, Etheridge Law Group, South-
 lake, TX, argued for appellant. Also represented by JAMES
 ETHERIDGE, RYAN S. LOVELESS, BRETT MANGRUM.

    PHILLIP EDWARD MORTON, Cooley LLP, Washington,
 DC, argued for appellees. Also represented by HEIDI LYN
 KEEFE, ANDREW CARTER MACE, LOWELL D. MEAD, MARK R.
 WEINSTEIN, Palo Alto, CA.
                 ______________________

     Before LOURIE, WALLACH, and CHEN, Circuit Judges.
 CHEN, Circuit Judge.
     Uniloc 2017 LLC (Uniloc) appeals from two consoli-
 dated inter partes review (IPR) decisions of the Patent Trial
 and Appeal Board (Board) finding unpatentable claims 1–
 8 and claims 9–12, 14–17, 25 and 26 of U.S. Patent No.
 8,995,433 (’433 patent) as obvious.
     Foremost at issue in this case is whether 35 U.S.C.
 § 314(d)’s “No Appeal” provision bars this court’s review of
 the Board’s conclusion that under § 315(e)(1) a petitioner
 is not estopped from maintaining the IPR proceeding be-
 fore it. Under the circumstances of this case, we hold that
 § 314(d) does not preclude this court from reviewing the
 Board’s § 315(e)(1) estoppel decision. We further conclude
 that the Board did not err in finding that LG Electronics
 Inc. (LG) is not estopped from maintaining its IPR chal-
 lenge to claims 1–8 and that Facebook and WhatsApp (col-
 lectively, Facebook) are not estopped from challenging
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 UNILOC 2017 LLC   v. FACEBOOK INC.                           3

 claim 7. As to the Board’s obviousness conclusions, we see
 no error in the Board’s unpatentability findings. Accord-
 ingly, we affirm.
                         BACKGROUND
                               A
      Uniloc is the owner of the ’433 patent, which is directed
 to “a system and method for enabling local and global in-
 stant [Voice over Internet Protocol (VoIP)] messaging over
 an IP network.” ’433 patent col. 1 ll. 21–23. The patent
 describes the implementation of two modes: “record mode”
 and “intercom mode.” Id. at col. 7 ll. 61–65. In record
 mode, the user’s speech is recorded into an audio file, and
 upon finalization, the user sends a signal to the server that
 the message is ready to be sent. Id. at col. 8 ll. 9–22. The
 message is then sent to the server and the server delivers
 the message to the selected recipient. Id. at col. 8 ll. 25–
 43. However, if the recipient is not currently available, i.e.,
 disconnected, the server temporarily saves the instant
 voice message and delivers it to the recipient when the re-
 cipient connects to its local server, i.e., becomes available.
 Id. The intercom mode operates similarly, but it allows for
 the instant voice message to be transmitted in real-time to
 the selected recipient by storing the message on buffers un-
 til the buffers fill and the message is then sent to the server
 to be transmitted to the recipient. Id. at col. 11 ll. 37–60.
 The instant voice message can also contain various attach-
 ments. Id. at col. 13 ll. 5–6.
    Claims 1 and 9 are the independent claims at issue
 here. 1 They state, in pertinent part, as follows:
     1. A system comprising:

     1   Although independent claim 6 of the ’433 patent is
 also on appeal, appellant makes no materially different ar-
 guments as to claim 6.
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 4                           UNILOC 2017 LLC   v. FACEBOOK INC.

     an instant voice messaging application including a
     client platform system for generating an instant
     voice message and a messaging system for trans-
     mitting the instant voice message over a packet-
     switched network via network interface;
     ...
     wherein the instant voice messaging application in-
     cludes a message database storing the instant voice
     message, wherein the instant voice message is rep-
     resented by a database record including a unique
     identifier; and
     wherein the instant voice messaging application in-
     cludes a file manager system performing at least
     one of storing, deleting and retrieving the instant
     voice messages from the message database in re-
     sponse to a user request.
     9. A system, comprising:
     an instant voice messaging application comprising:
     a client platform system . . . ;
     a messaging system . . . , and
     wherein the instant voice message application at-
     taches one or more files to the instant voice message.
 ’433 patent at claims 1, 9 (emphases added).
                                B
     Facebook filed two petitions for inter partes review of
 the ’433 patent on May 11, 2017. In the first petition (’1427
 IPR Pet.), Facebook challenged claims 1–8 as obvious un-
 der 35 U.S.C. § 103 with Zydney 2 and Clark 3 as references

     2     PCT App. Pub. No. WO 01/11824 A2.
     3     U.S. Patent No. 6,725,228.
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 UNILOC 2017 LLC   v. FACEBOOK INC.                           5

 for claims 1–6 and 8 and Zydney, Clark, and Appelman 4 as
 references for claim 7. In the second petition (’1428 IPR
 Pet.), Facebook alleged that claims 9, 12, 14, 17, 25, and 26
 would have been obvious under § 103 in view of Zydney,
 claims 11, 15, and 16 would have been obvious in view of
 Zydney and Greenlaw 5, and claim 10 would have been ob-
 vious in view of Zydney and Newton 6.
     Meanwhile, a different IPR proceeding challenging
 claims of the ’433 patent, IPR2017-00225, was already
 pending at the Board, petitioned for by Apple Inc. (Apple).
 On June 16, 2017, after it had filed the ’1427 IPR Pet. and
 ’1428 IPR Pet., Facebook filed a new petition, identical in
 substance to Apple’s IPR petition, challenging claims 1–6
 and 8 of the ’433 patent and a motion to join the Apple IPR.
 In response, the Board instituted this IPR and granted Fa-
 cebook’s motion to join Apple’s IPR on October 3, 2017.
     Aside from Apple and Facebook, yet another party was
 interested in invalidating certain claims of the ’433 pa-
 tent—LG. Before a decision issued on whether to institute
 Facebook’s IPR petitions, on September 11, 2017, LG filed
 IPR petitions identical in substance to Facebook’s ’1427
 and ’1428 IPR petitions and motions to join both of Face-
 book’s IPRs.
     The Board then, on December 4, 2017, instituted inter
 partes review for Facebook’s ’1427 and ’1428 IPR petitions. 7
 Given that Facebook was now a party to multiple different

