Court Opinion

ID: 9364906
Source: CourtListenerOpinion
Date Created: 2023-01-20 17:00:45.420188+00
Date Added: 2024-06-11T17:15:41.312818
License: Public Domain

Case: 21-2275   Document: 49    Page: 1     Filed: 01/20/2023

   United States Court of Appeals
       for the Federal Circuit
                 ______________________

 PERSONALIZED MEDIA COMMUNICATIONS, LLC,
              Plaintiff-Appellant

                           v.

                     APPLE INC.,
                   Defendant-Appellee
                 ______________________

                       2021-2275
                 ______________________

    Appeal from the United States District Court for the
 Eastern District of Texas in No. 2:15-cv-01366-JRG-RSP,
 Chief Judge J. Rodney Gilstrap.
                  ______________________

                Decided: January 20, 2023
                 ______________________

     KEVIN PAUL MARTIN, Goodwin Procter LLP, Boston,
 MA, argued for plaintiff-appellant. Also represented by
 GERARD JUSTIN CEDRONE, DOUGLAS J. KLINE, LANA S.
 SHIFERMAN; WILLIAM M. JAY, Washington, DC; SIDNEY
 CALVIN CAPSHAW, III, Capshaw DeRieux LLP, Gladewater,
 TX.

    JOHN C. O'QUINN, Kirkland & Ellis LLP, Washington,
 DC, argued for defendant-appellee. Also represented by
 NATHAN S. MAMMEN; GREG AROVAS, New York, NY; LUKE
 DAUCHOT, ELLISEN SHELTON TURNER, Los Angeles, CA;
 MARCUS EDWARD SERNEL, Chicago, IL.
Case: 21-2275       Document: 49    Page: 2   Filed: 01/20/2023

 2       PERSONALIZED MEDIA COMMUNICATIONS, LLC   v. APPLE INC.

    JEFFREY A. LAMKEN, MoloLamken LLP, Washington,
 DC, for amicus curiae Fair Inventing Fund. Also repre-
 sented by RAYINER HASHEM.
                 ______________________

         Before REYNA, CHEN, and STARK, Circuit Judges.
     Opinion for the court filed by Circuit Judge REYNA.
         Dissenting opinion filed by Circuit Judge STARK.
 REYNA, Circuit Judge.
     Personalized Media Communications, LLC appeals the
 final judgment of the District Court for the Eastern District
 of Texas that U.S. Patent No. 8,191,091 is unenforceable
 based on prosecution laches. The district court determined
 that Personalized Media Communications successfully em-
 ployed an inequitable scheme to extend its patent rights.
 Because the district court did not abuse its discretion in
 finding the patent unenforceable, we affirm.
                          BACKGROUND
      In 2015, Personalized Media Communications (“PMC”)
 sued Apple in the U.S. District Court for the Eastern Dis-
 trict of Texas, alleging that Apple FairPlay 1 infringed

     1    FairPlay is a digital rights management technology
 that Apple uses on its computers, mobile phones, and other
 devices. J.A. 2 (FF 1). FairPlay is software that prevents
 Apple users from unauthorized uses of content—such as il-
 legally copying songs on iTunes.          J.A. 25 (FF 68);
 Resp. Br. 22. To protect content, FairPlay encrypts data
 and uses “decryption keys” to control decryption.
 J.A. 25–26 (FF 69–70). Recognizing that “the weakest
 link” in a system’s security is the decryption key, Apple en-
 crypted the decryption key as an additional layer of protec-
 tion. Id.
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 PERSONALIZED MEDIA COMMUNICATIONS, LLC     v. APPLE INC.   3

 claim 13 (and related dependent claims) of U.S. Patent No.
 8,191,091 (the “’091 patent”). J.A. 2–3 (FF 1, 5). The case
 went to trial, where a jury returned a unanimous verdict,
 finding that Apple infringed at least one of claims 13–16.
 J.A. 3 (FF 5). The jury awarded PMC over $308 million in
 reasonable-royalty damages. Id.
     Thereafter, the district court held a bench trial on re-
 maining issues and found the ’091 patent unenforceable
 based on prosecution laches. J.A. 1–3. Relying on our re-
 cent decision in Hyatt, the court determined that laches re-
 quired a challenger to prove that the applicant’s delay was
 unreasonable and inexcusable under the totality of the cir-
 cumstances and that there was prejudice attributable to
 the delay. J.A. 28 (CL 4–7) (discussing Hyatt v. Hirshfeld,
 998 F.3d 1347, 1359–62 (Fed. Cir. 2021)). Under this
 framework, the court found that PMC engaged in an un-
 reasonable and unexplained delay amounting to an egre-
 gious abuse of the statutory patent system.
     The court described our recent Hyatt decision as a
 “white horse” case, with “remarkably similar” facts.
 J.A. 32, 41 (CL 15). The court explained that the patentee
 in Hyatt had filed 381 GATT-Bubble applications, and
 PMC had filed 328 GATT-Bubble applications. 2 J.A. 32

    2    During negotiations of the Agreement on Trade-Re-
 lated Aspects of Intellectual Property (“TRIPS Agree-
 ment”) at the Uruguay Round of the General Agreement on
 Tariff and Trade (“GATT”), the U.S. agreed to change the
 term of U.S. patents from 17 years following the date of
 issuance to 20 years following the patent’s priority date.
 Hyatt, 998 F.3d at 1352. In the months leading up to the
 law change, the U.S. Patent and Trademark Office (“PTO”)
 saw an enormous influx of so-called “GATT Bubble” appli-
 cations as applicants sought to take advantage of the exist-
 ing law providing a patent term keyed from issuance.
 Id. at 1352–53.
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 (CL 16). In addition, the court noted that as in Hyatt,
 where each application was a photocopy of one of 11 earlier
 patent applications, PMC’s applications derive from two
 earlier applications. J.A. 32 (CL 17). Similar to Hyatt,
 “PMC’s applications . . . were ‘atypically long and com-
 plex,’” containing over 500 pages of text and over 22 pages
 of figures. J.A. 33 (CL 20). And PMC filed each of its ap-
 plications with a single claim, then subsequently amended
 the claims, sometimes to recite identical language across
 different applications. J.A. 33 (CL 19). The court further
 explained that, like in Hyatt, “[o]ver time, PMC [] greatly
 increase[d] the total number of claims” in the range of
 6,000 to 20,000 claims. J.A. 10, 33–34 (FF 31, CL 21).
      The court also found the length of the delay similar to
 Hyatt because “PMC waited eight to fourteen years to file
 its patent applications and at least sixteen years to present
 the asserted claims for examination.” J.A. 32–33 (CL 18)
 (explaining that the applicant in Hyatt argued that he “de-
 layed only seven to 11 years to file the four applications at
 issue and between 10 and 19 years before presenting the
 claims now in dispute” (citing Hyatt, 998 F.3d at 1368)).
 Moreover, “as in Hyatt, even though the PTO suspended
 prosecution of PMC’s applications, such is directly attribut-
 able to the manner in which PMC prosecuted its applica-
 tions in the first place.” J.A. 35 (CL 25). The court
 reasoned that “PMC’s prosecution conduct made it virtu-
 ally impossible for the PTO to conduct double patenting,
 priority, or written description analyses.” J.A. 37 (CL 31).
 In addition to the scope and nature of PMC’s applications,
 the court pointed to PMC’s vast prior art disclosure, which
 included references having little-to-no relevance, and ex-
 aminers’ statements in office actions describing PMC’s
 prosecution strategy and conduct as improper. J.A. 37–38
 (CL 31, 34); J.A. 47–78 (listing references filling more than
 30 pages). Regardless, prosecution had been pending for
 “nearly ten years” before the PTO suspended it. J.A. 35
 (CL 25).
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 PERSONALIZED MEDIA COMMUNICATIONS, LLC     v. APPLE INC.   5

