Case: 18-1400   Document: 97     Page: 1   Filed: 03/18/2020




   United States Court of Appeals
       for the Federal Circuit
                 ______________________

                   FACEBOOK, INC.,
                      Appellant

                            v.

          WINDY CITY INNOVATIONS, LLC,
                   Cross-Appellant
               ______________________

 2018-1400, 2018-1401, 2018-1402, 2018-1403, 2018-1537,
                 2018-1540, 2018-1541
                ______________________

     Appeals from the United States Patent and Trademark
 Office, Patent Trial and Appeal Board in Nos. IPR2016-
 01156, IPR2016-01157, IPR2016-01158, IPR2016-01159,
 IPR2017-00659, IPR2017-00709.
                  ______________________

                 Decided: March 18, 2020
                 ______________________

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

    VINCENT J. RUBINO, III, Brown Rudnick, LLP, New
 York, NY, argued for cross-appellant. Also represented by
 ALFRED ROSS FABRICANT, ENRIQUE WILLIAM ITURRALDE,
 PETER LAMBRIANAKOS.
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 2               FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




     JEREMY COOPER DOERRE, Tillman Wright PLLC, Char-
 lotte, NC, as amicus curiae, pro se.

     JEFFREY ERIC SANDBERG, Appellate Staff, Civil Divi-
 sion, United States Department of Justice, Washington,
 DC, for amicus curiae United States. Also represented by
 SCOTT R. MCINTOSH, JOSEPH H. HUNT; THOMAS W. KRAUSE,
 JOSEPH MATAL, FARHEENA YASMEEN RASHEED, MOLLY R.
 SILFEN, Office of the Solicitor, United States Patent and
 Trademark Office, Alexandria, VA.

    DAVID E. BOUNDY, Cambridge Technology Law LLC,
 Newton, MA, as amicus curiae, pro se.
                 ______________________

       Before PROST, Chief Judge, PLAGER and O’MALLEY,
                        Circuit Judges.
 Opinion for the court filed by Chief Judge PROST, in which
       PLAGER and O’MALLEY, Circuit Judges, join.
     Additional views filed by Chief Judge PROST and Circuit
                  Judges PLAGER and O’MALLEY.
 PROST, Chief Judge.
     Windy City Innovations, LLC (“Windy City”) filed a
 complaint accusing Facebook, Inc. (“Facebook”) of infring-
 ing U.S. Patent Nos. 8,458,245 (“the ’245 patent”);
 8,694,657 (“the ’657 patent”); 8,473,552 (“the ’552 patent”);
 and 8,407,356 (“the ’356 patent”). In June 2016, exactly
 one year after being served with Windy City’s complaint,
 Facebook timely petitioned for inter partes review (“IPR”)
 of several claims of each patent. At that time, Windy City
 had not yet identified the specific claims it was asserting
 in the district court proceeding. The Patent Trial and Ap-
 peal Board (“Board”) instituted IPR of each patent. In Jan-
 uary 2017, after Windy City had identified the claims it
 was asserting in the district court litigation, Facebook filed
 two additional petitions for IPR of additional claims of the
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC               3



 ’245 and ’657 patents, along with motions for joinder to the
 already instituted IPRs on those patents. By the time of
 that filing, the one-year time bar of § 315(b) had passed.
 The Board nonetheless instituted Facebook’s two new
 IPRs, and granted Facebook’s motions for joinder.
      In the final written decisions, the Board delivered a
 mixed result, holding that Facebook had shown by a pre-
 ponderance of the evidence that some of the challenged
 claims are unpatentable as obvious but had failed to show
 that others were unpatentable as obvious. Importantly,
 many of the claims the Board found unpatentable were
 claims only challenged in the later-joined proceedings. Fa-
 cebook appealed, and Windy City cross-appealed on the
 Board’s obviousness findings. In its cross-appeal, Windy
 City also challenges the Board’s joinder decisions allowing
 Facebook to join its new IPRs to its existing IPRs and to
 include new claims in the joined proceedings.
     For the reasons explained below, we hold that the
 Board erred in allowing Facebook to join itself to a proceed-
 ing in which it was already a party, and also erred in al-
 lowing Facebook to add new claims to the IPRs through
 that joinder. We also hold that the Board’s obviousness de-
 terminations on the originally instituted claims are sup-
 ported by substantial evidence. We therefore affirm-in-
 part and vacate-in-part the Board’s final written decisions
 on the ’245 and ’657 patents, affirm the Board’s final writ-
 ten decision on the ’552 patent, and affirm-in-part the
 Board’s final written decision on the ’356 patent. We dis-
 miss as moot Facebook’s appeal of the Board’s final written
 decision on the ’356 patent with respect to claims 14 and
 33.
                               I
                               A
     The ’245, ’657, ’552, and ’356 patents share a common
 specification and claim priority to a patent application filed
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 4              FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 on April 1, 1996. 1 The patents are generally related to
 methods for communicating over a computer-based net-
 work. The specification discloses a system with a “control-
 ler computer [1],” a plurality of “participator computers 5,”
 and a “connection 13,” linking the controller computer with
 each of the participator computers, as shown in Figure 1
 below.




 ’245 patent at col. 4 l. 65–col. 5 l. 18, fig. 1. The specifica-
 tion describes “provid[ing] a chat capability suitable for
 handling graphical, textual, and multimedia information.”
 Id. at col. 2 ll. 15–17.
     Two features described in the specification are relevant
 to this appeal: (1) the ability to handle “out-of-band” multi-
 media information, i.e., information that a receiving com-
 puter may be unable to present on its own; and (2) the
 ability to control the dissemination of information among
 participator computers, which is referred to in the patents
 as “censorship” of content. The ’245 patent claims relate to
 the “out-of-band” feature, and the ’657, ’552, and ’356 pa-




     1   For convenience, references to the specification cite
 only the ’245 patent.
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC              5



 tent claims relate to the “censorship” features. These fea-
 tures are discussed in more detail in Part II.B when ad-
 dressing the technical merits of the appeal and cross-
 appeal.
                              B
      On June 2, 2015, Windy City filed a complaint against
 Facebook alleging infringement of the ’245, ’657, ’552, and
 ’356 patents (“the asserted patents”) in the U.S. District
 Court for the Western District of North Carolina. Windy
 City’s complaint did not specify which claims of the four
 asserted patents (collectively having a total of 830 claims)
 Facebook allegedly infringed. See J.A. 7996–8006 (alleging
 infringement of “claims of the patents-in-suit”). Facebook
 was served with the complaint on June 3, 2015, starting
 the statutory one-year clock for Facebook to file petitions
 for IPR of the asserted patents. See 35 U.S.C. § 315(b).
      On July 24, 2015, Facebook filed a motion to dismiss,
 arguing that the complaint did not provide adequate notice
 of Windy City’s infringement allegations because it did not
 identify which claims were asserted against which Face-
 book products. On August 25, 2015, Facebook filed a mo-
 tion to transfer the case to the U.S. District Court for the
 Northern District of California. The North Carolina dis-
 trict court did not rule on either motion for several months.
 On March 16, 2016, the North Carolina district court
 granted Facebook’s motion to transfer but did not rule on
 Facebook’s motion to dismiss.
     Upon transfer to the Northern District of California,
 the district court issued a scheduling order on April 6,
 2016, setting a case management conference for July 7,
 2016. 2 Under Northern District of California Patent Local



     2   The case management conference was ultimately
 held at a later date.
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 6              FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 Rule 3-1, Windy City would be required to identify its as-
 serted claims 14 days later—more than one month after the
 expiration of the one-year time bar to file petitions for IPR
 of the asserted patents. On May 4, 2016, with the one-year
 bar date approaching, Facebook filed a motion asking the
 district court to order Windy City to identify no more than
 40 asserted claims by May 16, 2016. The district court de-
 nied the motion on May 17, 2016.
      On June 3, 2016, the last day of the one-year window,
 Facebook filed a petition for IPR of each of the four asserted
 patents. The petitions challenged some, but not all, of the
 claims of each patent. Specifically, Facebook challenged
 claims 1–15, 17, and 18 of the ’245 patent; claims 189, 334,
 342, 348, 465, 580, 584, and 592 of the ’657 patent; claims
 1–61 and 64 of the ’552 patent; and claims 1–9, 12, 14–28,
 31, and 33–37 of the ’356 patent. The Board instituted re-
 view of all of the challenged claims and grounds in the pe-
 titions, except for claims 60 and 61 of the ’552 patent. 3
      More than four months after the one-year deadline to
 file IPRs, on October 19, 2016, Windy City identified the
 claims of each patent that it was asserting in the district
 court case. Some of the claims of the ’245 and ’657 patents
 that Windy City asserted were claims that Facebook had


     3   The Board’s institution decisions were issued prior
 to the Supreme Court’s decision in SAS Institute, Inc. v.
 Iancu, 138 S. Ct. 1348 (2018), which held that the Director
 cannot institute on fewer than all of the claims challenged
 in the petition. In this case, no party seeks SAS-based re-
 lief. “[A]lthough [SAS] now makes clear that the Board
 erred in limiting the scope of the IPRs it instituted and
 hence the scope of its final written decisions, we have juris-
 diction to address the merits of the Board’s final written
 decisions and . . . we need not, and will not, sua sponte re-
 vive the ‘non-instituted’ claims and grounds.” PGS Geo-
 physical AS v. Iancu, 891 F.3d 1354, 1357 (Fed. Cir. 2018).
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC                 7



 not challenged in its petitions for IPR of those patents. Fa-
 cebook then prepared two additional petitions for IPR chal-
 lenging these additional asserted claims. Specifically,
 these petitions challenged claims 19 and 22–25 of the ’245
 patent and claims 203, 209, 215, 221, 477, 482, 487, and
 492 of the ’657 patent. Because the petitions would other-
 wise have been time-barred under 35 U.S.C. § 315(b), Fa-
 cebook filed the petitions along with motions asking the
 Board to join each new proceeding to the already instituted
 IPR on the same patent under § 315(c). Windy City op-
 posed the motions for joinder.
      The Board granted Facebook’s motions for joinder and
 allowed the newly challenged claims to be added to the pro-
 ceedings. See J.A. 7385–402, 8162–76. In considering
 whether to grant the motions for joinder, the Board rea-
 soned that “although the newly challenged claims are not
 identical” to those challenged in the original petitions, “the
 substance is very similar such that the addition of [the
 new] claims . . . is not likely to affect the scope of the trial
 significantly.” J.A. 7393; see also J.A. 8168–69. The Board
 also noted that joinder would not significantly disrupt the
 trial schedule, briefing, or discovery. J.A. 7394, 8169. In
 addition, the Board determined that Facebook did not un-
 duly delay in challenging the new claims in the second pe-
 titions filed with the motions for joinder. J.A. 7394–97,
 8169–71. The Board agreed with Facebook that Windy
 City’s district court complaint generally asserting the
 “claims” of the asserted patents “cannot reasonably be con-
 sidered an allegation that Petitioner infringes all 830
 claims of the several patents asserted.” J.A. 7395; see also
 J.A. 8170. The Board therefore found that Facebook could
 not have reasonably determined which claims were as-
 serted against it within the one-year time bar. See J.A.
 7395–96, 8170. Once Windy City identified the asserted
 claims after the one-year time bar, the Board found that
 Facebook did not delay in challenging the newly asserted
 claims by filing the second petitions with the motions for
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 8              FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 joinder. J.A. 7397, 8170. For each new petition, the Board
 held that Facebook “has established good cause for joining
 this proceeding with the [existing] IPR.” J.A. 8172. Ac-
 cordingly, the Board ordered that each new IPR “is hereby
 joined with” the corresponding existing IPR.
     Two Administrative Patent Judges (“APJs”) on the
 panels joined concurring opinions, raising “concerns with
 permitting a party to, essentially, join to itself.” J.A. 7400;
 see also J.A. 8173. In their view, “§ 315(c), when properly
 interpreted, does not authorize same-party joinder because
 a party cannot be joined to a proceeding ‘as a party’ if it
 already is a party to that proceeding.” J.A. 7401, 8174.
 While this view was shared by two of the three APJs on the
 panel, it was expressed in a concurring opinion because,
 “the Director repeatedly has taken the position . . . that
 such same-party joinder is permitted by § 315(c)” and the
 concurring APJs agreed to follow that position in this case,
 “[d]espite [their] disagreement with the Director’s inter-
 pretation.” J.A. 7401 (citing Brief for Intervenor – Director
 of the United States Patent and Trademark Office at 32–
 39, Nidec Motor Corp. v. Zhongshan Broad Ocean Motor
 Co., 868 F.3d 1013 (Fed. Cir. 2017) (No. 16-2321)); see also
 J.A. 8174–75 (same). Over the concerns expressed in the
 concurrence, Facebook was permitted to join its otherwise
 time-barred IPR proceedings to instituted IPR proceedings
 where it was already a party.
     In its final written decision on the ’245 patent (which
 considered the claims challenged in the original petition as
 well as the second petition filed with the motion for join-
 der), the Board held that Facebook had failed to show by a
 preponderance of the evidence that claims 1–15, 17–19,
 and 22–25 are unpatentable as obvious. Facebook, Inc. v.
 Windy City Innovations, LLC, No. IPR2016-01156, Paper
 52, at 34 (P.T.A.B. Dec. 6, 2017) (“’245 Final Written Deci-
 sion”).
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC               9