     4   U.S. Patent No. 6,750,881.
     5   RAYMOND       GREENLAW      &   ELLEN   HEPP,
 INTRODUCTION TO THE INTERNET FOR ENGINEERS, 1–25
 (1999).
     6   HARRY NEWTON, NEWTON’S TELECOM DICTIONARY
 (18th ed. 2002).
     7   The Board consolidated the ’1427 IPR and ’1428
 IPR for the final written decision.
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 6                           UNILOC 2017 LLC   v. FACEBOOK INC.

 IPR proceedings challenging claims of the ’433 patent, the
 Board foresaw the possibility of a statutory estoppel issue
 arising under 35 U.S.C. § 315(e)(1). At the end of its insti-
 tution decision in the ’1427 IPR, the Board ordered the par-
 ties    to    “brief    the   applicability,    if  any,    of
 35 U.S.C. § 315(e)(1)” against Facebook, in light of the an-
 ticipated, soon-to-be-issued final written decision for the
 Apple IPR, to which Facebook was a joined party. Face-
 book, Inc. v. Uniloc USA, Inc., No. IPR2017-01427, 2017
 WL 6034153, at *10 (P.T.A.B. Dec. 4, 2017) (Institution De-
 cision). The Board did not issue a similar request for brief-
 ing in its institution decision for the ’1428 IPR. Notably, at
 the time of this supplemental briefing, LG’s petition and
 motion to join remained pending.
      In its § 315 supplemental brief, Facebook argued that
 it should not be estopped from challenging the patentabil-
 ity of any claim upon the issuance of a final written deci-
 sion in the Apple IPR, but even if the Board found it
 estopped, Facebook should at least continue as a petitioner
 here against claim 7, which was never challenged in the
 Apple IPR. See J.A. 606–07. Further, Facebook contended
 that, if LG’s IPR petition was granted and LG was joined
 as a party to the ’1427 IPR, then the ’1427 IPR should pro-
 ceed as to all challenged claims regardless of whether Fa-
 cebook was found estopped because LG was not a party in
 the Apple IPR. Id. at 610. In response, Uniloc contended
 that, once the Board issued a final written decision in the
 Apple IPR, Facebook would be estopped as to all claims
 challenged in the ’1427 IPR, requiring the Board to then
 terminate that proceeding. J.A. 617. In addition, Uniloc
 averred that “[a]llowing LG Electronics to join this IPR will
 create inefficiency and confusion. This IPR should be ter-
 minated and LG Electronics can, if it chooses to, file its own
 IPR.” Id.
     The Board subsequently instituted IPRs based on LG’s
 petitions and then granted LG’s motion to join the ’1427
 IPR and ’1428 IPR on March 6, 2018. J.A. 655. Uniloc then
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 UNILOC 2017 LLC   v. FACEBOOK INC.                           7

 filed its Patent Owner Responses to the original Facebook
 IPR petitions on March 23, 2018. In its ’1427 IPR response,
 inter alia, Uniloc contended that LG should be barred from
 maintaining the ’1427 IPR once the Board issues a final
 written decision in the Apple IPR because LG is estopped
 as a real party in interest (RPI) or privy to Facebook. See,
 e.g., J.A. 685.
     Two months later, on May 23, 2018, the Board issued a
 final written decision in the Apple IPR upholding the pa-
 tentability of all challenged claims. Six days later, on May
 29, 2018, the Board issued a decision in the ’1427 IPR dis-
 missing-in-part Facebook from the IPR, finding that Face-
 book was “estopped from maintaining the instant
 proceeding under § 315(e)(1)” as to the claims challenged
 in the Apple IPR, i.e., claims 1–6 and 8 of the ’433 patent.
 J.A. 756. As to claim 7, the Board reasoned that Facebook
 was not estopped from maintaining the proceeding for that
 claim because § 315(e)(1)’s estoppel provisions apply only
 to grounds that the petitioner raised or reasonably could
 have raised “with respect to that claim.” Id. at 756–57.
 Lastly, the Board concluded that “[t]he dismissal of Face-
 book . . . does not limit LG’s participation in any way,” id.
 at 758, and therefore, LG was “to assume the role of chal-
 lenger as to all claims, with Facebook[’s] . . . participation
 limited as to issues concerning solely claim 7,” id. at 759
 (emphasis omitted).
                               C
     The Board issued its final written decision in the con-
 solidated IPRs on November 20, 2018. The Board con-
 cluded that all of the challenged claims are unpatentable.
 Facebook, Inc. v. Uniloc 2017 LLC, Nos. IPR2017-01427,
 IPR2017-01428, 2018 WL 6271687, at *33 (P.T.A.B. Nov.
 30, 2018). The Board found that claims 1–6 and 8 of the
 ’433 patent would have been obvious over Zydney in view
 of Clark, with Zydney teaching all but the “message data-
 base” and Clark supplying this missing limitation. Id. at
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 8                           UNILOC 2017 LLC   v. FACEBOOK INC.