      “The only notable distinction” the court found between
 Hyatt and this case was that “Mr. Hyatt acknowledged he
 lacked a ‘master plan’ for demarcating his applications”
 whereas PMC developed the “Consolidation Agreement”
 with the PTO. J.A. 34 (CL 23). Under the Consolidation
 Agreement, PMC agreed to group its applications into 56
 subject-matter categories, with subcategories for each of
 the two priority dates. J.A. 14 (FF 39); J.A. 8081–82.
 Within the categories, PMC was to designate “A” applica-
 tions and “B” applications, with the PTO prioritizing “A”
 applications. Id. Rejected claims would transfer to the cor-
 responding “B” application and prosecution of “B” applica-
 tions was stayed until the corresponding “A” application
 issued. Id. PMC would abandon any remaining applica-
 tions that were not designated “A” or “B.” Id. This “A” ap-
 plication-to-“B” application examination scheme, in effect,
 gave PMC an additional bite at the apple to extend out
 prosecution of its many claims without the cost of having
 to file a continuation application. 3
     The court determined that the Consolidation Agree-
 ment alone does not operate to shift blame on the PTO.
 J.A. 34–35 (CL 24). The court explained that the Consoli-
 dation Agreement had to be understood in the context of
 PMC’s business-driven, unreasonable prosecution strat-
 egy. J.A. 36 (CL 28–30).
     Specifically, the court explained that prior to the
 GATT, PMC had an express prosecution policy of pursuing
 one application at a time and filing a continuation as the
 prior application reached issuance—with the sole purpose
 to delay issuance of PMC’s patents in order to extend
 PMC’s patents’ terms. 4 In addition, the court discussed

    3    The record does not explain how PMC and the PTO
 decided on the elements of the Consolidation Agreement.
     4   See J.A. 6 (FF 15) (discussing a 1990 document
 stating “[PMC’s] strategy is to prosecute coverage on its
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 6    PERSONALIZED MEDIA COMMUNICATIONS, LLC     v. APPLE INC.

 other documents from the same time period describing
 PMC’s strategy at the time of hiding its technologies, “qui-
 etly monitor[ing]” infringement, and “roll[ing] out” patents
 over time because “[o]nce infringement becomes wide-
 spread in an industry, the patented technology becomes so
 deeply embedded in commercial products that design
 around is not an option to infringers.” 5
      The court analyzed prosecution conduct concerning the
 asserted ’091 patent and found that PMC used the Consol-
 idation Agreement “to realize [PMC’s] initial strategy of se-
 rialized prosecution, notwithstanding the GATT
 amendments.” J.A. 36 (CL 28). In particular, the court
 explained that on July 18, 2002, the PTO accepted PMC’s
 request to designate Application No. 08/485,507 (the “’507
 application”) as the “B” application corresponding to Appli-
 cation No. 08/474,145 (the “’145 application”) and suspend
 prosecution of the ’507 application. J.A. 19 (FF 57). On
 February 4, 2003, PMC amended claim 22 of

 technologies deliberately over time in such a way that broad
 coverage is in effect at any given time while the duration of
 coverage is prolonged as long as possible.” (quoting J.A.
 37730–31)); J.A. 6 (FF 16) (discussing an April 1992 docu-
 ment explaining that PMC “believes that its intellectual
 property position will enable it to exercise far-reaching
 market control for as long as 30 to 50 years.” (quoting J.A.
 39220)).
     5   See J.A. 7 (FF 17–18) (discussing J.A. 37817); see
 also J.A. 7–8 (FF 19–20) (discussing a document dated Sep-
 tember 12, 1991, that states, “[i]n some cases markets had
 not yet matured to benefit from applications of [PMC’s]
 technologies . . . [so PMC] had deliberately chosen not to
 publicize widely its technologies or plans” and targets Ap-
 ple as one of several “companies that are natural candi-
 dates for participating in the commercialization of [PMC’s]
 technologies.” (quoting J.A. 37865, 37870)).
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 PERSONALIZED MEDIA COMMUNICATIONS, LLC                                    v. APPLE INC.                   7

 the ’145 application. J.A. 22 (FF 61). The amendment
 changed the claim from “[a] method of enabling a program-
 ming presentation at a receiver station” to “[a] method of
 decrypting programming at a receiver station” and intro-
 duced various encryption and decryption steps:

             '145 application claim 22                           ' 145 application claim 22
           (March 15 , 2002 amendment)                         (February 4, 2003 amendment)
  A method of enabling a programming                  A method of enaliling a decrypting
  presentation at a receiver station, said method     programming JJrnsentatisn at a receiver station,
  comprising the steps of:                            said method comprising the steps of:
          receiving an infonnation transmission               receiving an infonnation transmission
  from at least one of a local source and a remote    frnm at least ene sfa leeal ss8ree and a remste
  source, said infonnation transmission including     ss8ree, said infurmatien transmissien including
  disabled information;                               4tsahle4 encrypted information;
          detecting the presence of an instruct-to-           detecting the presence of an instruct-to-
  enable signal, said instruct-to-enable signal       enable signal, said inslmel 10 enalile signal
  designating enabling information;                   designating enaliling infurmalien;
          passing said instruct-to-enable signal to           passing said instruct-to-enable signal to
  a processor;                                        a processor;
          modifying a fashion in which said                   ms dif) ing determining a fashion in
  receiver station locates said enabling              which said receiver station locates sat4
  information in response to said instruct-to-        enaliling infum1a1i0n in resJJsnse 10 a fir st
  enable signal;                                      decryptio n key by processing said instruct-to-
          locating said enabling information          enable signal;
  based on said step of modifying a fashion;                  locating said enaliling infurmatien fi rst
          enabling said disabled information          decryption key based 011 said step of
  based on said step of locating said enabling        medifJ ing a fusaien determining;
  information; and                                            enabl-mg decrypting said 4tsahle4
          outputting       said      programming      encrypted infonnation eased en said sleJJ ef
  presentation based on said step of enabling said    lseating said enaliling infurmalisn using said
  disabled information.                               first decryption key; and
                                                              outputting       said       programming
  (DTX-1568 at 978)                                   JJresentalisn based on said step sfenaliling said
                                                      disaliled infurmalien decrypting.