      In its final written decision on the ’657 patent (which
 also considered the claims challenged in both the original
 petition and the second petition), the Board held that Fa-
 cebook had shown by a preponderance of the evidence that
 claims 189, 334, 342, 348, 465, 477, 482, 487, 492, 580, 584,
 and 592 are unpatentable as obvious but had failed to show
 that claims 203, 209, 215, and 221 are unpatentable as ob-
 vious. Facebook, Inc. v. Windy City Innovations, LLC,
 No. IPR2016-01159, Paper 52, at 56 (P.T.A.B. Dec. 6, 2017)
 (“’657 Final Written Decision”).
     In its final written decision on the ’552 patent, the
 Board held that Facebook had shown by a preponderance
 of the evidence that claims 2, 3, 5, 7, 10–17, 59, and 64 are
 unpatentable as obvious but had failed to show that claims
 1, 4, 6, 8, 9, and 18–58 are unpatentable as obvious. Face-
 book, Inc. v. Windy City Innovations, LLC, No. IPR2016-
 01158, Paper 47, at 59 (P.T.A.B. Dec. 6, 2017) (“’552 Final
 Written Decision”).
     In its final written decision on the ’356 patent, the
 Board held that Facebook had shown by a preponderance
 of the evidence that claims 1–9, 12, 15–28, 31, and 34–37
 are unpatentable as obvious but had failed to show that
 claims 14 and 33 are unpatentable as obvious. Facebook,
 Inc. v. Windy City Innovations, LLC, No. IPR2016-01157,
 Paper 47, at 59 (P.T.A.B. Dec. 6, 2017) (“’356 Final Written
 Decision”).
     Facebook timely appealed, and Windy City cross-ap-
 pealed. We have jurisdiction pursuant to 28 U.S.C.
 § 1295(a)(4)(A).
                               II
     On appeal, Facebook argues that the Board erred in
 finding that Facebook failed to prove that claims 1–15, 17–
 19, and 22–25 of the ’245 patent; claims 203, 209, 215, and
 221 of the ’657 patent; claims 1, 4, 6, 8, 9, and 18–58 of the
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 10             FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 ’552 patent; and claims 14 and 33 of the ’356 patent are
 unpatentable as obvious over the instituted grounds.
     In its cross-appeal, Windy City argues that the Board
 erred in finding that a person of ordinary skill in the art
 would have been motivated to combine the prior art refer-
 ences in each IPR. Windy City also argues that joinder was
 improper because 35 U.S.C. § 315(c) does not authorize
 same-party joinder and does not authorize joinder of new
 issues.
     We begin by addressing the joinder issue raised in
 Windy City’s cross-appeal then turn to the technical merits
 presented in Facebook’s appeal and Windy City’s cross-ap-
 peal.
                              A
     In its cross-appeal, Windy City argues that the Board’s
 decisions granting joinder were improper and should be re-
 versed. Windy City presents two issues of statutory inter-
 pretation: whether 35 U.S.C. § 315(c) permits a person to
 be joined as a party to a proceeding in which it was already
 a party (“same-party” joinder); and whether it permits new
 issues to be added to an existing IPR through joinder (“new
 issue” joinder), including issues that would otherwise be
 time-barred.
                              1
     Statutory interpretation is an issue of law that we re-
 view de novo. Unwired Planet, LLC v. Google Inc., 841 F.3d
 1376, 1379 (Fed. Cir. 2016). “In statutory construction, we
 begin ‘with the language of the statute.’” Kingdomware
 Techs., Inc. v. United States, 136 S. Ct. 1969, 1976 (2016)
 (quoting Barnhart v. Sigmon Coal Co., 534 U.S. 438, 450
 (2002)). Our “first step ‘is to determine whether the lan-
 guage at issue has a plain and unambiguous meaning with
 regard to the particular dispute in the case.’” Barnhart,
 534 U.S. at 450 (quoting Robinson v. Shell Oil Co., 519 U.S.
 337, 340 (1997)). “It is a ‘fundamental canon of statutory
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC                11



 construction that the words of a statute must be read in
 their context and with a view to their place in the overall
 statutory scheme.’” Food & Drug Admin. v. Brown & Wil-
 liamson Tobacco Corp., 529 U.S. 120, 133 (2000) (quoting
 Davis v. Mich. Dep’t of Treasury, 489 U.S. 803, 809 (1989)).
                               2
    35 U.S.C. § 315 governs the relationship between IPRs
 and other proceedings. Sections 315(b) and (c) recite:
     (b) Patent Owner’s Action.—An inter partes re-
     view may not be instituted if the petition request-
     ing the proceeding is filed more than 1 year after
     the date on which the petitioner, real party in in-
     terest, or privy of the petitioner is served with a
     complaint alleging infringement of the patent. The
     time limitation set forth in the preceding sentence
     shall not apply to a request for joinder under sub-
     section (c).
     (c) Joinder.—If the Director institutes an inter
     partes review, the Director, in his or her discretion,
     may join as a party to that inter partes review any
     person who properly files a petition under section
     311 that the Director, after receiving a preliminary
     response under section 313 or the expiration of the
     time for filing such a response, determines war-
     rants the institution of an inter partes review un-
     der section 314.
     Windy City argues that § 315(c) does not authorize
 same-party joinder and also that it does not authorize join-
 der of new issues material to patentability, such as new
 claims or new grounds. Facebook disputes both points, ar-
 guing that § 315(c) authorizes same-party joinder and that
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 12             FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 it does not prohibit joinder of new issues. 4 Both Windy City
 and Facebook contend that the statute is clear and unam-
 biguous in favor of their respective interpretations. See
 Cross-Appellant’s Response Br. 40, 44; Appellant’s Reply
 and Response Br. 28, 31.
     We agree with Windy City on both points. The clear
 and unambiguous text of § 315(c) does not authorize same-
 party joinder, and does not authorize the joinder of new is-
 sues.
     Beginning with the statutory language, § 315(b) artic-
 ulates the time-bar for when an IPR “may not be insti-
 tuted.” 35 U.S.C. § 315(b). But § 315(b) includes a specific


      4   Facebook also argues that Windy City waived its
 arguments challenging the Board’s joinder decisions by
 failing to raise them before the Board. But Windy City op-
 posed Facebook’s motions for joinder, arguing that “[g]rant-
 ing joinder would result in Facebook circumventing . . .
 statutory limitations on petitioners, all within the Board’s
 familiarity . . . .” J.A. 7371, 8147. The Board was quite fa-
 miliar with the issue, as evidenced by the concurring opin-
 ion, where two APJs expressed the view that “§ 315(c),
 when properly interpreted, does not authorize same-party
 joinder because a party cannot be joined to a proceeding ‘as
 a party’ if it already is a party to that proceeding.”
 J.A. 7401, 8174. The concurring opinion also noted its “dis-
 agreement with the Director’s interpretation” of § 315(c)
 permitting same-party joinder. J.A. 7401, 8174–75. More-
 over, Windy City sought a writ of mandamus challenging
 the joinder decisions, which we denied while noting that “it
 is clear that Windy City will have an opportunity in the
 relatively near future to address its concerns through a re-
 sponse or cross-appeal” in this case. In re: Windy City In-
 novations, LLC, No. 18-102, ECF No. 19, at 3 (Fed. Cir.
 2018) (per curiam). Windy City has not waived its right to
 challenge the Board’s joinder decisions.
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC               13



 exception to the time bar. By its own terms, “[t]he time
 limitation . . . shall not apply to a request for joinder under
 subsection (c).” Id.; see also Click-To-Call Techs., LP v. In-
 genio, Inc., YellowPages.com, LLC, 899 F.3d 1321, 1331
 (Fed. Cir. 2018) (“Congress also demonstrated that it knew
 how to provide an exception to the time bar by including a
 second sentence in the provision: ‘The time limitation set
 forth in the preceding sentence shall not apply to a request
 for joinder under subsection (c).’” (quoting 35 U.S.C.
 § 315(b))), cert. granted in part sub nom, Dex Media, Inc. v.
 Click-To-Call Techs., LP, 139 S. Ct. 2742 (2019).
      The joinder provision, § 315(c), states: “If the Director
 institutes an inter partes review, the Director, in his or her
 discretion, may join as a party to that inter partes review
 any person who properly files a petition under section 311
 that the Director . . . determines warrants the institution
 of an inter partes review under section 314.” 35 U.S.C.
 § 315(c). The plain language of § 315(c) indicates that the
 exception to the time bar offered by the joinder provision
 only applies if there is an instituted IPR, meaning that a
 first petition must have been timely under § 315(b), among
 other requirements. Subsection (c) then provides that after
 an inter partes review has been instituted, the Director, in
 his or her discretion, “may join” “as a party to that inter
 partes review” “any person” who has filed “a petition under
 section 311 that the Director . . . determines warrants the
 institution of an inter partes review under section 314.”
 35 U.S.C. § 315(c) (emphases added).
                               3
     We first address whether the language of § 315(c) au-
 thorizes same-party joinder, i.e., the joinder of a person as
 a party to a proceeding in which it is already a party. As
 an initial matter, however, we note that this is not what
 the Board purported to be doing in the proceedings at issue.
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 14             FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