 *14, *22, *24. Likewise, the Board concluded that claim 7
 is unpatentable as obvious under a similar combination of
 Zydney, Clark, and Appelman. Id. at *24. The Board also
 concluded that claims 9–12, 14–17, 25, and 26 are un-
 patentable as obvious, with Zydney again as the primary
 reference. Id. at *27, *29, *31–33. Relevant to this appeal,
 the Board explained that Zydney teaches the “attaches one
 or more files to the instant voice message” limitation of the
 challenged claims. Id. at *25. In reaching this conclusion,
 the Board reasoned that “attach” as used in the claims re-
 ferred to creating an association between the files and the
 instant voice message, id. at *7, the instant voice message
 in this phrase construed as “data content including a rep-
 resentation of an audio message,” id.
      Uniloc sought rehearing before the Board following this
 final written decision. Uniloc’s principal contention in
 seeking rehearing in the ’1427 IPR was that the proceeding
 as a whole should have been terminated once the original
 petitioner, Facebook, was deemed estopped, because
 “[j]oined parties are privy to a petitioner.” J.A. 907. Uniloc
 argued that rehearing was warranted in the ’1428 IPR be-
 cause it was denied proper notice in violation of due pro-
 cess. This was because, Uniloc contended, “[t]he Board sua
 sponte provided a definition of the term ‘attaches’ that was
 not advanced by” the parties or supported by the record.
 J.A. 2313. The Board denied both rehearing requests. J.A.
 105, 210.
    Uniloc appeals both final decisions to our court. 8 We
 have jurisdiction pursuant to 28 U.S.C. § 1295(a)(4)(A).

     8   Though LG participated in this appeal through the
 briefing stage, LG is no longer a party to the case. See Ap-
 pellant’s Unopposed Mot. to Withdraw LG Electronics, Inc.
 as a Party, ECF No. 56; ECF No. 57 (granting motion).
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 UNILOC 2017 LLC   v. FACEBOOK INC.                           9

                          DISCUSSION
     Uniloc raises four main disputes on appeal: (1) the
 Board erred in finding that LG is not estopped from chal-
 lenging claims 1–8 in view of its purported relationship
 with Facebook as an RPI or privy; (2) the Board erred in
 finding that Facebook is not estopped from challenging
 claim 7; (3) the Board erred in its unpatentability determi-
 nation of claims 1–8 because the cited references do not
 teach the “instant voice message application” of the claims;
 and (4) the Board erred in its unpatentability determina-
 tion of claims 9–12, 14–17, 25, and 26 because the cited ref-
 erences do not teach the claimed “attaches . . . to”
 limitation. We address each argument in turn.
                               A
     Before we address the merits of Uniloc’s estoppel argu-
 ment against LG, we consider as an initial matter whether
 we may review this particular challenge. As we have seen
 since the onset of IPRs, questions can arise as to whether
 we have the authority to review certain matters addressed
 in an IPR that are not directly related to the ultimate pa-
 tentability decisions the Board renders in a final written
 decision. See, e.g., Thryv, Inc. v. Click-To-Call Techs., LP,
 –––U.S.–––, 140 S. Ct. 1367 (2020); SAS Institute Inc. v.
 Iancu, –––U.S.–––, 138 S. Ct. 1348 (2018); Cuozzo Speed
 Techs., LLC v. Lee, –––U.S.–––, 136 S. Ct. 2131 (2016).
     Uniloc’s challenge attacks the Board’s finding that LG
 is not an RPI or privy of Facebook and thus not estopped
 from challenging claims 1–6 and 8 9 of the ’433 patent under

     9    Because the Board found that Facebook is not es-
 topped from challenging claim 7 of the ’433 patent, the po-
 tential scope of estoppel for LG extends only to those claims
 for which Facebook was found estopped, i.e., claims 1–6
 and 8. Uniloc argues on appeal that the Board’s conclusion
 that Facebook is not estopped for claim 7 is incorrect and
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 10                           UNILOC 2017 LLC   v. FACEBOOK INC.

 § 315(e)(1). 10 In other words, Uniloc contends that because
 Facebook is estopped by the Apple IPR final written deci-
 sion from maintaining a challenge to those claims in this
 proceeding (a ruling Facebook does not contest), LG, as an
 alleged “real party in interest or privy of the petitioner”
 likewise is estopped from maintaining this same challenge
 per § 315(e)(1). As to the issue of reviewability, we consider
 the question before us to be whether 35 U.S.C. § 314(d)
 statutorily precludes judicial review, following a final writ-
 ten decision in an inter partes review proceeding, of a chal-
 lenge to the Board’s conclusion that under § 315(e)(1) a
 petitioner is not estopped from maintaining the proceeding
 before it. We conclude, under the circumstances here, we
 are not statutorily precluded from reviewing such a chal-
 lenge.
     Subsection 314(d) dictates that “[t]he determination by
 the Director [of the Patent Office] whether to institute an

 that LG should too be found estopped for claim 7. But as
 we conclude infra, the Board did not err in finding that Fa-
 cebook is not estopped as to claim 7. Accordingly, no po-
 tential estoppel for claim 7 can extend to LG as an alleged
 RPI or privy of Facebook.
     10  The text of 35 U.S.C. § 315(e)(1) is as follows:
      (e) Estoppel.—
      (1) Proceedings before the Office.—
      The petitioner in an inter partes review of a claim
      in a patent under this chapter that results in a final
      written decision under section 318(a), or the real
      party in interest or privy of the petitioner, may not
      request or maintain a proceeding before the Office
      with respect to that claim on any ground that the
      petitioner raised or reasonably could have raised
      during that inter partes review.
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 UNILOC 2017 LLC   v. FACEBOOK INC.                          11