                                                      (DTX- 1568 at 1132, 1177)

 Id. The court found that the February 4, 2003 amendment
 was the first time that encryption, decryption, and decryp-
 tion keys were a part of this claim. Id.
     That same year, the PTO stayed the prosecution of
 PMC’s applications pending resolution of eleven reexami-
 nation proceedings on related, issued patents. J.A. 16 (FF
 46). The stay lasted several years, as reexamination con-
 tinued, and was lifted in 2009. J.A. 16 (FF 46–47).
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     Once prosecution reopened, the PTO rejected amended
 claim 22 of the ’145 application claiming the “decrypting
 programming” method. J.A. 23 (FF 63). PMC subse-
 quently amended claim 22 significantly, and the ’145 appli-
 cation ultimately issued. Id.
     But on April 11, 2011, PMC reintroduced the rejected
 “decrypting programming” method claim to the ’507 appli-
 cation (the corresponding “B” application), as a part of sev-
 eral other claim amendments. J.A. 23 (FF 64). PMC told
 the PTO that the amendments “place the claims in condi-
 tion for allowance,” despite the “decrypting programming”
 claim having previously been rejected. Id. This time, how-
 ever, the claim was allowed in large part. J.A. 24 (FF 65).
 The ’507 application issued as the asserted ’091 patent,
 with the reintroduced claim as claim 13. Id. The ’091 pa-
 tent is set to expire in 2027—forty years after its 1987 pri-
 ority date. 6 J.A. 36 (CL 30).
     The court concluded that “the only rational explanation
 for PMC’s approach to prosecution is a deliberate strategy
 of delay” and that “PMC’s actions were a conscious and
 egregious misuse of the statutory patent system.”
 J.A. 38 (CL 35). Thus, the court found that Apple met its
 burden to prove the first element of laches.
     The court then turned to prejudice.        J.A. 38–41
 (CL 36–47). The court explained that Apple had already
 begun developing the accused FairPlay system by 2003, the
 year that PMC first added the asserted technology to the
 ’091 patent’s predecessor. J.A. 39–40 (CL 38–43). Further,
 the ’091 patent issued in 2012—seven years after FairPlay

     6   The parties appear to dispute whether the ’091 pa-
 tent also claims priority to PMC’s 1981 application. Com-
 pare Appellant’s Br. 8, with Resp. Br. 3. We do not resolve
 this dispute as it is unnecessary for the purposes of this
 appeal.
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 PERSONALIZED MEDIA COMMUNICATIONS, LLC      v. APPLE INC.    9

 had already matured into the version accused of infringe-
 ment. J.A. 39 (CL 38). The court reasoned that the prose-
 cution delays had to be understood in the context of PMC’s
 expressed desire to extend its patent rights as long as pos-
 sible and conceal its inventions until infringement was
 deeply embedded into the industry. J.A. 40 (CL 45). This
 scheme contributed to the prejudice, which was under-
 scored by the fact that a jury found that Apple’s FairPlay
 technology infringed the ’091 patent. J.A. 39 (CL 39).
 Thus, Apple established prejudice, and laches rendered
 the ’091 patent unenforceable.
    PMC timely appeals the laches determination.             We
 have jurisdiction under 28 U.S.C. § 1295(a)(1).
                    STANDARD OF REVIEW
     We review a district court’s determination of prosecu-
 tion laches for abuse of discretion. Cancer Research Tech.
 Ltd. v. Barr Labs Inc., 625 F.3d 724, 728–29
 (Fed. Cir. 2010). “‘We may find an abuse of discretion on a
 showing that the court . . . exercised its discretion based
 upon an error of law or clearly erroneous factual findings.’”
 SiOnyx LLC v. Hamamatsu Photonics K.K., 981 F.3d 1339,
 1349 (Fed. Cir. 2020) (quoting Innogenetics, N.V. v. Abbott
 Labs, 512 F.3d 1363, 1379 (Fed. Cir. 2008)).
                         DISCUSSION
     Prosecution laches is an equitable affirmative defense
 dating back to the early 1900s. Hyatt, 998 F.3d at 1360.
 Prosecution laches may render a patent unenforceable
 where a patentee’s conduct “constitutes an egregious mis-
 use of the statutory patent system.” Id. at 1360–61 (cita-
 tion omitted). Prosecution laches requires proving two
 elements: (1) the patentee’s delay in prosecution must be
 unreasonable and inexcusable under the totality of circum-
 stances and (2) the accused infringer must have suffered
 prejudice attributable to the delay. Id. at 1362. We con-
 clude that the district court did not abuse its discretion by
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 10   PERSONALIZED MEDIA COMMUNICATIONS, LLC     v. APPLE INC.