     As described above, the plain language of § 315(c) al-
 lows the Director “to join as a party [to an already insti-
 tuted IPR] any person” who meets certain requirements.
 35 U.S.C. § 315 (emphases added). When the Board insti-
 tuted Facebook’s later petitions and granted its joinder mo-
 tions, however, the Board did not purport to be joining
 anyone as a party. Rather, the Board understood Facebook
 to be requesting that its later proceedings be joined to its
 earlier proceedings. J.A. 8163 (“Facebook filed a Motion for
 Joinder . . . requesting that this proceeding by joined with
 [its prior IPR]”). It granted this request accordingly.
 J.A. 8172 (“Further Ordered that IPR2017-00709 is hereby
 joined with IPR2016-01156”). In other words, an essential
 premise of the Board’s decision was that § 315(c) authorizes
 two proceedings to be joined, rather than joining a person
 as a party to an existing proceeding.
     That understanding of § 315(c) is contrary to the plain
 language of the provision. Section 315(c) authorizes the
 Director to “join as a party to [an IPR] any person who”
 meets certain requirements, i.e., who properly files a peti-
 tion the Director finds warrants the institution of an IPR
 under § 314. No part of § 315(c) provides the Director or
 the Board with the authority to put two proceedings to-
 gether. That is the subject of § 315(d), which provides for
 “consolidation,” among other options, when “[m]ultiple pro-
 ceedings” involving the patent are before the PTO.
 35 U.S.C. § 315.
     The difference between joining two proceedings and
 joining a person “as a party” is a matter of the plain mean-
 ing of familiar legal terms. Courts construe legal terms in
 a statute to have their customary, ordinary meaning in law
 unless there is a strong reason to infer a departure from
 that meaning. See, e.g., Microsoft Corp. v. i4i Ltd. Partner-
 ship, 564 U.S. 91, 101 (2011) (“where Congress uses a com-
 mon-law term in a statute, we assume the ‘term . . . comes
 with a common law meaning, absent anything pointing an-
 other way.’”). Facebook has not identified any customary,
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC             15



 ordinary usage of “joining a person as a party to a proceed-
 ing” as referring to combining the proceedings, or any indi-
 cation of a congressional intent to depart from the normal
 usage that keeps these things distinct. Indeed, the statute
 recognizes the difference by addressing joinder in § 315(c)
 and consolidation in § 315(d). Counsel and judges in all
 federal proceedings are familiar with this distinction. For
 example, the difference between Federal Rules of Civil Pro-
 cedure 19 and 20 (relating to joinder of persons), and Rule
 42 (relating to consolidation of proceedings), generally par-
 allels the difference between § 315(c) and § 315(d). Accord-
 ingly, the unambiguous language of § 315(c) does not
 provide for two proceedings to be joined, as the Board pur-
 ported to order here.
     We recognize that, notwithstanding the language it
 used, the Board may have been intending to convey that it
 was joining Facebook as a party to its previously instituted
 IPRs, and not joining the IPR proceedings themselves. In
 their concurrence, for example, APJs McKone and Lee re-
 ferred to the majority opinion as “permitting a party to, es-
 sentially, join to itself.” J.A. 7400. The parties themselves
 appear to have interpreted the Board’s decision this way,
 and have conducted this appeal accordingly. See, e.g.,
 Cross-Appellant’s Response Br. 16 (“the Board . . . allowed
 Facebook to join its own previously-filed IPRs”); Appel-
 lant’s Reply and Response Br. 31 (“the Board . . . join[ed]
 Facebook to the previously-instituted IPRs . . . so called
 ‘same-party’ joinder”).
     Assuming that the Board in fact joined Facebook “as a
 party” to its existing IPRs, the question before us is
 whether § 315(c) authorizes a person to be joined as a party
 to a proceeding in which it is already a party. The clear
 and unambiguous language of § 315(c) confirms that it does
 not. Subsection (c) allows the Director to “join as a party
 to [an IPR] any person who” meets certain threshold re-
 quirements. It would be an extraordinary usage of the
 term “join as a party” to refer to persons who were already
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 16             FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 parties. Again, under the Federal Rules of Civil Procedure
 for example, joinder of a person as a party is uniformly
 about adding someone that is not already a party. We are
 not aware of any legal context in which a person is permit-
 ted to join “as a party” to a proceeding in which it is already
 a party. Again, we must construe legal terms in a statute
 to have their customary, ordinary meaning in law unless
 there is a strong reason to infer a departure from that
 meaning. See, e.g., Microsoft, 564 U.S. at 101. We see no
 basis for inferring a departure in the present context.
      We recognize that the Board’s Precedential Opinion
 Panel analyzed this issue in Proppant Express Investments,
 LLC v. Oren Technologies, LLC, No. IPR2018-00914, Paper
 38 (P.T.A.B. Mar. 13, 2019), and came to the opposite con-
 clusion. Id. at 5 (“§ 315(c) permits a petitioner to be joined
 to a proceeding in which it is already a party.”). But that
 conclusion, which allowed same-party joinder, is incorrect
 under the unambiguous meaning of the statute. The
 Board’s conclusion in Proppant hinged on the statute’s use
 of the phrase “any person.” Id. The Board reasoned that
 because the word “any” necessarily carries “an expansive
 meaning,” the phrase “any person” provides the Director
 with the authority, should he wish, to join “every person
 who properly files a petition that warrants institution,” in-
 cluding oneself. Id. at 5–6 (internal quotations and cita-
 tions omitted). But the full phrase used by § 315(c) is that
 the Director “may join as a party [to the IPR] any person”
 who meets certain requirements (including, i.e., having its
 own petition that warrants institution). The phrase “join
 as a party to a proceeding” on its face limits the range of
 “person[s]” covered to those who, in normal legal discourse,
 are capable of being joined as a party to a proceeding (a
 group further limited by the own-petition requirements),
 and an existing party to the proceeding is not so capable.
 A statute saying that “a person may marry any person who
 is older than 16 . . . ” would not, by virtue of the “any per-
 son” language, authorize marriage to oneself. The word
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC               17



 “marry” necessarily requires another person. The “join as
 a party” language does the same here. A party cannot logi-
 cally be “join[ed] as a party” in a proceeding if it is already
 a party to that proceeding.
     Accordingly, we hold that the clear and unambiguous
 meaning of § 315(c) does not authorize joinder of two pro-
 ceedings, and does not authorize the Director to join a per-
 son to a proceeding in which that person is already a party.
                               4
      The Board’s interpretation of § 315(c) is contrary to the
 unambiguous meaning of the statute for a second reason.
 Setting aside the question of same-party joinder, the lan-
 guage in 315(c) does no more than authorize the Director
 to join 1) a person 2) as a party, 3) to an already instituted
 IPR. This language does not authorize the joined party to
 bring new issues from its new proceeding into the existing
 proceeding, particularly when those new issues are other-
 wise time-barred. As discussed above, § 315(c) authorizes
 joinder of a person as a party, not “joinder” of two proceed-
 ings.
     The strongest case that Facebook can make is that the
 statute does not expressly prohibit the introduction of new
 issues in the joined proceedings. Appellant’s Reply and Re-
 sponse Br. 28 (“The statute . . . does not prohibit the con-
 sideration of new claims or issues in the joined
 proceedings.”); id. (“Nothing in this text states or implies
 that when a person joins an instituted IPR, that person
 cannot address any new claims or issues beyond the al-
 ready-instituted IPR.”).
     The lack of an express prohibition, however, does not
 make § 315(c) ambiguous as to whether it permits joinder
 of new issues. Rather, it simply permits the Director, at
 his or her discretion, to join any person as a party to an
 already-instituted IPR. The already-instituted IPR to
 which a person may join as a party is governed by its own
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 18              FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 petition and is confined to the claims and grounds chal-
 lenged in that petition. SAS Inst., Inc. v. Iancu, 138 S. Ct.
 1348, 1356 (2018) (“[T]he petitioner’s petition, not the Di-
 rector’s discretion, is supposed to guide the life of the liti-
 gation.”); id. at 1355 (“Congress chose to structure a
 process in which it’s the petitioner, not the Director, who
 gets to define the contours of the proceeding.”). We there-
 fore conclude that the unambiguous meaning of § 315(c) is
 that it allows the Director discretion to join a person as a
 party to an already instituted IPR but does not permit the
 joined party to bring new issues from the newer proceeding
 into the existing proceeding. Any other conclusion would
 improperly join proceedings, rather than parties—which
 § 315(c) does not authorize.
     Our interpretation of § 315(c) is also consistent with
 the statutory scheme of § 315 as a whole, as illustrated by
 the neighboring subsections. For example, as noted previ-
 ously, § 315(d) specifically contemplates “consolidation” of
 two proceedings and their respective issues. Section 315(d)
 recites:
      [D]uring the pendency of an inter partes review, if
      another proceeding or matter involving the patent
      is before the Office, the Director may determine the
      manner in which the inter partes review or other
      proceeding or matter may proceed, including
      providing for . . . consolidation . . . of any such mat-
      ter or proceeding.
 35 U.S.C. § 315(d). This section thus authorizes consolida-
 tion of, for example, multiple instituted (and therefore
 timely) IPRs and the issues contained therein, even when
 the issues may not be identical. There is a clear distinction
 between § 315(c), which refers to the joinder of a person as
 a party, and § 315(d), which refers to the consolidation of
 multiple proceedings and the issues in each. Construing
 § 315(c) to permit joinder of proceedings, and all the new
 issues therein, would render § 315(d) superfluous, which is
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC                19



 disfavored in statutory interpretation. See Marx v. Gen.
 Revenue Corp., 568 U.S. 371, 386 (2013) (“[T]he canon
 against surplusage is strongest when an interpretation
 would render superfluous another part of the same statu-
 tory scheme.”). Again, construing § 315(c) to allow unfet-
 tered joinder of proceedings is inconsistent with all
 common understandings of the terms “joinder” and “consol-
 idation.”
      Our interpretation is further supported by the legisla-
 tive history of § 315(c). The final committee report states
 that under § 315(c), “[t]he Director may allow other peti-
 tioners to join an inter partes . . . review.” H.R. Rep.
 No. 112-98, pt. 1, at 76 (2011), as reprinted in 2011
 U.S.C.C.A.N. 67, 100 (emphasis added). Like the statutory
 language itself, this contemplates allowing a person to join
 an already-instituted IPR as a party but not to bring with
 it its new issues. See Nidec, 868 F.3d at 1020 (Dyk, J., con-
 curring).
     Facebook too relies on the legislative history, arguing
 that the following statement from Senator Kyl, particularly
 the final sentence in the excerpt below, shows that § 315(c)
 explicitly contemplates joinder of new issues:
     Sections 315(c) and 325(c) allow joinder of inter
     partes and post-grant reviews. The Office antici-
     pates that joinder will be allowed as of right—if an
     inter partes review is instituted on the basis of a
     petition, for example, a party that files an identical
     petition will be joined to that proceeding, and thus
     allowed to file its own briefs and make its own ar-
     guments. If a party seeking joinder also presents
     additional challenges to validity that satisfy the
     threshold for instituting a proceeding, the Office
     will either join that party and its new arguments
     to the existing proceeding, or institute a second
     proceeding for the patent.
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 20             FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 157 Cong. Rec. S1360, S1376 (daily ed. Mar. 8, 2011) (state-
 ment of Sen. Kyl). We disagree for at least three reasons.
     First, the scenario described by Senator Kyl does not
 apply to the situation at hand. One option described in the
 final sentence is “to institute a second proceeding for the
 patent,” which would require the second petition to be
 timely filed. The scenario Senator Kyl describes therefore
 assumes two timely-filed petitions. 5 Because Senator Kyl’s
 statement refers to two timely-filed petitions, we do not
 find it instructive for understanding Congress’ intent about
 whether to allow joinder of new issues from a time-barred
 petition.
     Second, it is unclear which portions of Senator Kyl’s
 statement refer to § 315(c) and which refer to § 325(c). The
 final sentence regarding “additional challenges” may relate
 to post-grant reviews under § 325(c), which is titled “join-
 der” but expressly contemplates consolidation of issues
 presented in multiple petitions. See 35 U.S.C. § 325(c) (“If
 more than 1 petition for a post-grant review under this
 chapter is properly filed against the same patent and the
 Director determines that more than 1 of these petitions
 warrants the institution of a post-grant review under sec-
 tion 324, the Director may consolidate such reviews into a
 single post-grant review.”).
     Third, this single, ambiguous comment from one sena-
 tor cannot override the final committee report, much less
 the plain statutory language. See Garcia v. United States,
 469 U.S. 70, 76 (1984) (“In surveying legislative history we
 have repeatedly stated that the authoritative source for
 finding the Legislature’s intent lies in the Committee Re-