 inter partes review under this section shall be final and
 nonappealable.” The Supreme Court in Cuozzo interpreted
 this provision as overcoming the strong presumption in fa-
 vor of judicial review “where the grounds for attacking the
 decision to institute inter partes review consist of questions
 that are closely tied to the application and interpretation
 of statutes related to the Patent Office’s decision to initiate
 inter partes review.” Cuozzo, 136 S. Ct. at 2141. In Cuozzo,
 the Court held that judicial review was precluded by
 § 314(d) for a challenge to the Board’s determinations un-
 der § 312(a)(3), which mandates that a petitioner identify
 the grounds of the challenge with particularity, because
 this is “little more than a challenge to the Patent Office’s
 conclusion, under § 314(a), that the information presented
 in the petition warranted review.” Cuozzo, 136 S. Ct. at
 2142 (internal quotation marks omitted).
      The Supreme Court has since addressed the judicial re-
 view bar under § 314(d) for other challenges stemming
 from decisions of the Patent Office in inter partes review
 proceedings. For example, the Court concluded in SAS In-
 stitute that § 314(d) does not preclude judicial review of a
 claim that the agency “exceeded its statutory authority” in
 limiting an inter partes review to fewer than all the claims
 challenged in the petition. 138 S. Ct. at 1359. The Court
 reached the opposite conclusion for reviewability with re-
 spect to § 315(b) in Thryv, however, explaining that the pe-
 tition time bar of § 315(b) “expressly governs institution
 and nothing more,” such that “a contention that a petition
 fails under § 315(b) is a contention that the agency should
 have refused ‘to institute an inter partes review.’” 140 S.
 Ct. at 1373 (quoting § 314(d)). The Court explained that
 review was therefore precluded despite the presumption of
 judicial review. Id. at 1374.
      This court has considered additional types of Board de-
 cisions in which the statutory bar of § 314(d) (and similar
 provisions) against judicial review may (or may not) apply.
 In Medtronic, we reasoned that the Board’s decision to
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 12                          UNILOC 2017 LLC   v. FACEBOOK INC.

 terminate proceedings in view of a party’s failure to name
 all RPIs under § 312(a)(2) is not reviewable because “[t]he
 Board’s reconsideration . . . is fairly characterized as a de-
 cision whether to institute proceedings, the review of which
 is barred by § 314(d).” Medtronic, Inc. v. Robert Bosch
 Healthcare Sys., Inc., 839 F.3d 1382, 1385 (Fed. Cir. 2016).
     On the other hand, in Credit Acceptance Corp. v.
 Westlake Services, we held that judicial review of a chal-
 lenge to the Board’s application of the estoppel provision of
 § 325(e)(1) is not precluded by § 324(e) 11 because this pro-
 vision “is not limited to the institution stage” and “could
 operate to terminate a proceeding even where there existed
 no cause for termination at the time a petition was insti-
 tuted . . . .” 859 F.3d 1044, 1050 (Fed. Cir. 2017). In that
 case, the alleged estoppel-triggering event did not occur un-
 til after the institution of the covered business method
 (CBM) patent review proceeding, and thus could not have
 affected the decision to initiate the administrative proceed-
 ing. We thus explained that “the estoppel dispute in this
 case is neither a challenge to the Board’s institution deci-
 sion, nor is it ‘closely tied’ to any ‘statute[] related to the
 Patent Office’s decision to initiate [CBM] review.’” Id. at
 1051 (quoting Cuozzo, 136 S. Ct. at 2141).
      More recently, we held the inverse scenario of that in
 Medtronic is likewise not reviewable. That is, a challenge
 “that the Board failed to comply with [the RPI requirement
 of] § 312(a)(2)” and should have terminated the proceeding
 is merely “‘a contention that the agency should have re-
 fused to institute an inter partes review,’” and therefore not
 reviewable by this court in view of § 314(d). ESIP Series 2,

      11  Subsection 324(e) is nearly identical in language to
 § 314(d) but applies to other post-grant proceedings. It
 states: “The determination by the Director whether to in-
 stitute a post-grant review under this section shall be final
 and nonappealable.” § 324(e).
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 UNILOC 2017 LLC   v. FACEBOOK INC.                          13

 LLC v. Puzhen Life USA, LLC, 958 F.3d 1378, 1386 (Fed.
 Cir. 2020) (quoting Thryv, 140 S. Ct. at 1373–74). Addi-
 tionally, we determined, in Facebook, Inc. v. Windy City In-
 novations, LLC, that judicial review is not precluded by
 § 314(d) for challenges to “whether the Board’s joinder de-
 cisions exceeded the statutory authority provided by
 § 315(c),” because this challenge was not related to the in-
 stitution decision but rather concerned “whether the PTO
 had exceeded its statutory authority as to the manner in
 which the already-instituted IPR proceeded.” 973 F.3d
 1321, 1332 (Fed. Cir. 2020).
     With that background, we turn now to the question in
 this case of whether we may review the Board’s decision
 that LG is not estopped from maintaining its challenge
 against claims 1–6 and 8. Considering the strong presump-
 tion of reviewability of agency action, we see no indication
 that § 314(d) precludes judicial review of the Board’s appli-
 cation of § 315(e)(1)’s estoppel provision in this case, in
 which the alleged estoppel-triggering event occurred after
 institution. Such a holding is a natural consequence of our
 reasoning in Credit Acceptance. We concluded there that
 we could review the patent owner’s challenge to the Board’s
 decision that the petitioner was not estopped from main-
 taining a patentability challenge under a nearly identical
 statutory estoppel provision, albeit as applied to the CBM
 scheme. See Credit Acceptance, 859 F.3d at 1050–51.
     As the Supreme Court elucidated in Northcross v.
 Board of Education of Memphis City Schools, when one
 statute “tracks the wording of” another, this is a “strong
 indication that the two statutes should be interpreted pari
 passu,” particularly if the two provisions share a common
 purpose. 412 U.S. 427, 428 (1973) (per curiam) (interpret-
 ing the language of the Emergency School Aid Act of 1972
 to allow for the ordinary award of attorneys’ fees because
 the relevant provision of the Act “tracks the wording” of the
 similarly focused Civil Rights Act of 1964, which the Court
 had previously interpreted as providing for such ordinary
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 14                          UNILOC 2017 LLC   v. FACEBOOK INC.