 legally erring or making clearly erroneous factual findings
 in determining that Apple established both laches ele-
 ments.
            Unreasonable and Inexcusable Delay
     PMC argues that the district court erred in finding an
 unreasonable and inexcusable delay, such that the district
 court failed to consider the totality of the circumstances.
 We disagree.
     First, PMC argues legal error because its “conduct
 looks nothing like Hyatt or the handful of other cases that
 have found prosecution laches.” Appellant’s Br. 39. This
 is not a legal error and is factually incorrect.
     Laches is an equitable and flexible doctrine that re-
 quires considering the totality of the circumstances. Hyatt,
 998 F.3d at 1359–66. In Hyatt, we found that the district
 court improperly failed to consider the totality of the cir-
 cumstances by repeatedly discounting or ignoring relevant
 evidence. Id. Thus, PMC’s argument rests on a faulty
 premise: that PMC’s conduct has to look like “Hyatt or the
 handful of other [laches] cases.” Appellant’s Br. 39. Set-
 ting this aside, this case is very similar to Hyatt and prior
 cases, and, in some ways, involves even more egregious
 facts because, as the district court found, the record shows
 that PMC institutionalized its abuse of the patent system
 by expressly adopting and implementing dilatory prosecu-
 tion strategies, specifically to ambush companies like Ap-
 ple many years after PMC filed its applications.
      Second, PMC asserts that its “compliance” with the
 Consolidation Agreement and the PTO’s rules precludes a
 finding of laches as a matter of law. Appellant’s Br. III(B);
 id. at 38, 46–47, 50–51. We disagree.
     In Hyatt, the PTO used “atypical procedures”—as it did
 here—to facilitate prosecution because the applicant, like
 PMC, had filed hundreds of burdensome GATT-Bubble ap-
 plications. Hyatt, 998 F.3d at 1354–55, 1370. Still, we
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 found that the PTO met its burden to prove an unreasona-
 ble and unjustifiable delay. Id. at 1369. We also explained
 that “[a]n applicant must . . . not only comply with the stat-
 utory requirements and PTO regulations but must also
 prosecute its applications in an equitable way.” Id. at 1366.
 Moreover, PMC’s compliance with the Consolidation
 Agreement supports, rather than refutes, a finding of un-
 reasonable and inexcusable delay. PMC’s agreement to
 structure a serial examination of a claim through first an
 A application and then a B application gave PMC the very
 kind of prosecution delays that supported PMC’s campaign
 for drawn-out prosecution. J.A. 36 (CL 28).
     Third, PMC asserts that the “district court improperly
 disregarded the reasons for the prosecution’s length.” Ap-
 pellant’s Br. III(C). PMC points to delays in prosecution
 that occurred due to the PTO grappling with PMC’s GATT-
 Bubble applications and attempting to resolve overlapping
 issues across many of PMC’s applications. Id. at 42–43.
      In Hyatt, we rejected a similar argument and explained
 that “a delay by the PTO cannot excuse the appellant’s own
 delay.” Hyatt, 998 F.3d at 1364–65 (citation omitted) (find-
 ing that the district court erroneously found the PTO solely
 responsible for a 9-year stay on prosecution, when the pe-
 riod was “directly attributable to” the applicant’s conduct
 and the stay’s outcome could have “rendered meaningless”
 PTO time spent examining the applications). Unlike in Hy-
 att, the district court here determined that the various
 prosecution delays occurred because of issues PMC inten-
 tionally created, correctly focusing on PMC’s inequitable
 prosecution. Compare id. at 1365, with J.A. 12–13
 (FF 35–36) (discussing the In re Schneller stay), and J.A.
 16 (FF 46–47) (discussing the reexamination stay), and
 J.A. 35 (CL 25) (“[E]ven though the PTO suspended prose-
 cution of PMC’s applications, such is directly attributable
 to the manner in which PMC prosecuted its applications in
 the first place.”).
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      Fourth, PMC argues that the “district court committed
 legal error by relying on the simple number of PMC’s ap-
 plications.” Appellant’s Br. III(D). This argument also
 fails.
     While we discussed in Hyatt the fact that the applicant
 had filed 381 GATT-Bubble applications, we also consid-
 ered other facts evidencing an unreasonable and unex-
 plained delay.      See Hyatt, 998 F.3d at 1353, 1367
 (considering the applications’ length and complexity).
 Thus, the district court here did not legally err by consid-
 ering that PMC filed 328 GATT-Bubble applications as a
 part of the court’s analysis, which also properly considered
 other relevant facts.
      Fifth, PMC argues that it was a legal error for the dis-
 trict court to find delay due to PMC adding “narrowing”
 limitations directed to encryption and decryption in 2003,
 years after the priority date of the ’091 patent. Appel-
 lant’s Br. 47–48; Reply Br. 28–29. PMC, however, merely
 asserts that the 2003 amendments are “narrowing” with-
 out any attempt to explain why this is so, especially in view
 of the significant overhaul to the claims. See id. PMC does
 not cite case law holding legal error in a similar situation.
 In light of the significant amendments made in 2003, we
 are not persuaded that the district court erred in conclud-
 ing that PMC unreasonably delayed in presenting the en-
 cryption and decryption subject matter.
     PMC misconstrues the district court’s rationale for
 finding delay due to the 2003 amendments. The district
 court faulted PMC for waiting until 2003—sixteen years
 after the priority date of the ’091 patent and nearly eight
 years after PMC filed its 328 GATT-bubble applications—
 to include the subject encryption and decryption limita-
 tions to the claims. J.A. 39–40 (CL 38, 42). In Hyatt, we
 found that a similar delay in presenting claims was suffi-
 cient to trigger prosecution laches. Hyatt, 998 F.3d at
 1367–68. In particular, we found that a delay of between
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 PERSONALIZED MEDIA COMMUNICATIONS, LLC       v. APPLE INC.   13

 7–11 years to file applications and 10–19 years before pre-
 senting claims contributed to the unreasonableness of the
 delay. Id. at 1368. We also found that the district court
 erroneously “ignored evidence of Hyatt’s pattern of rewrit-
 ing or shifting claims midway through prosecution” and
 that it was not enough for the district court to merely note
 that “it is ‘not unusual to see a few claims rewritten’” and
 that “the PTO accepted the amendments and continued ex-
 amination.” Id. at 1363. The district court properly con-
 sidered the facts surrounding the amendment to find delay.
 J.A. 22–25, 36–38 (FF 61–67; CL 28–35).
      In sum, the district court did not legally err. The dis-
 trict court correctly considered the totality of the circum-
 stances and did not disregard or ignore relevant facts.
      PMC also asserts that several of the district court’s fac-
 tual findings concerning the first laches element amount to
 an abuse of discretion. Appellant’s Br. IV. First, PMC as-
 serts that Apple needed an expert on PTO proceedings to
 support its case. Id. at 2, 52–53. Hyatt does not require
 PTO testimony for a laches determination to be supported,
 and PMC cites no case law suggesting otherwise. Nor is
 there any other basis in the record to suggest that the dis-
 trict court needed an expert’s specialized knowledge to help
 understand the administrative records and the PTO regu-
 lations in this case.
     Second, PMC argues that the district court clearly
 erred because it found PMC contributed to the delay by
 making it “virtually impossible for the PTO to conduct dou-
 ble patenting, priority, or written description analyses,”
 but the PTO has issued over 100 patents to PMC. Id. at 52
 (quoting J.A. 37 (CL 31)). That the PTO issued PMC many
 patents does not suggest clear error—especially given how
 many other facts weigh against PMC here. See Symbol
 Techs., Inc. v. Lemelson Med., Educ. & Rsch. Found., 422
 F.3d 1378, 1380–85 (Fed. Cir. 2005) (affirming the court’s
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 14       PERSONALIZED MEDIA COMMUNICATIONS, LLC   v. APPLE INC.