      5  As noted above, the proper mechanism for combin-
 ing the issues raised in two timely-filed IPRs is consolida-
 tion under § 315(d), not joinder under § 315(c).
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC               21



 ports on the bill, which ‘represen[t] the considered and col-
 lective understanding of those Congressmen involved in
 drafting and studying proposed legislation.’ We have es-
 chewed reliance on the passing comments of one Member.”
 (alteration in original) (citation omitted) (quoting Zuber v.
 Allen, 396 U.S. 168, 186 (1969))); Milner v. Dep’t of Navy,
 562 U.S. 562, 572 (2011) (“We will not . . . allow[] ambigu-
 ous legislative history to muddy clear statutory lan-
 guage.”).
     Finally, Facebook argues that there are important pol-
 icy rationales that run counter to our interpretation. Ap-
 pellant’s Reply and Response Br. 37–38. Specifically,
 Facebook argues that it was appropriate for the Board to
 permit joinder given the unique facts of this case, where at
 the end of the one-year time bar Windy City had not yet
 identified which of the 830 claims of four patents it was
 asserting against Facebook. Facebook submits that the
 view we adopt today leaves a dangerous incentive for pa-
 tent owners to file suit on patents containing hundreds of
 claims and then “steadfastly delay[] the litigation through
 various stalling tactics [and] . . . ‘run out the clock’ on the
 one year bar under § 315(b) before identifying asserted
 claims.” Id. at 37. This, according to Facebook, leaves ac-
 cused infringers “stuck between a rock and a hard place”
 with only two options: (1) file petitions addressing each of
 the hundreds of claims; or (2) file petitions on a fraction of
 the claims with the risk that the patent owner will assert
 claims that were not covered by the petitions. Id. at 37–38.
     We do not disagree with Facebook that the result in
 this particular case may seem in tension with one of the
 AIA’s objectives for IPRs “to provide ‘quick and cost effec-
 tive alternatives’ to litigation in the courts.” PPC Broad-
 band, Inc. v. Corning Optical Commc’ns RF, LLC, 815 F.3d
 734, 741 (Fed. Cir. 2016) (emphasis added) (quoting H.R.
 Rep. No. 112-98, pt. 1, at 48 (2011), as reprinted in 2011
 U.S.C.C.A.N. 67, 78). Indeed, it is fair to assume that when
 Congress imposed the one-year time bar of § 315(b), it did
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 22             FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 not explicitly contemplate a situation where an accused in-
 fringer had not yet ascertained which specific claims were
 being asserted against it in a district court proceeding be-
 fore the end of the one-year time period. We also recognize
 that our analysis here may lead defendants, in some cir-
 cumstances, to expend effort and expense in challenging
 claims that may ultimately never be asserted against
 them.
      Petitioners who, like Facebook, are faced with an enor-
 mous number of asserted claims on the eve of the IPR filing
 deadline, are not without options. As a protective measure,
 filing petitions challenging hundreds of claims remains an
 available option for accused infringers who want to ensure
 that their IPRs will challenge each of the eventually as-
 serted claims. An accused infringer is also not obligated to
 challenge every, or any, claim in an IPR. Accused infring-
 ers who are unable or unwilling to challenge every claim in
 petitions retain the ability to challenge the validity of the
 claims that are ultimately asserted in the district court. Ac-
 cused infringers who wish to protect their option of pro-
 ceeding with an IPR may, moreover, make different
 strategy choices in federal court so as to force an earlier
 narrowing or identification of asserted claims. Finally, no
 matter how valid, “policy considerations cannot create an
 ambiguity when the words on the page are clear.” SAS,
 138 S. Ct. at 1358. That job is left to Congress and not to
 the courts. See Lamie v. U.S. Tr., 540 U.S. 526, 542 (2004)
 (“If Congress enacted into law something different from
 what it intended, then it should amend the statute to con-
 form it to its intent.”). In the meantime, we must abide by
 the clear and unambiguous statutory language. 6



      6  District courts may alleviate or altogether avoid
 situations like this by adopting patent local rules or stand-
 ing orders that require early identification of infringement
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC               23



     In sum, we conclude that the clear and unambiguous
 language of § 315(c) does not authorize same-party joinder,
 and also does not authorize joinder of new issues, including
 issues that would otherwise be time-barred.
                               5
     We now turn to the question of what, if any, deference
 is owed to the PTO’s interpretation of § 315(c). Because we
 conclude that the clear and unambiguous language of
 § 315(c) does not authorize same-party joinder or joinder of
 new issues, we need not defer to the PTO’s interpretation
 of § 315(c). See Chevron, U.S.A., Inc. v. Nat. Res. Def.
 Council, Inc., 467 U.S. 837, 842–43 (1984) (“If the intent of
 Congress is clear, that is the end of the matter; for the
 court, as well as the agency, must give effect to the unam-
 biguously expressed intent of Congress.”). “Even un-
 der Chevron, we owe an agency’s interpretation of the law
 no deference unless, after ‘employing traditional tools of
 statutory construction,’ we find ourselves unable to discern
 Congress’s meaning.” SAS, 138 S. Ct. at 1358 (quoting
 Chevron, 467 U.S. at 843 n.9). As explained above, after




 contentions. See, e.g., O2 Micro Int’l Ltd. v. Monolithic
 Power Sys., Inc., 467 F.3d 1355, 1364 (Fed. Cir. 2006)
 (“[T]he local rules in question are . . . designed specifically
 to ‘require parties to crystallize their theories of the case
 early in the litigation’ so as to ‘prevent the “shifting sands”
 approach to claim construction.’” (quoting Atmel Corp. v.
 Info. Storage Devices Inc., No. C 95-1987 FMS, 1998 WL
 775115, at *2 (N.D. Cal. Nov. 5, 1998))). Indeed, most
 courts with patent-heavy dockets have done just that, indi-
 cating that the “policy” reasons used to justify such an odd
 reading of the statutory scheme are less compelling than
 Facebook contends.
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 24             FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 applying the traditional tools of statutory interpretation,
 we are left with no ambiguity that could warrant deference.
                               6
     In light of the foregoing, we hold that the Board’s join-
 der decisions, which allowed Facebook to join itself to a pro-
 ceeding in which it was already a party, and to add
 otherwise time-barred issues to the IPRs, were improper
 under § 315(c). 7 We therefore vacate-in-part the Board’s
 final written decisions. Specifically, the Board’s final writ-
 ten decision on the ’245 patent is vacated with respect to
 claims 19 and 22–25, and the Board’s final written decision
 on the ’657 patent is vacated with respect to claims 203,
 209, 215, 221, 477, 482, 487, and 492, all of which were
 added to the proceedings through improper joinder.
                               B
     We now turn to the technical merits of this appeal and
 review the Board’s obviousness determinations that are
 not vacated based on our holding on joinder.
                               1
     Obviousness is a question of law based on underlying
 factual determinations. Belden Inc. v. Berk-Tek LLC, 805
 F.3d 1064, 1073 (Fed. Cir. 2015). We review the Board’s
 ultimate obviousness determination de novo and underly-
 ing factual findings for substantial evidence. Harmonic
 Inc. v. Avid Tech., Inc., 815 F.3d 1356, 1363 (Fed. Cir.
 2016). Substantial evidence is “more than a mere scintilla”
 and means “‘such relevant evidence as a reasonable mind


      7  As noted above, to the extent the Board’s decision
 could be read as having joined Facebook’s two IPR proceed-
 ings, rather than having joined Facebook as a party to its
 own existent proceeding, that was also improper and con-
 trary to the unambiguous language of § 315(c).
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC             25



 might accept as adequate to support a conclusion.’” Biestek
 v. Berryhill, 139 S. Ct. 1148, 1154 (2019) (quoting Consol.
 Edison Co. v. NLRB, 305 U.S. 197, 229 (1938)). We review
 the Board’s determination of the broadest reasonable inter-
 pretation of the claim language de novo. Straight Path IP
 Grp., Inc. v. Sipnet EU S.R.O., 806 F.3d 1356, 1360 (Fed.
 Cir. 2015). 8
                              2
     We begin with the ’245 patent. As mentioned above,
 the disputed claims of the ’245 patent relate to the ability
 to handle “out-of-band” information (i.e., information that
 a participator computer may not be able to present on its
 own).
     In its original, timely petition for IPR of the ’245 pa-
 tent, Facebook challenged claims 1–15, 17, and 18. The
 Board instituted review of claims 1–5, 7, and 9–14 based
 on obviousness over Roseman, 9 Rissanen, 10 Vetter, 11



     8    We note that the PTO has since changed the claim
 construction standard used in IPR proceedings. See
 37 C.F.R. § 42.100(b); Changes to the Claim Construction
 Standard for Interpreting Claims in Trial Proceedings Be-
 fore the Patent Trial and Appeal Board, 83 Fed. Reg.
 51,340, 51,340 (Oct. 11, 2018). The new standard applies
 only to petitions filed on or after November 13, 2018, and
 therefore does not impact these IPRs, which were to be con-
 strued using the broadest reasonable interpretation in
 light of the specification. Cuozzo Speed Techs., LLC v. Lee,
 136 S. Ct. 2131, 2146 (2016).
     9    U.S. Patent No. 6,608,636 (J.A. 1195–227).
     10   European Patent Application No. 0621532
 (J.A. 1228–39).
     11   Ronald J. Vetter, Videoconferencing on the Internet,
 IEEE Computer Society 77–79 (Jan. 1995).
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 26              FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 Pike, 12 and Westaway; 13 and instituted review of claims 6,
 8, 15, 17, and 18 based on obviousness over the same refer-
 ences and Lichty. 14 As discussed above, claims 19 and 22–
 25 were improperly added through joinder.
     In its final written decision on the ’245 patent, the
 Board held that Facebook had failed to show by a prepon-
 derance of the evidence that claims 1–15, 17–19, and 22–
 25 are unpatentable as obvious. ’245 Final Written Deci-
 sion, at 34. Facebook appeals the Board’s determination
 that these claims are not unpatentable as obvious. As pre-
 viously discussed, joinder of claims 19 and 22–25 was im-
 proper, so the final written decision is vacated with respect
 to those claims. Here, we address remaining claims 1–15,
 17, and 18.
      The disputed limitation of claim 1 of the ’245 patent is:
      the second of said participator computers inter-
      nally determines whether or not the second of the
      participator computers can present the communi-
      cation, if it is determined that the second of the par-
      ticipator computers can not present the
      communication then obtaining an agent with an
      ability to present the communication, and other-
      wise presenting the communication independent of
      the first of the independent participator computers
      and the computer.
 ’245 patent at claim 1. Independent claim 7 recites sub-
 stantially the same limitation as claim 1. See id. at claim



      12 Mary Ann Pike et al., Using Mosaic (1994)
 (J.A. 1246–397).
     13  U.S. Patent No. 5,226,175 (J.A. 1398–408).
     14  Tom Lichty, The Official America Online for Mac-
 intosh Membership Kit & Tour Guide (2nd ed. 1994)
 (J.A. 1409–529).
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC             27