 award). Thus, just as we concluded for the CBM estoppel
 provision of § 325(e)(1) in Credit Acceptance, we likewise
 interpret the similarly worded and focused IPR estoppel
 provision of § 315(e)(1) as not so closely tied to institution
 to render judicial review precluded when the estoppel-trig-
 gering event arises after institution. See 859 F.3d at 1049–
 52 (considering the Supreme Court’s caselaw on reviewa-
 bility under § 314(d) and concluding that the appellant’s
 challenge under § 325(e)(1) “is neither a challenge to the
 Board’s institution decision, nor is it ‘closely tied’ to any
 ‘statute[] related to the Patent Office’s decision to initiate
 [CBM] review.’” (quoting Cuozzo, 136 S. Ct. at 2141) (mod-
 ifications in original))). Section 315(e)(1)’s use of “main-
 tain” contemplates that the estoppel provision “governs at
 any stage of a subsequent proceeding before the PTO—its
 application is not limited to the institution stage.” Credit
 Acceptance, 859 F.3d at 1050.
      Critically, the particular circumstances in Credit Ac-
 ceptance, i.e., one in which no cause for termination at the
 time of petition existed and the basis for termination devel-
 oped while the proceeding was ongoing, is exactly that
 which happened here. When the Board instituted review
 in the ’1427 IPR, no estoppel could apply because no final
 written decision had been reached in the Apple IPR.
 Though the Board’s institution decision ordered supple-
 mental briefing regarding the potential, future applicabil-
 ity of § 315(e)(1)’s estoppel provision, due to its awareness
 of the advanced state of the Apple IPR, the Apple IPR final
 written decision did not issue until months after institution
 in this proceeding. The Board’s “no estoppel” decision thus
 was later than and separate from its earlier institution de-
 cision, and, consistent with the facts and reasoning of
 Credit Acceptance, is a decision we may review. See Credit
 Acceptance, 859 F.3d at 1049–52; see also Windy City, 973
 F.3d at 1332 (explaining that § 315(c) joinder challenges
 are reviewable by this court despite § 314(d) because “the
 joinder decision is made after a determination that a
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 UNILOC 2017 LLC   v. FACEBOOK INC.                          15

 petition warrants institution, thereby affecting the manner
 in which an IPR will proceed”) (citation omitted)).
      Finding Uniloc’s estoppel challenge as to LG reviewa-
 ble, we now consider the merits of that challenge. “Deter-
 mining whether a []party is a[n] [RPI] demands a flexible
 approach that takes into account both equitable and prac-
 tical considerations,” with the heart of the inquiry focused
 on “whether a petition has been filed at a []party’s behest.”
 Applications in Internet Time, LLC v. RPX Corp., 897 F.3d
 1336, 1351 (Fed. Cir. 2018) (citation and internal quotation
 marks omitted). This determination has no bright-line
 test—relevant considerations, however, may include,
 “whether a []party exercises [or could exercise] control over
 a petitioner’s participation in a proceeding, or whether a
 []party is funding the proceeding or directing the proceed-
 ing.” Id. at 1342–43 (citing Office Patent Trial Practice
 Guide, 77 Fed. Reg. 48,756, 48,759 (Aug. 14, 2012)). Privity
 is also a highly fact-based inquiry, similarly “focus[ing] on
 the relationship between the named IPR petitioner and the
 party in the prior lawsuit.” WesternGeco LLC v. Ion Geo-
 physical Corp., 889 F.3d 1308, 1319 (Fed. Cir. 2018) (em-
 phasis added). That is, whether a party is in privity with
 another depends on the nature of the relationship between
 the two; “it is important to determine whether the peti-
 tioner and the prior litigant’s relationship—as it relates to
 the lawsuit—is sufficiently close that it can be fairly said
 that the petitioner [already] had a full and fair opportunity
 to litigate” the issues it now seeks to assert. See id. This
 inquiry is grounded in due process concerns for both the
 petitioner (here, LG) and the opposing party (here, Uniloc).
 See id. (citing Taylor v. Sturgell, 553 U.S. 880 (2008)). In
 other words, the inquiry has a dual-focus on preventing the
 petitioner from now lodging a successive attack for which
 it already had a first bite, thus, protecting the defending
 party from an unwarranted second attack, while also en-
 suring that the petitioner is not unfairly limited in its abil-
 ity to lodge its challenges if it has not had a full and fair
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 16                          UNILOC 2017 LLC   v. FACEBOOK INC.

 opportunity to do so already. Whether a party is an RPI or
 privy is a question of fact we review for substantial evi-
 dence. See Applications in Internet Time, 897 F.3d at 1356.
      Uniloc asserts that LG is an RPI or privy of Facebook
 because it “agreed to be bound by the determination of is-
 sues in the [’1427 IPR] proceeding below” and “exerted con-
 trol over substantive filings and oral argument in the
 [’1427 IPR] proceeding below.” Appellant’s Br. at 20. The
 Board agreed with LG that the evidence was simply insuf-
 ficient to establish a key consideration of the RPI analy-
 sis—control. The Board further considered the nature of
 the relationship between the parties for privity based on
 the prior inter partes proceeding, i.e., the Apple IPR, and
 found that nothing in the record supported the conclusion
 that the two parties are “sufficiently close such that both
 should be bound by the trial outcome and related estop-
 pels.” J.A. 104 (quoting WesternGeco, 889 F.3d at 1317–
 22).
     The Board’s determination that LG is not an RPI or
 privy of Facebook is supported by substantial evidence.
 Uniloc’s somewhat conclusory arguments never attempt to
 differentiate its position as to RPI and privy, instead
 simply asserting that LG must be one or the other. But
 just because LG expressed an interest in challenging the
 ’433 patent’s patentability, through its filing of its own IPR
 petition and joinder motion, does not by itself make LG an
 RPI to Facebook’s IPR. The record lacks any evidence that
 LG exercised any control over Facebook’s decision to file for
 inter partes review (either in the Apple IPR and in this IPR)
 or Facebook’s arguments made during the proceedings, and
 vice versa. Moreover, nothing in the record suggests that
 Facebook recruited LG to join as a party to the Facebook
 IPR, thereby making LG an agent advancing Facebook’s
 interests. That is, we see no evidence in the record to sug-
 gest that LG is acting “as a proxy [in the ’1427 IPR] for
 [Facebook] to relitigate the same issues” Facebook already
 presented in the Apple IPR. WesternGeco, 889 F.3d at 1319
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 (citing Taylor, 553 U.S. at 894–95). Instead, the record
 shows that LG, through its own counsel, filed its own IPR
 petitions in an effort to be recognized as an additional party
 to the proceeding here, seeking to assert its own inter-
 ests. 12
     The record likewise does not present evidence that LG
 and Facebook, beyond their relationship as joined parties
 in this proceeding, have any sort of “preexisting, estab-
 lished relationship” that indicates coordination amongst
 the two regarding the Apple IPR. See Applications in In-
 ternet Time, 897 F.3d at 1351. Without such evidence of
 control, in addition to no evidence of joint funding, or even
 any evidence of substantial coordination between the par-
 ties as to their respective decisions to bring these proceed-
 ings, a finding that LG is an RPI of or in privity with
 Facebook here would be improper. See WesternGeco, 889
 F.3d at 1320–21 (explaining, in finding no privity, that the
 evidence demonstrated the parties were represented by dif-
 ferent counsel, had no control over each other, had no col-
 lective funding, and lacked substantive involvement with