 finding of laches, despite the patentee having many issued
 patents).
      Third, PMC argues that the district court should not
 have considered the office actions where examiners harshly
 criticized PMC’s prosecution strategy.               Appel-
 lant’s Br. 53–55. The district court was within its purview
 to consider these statements as evidence. J.A. 14–16, 17–
 19, 38 (FF 40–45, 52–55; CL 34). Further, the court
 properly considered the context of the criticisms and rea-
 sonably weighed them in view of other evidence. 7 Id.
     Fourth, PMC argues that the district court clearly
 erred because it misinterpreted PMC’s internal documents.
 Id. at 57–58. PMC argues that its document stating that
 PMC’s “intellectual property position will enable [PMC] to
 exercise far-reaching market control for as long as 30 to 50
 years,” referred to copyrights, not patents. Id.
      The district court did not clearly err; the document it-
 self describes “issued and pending patents.” See J.A. 8573.
 And the court corroborated this document with similar ev-
 idence. See J.A. 6–7 (FF 16–17); see also J.A. 9425–26 (tes-
 timony that PMC’s patent strategy was to extend its
 intellectual property rights and coverage out 30 to 50
 years).

      7  PMC also rehashes several other instances where
 the district court rejected PMC’s interpretation of the pros-
 ecution history. Appellant’s Br. 55–56 (arguing clear error
 by rejecting PMC testimony concerning discussions with
 the PTO); id. at 56 (disputing the district court’s finding
 that PMC filed duplicate claims); id. at 56–57 (disputing
 the district court’s finding that the prior art PMC submit-
 ted was irrelevant because “there was a reasonable expla-
 nation” for PMC submitting the references).            These
 arguments amount to mere disagreement, not clearly erro-
 neous factual findings.
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 PERSONALIZED MEDIA COMMUNICATIONS, LLC      v. APPLE INC.   15

     Along those same lines, PMC argues that the district
 court clearly erred by considering PMC’s document describ-
 ing a strategy of keeping “patents hidden while industry
 infringement is quietly monitored” because that strategy
 would support “post-issuance laches, which since SCA Hy-
 giene is not even a defense” as opposed to prosecution
 laches. Appellant’s Br. 58 (quoting SCA Hygiene, 580 U.S.
 328). Put simply, PMC’s enforcement strategy is part of
 the “totality of the circumstances” here. See Hyatt, 998
 F.3d at 1362; see also Symbol Techs., 422 F.3d at 1385 (ex-
 plaining that actions taken “for the business purpose of de-
 laying [] issuance can be considered an abuse of the patent
 system”).
     In sum, the district court’s factual findings were not
 clearly erroneous. Thus, the district court did not abuse its
 discretion in finding that PMC’s delay in prosecution was
 unreasonable and inexcusable under the totality of circum-
 stances.
                          Prejudice
     Laches requires that the accused infringer suffered
 prejudice attributable to the delay. Hyatt, 998 F.3d at
 1362. An accused infringer can establish prejudice by prov-
 ing that it “invested in, worked on, or used the claimed
 technology during the period of delay.” Id. (citation omit-
 ted). We affirm the district court’s finding that PMC’s de-
 lay prejudiced Apple.
     PMC argues that the district court abused its discre-
 tion in finding that PMC’s delay prejudiced Apple. Appel-
 lant’s Br. V; Reply Br. II. We disagree.
     PMC argues that the district court erred because “Ap-
 ple needed to prove that PMC still was engaged in egre-
 gious conduct causing delays after 2003, which is when the
 district court found Apple began developing FairPlay.” Ap-
 pellant’s Br. 59. This argument misconstrues the record
 and the law.
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 16       PERSONALIZED MEDIA COMMUNICATIONS, LLC   v. APPLE INC.

      PMC incorrectly assumes that the district court did not
 find that PMC was still engaging in “conduct causing de-
 lays after 2003.” Id. The district court found that the de-
 liberate strategy of delay began at least in 1995 and
 continued through PMC filing this suit in 2015.
 See, e.g., J.A. 38, 40 (CL 35, 44). The court found that in
 2011, while PMC was in pre-suit negotiations with Apple,
 PMC reintroduced a previously-rejected claim in
 the ’507 application (the “B” application). See, e.g., J.A. 23–
 25, 39–40 (FF 64–67; CL 41–45). PMC did not mention the
 application or claim to Apple during negotiations. J.A. 40
 (CL 44). PMC was able to get the claim quickly granted,
 assert that claim against Apple, and obtain a damages
 award. J.A. 3, 40 (FF 5; CL 43). This shows that the dis-
 trict court did not err by determining that well after 2003
 PMC was still implementing its express strategy of delay
 to “reserve [its] patent till the trade independently devel-
 ops, and then [] pounce upon it for a full term.” 8 Victor
 Talking Mach. Co. v. Thomas A. Edison, Inc., 229 F. 999,
 1000–01 (2d Cir. 1916); see also J.A. 40 (CL 45) (“All of
 these events must be viewed in the context of PMC’s origi-
 nal plans: to prosecute its patents serially over time and
 keep them hidden until infringement was engrained and
 widespread.”).

      8  We disagree with the dissent’s suggestion that the
 period of delay ended before 2000. See Dissent pp. 14–16.
 The district court did not clearly err in finding that the pe-
 riod of delay lasted until at least 2003, when PMC intro-
 duced the encryption and decryption subject matter into
 the ’145 “A” application, and further until 2011, when PMC
 reintroduced the previously-rejected claim from the ’145
 “A” application into the ’507 “B” application, for the reasons
 discussed in this section and above, see Discussion supra
 pp. 10–15.
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 PERSONALIZED MEDIA COMMUNICATIONS, LLC       v. APPLE INC.   17