 7. All of the remaining claims at issue depend from claim 1
 or 7.
     Facebook conceded before the Board that the primary
 reference, Roseman, does not disclose the disputed limita-
 tion. ’245 Final Written Decision, at 29 (“Indeed, Petitioner
 admits that ‘Roseman does not appear to contemplate the
 scenario in which the second participant computer inter-
 nally determines that it cannot present the communi-
 cation.’” (emphasis in original) (quoting J.A. 457
 (Petition))). Facebook relied on Pike or, alternatively,
 Westway to satisfy this limitation. Pike describes a system
 where a user can manually search for and install software
 to open a specific file type, and Westway describes a pro-
 gram that automatically obtains a software to present a
 communication if the program determines that it cannot.
 See id. at 18–19.
     The Board determined that Facebook failed to explain
 “why a skilled artisan would have incorporated this feature
 into Roseman’s local computers (participator computers) in
 light of Roseman’s system, which processes images at the
 host, not the local computers.” Id. at 29 (emphasis added).
 The Board reasoned that:
     The most logical reading of Roseman is that its lo-
     cal computers already have software sufficient to
     render the common image that the host provides to
     them. Thus, Petitioner’s argument that Pike and
     Westaway would have been applied because of the
     possibility that a meeting participant would place
     a document on the table that other participants
     would not have the correct software to view is not
     applicable to Roseman. Petitioner has not ex-
     plained why, in the case where the host is unable
     to present a communication received from a local
     computer as part of its common image, a local com-
     puter would make an internal determination to
     that effect, or why users at the local computers
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 28             FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




      would seek out software to present the communica-
      tion.
 Id. at 29–30 (citation omitted). In reaching this conclusion,
 the Board considered Facebook’s expert’s testimony but de-
 termined that it did not “add materially to Petitioner’s un-
 persuasive attorney argument” because it “merely
 repeat[ed] Petitioner’s argument, nearly verbatim, without
 citation to the basis for his testimony.” Id. at 30. Substan-
 tial evidence supports the Board’s assessment and weigh-
 ing of this evidence, and we decline to reweigh the evidence
 on appeal. See In re NTP, Inc., 654 F.3d 1279, 1292 (Fed.
 Cir. 2011) (“This court does not reweigh evidence on ap-
 peal, but rather determines whether substantial evidence
 supports the Board’s fact findings.”).
     On appeal, Facebook argues that the Board’s underly-
 ing understanding of Roseman (that it processes images at
 the host, not the local computers) was incorrect. As ex-
 plained below, substantial evidence supports the Board’s
 understanding of Roseman, which in turn supports its de-
 termination that claim 1 would not have been obvious over
 the asserted prior art.
      Facebook argues that there are at least two instances
 where Roseman processes images at the local participant
 computers—the “note passing” feature and the “document
 sharing” feature. Appellant’s Opening Br. 29–35. The
 note-passing feature in Roseman allows a conference par-
 ticipant to send a private note to another participant,
 which only the recipient can view. Roseman explains that
 “[w]hen the other party [recipient] sees the note on his pic-
 ture, as in FIG. 12, he can drag it to a private viewing area,
 double-click it, and read it. No other people are aware of
 the passed note.” J.A. 1223, col. 9 ll. 28–31 (emphasis
 added). The document sharing feature allows a participant
 to drag a data file from outside the conference room window
 onto the table of the conference room to share it with other
 participants who can open it. These two features, Facebook
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC            29



 argues, show that Roseman generates images at the local
 participant computers.
     Facebook’s argument requires us to agree that the area
 outside the virtual conference room of Roseman is outside
 the software system of Roseman entirely, rather than just
 outside the virtual meeting room. Referring to Figure 10
 of Roseman below, Facebook’s position is that the area out-
 side of the meeting room (everything except the box in the
 bottom left corner) is outside of the Roseman software en-
 tirely and is on the participants’ local desktops:




 Appellant’s Opening Br. 29–30 (citing J.A. 1204, fig. 10).
 Facebook cites no evidence supporting this position. With-
 out any citation or support, Facebook simply equates the
 area outside of the conference room with “the local com-
 puter,” id. at 29, 31, or “the user’s desktop,” id. at 30.
      As Windy City notes, there is substantial evidence to
 support the understanding that the entire area shown in
 Figure 10 is within the Roseman software system, with the
 box in the bottom left corresponding to a specific meeting
 room within the system. See Cross-Appellant’s Response
 Br. 21–22. Roseman does not state that the area outside of
 the meeting room in Figure 10 is “outside the system” or
 “outside the software.” Roseman refers to this area outside
 the meeting room as a “private viewing area.” J.A. 1223,
 col. 9 ll. 28–31 (explaining that once “the other party sees
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 30             FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 the note on his picture, as in FIG. 12, he can drag it to a
 private viewing area, double-click it, and read it”). Refer-
 ring to this area as the “private viewing area” suggests that
 this is still part of the Roseman system and that the host
 can create the images seen in this private area rather than
 the images being created locally.
     Facebook’s position, which is based on attorney argu-
 ment rather than evidence in the record, does not persuade
 us that the Board’s understanding of Roseman’s system is
 incorrect. It also does not undermine the substantial evi-
 dence that supports the Board’s finding that claim 1 would
 not have been obvious over the prior art of record. We
 therefore affirm the Board’s holding that claims 1–15, 17,
 and 18 of the ’245 patent are not unpatentable as obvious
 over the asserted prior art.
     The final written decision on the ’245 patent is there-
 fore affirmed-in-part (claims 1–15, 17, and 18) and vacated-
 in-part (claims 19 and 22–25).
                              3
     We now turn to the ’657 patent. As mentioned above,
 the ’657 patent relates generally to the “censorship” fea-
 tures that control the dissemination of information among
 participator computers.
     In its original, timely petition for IPR of the ’657 pa-
 tent, Facebook challenged claims 189, 334, 342, 348, 465,
 580, 584, and 592. The Board instituted review of all of the
 challenged claims based on obviousness over Roseman,
 Rissanen, Vetter, Pike, and Lichty. As discussed above,
 claims 203, 209, 215, 221, 477, 482, 487, and 492 were im-
 properly added through joinder.
     In its final written decision on the ’657 patent, the
 Board held that Facebook had shown by a preponderance
 of the evidence that claims 189, 334, 342, 348, 465, 477,
 482, 487, 492, 580, 584, and 592 are unpatentable as obvi-
 ous but had failed to show that claims 203, 209, 215, and
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC             31



 221 are unpatentable as obvious. ’657 Final Written Deci-
 sion, at 56.
     Facebook appeals the Board’s determination that
 claims 203, 209, 215, and 221 are not unpatentable as ob-
 vious. As previously discussed, joinder of each of these
 claims was improper, so the final written decision is va-
 cated with respect to those claims. We therefore do not ad-
 dress the technical merits of Facebook’s appeal of these
 claims.
     Windy City’s cross-appeal challenges the Board’s deter-
 mination that claims 189, 334, 342, 348, 465, 477, 482, 487,
 492, 580, 584, and 592 are unpatentable as obvious. As
 previously discussed, joinder of claims 477, 482, 487, and
 492 was improper, so the final written decision is vacated
 with respect to those claims. Here, we address remaining
 claims 189, 334, 342, 348, 465, 580, 584, and 592.
      The claims at issue recite a “database” that stores “to-
 kens” (e.g., user identity information). Roseman teaches
 the use of “keys” provided to users that enable users to ac-
 cess a conference “room” through a “door” (i.e., using the
 key to “open the door”). J.A. 1223, col. 9 ll. 34–48, 54–55,
 col. 10 ll. 61–64. Roseman describes that each meeting
 room “‘knows’ about each key and its invitation level.”
 J.A. 1223, col. 9 ll. 49–51. However, the Board found that
 Roseman does not explicitly describe the underlying struc-
 ture that stores the keys in the conference system. ’657 Fi-
 nal Written Decision, at 29–30. Facebook argued that
 Rissanen teaches storing user authentication information,
 such as user identity information and passwords, in a da-
 tabase, and that such teaching would have been applicable
 to the keys of Roseman. Id. at 30. The Board agreed and
 found that “Rissanen teaches a database that stores data
 with persistence and tools for interacting with the data-
 base.” Id. at 31.
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 32             FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




     The issue before the Board, therefore, was whether it
 would have been obvious to combine Roseman and Ris-
 sanen to store the keys in a “database,” as claimed. The
 Board considered the evidence and concluded that the use
 of a database, as described in Rissanen, “would be a
 straightforward and predictable choice for storing Rose-
 man’s keys.” Id.
     In its cross-appeal, Windy City argues that the Board
 erred in finding that it would have been obvious to combine
 Roseman and Rissanen. Windy City argues that the
 Board’s analysis was infected by hindsight and that it did
 not adequately explain how someone skilled in the art
 would build the combined Roseman and Rissanen system.
 Cross-Appellant’s Response Br. 35–39; see also id. at 36 (ar-
 guing that carrying out the combination “would take sub-
 stantial creativity”); id. at 38 (arguing that the Board “does
 not address the difficulty” of making this combination). We
 find no legal error in these aspects of the Board’s obvious-
 ness analysis.
     As an initial matter, “[a] person of ordinary skill is also
 a person of ordinary creativity, not an automaton,” so the
 fact that it would take some creativity to carry out the com-
 bination does not defeat a finding of obviousness. KSR Int’l
 Co. v. Teleflex Inc., 550 U.S. 398, 421 (2007); see
 also ClassCo, Inc. v. Apple, Inc., 838 F.3d 1214, 1219 (Fed.
 Cir. 2016) (“The rationale of KSR does not support [the]
 theory that a person of ordinary skill can only perform com-
 binations of a puzzle element A with a perfectly fitting puz-
 zle element B.”). The Board also correctly rejected Windy
 City’s argument about the difficulty of physically creating
 the combination, noting that Facebook was not arguing
 that Rissanen’s database would be bodily incorporated into
 Roseman’s system. ’657 Final Written Decision, at 35. Re-
 gardless, “[t]he test for obviousness is not whether the fea-
 tures of a secondary reference may be bodily incorporated
 into the structure of the primary reference.” Allied Erecting
 & Dismantling Co. v. Genesis Attachments, LLC, 825 F.3d
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC            33



 1373, 1381 (Fed. Cir. 2016) (quoting In re Keller, 642 F.2d
 413, 425 (C.C.P.A. 1981)).
      The only remaining issue is whether the Board’s fac-
 tual findings underpinning its determination are sup-
 ported by substantial evidence. We hold that they are.
 There is substantial evidence of record supporting the
 Board’s finding that the use of a database “would be a
 straightforward and predictable choice for storing Rose-
 man’s keys.” ’657 Final Written Decision, at 31. For exam-
 ple, Facebook’s expert Dr. Lavian testified that “[d]atabase
 technologies predated the [challenged patents] by decades,
 and it was known to use databases to store user identity
 and authentication information (‘tokens’).” J.A. 6249, ¶ 51.
 Dr. Lavian also explained why a person of skill in the art
 would have been motivated to combine Roseman with Ris-
 sanen, specifically that “[a] skilled artisan would under-
 stand that the user identity and password information in
 Rissanen is analogous to the ‘keys’ in Roseman, and would
 be motivated to make this combination.” J.A. 6250, ¶ 52.
 Substantial evidence supports the Board’s determination
 that it would have been obvious to store the keys in Rose-
 man in a database. We therefore affirm the Board’s hold-
 ing that claims 189, 334, 342, 348, 465, 580, 584, and 592
 of the ’657 patent are unpatentable as obvious over the as-
 serted prior art.
     The final written decision on the ’657 patent is there-
 fore affirmed-in-part (claims 189, 334, 342, 348, 465, 580,
 584, and 592) and vacated-in-part (claims 203, 209, 215,
 221, 477, 482, 487, and 492).
                              4
    We next address the ’552 patent, which also relates
 generally to “censorship” features.
     Facebook’s petition for IPR challenged claims 1–61 and
 64 of the ’552 patent. The Board instituted review of claims
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 34              FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 1–59 and 64 based on obviousness over Roseman, Ris-
 sanen, Vetter, Pike, and Lichty. The Board did not insti-
 tute review of claims 60 and 61. 15
     In its final written decision on the ’552 patent, the
 Board held that Facebook had shown by a preponderance
 of the evidence that claims 2, 3, 5, 7, 10–17, 59, and 64 are
 unpatentable as obvious but had failed to show that claims
 1, 4, 6, 8, 9, and 18–58 are unpatentable as obvious. ’552
 Final Written Decision, at 59.
     Facebook appeals the Board’s determination that
 claims 1, 4, 6, 8, 9, and 18–58 are not unpatentable as ob-
 vious. Facebook’s argument focuses on the following “au-
 thorization step” of claim 1:
      the controller computer system controlling real-
      time communications by:
      storing each said user identity and a respective au-
      thorization to send multimedia data, the multime-
      dia data comprising graphical data; and
      if permitted by the user identity corresponding to
      one of the participator computers, allowing the one
      of the participator computers to send multimedia
      data to another of the participator computers.
 ’552 patent at claim 1.
     Before the Board, Facebook argued that these authori-
 zation limitations were satisfied by Roseman, which de-
 scribes using stored keys, associated with user identities,
 for controlling admission to a particular conference.
 ’552 Final Written Decision, at 53. Facebook argued that
 the authorization limitation was satisfied by Roseman be-
 cause a user who is not authorized to access a room could
 not send multimedia data to conference room participants.