     12  Uniloc’s estoppel theory for LG relies in part on its
 assertion that LG “unequivocally represent[ed] that it
 would be bound by the Board’s decisions as to the original
 petitioners and that it would not advance any separate ar-
 guments from those advanced by [Facebook].” Appellant’s
 Br. at 24. But that argument misunderstands LG’s posi-
 tion, as LG’s joinder motion in the ’1427 IPR makes clear
 that LG had its own interests in challenging the ’433 pa-
 tent and that it would continue to pursue the IPR even if
 Facebook, for any reason, was no longer a petitioner. See
 J.A. 3345; see also J.A. 3340 (“[LG’s] interests may not be
 adequately protected in the Facebook IPR proceedings,
 particularly[, for example,] if the Facebook Petitioner set-
 tles with the Patent Owner. [LG] should be allowed to join
 in a proceeding affecting a patent asserted against it.”).
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 18                          UNILOC 2017 LLC   v. FACEBOOK INC.

 each other). The mere fact that the Board procedurally re-
 quired LG and Facebook to consolidate their arguments
 and evidence in combined filings in this proceeding does
 not, without more, make them privies of each other such
 that one petitioner automatically loses its rights to assert
 its challenge once the other petitioner loses its rights
 through estoppel.
      We decline, as the Board too did, to conclude that LG
 is estopped as result of Facebook’s participation in the Ap-
 ple IPR, merely by way of its joinder as a party in this later
 proceeding. Uniloc suggests that the Board, in reaching
 this conclusion, failed to address its arguments regarding
 Kofax, Inc. v. Uniloc USA, Inc., No. IPR2015-01207, 2016
 WL 8944779 (P.T.A.B. July 20, 2016). 13 Appellant’s Br. at
 21–23. Uniloc asserts that Kofax held that “co-petitioners”
 are automatically RPIs or privies of one another, but this
 misunderstands that decision. Kofax, which is non-binding
 on this court, determined that co-petitioners Ubisoft and
 Zebra in an IPR proceeding were RPIs of one another be-
 cause Ubisoft had named Zebra as an RPI in its filings to
 the Board, due to a preexisting relationship between them.
 2016 WL 8944779, at *1–2. Thus, once Ubisoft was es-
 topped from maintaining the IPR by its role as a petitioner
 in an earlier, different IPR, Zebra, as an undisputed RPI,
 was also estopped. Id. This situation is not the same as
 that here because Facebook did not list LG as an RPI in the
 ’1427 IPR making LG unlike Zebra.
     In view of the foregoing, substantial evidence supports
 the finding that LG acted of its own accord in the ’1427 IPR

      13 Uniloc suggests, without pointing to any specific in-
 stance, that the Board also erred in “misplac[ing] the bur-
 den of proof” in its RPI and privity analysis. This
 accusation is not supported by record.
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 UNILOC 2017 LLC   v. FACEBOOK INC.                          19

 for claims 1–6 and 8 and is not estopped from maintaining
 its patentability challenge in this proceeding.
                               B
     Uniloc, second, challenges the Board’s estoppel deter-
 mination for Facebook. Specifically, Uniloc asserts that
 Facebook is estopped from challenging claim 7 of the ’433
 patent because the Board found Facebook estopped from
 challenging the same claims the Board adjudicated in the
 Apple IPR, claims 1–6 and 8. Appellant’s Br. at 25–26.
 This estoppel should also apply to claim 7 because, Uniloc
 argues, claim 7 depends from claim 1 and the Board, by
 allowing such a challenge on claim 7, essentially allowed
 Facebook to continue to attack claim 1, which is broader in
 scope than claim 7. Id. at 26–27. Uniloc notes, moreover,
 that “[t]he Board’s partial dismissal [of Facebook for estop-
 pel on claims 1–6 and 8] essentially resulted in an imper-
 missible partial institution” in violation of SAS Institute.
 Id. at 25.
      As a threshold matter, for the reasons set forth above,
 the Board’s determination that Facebook was not estopped
 here from maintaining its challenge to claim 7 is subject to
 judicial review because it was a separate and later deter-
 mination not closely tied to institution and therefore not
 barred by § 314(d). Facebook argues, nonetheless, that we
 should decline to entertain this challenge because LG was
 also a petitioner for claim 7 and the petition could stand on
 that basis alone. Appellees’ Br. at 43. We decline, however,
 to speculate as to what this proceeding would have looked
 like absent Facebook’s participation for claim 7—we take
 the facts as they are, i.e., Facebook was a named petitioner
 for claim 7, remains a party to this appeal solely because
 its now-lone challenge to claim 7, and Uniloc may challenge
 whether this role was appropriate in view of § 315(e)(1).
      Despite Uniloc’s contentions, we see no error in the
 Board’s determination that the Apple IPR final written de-
 cision, which did not address claim 7, does not estop
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 20                           UNILOC 2017 LLC   v. FACEBOOK INC.