      We find no clear error in the district court’s determina-
 tion that PMC engaged in conduct causing delays at least
 through 2011. PMC ignores the effect of its Consolidation
 Agreement with the PTO, which permitted PMC in 2011 to
 re-file the same decryption claim in the ’507 “B” application
 that was not allowed in the corresponding ’145 “A” applica-
 tion. By taking a second bite at the examination apple
 through the “B” application, PMC further lengthened the
 examination process beyond normal prosecution proce-
 dure, creating improper delay during prosecution. That
 the PTO suspended prosecution for a period of time does
 not negate the fact that Apple had begun developing Fair-
 Play well before PMC was engaging in these amendments.
     Even if the district court’s analysis had found that the
 period of PMC’s delay ended by 2003, the district court
 properly concluded that PMC’s delayed presentation of the
 decryption claim in 2003 prejudiced Apple because, as the
 court found, “[i]n so delaying, PMC prejudiced Apple,
 which had already begun investing in FairPlay’s develop-
 ment and continued to do so.” J.A. 39 (CL 38). 9 The record
 indicates that Apple began developing FairPlay before
 2003. Apple began developing FairPlay “in the early
 2000s” and “launched” FairPlay with the Apple Music store
 in 2003. J.A. 26 (FF 71); J.A. 4713 at 684:1–4 (“Q: When
 did Apple begin developing FairPlay? A: In . . . the early

     9    Although the district court stated in a later part of
 its opinion that “Apple began developing FairPlay in 2003,”
 J.A. 39 (CL 40 (citing FF 71)), we take this statement to be
 a typo because it refers to but is inconsistent with the dis-
 trict court’s previous findings that “Apple began developing
 FairPlay in the early 2000s” and launched FairPlay “to-
 gether with the Apple Music store in 2003,” J.A. 26 (FF 71);
 see also J.A. 39 (CL 38) (stating that by the time PMC in-
 troduced the decryption claim in 2003, Apple “had already
 begun investing in FairPlay’s development”).
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 18   PERSONALIZED MEDIA COMMUNICATIONS, LLC      v. APPLE INC.

 2000s”), 684:21–23 (“Q: Now, when did Apple first launch
 FairPlay? A: We launched FairPlay together with the Ap-
 ple Music store, which I believe was in 2003”); J.A. 8085
 (¶¶ 73, 76) (parties stipulating that Apple began develop-
 ing FairPlay “in the early 2000s” and the iTunes Music
 Store launching in 2003). Because Apple began developing
 FairPlay in the early 2000s and launched it in 2003, Apple
 necessarily invested in or worked on FairPlay before 2003,
 which is undisputedly during the period of delay.
     In sum, the district court did not abuse its discretion in
 finding that Apple established prejudice.
                         CONCLUSION
     The district court did not abuse its discretion in finding
 that Apple established laches, rendering the ’091 patent
 unenforceable. We have considered PMC’s remaining ar-
 guments and find them unpersuasive. For the foregoing
 reasons, we affirm the district court’s decision.
                         AFFIRMED
                            COSTS
 Costs to Apple.
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    United States Court of Appeals
        for the Federal Circuit
                   ______________________

 PERSONALIZED MEDIA COMMUNICATIONS, LLC,
              Plaintiff-Appellant

                              v.

                       APPLE INC.,
                     Defendant-Appellee
                   ______________________

                         2021-2275
                   ______________________

    Appeal from the United States District Court for the
 Eastern District of Texas in No. 2:15-cv-01366-JRG-RSP,
 Chief Judge J. Rodney Gilstrap.
                  ______________________

 STARK, Circuit Judge, dissenting.
     I agree with the Majority that the district court did not
 abuse its discretion in finding, based on the totality of the
 circumstances, that Personalized Media Communications,
 LLC’s (“PMC”) delay in prosecuting its patent was unrea-
 sonable and inexcusable. To prevail on its laches claim,
 however, Apple also had to show that it suffered prejudice
 during the period in which PMC was wrongfully delaying
 prosecution. Apple failed to do so. Accordingly, I would
 reverse the district court’s judgment that PMC’s U.S.
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 2       PERSONALIZED MEDIA COMMUNICATIONS, LLC   v. APPLE INC.

 Patent No. 8,191,091 (“’091 patent”) is unenforceable due
 to prosecution laches. 1
                               I
      We review the district court’s conclusion that Apple
 met its burden to prove prosecution laches for abuse of dis-
 cretion. See Cancer Rsch. Tech. Ltd. v. Barr Labs., Inc., 625
 F.3d 724, 728-29 (Fed. Cir. 2010) (“Cancer Research”). “‘We
 may find an abuse of discretion on a showing that the court
 made a clear error of judgment in weighing relevant factors
 or exercised its discretion based upon an error of law or
 clearly erroneous factual findings.’” SiOnyx LLC v. Hama-
 matsu Photonics K.K., 981 F.3d 1339, 1349 (Fed. Cir. 2020)
 (quoting Innogenetics, N.V. v. Abbott Labs., 512 F.3d 1363,
 1379 (Fed. Cir. 2008)). Importantly, “we review the legal
 standard applied by the district court de novo.” Cancer Re-
 search, 625 F.3d at 729. Thus, notwithstanding that our
 ultimate standard of review is for abuse of discretion, we
 may reverse where a district court commits legal error. See
 id. at 732.
     To prevail on its prosecution laches counterclaim, Ap-
 ple has to prove both that (1) PMC’s “delay in prosecution

     1   Because Apple asserted other affirmative defenses
 to infringement that the district court did not have to
 reach, I would remand for that court to address these tried
 but unresolved defenses. See J.A. 2 n.2 (“As Apple has pre-
 vailed on its counterclaim—extinguishing any liability for
 patent infringement—the Court does not reach Apple’s af-
 firmative defenses of obviousness-type double patenting
 and unclean hands.”); J.A. 3 (FF 7) (noting district court
 heard evidence and argument on “prosecution laches,
 OTDP [obviousness-type double patenting], and unclean
 hands”).
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 PERSONALIZED MEDIA COMMUNICATIONS, LLC      v. APPLE INC.   3

 was unreasonable and inexcusable[ 2] under the totality of
 circumstances,” and (2) it “suffered prejudice attributable
 to the delay.” Hyatt v. Hirshfeld, 998 F.3d 1347, 1362 (Fed.
 Cir. 2021). Proving the prejudice necessary to succeed on
 a prosecution laches defense to infringement “requires
 proving intervening rights.” Id. at 1369. Establishing in-
 tervening rights, in turn, requires showing “‘that either the
 accused infringer or others invested in, worked on, or used
 the claimed technology during the period of delay.’” Id.
 (quoting Cancer Research, 625 F.3d at 729) (emphasis
 added). Because the prejudice Apple suffered must be
 “prejudice attributable to the delay,” Apple must prove it
 was prejudiced at some point during the period in which
 PMC was engaged in unreasonable and inexcusable prose-
 cution delay. See Cancer Research, 625 F.3d at 732.
      Our analysis in Cancer Research confirms this under-
 standing of Apple’s burden. In Cancer Research, the dis-
 trict court had decided that “prosecution laches did not
 require a showing of intervening rights but rather turned
 on whether under the totality of the circumstances [the pa-
 tentee’s] delay in prosecution in light of the PTO’s utility
 rejections was unreasonable and unexplained.” Id. at 727.
 We rejected this conclusion and, instead, explicitly “recog-
 nize[d] intervening adverse rights as a requirement to
 holding a patent unenforceable for prosecution laches.” Id.