      15   See supra note 3.
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC             35



 The Board rejected this argument and determined that
 Roseman only describes a key granting a user admission to
 a virtual conference room and does not describe keys as de-
 termining what a user can do in a conference room once
 admitted. Id. The Board reasoned that “it does not follow
 that the key [of Roseman] provides permissions for behav-
 ior within a conference room, such as authorization to send
 multimedia data.” Id.; see also id. (“We are not persuaded
 that such a key [granting access to a conference room] con-
 stitutes stored authorization to engage in certain activities
 once admitted.”).
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 36             FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




     On appeal, Facebook argues that the Board erred by
 narrowly construing the authorization limitations to re-
 quire determining what a user can do in a conference room,
 not just whether they should be admitted. Appellant’s
 Opening Br. 42–44. We do not think the Board erred in its
 claim construction. Most importantly, the Board’s con-
 struction is supported by the intrinsic evidence, including
 Figure 3 (below), which describes checking the user’s per-
 mission prior to authorizing the user to send multimedia
 data.




 ’552 patent at fig. 3 (highlighting added) (Block 50),
 col. 6 ll. 20–23 (“the logic flows to Block 50, which tests
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC              37



 whether a user has post permission. If the user has post
 permission, the logic flows to Block 48”).
      Under the Board’s construction, which we think is cor-
 rect, the Board’s determination that Roseman does not sat-
 isfy this limitation is supported by substantial evidence.
 As described above, the Board considered and rejected Fa-
 cebook’s arguments and determined that Roseman only de-
 scribes a key granting a user admission to a virtual
 conference room and did not describe keys as determining
 what a user can do in a conference room once admitted.
 ’552 Final Written Decision, at 53. This determination is
 supported by substantial evidence, including the disclosure
 of Roseman itself. See id. (citing J.A. 1223 col. 9 ll. 34–55,
 col. 10 ll. 61–65). And, like the Board, we are also not per-
 suaded that a key that grants admission also includes an
 authorization to send multimedia data in a conference
 room. See id. We therefore affirm the Board’s holding that
 claims 1, 4, 6, 8, 9 and 18–58 of the ’552 patent are not un-
 patentable as obvious over the asserted prior art.
     Windy City’s cross-appeal challenges the Board’s deter-
 mination that claims 2, 3, 5, 7, 10–17, 59, and 64 are un-
 patentable as obvious. Windy City makes the same
 argument it made for the ’657 patent—that it would not
 have been obvious to combine Roseman and Rissanen. For
 the same reasons explained above with respect to the
 ’657 patent, substantial evidence supports the Board’s
 finding that it would have been obvious to combine Rose-
 man and Rissanen to arrive at the claimed invention of the
 ’552 patent. We therefore affirm the Board’s holding that
 claims 2, 3, 5, 7, 10–17, 59, and 64 of the ’552 patent are
 unpatentable as obvious over the asserted prior art.
     The final written decision on the ’552 patent is there-
 fore affirmed.
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 38             FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




                              5
    Finally, we address the ’356 patent, which also relates
 generally to “censorship” features.
     Facebook’s petition for IPR challenged claims 1–9, 12,
 14–28, 31, and 33–37 of the ’356 patent. The Board insti-
 tuted review of claims 1–5, 8, 9, 12, 14–16, 19–24, 27, 28,
 31, 33–35, and 37 based on obviousness over Roseman, Ris-
 sanen, and Vetter; claims 6, 7, 17, 26, and 36 based on ob-
 viousness over Roseman, Rissanen, Vetter, and Pike;
 claims 18 and 25 based on obviousness over Westaway; and
 claims 6, 8, 15, 17, and 18 based on obviousness Roseman,
 Rissanen, Vetter, and Gosling. 16
     In its final written decision on the ’356 patent, the
 Board held that Facebook had shown by a preponderance
 of the evidence that claims 1–9, 12, 15–28, 31, and 34–37
 are unpatentable as obvious but had failed to show that
 claims 14 and 33 are unpatentable as obvious. ’356 Final
 Written Decision, at 59.
     Facebook appealed the Board’s determination that
 claims 14 and 33 were not unpatentable as obvious. How-
 ever, claims 14 and 33 were found unpatentable by the
 Board in a separate IPR from which Windy City voluntarily
 dismissed its appeal. See Windy City Innovations, LLC v.
 Facebook Inc., No. 18-1543, ECF No. 24, at 1–2 (Fed. Cir.
 May 14, 2018) (dismissing appeal of No. IPR2016-01067).
 Windy City argued that Facebook’s appeal regarding
 claims 14 and 33 of the ’356 patent is moot. Cross-Appel-
 lant’s Response Br. 5 n.1. Facebook agreed. Appellant’s
 Reply and Response Br. 20 (“Facebook concurs that its ap-
 peal on claims 14 and 33 of the ’356 patent is moot because



      16 James Gosling, Java Intermediate Bytecodes, ACM
 SIGPLAN Workshop on Intermediate Representations
 (Jan. 1995).
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC            39



 those claims are finally invalid.”). We agree that Face-
 book’s appeal of the final written decision on the ’356 pa-
 tent is moot, dismiss that portion of Facebook’s appeal, and
 therefore do not address claims 14 and 33.
     Windy City’s cross-appeal challenges the Board’s deter-
 mination that claims 1–9, 12, 15–28, 31, and 34–37 are un-
 patentable as obvious. Windy City makes the same
 argument it made for the ’657 patent—that it would not
 have been obvious to combine Roseman and Rissanen. For
 the same reasons explained above with respect to the
 ’657 patent, substantial evidence supports the Board’s
 finding that it would have been obvious to combine Rose-
 man and Rissanen to arrive at the claimed invention of the
 ’356 patent. We therefore affirm the Board’s holding that
 claims 1–9, 12, 15–28, 31, and 34–37 of the ’356 patent are
 unpatentable as obvious over the asserted prior art.
      The final written decision on the ’356 patent is there-
 fore affirmed-in-part (claims 1–9, 12, 15–28, 31, and 34–
 37).
                              6
     We have considered the parties’ remaining arguments
 on the technical merits of the appeal and cross-appeal and
 find them unpersuasive.
                             III
     We hold that the clear and unambiguous language of
 § 315(c) does not authorize same-party joinder or joinder of
 new issues. The Board’s joinder decisions in this case,
 which allowed Facebook to add otherwise time-barred is-
 sues to its IPRs, were therefore improper under § 315(c).
 We accordingly vacate the Board’s final written decisions
 with respect to the claims improperly added through join-
 der. We also hold that substantial evidence supports the
 Board’s obviousness determinations.
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 40             FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




     In sum, the Board’s final written decision on the
 ’245 patent is affirmed with respect to claims 1–15, 17, and
 18 and vacated with respect to claims 19 and 22–25. The
 Board’s final written decision on the ’657 patent is affirmed
 with respect to claims 189, 334, 342, 348, 465, 580, 584, and
 592 and vacated with respect to claims 203, 209, 215, 221,
 477, 482, 487, and 492. The Board’s final written decision
 on the ’552 patent is affirmed. The Board’s final written
 decision on the ’356 patent is affirmed with respect to
 claims 1–9, 12, 15–28, 31, and 34–37. Facebook’s appeal of
 the Board’s final written decision on the ’356 is dismissed
 as moot with respect to claims 14 and 33.
       AFFIRMED-IN-PART, VACATED-IN-PART,
              DISMISSED-IN-PART
                            COSTS
      The parties shall bear their own costs.
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    United States Court of Appeals
        for the Federal Circuit
                  ______________________

                    FACEBOOK, INC.,
                       Appellant

                             v.

          WINDY CITY INNOVATIONS, LLC,
                   Cross-Appellant
               ______________________

  2018-1400, 2018-1401, 2018-1402, 2018-1403, 2018-1537,
                  2018-1540, 2018-1541
                 ______________________

     Appeals from the United States Patent and Trademark
 Office, Patent Trial and Appeal Board in Nos. IPR2016-
 01156, IPR2016-01157, IPR2016-01158, IPR2016-01159,
 IPR2017-00659, IPR2017-00709.
                  ______________________

 Additional views by PROST, Chief Judge, PLAGER and
 O’MALLEY, Circuit Judges.
     The majority opinion concludes that the clear and un-
 ambiguous language of 35 U.S.C. § 315(c) does not author-
 ize same-party joinder and does not authorize joinder of
 new issues. Because the opinion concludes that § 315(c) is
 unambiguous, the majority does not address the question
 of what, if any, deference is owed to the PTO’s interpreta-
 tion of § 315(c) by the Board’s Precedential Opinion Panel
 (“POP”) in Proppant Express Investments, LLC v. Oren
 Technologies, LLC, No. IPR2018-00914, Paper 38 (P.T.A.B.
 Mar. 13, 2019).
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 2              FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




     Contrary to our conclusions, however, both parties con-
 tend that a proper reading of § 315(c) unambiguously sup-
 ports their respective—dramatically opposing—views of
 how the provision operates. Logically, while they do not
 say so expressly, the implication of their disagreement is
 that there is ambiguity in the statute that we do not per-
 ceive. Given this, and in light of the extensive attention
 the parties gave to the issue of deference, we address what
 our alternative holding would be if § 315(c) were deemed
 ambiguous.
     Facebook argues that the POP opinion in Proppant de-
 serves Chevron deference, see Chevron, U.S.A., Inc. v. Nat-
 ural Resources Defense Council, Inc., 467 U.S. 837 (1984),
 or at least Skidmore deference, see Skidmore v. Swift & Co.,
 323 U.S. 134, 140 (1944), and that we should, thus, defer
 to the conclusion in the opinion that joinders like those at
 issue in this case are permissible. The government, follow-
 ing oral argument in this case and upon our request for its
 views, filed a brief likewise arguing for Chevron, or at least
 Skidmore, deference for the Board’s interpretation of
 § 315(c). Having considered these arguments, we conclude
 that, were the statute ambiguous, we would alternatively
 resolve this matter in the same way. Specifically, we would
 find that no deference is due to the POP opinion in Prop-
 pant and that the most reasonable reading of § 315(c) is the
 one we adopt in our majority opinion.
                               I
     At the time of the principal briefing in this appeal, dif-
 ferent panels of the Board had issued conflicting nonprece-
 dential decisions on the proper interpretation of § 315(c).
 Compare, e.g., Target Corp. v. Destination Maternity,
 Corp., No. IPR2014-00508, Paper 28, at 6–17 (P.T.A.B.
 Feb. 12, 2015) (over dissenting opinion, permitting same-
 party joinder and joinder of new issues), with SkyHawke
 Techs., LLC v. L&H Concepts, LLC, No. IPR2014-01485,
 Paper 13, at 3–4 (P.T.A.B. Mar. 20, 2015) (rejecting same-
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC              3