 Facebook from maintaining its challenge in this proceeding
 to claim 7. Section 315 explicitly limits the estoppel to the
 claims previously challenged and for those proceedings
 that resulted in a final written decision:
      The petitioner in an inter partes review of a claim
      in a patent under this chapter that results in a final
      written decision under section 318(a) . . . may not
      request or maintain a proceeding before the Office
      with respect to that claim on any ground that the
      petitioner raised or reasonably could have raised
      during that inter partes review.
 § 315(e)(1) (emphases added). Because claim 7 was not at
 issue in the Apple IPR, the plain language of the statute
 supports the conclusion that Facebook is not estopped from
 challenging this claim in this proceeding, regardless of its
 dependency on claim 1. Moreover, as a joined party in the
 Apple IPR, Facebook could not have raised any grounds for
 the patentability of claim 7 because claim 7 was not already
 challenged in the proceeding. See Windy City, 973 F.3d at
 1338 (“We conclude that the clear and unambiguous lan-
 guage of § 315(c) . . . does not authorize joinder of new is-
 sues . . . .”); see also Network-1 Techs., Inc. v. Hewlett-
 Packard Co., 981 F.3d 1015, 1027 (Fed. Cir. 2020) (“Thus,
 according to the statute, [§ 315(e),] a party is only estopped
 from challenging claims in the final written decision based
 on grounds that it ‘raised or reasonably could have raised’
 during the IPR. Because a joining party cannot bring with
 it grounds other than those already instituted, that party
 is not statutorily estopped from raising other invalidity
 grounds.”). Accordingly, that claim 7 was not at issue in
 the Apple IPR is enough to conclude that Facebook may
 challenge it here.
     Uniloc relies on SAS Institute as suggesting that the
 Board’s partial dismissal of Facebook results in an im-
 proper partial institution. Appellant’s Br. at 25. We disa-
 gree. SAS Institute rejected the Board’s decision there to
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 UNILOC 2017 LLC   v. FACEBOOK INC.                          21

 grant only “partial institution” of a petition for inter partes
 review because such a practice was inconsistent with 35
 U.S.C. § 318(a)’s mandate that “the Patent Trial and Ap-
 peal Board shall issue a final written decision with respect
 to the patentability of any patent claim challenged by the
 petitioner.” See 138 S. Ct. at 1354 (internal quotation
 marks omitted) (quoting § 318(a)). Unlike SAS Institute,
 the Board here reached a final written decision on all the
 petitioned claims, due to LG’s status as a petitioner. That
 fact alone is enough to dismiss Uniloc’s argument and ren-
 der irrelevant Facebook’s partial dismissal from the ’1427
 IPR.
                               C
     Uniloc’s third and fourth challenges on appeal both re-
 late to the Board’s obviousness determinations. “Whether
 a claimed invention is unpatentable as obvious under § 103
 is a question of law based on underlying findings of fact.”
 In re Gartside, 203 F.3d 1305, 1316 (Fed. Cir. 2000). “The
 Board’s legal conclusion of obviousness is reviewed de
 novo.” Id. This court reviews the Board’s factual determi-
 nations in an obviousness analysis for substantial evi-
 dence. Id.
     As to claims 1–8, Uniloc argues that the combination of
 Zydney and Clark does not teach the claimed “instant voice
 messaging application” because the claims require that the
 “message database” be embedded into the software agent
 itself, i.e., Clark’s message database must be embedded
 into Zydney’s software agent, not just Zydney’s system.
 Appellant’s Br. at 32.
     The Board’s finding in this respect is supported by sub-
 stantial evidence. Uniloc suggests that the Board imper-
 missibly strayed from the petition in reaching its finding,
 but the petition noted that Clark explicitly teaches incor-
 porating its message database into messaging client soft-
 ware, which corresponds to Zydney’s software agent, see
 J.A. 478–81.      Specifically, Clark explains that its
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 22                         UNILOC 2017 LLC   v. FACEBOOK INC.

 “invention can advantageously be integrated with messag-
 ing client software and/or messaging server software, such
 as e-mail software, to facilitate the organization of elec-
 tronic messages.” Clark col. 4 ll. 36–39 (emphases added).
 Clark also teaches elsewhere that its message database
 would be incorporated into the client computer in its soft-
 ware. See id. at col. 10 ll. 27–33, 47–52 and figs. 4A, 4B,
 and 4C. Furthermore, the Board credited the testimony of
 petitioner’s expert, Dr. Lavian, who testified that Clark’s
 stated goal of organization of electronic messages would
 have provided motivation for a skilled artisan to combine
 the message database of Clark into Zydney’s software. See
 Facebook, 2018 WL 6271687, at *15 (citing Dr. Lavian’s
 declaration). We conclude therefore that Uniloc’s argu-
 ment is without merit and that substantial evidence sup-
 ports the Board’s finding that the references teach the
 “instant voice messaging application” limitation of the
 challenged claims.
                              D
      Uniloc’s final argument is that the Board erred in con-
 cluding that claims 9–12, 14–17, 25, and 26 are unpatent-
 able because Zydney does not disclose the “attaches one or
 more files to the instant voice message” (“attaches to”) lim-
 itation recited in claim 9. Claims 10–12, 14–17, 25, and 26
 all depend from claim 9. Uniloc lodges several challenges.
 First, Uniloc argues that the Board’s adoption of its pro-
 posed construction of the “instant voice message” term is
 dispositive. Appellant’s Br. at 32. Second, Uniloc contends
 that the Board improperly shifted the burden of proof. Id.
 at 39. Third, Uniloc claims that the Board violated its due
 process in sua sponte construing the “attaches to” limita-
 tion in its final written decision. Id. at 40–41. Fourth,
 Uniloc attacks the Board’s determination that Zydney dis-
 closes the “attaches to” limitation as not supported by sub-
 stantial evidence. Id. at 43–51. We are unpersuaded.
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 UNILOC 2017 LLC   v. FACEBOOK INC.                          23