     2   We have sometimes referred to the required show-
 ing as “unreasonable and unexplained delay,” and at other
 times as “unreasonable and inexcusable” delay. Compare,
 e.g., Maj. Op. at 3, 12 (“unexplained”); Hyatt, 998 F.3d at
 1360 (“unexplained”); Cancer Research, 625 F.3d at 728
 (“unexplained”), with Maj. Op. at 3, 9, 10, 11, 15 (“inexcus-
 able”); Hyatt, 998 F.3d at 1362 (“inexcusable”); Cancer Re-
 search, 625 F.3d at 729 (“inexcusable”). No party argues
 there is any material difference between these formula-
 tions.
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 4    PERSONALIZED MEDIA COMMUNICATIONS, LLC       v. APPLE INC.

 at 729-31. Moreover, we declined to find intervening
 rights, and hence the prejudice necessary to prove laches,
 where an inventor merely “delay[s] in prosecuting and is-
 suing its patent application,” observing that our cases and
 “[t]he Supreme Court cases underlying the [laches] doc-
 trine all rely on a finding that the applicant’s delay in pros-
 ecution adversely affected others working in the same
 field.” Id. (discussing Woodbridge v. United States, 263
 U.S. 50 (1923); Webster Elec. Co. v. Splitdorf Elec. Co., 264
 U.S. 463 (1924); Crown Cork & Seal Co. v. Ferdinand Gut-
 mann Co., 304 U.S. 159 (1938); and Gen. Talking Pictures
 Corp. v. Western Elec. Co., 304 U.S. 175 (1938)). We then
 expressly held that “to establish prejudice an accused in-
 fringer must show evidence of intervening rights, i.e., that
 either the accused infringer or others invested in, worked
 on, or used the claimed technology during the period of de-
 lay.” Id. at 729 (second emphasis added).
      Our application of this standard to the facts in Cancer
 Research, and our conclusion as to the relevant period of
 delay, provides further guidance. The patentee’s predeces-
 sor filed its original patent application, which matured into
 the patent-in-suit, in 1982, and then in 1991 “ownership of
 the patent application changed hands” to Cancer Research.
 Id. at 726. Thereafter, Cancer Research began to move the
 prosecution along at a reasonable pace, and the patent
 eventually issued in 1993. See id. at 726-27. We found that
 the pertinent period during which the accused infringer
 had to prove prejudice was “between 1982 and 1991,” id. at
 726, 732, and did not include 1991 to 1993.
     We next considered whether Barr, the party asserting
 prosecution laches as a defense to infringement, had devel-
 oped intervening rights during the pertinent period. Barr
 had filed an Abbreviated New Drug Application (“ANDA”)
 to market its infringing product in 2007. See id. at 727.
 Because “Barr filed its ANDA more than thirteen years af-
 ter the issuance of Cancer Research’s patent,” we con-
 cluded that Barr was “hardly prejudiced by the delay in the
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 PERSONALIZED MEDIA COMMUNICATIONS, LLC       v. APPLE INC.   5

 issuance of the [patent-in-suit], in 1993.” Id. at 731. As
 Barr likewise failed to identify any other way in which it or
 another entity 3 or the public was prejudiced by the patent
 applicant’s delay between 1982 and 1991, it had failed to
 prove prosecution laches. See id. at 732. Any prejudice
 that Barr or anyone else may have developed after 1991—
 that is, after the patent applicant stopped acting unreason-
 ably and inexcusably—was irrelevant to our analysis. 4
     Apple distinguishes Cancer Research by inviting us to
 eliminate the line between the “period of delay,” as we un-
 derstood and applied that term in Cancer Research, and the
 period after the pertinent delay, which is not relevant to
 the prejudice analysis. See, e.g., Appellee’s Br. 74 (“Even if
 it were somehow true, as PMC suggests, that PMC’s af-
 firmative misconduct had stopped by 2003, the delay in
 prosecution continued due to its [PMC’s] earlier miscon-
 duct.”); id. (“Whereas the delay in Cancer Research con-
 sisted of a defined period of delay . . . this case involves
 conduct deliberately intended to (and that did)

     3    Although our cases allow a party asserting laches
 to satisfy the prejudice prong by identifying prejudice dur-
 ing the pertinent time to others besides the party itself, see,
 e.g., Cancer Research, 625 F.3d at 729, Apple has not at-
 tempted to make such a showing in this case, see Appellee’s
 Br. 71-77.
      4   The dissenting opinion in Cancer Research was
 based on this very aspect of the holding. In dissent, Judge
 Prost disagreed with the “temporal limitation that the prej-
 udice exist[] during the period of delay,” which she faulted
 as a “new requirement” the Cancer Research majority was
 improperly imposing on parties asserting prosecution
 laches. 625 F.3d at 735-37; see also id. at 737 (“[I]t is not
 appropriate to confine the inquiry to the period of time
 when Cancer Research was actively delaying prosecu-
 tion.”).
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 6       PERSONALIZED MEDIA COMMUNICATIONS, LLC   v. APPLE INC.

 affirmatively hamper the PTO’s examination and cause on-
 going delay in examination for years after its occurrence.”);
 id. (arguing law permits “considering the delay resulting
 from those [delaying] acts”). I believe we should reject this
 invitation and adhere to the legal requirement that preju-
 dice be shown to have occurred during the patentee’s period
 of unreasonable and inexcusable delay. 5 If we were to do
 so, it would follow that Apple has failed to meet its burden
 and the district court’s finding of laches could not stand.
                              II
     Turning to the facts before us, there is no material dis-
 pute as to the date by which Apple obtained intervening
 rights in the technology the jury found to be infringing.
 The acquisition of such intervening rights depends on the
 timing of Apple’s “invest[ment] in, work[] on, or use[]” of
 the infringing FairPlay technology. Cancer Research, 625
 F.3d at 729. The district court found that Apple proved it
 began this work “in the early 2000s.” J.A. 26 (FF 71). The
 Majority affirms this finding and I agree it is not clearly