 party joinder and joinder of new issues), and Proppant Ex-
 press Invs., LLC v. Oren Techs., LLC, No. IPR2018-00914,
 Paper 21, at 4–6 (P.T.A.B. Nov. 8, 2018) (rejecting same-
 party joinder and joinder of new issues). As explained
 above, the Board in this case, over the “concerns” of the
 concurring APJs who expressed their “disagreement with
 the Director’s interpretation,” permitted Facebook to join
 itself as a party to the already instituted IPRs and allowed
 Facebook to join new claims to the proceedings. See Face-
 book, Inc. v. Windy City Innovations, LLC, No. IPR2017-
 00659, Paper 11 (P.T.A.B. July 31, 2017) (instituting IPR
 and granting joinder); Facebook, Inc. v. Windy City Innova-
 tions, LLC, No. IPR2017-00709, Paper 11 (P.T.A.B. August
 1, 2017) (same).
      In its principal briefing in this appeal, Facebook asked
 us to give Chevron deference to the Board’s interpretation
 of § 315(c) in this case. But Facebook cited no authority
 that would support giving a nonprecedential Board deci-
 sion Chevron deference. Indeed, we have never given such
 nonprecedential Board decisions Chevron deference. See,
 e.g., Power Integrations, Inc. v. Semiconductor Components
 Indus., LLC, 926 F.3d 1306, 1318 (Fed. Cir. 2019) (“[W]e
 decline to give Chevron deference to these nonprecedential
 Board decisions, which do not even bind other panels of the
 Board.”); see also United States v. Mead Corp., 533 U.S.
 218, 230–31 (2001).
     In September 2018, while this appeal was pending, the
 Director outlined new procedures to create and govern the
 POP. The POP’s purpose is to “establish binding agency
 authority concerning major policy or procedural issues, or
 other issues of exceptional importance in the limited situa-
 tions where it is appropriate to create such binding agency
 authority through adjudication before the Board.” Patent
 Trial and Appeal Board, Standard Operating Procedure 2
 (Rev. 10), at 3 (Sept. 20, 2018) (hereinafter “SOP 2”),
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 4              FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 https://www.uspto.gov/sites/default/files/docu-
 ments/SOP2%20R10%20FINAL.pdf. 1
    After the principal briefing was completed, but before
 we heard oral argument in this appeal, the Director con-
 vened a POP in Proppant to address the following issues:
     1. Under 35 U.S.C. § 315(c) may a petitioner be
     joined to a proceeding in which it is already a
     party?
     2. Does 35 U.S.C. § 315(c) permit joinder of new is-
     sues into an existing proceeding?
     3. Does the existence of a time bar under 35 U.S.C.
     § 315(b), or any other relevant facts, have any im-
     pact on the first two questions?
 Proppant Express Invs., LLC v. Oren Techs., LLC,
 No. IPR2018-00914, Paper 24, at 2 (P.T.A.B. Dec. 3, 2018).
 In Proppant, the POP held that § 315(c) “provides discre-
 tion to allow a petitioner to be joined to a proceeding in
 which it is already a party and provides discretion to allow
 joinder of new issues into an existing proceeding.” Prop-
 pant Express Invs., LLC v. Oren Techs., LLC, No. IPR2018-
 00914, Paper 38, at 4 (P.T.A.B. Mar. 13, 2019). The POP
 also stated that “the Board will exercise this discretion only
 in limited circumstances—namely, where fairness requires
 it and to avoid undue prejudice to a party.” Id. For exam-
 ple, the POP stated that the Board may exercise this dis-
 cretion based on “actions taken by a patent owner in a co-



     1   The POP is made up of three members of the Board.
 By default, the three members are the Director, the Com-
 missioner for Patents, and the PTAB Chief Judge. The Di-
 rector may replace the default members with the Deputy
 Director, the Deputy Chief Judge, or an Operational Vice
 Chief Judge and may determine that a panel of more than
 three members is appropriate. SOP 2, at 4.
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC              5



 pending litigation such as the late addition of newly as-
 serted claims.” Id.
      Following Proppant, Facebook filed a notice of supple-
 mental authority identifying the POP opinion and arguing
 that it deserved Chevron deference. Facebook, Inc. v.
 Windy City Innovations, LLC, No. 18-1400, ECF No. 56, at
 1–2 (Fed. Cir. Mar. 20, 2019) (“The PTO’s precedential stat-
 utory interpretation of § 315(c)—provided after notice, pub-
 lic comment, and hearing—is entitled to Chevron deference
 to the extent the Court finds textual ambiguity.”). Windy
 City did not respond to Facebook’s notice of supplemental
 authority.
     After oral argument in this appeal, we invited the Di-
 rector, who had not intervened in the case, to file a brief
 expressing his views on “what, if any, deference should be
 afforded to decisions of a Patent Trial and Appeal Board
 Precedential Opinion Panel (‘POP’), and specifically to the
 POP opinion in Proppant Express Investments, LLC v. Oren
 Technologies, LLC, No. IPR2018-00914, Paper 38 (P.T.A.B.
 Mar. 13, 2019).” Facebook, Inc. v. Windy City Innovations,
 LLC, No. 18-1400, ECF No. 64, at 1–2 (Fed. Cir. Aug. 12,
 2019) (per curiam). The government filed a brief in re-
 sponse, both Facebook and Windy City replied, and two
 amici filed briefs on the issue. Facebook, Inc. v. Windy City
 Innovations, LLC, No. 18-1400, ECF Nos. 76 (government),
 79, 90 (amici), 91 (Facebook), 92 (Windy City).
     In its response, the government argued that POP opin-
 ions interpreting the AIA, including Proppant, are entitled
 to Chevron, or at least Skidmore, deference. Facebook
 agreed with the government’s position on deference.
 Windy City argued that POP opinions, including Proppant,
 are not entitled to any deference, as did the non-govern-
 ment Amici.
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 6              FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




                               II
      We apply Chevron deference to an agency’s implemen-
 tation of a particular statutory provision only “when it ap-
 pears that Congress delegated authority to the agency
 generally to make rules carrying the force of law, and that
 the agency interpretation claiming deference was promul-
 gated in the exercise of that authority.” Mead, 533 U.S. at
 226–27. The Supreme Court has stated that “a very good
 indicator of delegation meriting Chevron treatment in [sic,
 *is] express congressional authorizations to engage in the
 process of rulemaking or adjudication that produces regu-
 lations or rulings for which deference is claimed.” Id. at
 229.
      In the AIA, Congress delegated certain rulemaking au-
 thority to the Director. Notably, such delegation specifi-
 cally provides that the Director shall “prescribe
 regulations.” 35 U.S.C. § 316(a). For example, § 316(a)(4)
 recites that “[t]he Director shall prescribe regulations es-
 tablishing and governing inter partes review under this
 chapter and the relationship of such review to other pro-
 ceedings under this title.” Id. at § 316(a)(4) (emphasis
 added). And, related to joinder, § 316(a)(12) recites that
 “[t]he Director shall prescribe regulations setting a time pe-
 riod for requesting joinder under section 315(c).” Id. at
 § 316(a)(12) (emphasis added). 2



     2   The PTO prescribed the following regulation set-
 ting the time to file a request for joinder as one month after
 the date of institution of the IPR for which joinder is re-
 quested:
     (b) Request for joinder. Joinder may be requested
     by a patent owner or petitioner. Any request for
     joinder must be filed, as a motion under § 42.22, no
     later than one month after the institution date of
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC               7



      The express delegation of rulemaking authority, thus,
 is for the Director to promulgate regulations governing the
 conduct of IPRs. “[W]hen Congress expressly delegates to
 the Director the ability to adopt legal standards and proce-
 dures by prescribing regulations, the Director can only ob-
 tain Chevron deference if it adopts such standards and
 procedures by prescribing regulations.” See, e.g., Aqua
 Prods., Inc. v. Matal, 872 F.3d 1290, 1334 (Fed. Cir. 2017)
 (en banc) (Moore, J., concurring); see id. (“The Board may
 adopt a legal standard through a precedential decision in
 an individual case, but that legal standard will not receive
 Chevron deference when Congress only authorized the
 agency to prescribe regulations.”). There is no indication
 in the statute that Congress either intended to delegate
 broad substantive rulemaking authority to the Director to
 interpret statutory provisions through POP opinions or in-
 tended him to engage in any rulemaking other than
 through the mechanism of prescribing regulations.
     The AIA also includes an express delegation to the
 Board to “conduct each inter partes review instituted under
 this chapter.” 35 U.S.C. § 316(c). Critically, Congress’s
 delegation in the AIA for the adjudication of patentability
 in IPRs is not a delegation of authority to issue adjudica-
 tive decisions interpreting statutory provisions of the AIA.
 See Gonzales v. Oregon, 546 U.S. 243, 258 (2006) (“Chevron
 deference . . . is not accorded merely because the statute is
 ambiguous and an administrative official is involved. To
 begin with, the rule must be promulgated pursuant to au-
 thority Congress has delegated to the official.”); e.g., Mead,
 533 U.S. at 231–32 (declining to give Chevron deference



     any inter partes review for which joinder is re-
     quested.        The    time    period  set    forth
     in § 42.101(b) shall not apply when the petition is
     accompanied by a request for joinder.
 37 C.F.R. § 42.122(b).
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 8              FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 when, “[o]n the face of the statute . . . the terms of the con-
 gressional delegation give no indication that Congress
 meant to delegate authority to . . . issue . . . rulings with
 the force of law”). Thus, as with the Director, there is no
 indication in the statute that Congress intended to dele-
 gate authority to the Board to interpret statutory provi-
 sions through generally applicable POP opinions and there
 is nothing in the AIA that displaces our obligation under
 the Administrative Procedure Act to review the Board’s le-
 gal conclusions without deference to the trial forum. See
 HTC Corp., ZTE (USA) v. Cellular Commc’ns Equip., LLC,
 877 F.3d 1361, 1367 (Fed. Cir. 2017) (“Under the APA, we
 review the Board’s legal conclusions de novo and its factual
 findings for substantial evidence.”).
     Notably absent from the AIA, accordingly, is any con-
 gressional authorization, for either the Director or the
 Board, to undertake statutory interpretation through POP
 opinions. Thus, just as we give no deference to nonprece-
 dential Board decisions, we see no reason to afford defer-
 ence to POP opinions.
      The government nonetheless argues that, because
 “Congress has expressly delegated authority to adjudicate
 IPRs” and to “enact regulations,” “both of the quintessen-
 tial forms of lawmaking authority discussed in Mead, ‘ad-
 judication [and] notice-and-comment rulemaking,’ are
 present.” Thus, the government argues, the Board’s POP
 opinion interpreting § 315(c) should be entitled to Chevron
 deference. Facebook, Inc. v. Windy City Innovations, LLC,
 No. 18-1400, ECF No. 76, at 6 (alteration in original). We
 disagree.
     According to the government, POP opinions are compa-
 rable to processes employed by other adjudicative bodies
 with rulemaking authority to which the Supreme Court
 has afforded Chevron deference. But in each of the exam-
 ples cited by the government, the statutory delegation of
 authority is not analogous to the authority delegated by the
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC                 9