     Uniloc’s broader argument appears largely to hinge on
 the construction of the “attaches one or more files to the
 instant voice message” and “instant voice message” terms.
 Claim construction is a legal issue reviewed de novo, based
 on underlying factual findings that are reviewed for sub-
 stantial evidence. Personal Web Techs., LLC v. Apple, Inc.,
 848 F.3d 987, 990 (Fed. Cir. 2017). The Board adopted
 Uniloc’s proposed construction, construing “instant voice
 message” to mean “data content including representation
 of an audio message.” Facebook, 2018 WL 6271687, at *5.
 Neither party disputes this construction on appeal.
      Uniloc does, however, take issue with the Board’s con-
 struction of “attaches one or more files to the [data content
 including representation of an audio message]” limitation,
 suggesting that the Board’s interpretation of the “attaches
 to” limitation is inconsistent with its interpretation of “in-
 stant voice message.” The Board construed this “attaches
 to” limitation to mean “indicating that another file (or files)
 is associated with the ‘instant voice message.’” Id. at *8. 14
 Uniloc contends that the “attaches to” term requires more
 than a mere association with the audio file; it requires that
 the attachments be directly appended to the audio file it-
 self, not just to the container for this file. Appellant’s Br.
 at 42. This is because, it argues, the instant voice message,
 as construed by the Board, is equivalent to the audio file,

     14   Per recent regulation, the Board applies the Phil-
 lips claim construction standard to IPR petitions filed on or
 after November 13, 2018. See Changes to the Claim Con-
 struction Standard for Interpreting Claims in Trial Pro-
 ceedings Before the Patent Trial and Appeal Board, 83 Fed.
 Reg. 51,340 (Oct. 11, 2018) (codified at 37 C.F.R.
 § 42.100(b)). Because Facebook filed the petitions before
 November 13, 2018, the broadest reasonable interpretation
 standard applies to the IPR decisions on appeal.
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 24                          UNILOC 2017 LLC   v. FACEBOOK INC.

 not a container including the audio file. We agree with the
 Board.
     The claims and written description support the Board’s
 construction of the “attaches to” limitation as requiring as-
 sociation with the instant voice message container. The
 written description explains that the attachment of a file
 can be completed through a “drag-and-drop” method creat-
 ing “linkages” between the files and the instant voice mes-
 sage. See ’433 patent col. 13 ll. 35–40. Further, claim 14,
 which depends from claim 9, similarly recites that the at-
 taching function is accomplished through a “link” between
 the instant voice message and the files. Considering the
 intrinsic evidence and the broadest reasonable interpreta-
 tion standard, the Board’s broader construction of “attach-
 ing to” is the best reading of the limitation as used in the
 ’433 patent. Uniloc fails to point to specific teachings in the
 ’433 patent that demonstrate that a narrower construction
 is warranted. Moreover, we disagree with Uniloc that the
 Board improperly shifted the burden onto Uniloc in con-
 struing the claims. Based on our review of the entirety of
 the Board’s reasoning, the Board fairly weighed the argu-
 ments of each side and properly reached its conclusion.
      As to Uniloc’s argument that it was denied proper no-
 tice of the construction of this term, we, again, respectfully
 disagree. Filings from as early as the ’1428 IPR Pet. in-
 cluded assertions that Zydney disclosed the “attaches to”
 limitation by attaching the files to the “voice container,”
 see, e.g., J.A. 1902–06. During the IPR, Uniloc itself made
 assertions that the “attaches to” claim language required
 the attaching to be directly to the audio file. See J.A. 883.
 This term was also discussed in detail at the hearing before
 the Board. See, e.g., J.A. 2231–32 (Hearing Transcript).
 We determine, consequently, that Uniloc was afforded suf-
 ficient opportunity and notice to address the construction
 of this term.
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 UNILOC 2017 LLC   v. FACEBOOK INC.                          25

     Given the construction of the “attaches to” term, the
 Board’s finding that Zydney discloses this limitation is sup-
 ported by substantial evidence. Just as the Board noted,
 “Zydney . . . accomplishes ‘attachments’ in the same man-
 ner as the ’433 patent, by making an association between
 the instant voice message and the file attachment.” Face-
 book, 2018 WL 6271687, at *25. The Board pointed to Fig-
 ure 6 of Zydney as disclosing this associating between the
 attachment and the voice container. Id. The Board also
 credited the testimony of the petitioner’s expert “that a per-
 son of ordinary skill in the art would have found it obvious
 that attaching files to a voice container would have been
 part of the process [in Zydney] of packing the message into
 a voice container.” Id. Facebook explains, and Uniloc
 agrees, see Appellant’s Br. at 50 (citing its expert’s testi-
 mony about Zydney), that the attaching method disclosed
 by Zydney is a standard technique—Multipurpose Internet
 Mail Extension (MIME) format, Appellees’ Br. at 49–50.
 The Board relied on Zydney’s teachings of the MIME for-
 mat, which allows attachment of files to be specified in a
 message header, to demonstrate that Zydney discloses at-
 taching the files to the voice container. In view of this evi-
 dence, we find the Board’s conclusion to be substantially
 supported.
                         CONCLUSION
     We have considered Uniloc’s remaining arguments and
 are unpersuaded. We affirm the Board’s findings of un-
 patentability for claims 1–12, 14–17, 25, and 26 of the ’433
 patent.
                         AFFIRMED