 AIA. For example, in the context of the Board of Immigra-
 tion Appeals, Congress has charged the Attorney General
 with administering the Immigration and Nationality Act.
 The statute specifically provides that “a ‘ruling by the At-
 torney General with respect to all questions of law shall be
 controlling.’” See Negusie v. Holder, 555 U.S. 511, 516–17
 (2009) (quoting 8 U.S.C. § 1103(a)(1)). “The Attorney Gen-
 eral, in turn, has delegated [its authority] to the BIA . . . in
 the course of considering and determining cases before it.”
 Id. at 517 (internal quotation marks omitted). In that con-
 text, the Supreme court concluded that “the BIA should be
 accorded Chevron deference as it gives ambiguous statu-
 tory terms ‘concrete meaning through a process of case-by-
 case adjudication.’” Id. (quoting I.N.S. v. Aguirre-Aguirre,
 526 U.S. 415, 419 (1999)).
      The government’s other examples also include broader
 delegations of authority from Congress to the agency than
 the AIA affords. See, e.g., Suprema, Inc. v. Int’l Trade
 Comm’n, 796 F.3d 1338, 1345 (Fed. Cir. 2015) (noting that
 “[t]here is no dispute that Congress has delegated author-
 ity to the Commission to resolve ambiguity in Section 337
 if the Commission does so through formal adjudicative pro-
 cedures”); Holly Farms Corp. v. NLRB, 517 U.S. 392, 398–
 99 (1996) (statutory grant in the National Labor Relations
 Act, 29 U.S.C. § 156, grants the National Labor Relations
 Board “authority from time to time to make, amend, and
 rescind, in the manner prescribed by [the Administrative
 Procedure Act], such rules and regulations as may be nec-
 essary to carry out the provisions of this subchapter”); U.S.
 Postal Serv. v. Postal Regulatory Comm’n, 599 F.3d 705,
 710 (D.C. Cir. 2010) (finding that the statute “clearly dele-
 gated to the Commission” the authority “to implement and
 thereby to interpret” the statutory provision in question).
     The organization of the PTO is not analogous to the
 agencies in the examples cited by the government. Unlike
 those examples, which have a single delegee with both rule-
 making and adjudicatory powers, Congress organized the
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 10             FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 PTO with certain powers delegated to the Director, and
 others delegated to the Board. See, e.g., 35 U.S.C. § 2 (del-
 egating “specific powers” to the “Office,” subject to the Sec-
 retary of Commerce), § 3 (vesting powers and duties of the
 Office in the Director), § 6 (establishing the Board and de-
 scribing its “[d]uties”). Most notably, and as discussed
 above, in the AIA Congress expressly divided the delega-
 tion of rulemaking and adjudicatory powers between the
 Director and the Board. Congress delegated the power to
 prescribe certain regulations to the Director, 35 U.S.C.
 § 316(a); see also id. at § 316(b), and delegated the power to
 adjudicate IPRs to the Board, id. at § 316(c).
     As the Supreme Court clarified in Martin v. Occupa-
 tional Safety and Health Review Commission, 499 U.S. 144,
 154 (1991), an agency with a bilateral structure differs
 from an agency with a unilateral structure:
      [I]n traditional agencies—that is, agencies pos-
      sessing a unitary structure—adjudication operates
      as an appropriate mechanism not only for factfind-
      ing, but also for the exercise of delegated lawmak-
      ing     powers,       including    lawmaking      by
      interpretation. . . . because the unitary agencies in
      question also had been delegated the power to
      make law and policy through rulemaking.
 Id. at 154 (emphasis added). Conversely, in agencies where
 Congress has not expressly delegated both rulemaking and
 adjudicative authority to a single delegee, as in the PTO,
 adjudication may not operate as an appropriate mecha-
 nism for the exercise of rulemaking. See id. at 154–55.
     In light of the limited authority delegated by the AIA,
 we decline to defer to the POP opinion on this issue of stat-
 utory interpretation—a pure question of law that is not
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC                 11



 within the specific expertise of the agency. 3 Aqua Prods.,
 872 F.3d at 1320 (plurality opinion) (“Because Chevron def-
 erence displaces judicial discretion to engage in statutory
 interpretation, it requires a relatively formal expression of
 administrative intent, one with the force and effect of
 law.”); see also id. at 1324 (Moore, J., concurring) (“The
 point of Chevron is to encourage courts to defer to agencies
 on issues that ‘implicate[] agency expertise in a meaningful
 way.’” (quoting Sandoval v. Reno, 166 F.3d 225, 239 (3d
 Cir. 1999) (alteration in original)))); see also Kisor v. Wilkie,
 139 S. Ct. 2400, 2414 (2019) (explaining that deference is
 unwarranted “when a court concludes that an interpreta-
 tion does not reflect an agency’s authoritative, expertise-
 based, ‘fair[, or] considered judgment.’” (alteration in origi-
 nal) (emphasis added) (quoting Auer v. Robbins, 519 U.S.
 452, 462 (1997) (citing Mead, 533 U.S. at 229–31). The in-
 terpretation of § 315(c) and the proper understanding of
 the interplay between § 315(b) and (c) are pure questions
 of law that do not implicate the PTO’s expertise. See id.
 POP opinions, like all Board opinions, are subject to the
 well-established standard of review directed by the APA.
 Notably, the government refuses to address the question of
 how far the position it takes on Chevron deference in this
 case would extend into our review of interpretations of pa-
 tentability provisions addressed in other POP opinions.
 Facebook, Inc. v. Windy City Innovations, LLC, No. 18-
 1400, ECF No. 76, at 5 n.2 (“[T]his brief does not address
 whether the POP’s interpretations of patentability provi-
 sions of the Patent Act, 35 U.S.C. §§ 101–105, would be


     3   We have previously held that “an agency without
 substantive rulemaking authority cannot claim Chevron
 deference for statutory interpretations rendered in the
 course of administrative proceedings.” Pesquera Mares
 Australes Ltda. v. United States, 266 F.3d 1372, 1382 n.6
 (Fed. Cir. 2001).
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 12             FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 entitled to Chevron deference.”). In our view, this is no
 small matter.
     Facebook also argues that the POP opinion in Proppant
 is entitled to Chevron deference because it was “provided
 after notice, public comment, and hearing.” Facebook, Inc.
 v. Windy City Innovations, LLC, No. 18-1400, ECF No. 56,
 at 2. The government elaborates on this point, contending
 that the interpretation rendered in the POP opinion in
 Proppant resulted from a “highly structured process,” “fol-
 lowing notice to the public; . . . further written briefing by
 the parties and six amici; and an oral hearing.” Facebook,
 Inc. v. Windy City Innovations, LLC, No. 18-1400, ECF
 No. 76, at 6.
     To the extent that Facebook or the government argues
 that this is comparable to notice-and-comment rulemak-
 ing, we disagree. While the POP in Proppant issued an or-
 der listing the issues it intended to review, solicited briefs
 from the parties and amici, and held an oral hearing, the
 POP procedure falls short of traditional notice-and-com-
 ment rulemaking that could receive Chevron deference.
     For example, the announcement that a POP has been
 convened and the issues it will review is not published in
 the Federal Register. Instead, it is issued as an order in
 the docket of the case. See SOP 2, at 7 (“[T]he Precedential
 Opinion Panel will enter an order notifying the parties and
 the public when the Precedential Opinion Panel has been
 designated and assigned to a particular Board case. The
 order will further identify the issues the Precedential Opin-
 ion Panel intends to resolve and the composition of the
 panel.”). 4 There is no formal opportunity for public



      4  The process for convening a POP is even less visible
 to the public. The Director may convene a POP sua sponte.
 A party to a proceeding or a member of the Board may also
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC             13



 comment. In fact, while the parties and amici were invited
 to file briefs in Proppant, the POP is not required to invite
 either. Id. (“[T]he Precedential Opinion Panel may request
 additional briefing on identified issues, and, in appropriate
 circumstances, may further authorize the filing of amicus
 briefs.” (emphases added)).
     Finally, POP opinions, once decided, are not published
 in the Federal Register. Instead, they are “posted to the
 Board’s Precedential Decisions Web page.” Id. at 8. As a
 result, unlike final rules published in the Federal Register
 that may be challenged by interested parties in court, see
 5 U.S.C. § 553, there is no opportunity for amici—to the ex-
 tent they were invited—to challenge the final POP decision
 in court. Indeed, in a number of circumstances, including
 where the parties have settled or a party does not have
 standing to appeal, the POP decision may not be subject to
 judicial review at all.
      Issuing an order that a POP panel has been convened
 in a particular case and soliciting amicus briefs is not
 equivalent in form or substance to traditional notice-and-
 comment rulemaking. See, e.g., Mead, 533 U.S. at 231, 233
 (denying Chevron deference to Customs’ Classifications
 rulings, in which Customs “does not generally engage in
 notice-and-comment practice when issuing them,” and de-
 scribing Customs’ practice in making them as “present[ing]
 a case far removed . . . from notice-and-comment process”).
 It is, instead, similar to what courts regularly do when
 seeking input which may help inform their adjudicatory
 function. Nor is the precedential value of POP opinions a
 sufficient reason to afford Chevron deference. Id. at 232
 (“[P]recedential value alone does not add up to Chevron en-
 titlement.”). The fact that legal determinations may be




 recommend POP review by sending an email to the Board.
 See SOP 2, at 5–6.
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 14             FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC




 binding on future Board panels does not enhance the
 standing of that determination when reviewed on appeal.
     The law has long been clear that the Director has no
 substantive rule making authority with respect to interpre-
 tations of the Patent Act. Cooper Techs. Co. v. Dudas, 536
 F.3d 1330, 1336 (Fed. Cir. 2008). The Board, similarly, his-
 torically has been given adjudicatory authority—similar to
 that given to courts—to decide the issues presented to it.
 The Director’s new delegation of authority in the AIA to
 establish procedures by regulation for the conduct of IPRs
 does not confer new statutory interpretive authority to the
 Board or change the standard under which we review their
 conclusions. And, the Board’s authority to adjudicate IPRs
 does not confer rulemaking authority upon the Director
 that extends to all legal questions the Board adjudicates.
 As noted above, the PTO’s structure has never been the
 type of unitary structure at issue in the cases upon which
 the government relies.
                               III
     In just three sentences at the end of its brief, the gov-
 ernment asks for Skidmore deference if we do not apply
 Chevron deference. The government articulates the Skid-
 more standard and includes a single sentence of explana-
 tion of why it should apply. As an initial matter, such a
 conclusory assertion with no analysis is insufficient to de-
 velop and preserve the issue. See Trading Techs. Int’l, Inc.
 v. IBG LLC, 921 F.3d 1378, 1385 (Fed. Cir. 2019) (citing
 United States v. Great Am. Ins. Co. of N.Y., 738 F.3d 1320,
 1328 (Fed. Cir. 2013) (“It is well established that argu-
 ments that are not appropriately developed in a party’s
 briefing may be deemed waived.”)).
      Nevertheless, in our view, Skidmore deference does not
 apply. Under Skidmore, “‘[t]he weight [accorded to an ad-
 ministrative] judgment in a particular case will depend
 upon the thoroughness evident in its consideration, the va-
 lidity of its reasoning, its consistency with earlier and later
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 FACEBOOK, INC. v. WINDY CITY INNOVATIONS, LLC            15



 pronouncements, and all those factors which give it power
 to persuade, if lacking power to control.” Mead, 533 U.S. at
 228 (second alteration in original) (quoting Skidmore, 323
 U.S. at 140). The considerations listed in Skidmore weigh
 against affording deference here. For example, as ex-
 plained in the majority opinion, we find the Director’s in-
 terpretation of § 315(c) to be inconsistent with the plain
 language of the statute and therefore unpersuasive. See
 PhotoCure ASA v. Kappos, 603 F.3d 1372, 1376 (Fed. Cir.
 2010) (“Even if some level of deference were owed to the
 PTO’s interpretation, neither Chevron nor Skidmore per-
 mits a court to defer to an incorrect agency interpreta-
 tion.”); Aqua Prod., 872 F.3d at 1316 (“[D]eference to
 misinterpretation of a statute is impermissible.”).
                             IV

     In sum, even if § 315(c) were ambiguous—which it is
 not—we would conclude in the alternative that on appeal
 the PTO’s interpretation set forth in the POP opinion in
 Proppant is not deserving either of Chevron or Skidmore
 deference. We would then conclude—again in the alterna-
 tive—that the most reasonable interpretation of § 315(c) is
 the one we afford it in our majority opinion.