     5   In Hyatt, 998 F.3d at 1370, we said that “where a
 patent applicant has committed a clear abuse of the PTO’s
 patent examination system, the applicant’s abuse and its
 effects meet the prejudice requirement of prosecution
 laches.” I read this statement as limited to the § 145 con-
 text in which Hyatt arose, where the entity confronting the
 burden to show prejudice was the PTO, not a patent in-
 fringer. It makes sense that the PTO can show prejudice
 by proving it, the PTO, was clearly abused by the applicant.
 I am not aware of this Court making similar statements
 when the party asserting prosecution laches is an accused
 infringer.
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 PERSONALIZED MEDIA COMMUNICATIONS, LLC      v. APPLE INC.   7

 erroneous. The earliest date by which Apple obtained in-
 tervening rights, then, was January 2000. 6
      Consequently, Apple must also prove that PMC was
 engaged in unreasonable and inexcusable prosecution de-
 lay in or after January 2000. If all of PMC’s improper delay
 concluded before January 2000, before Apple began work-
 ing on FairPlay, then whatever prejudice Apple suffered is
 not “attributable to” PMC’s delay. While Apple does not
 agree that this is the proper analysis—believing, as it per-
 suaded the district court, that the lingering post-2000 im-
 pact of PMC’s pre-2000 delay is sufficient to make Apple’s
 post-2000 development of FairPlay dispositive in our prej-
 udice analysis—it contends, in the alternative, that it
 proved unreasonable and inexcusable prosecution delay af-
 ter 2000. I disagree.
     As PMC observes, the district court’s focus in finding
 delay was primarily on PMC’s activities between 1987 and

     6   In fact, the record strongly suggests that Apple did
 not work on what became FairPlay until 2002. Apple’s ap-
 pellate briefing indicates Apple started developing Fair-
 Play after launching iTunes and the iPod in late 2001. See
 Appellee’s Br. 22 (citing J.A. 4706-07, 4712-13, 8085 (Stip.
 ¶ 76)). In closing argument at the bench trial, Apple’s
 counsel told the district court that FairPlay “[l]aunched in
 April of 2003, [and was] developed shortly before that.”
 Personalized Media Commc’ns, LLC v. Apple, Inc., No.
 2:15-cv-01366, ECF No. 645 (Bench Trial Transcript), at
 237. Moreover, FairPlay did not “mature[]” into the ver-
 sion that infringes the asserted claims until perhaps as late
 as 2005. J.A. 39 (CL 38) (“By 2005 . . . FairPlay had ma-
 tured into the version accused of infringement.”); see also
 J.A. 26 (FF 72). Because PMC’s unreasonable and inexcus-
 able delay had ended before 2000, the specific date in the
 2000s when Apple acquired intervening rights is immate-
 rial.
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 8    PERSONALIZED MEDIA COMMUNICATIONS, LLC      v. APPLE INC.

 1995. The district court relied on the number of applica-
 tions PMC filed in 1995, and the fact that “PMC’s 328 ap-
 plications derive[d] from two earlier applications,
 respectively filed in 1981 and 1987. These pre-date PMC’s
 1995 applications by 8 to 14 years.” J.A. 32 (CL 17). The
 district court compared PMC’s filing delays to the delays
 involved in Hyatt, concluding that “PMC delayed filing of
 its applications for a comparable period.” J.A. 32-33
 (CL 18). The district court noted that PMC’s applications
 were filed with a small number of claims, J.A. 33 (CL 19),
 which were later multiplied and amended, J.A. 33-34
 (CL 21), and the applications themselves were lengthy and
 complex, J.A. 33 (CL 20). The district court also pointed to
 the large number of references PMC disclosed as pertinent
 prior art. J.A. 34 (CL 22).
      When addressing PMC’s post-2000 prosecution con-
 duct, the district court specifically mentions a 2002 office
 action, which PMC was slow in responding to; a 2003
 amendment to what became independent claim 13 of the
 ’091 patent; and PMC’s 2011 reintroduction—as a proposed
 “B” application claim—of what had been rejected as an “A”
 application claim and eventually became claim 13 of the
 ’091 patent. Thus, the only conduct after 2000 that either
 the district court or Apple points to as constituting unrea-
 sonable and inexcusable prosecution delay is: (i) the 2002
 failure to respond promptly to an office action; (ii) the 2003
 claim amendment; and (iii) the 2011 reintroduction of what
 became claim 13 of the ’091 patent. As I see it, none of
 these actions, either individually or as part of the totality
 of circumstances, were the type of “egregious misuse of the
 statutory patent system” we have required to find prosecu-
 tion laches. Cancer Research, 625 F.3d at 728.
                               A
     Apple points to PMC’s January 2003 response to a July
 2002 office action as abusive prosecutorial conduct. See Ap-
 pellee’s Br. 45-46. While I agree with Apple that the
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 PERSONALIZED MEDIA COMMUNICATIONS, LLC        v. APPLE INC.   9

 district court could properly consider this evidence, I disa-
 gree that PMC’s activities in 2002 and 2003 widen the win-
 dow of unreasonable and inexcusable delay to a period after
 2000.
     In the July 2002 office action, the examiner expressed
 frustration with PMC’s “misle[a]d[ing]” statements about
 priority dates for the claims in U.S. Patent Application No.
 08/474,145 (“’145 application”). J.A. 15 (FF 43). The exam-
 iner wrote that the PTO “continue[d] to struggle in its ef-
 forts to make [§ 112 ¶ 1] determinations for the 10,000 or
 so pending amended claims,” adding that PMC failed to
 identify “precisely what is being claimed.” J.A. 16 (FF 44)
 (emphasis and alteration in original).
     The office action specified a three-month period during
 which PMC could reply, while also noting that extensions
 might be available under 37 C.F.R. § 1.136(a), adding that
 in no event could a reply be filed more than six months af-
 ter the July 31, 2002 mailing date of the office action.
 J.A. 48027-28. Precisely six months after the mailing date,
 on January 31, 2003, PMC filed its reply, simultaneously
 requesting a three-month extension under § 1.136(a) and
 paying the fee for the extension. J.A. 48135-36. PMC’s
 January 2003 reply thoroughly responded to the exam-
 iner’s concerns. See J.A. 48137-80. Thereafter, prosecu-
 tion proceeded, including by PMC filing two information
 disclosure statements. See File History of U.S. Patent No.
 7,992,169 (showing information disclosure statements filed
 on February 7, 2003, and May 5, 2003); see also J.A. 48299.
     The district court found that the July 2002 office action
 was a relevant example of PMC’s prosecution misconduct,
 see J.A. 15-16 (FF 42-45), although the district court did
 not rely on or cite to these findings of fact in explicating its
 conclusions of law on unreasonable and inexcusable delay
 or prejudice, see J.A. 30-41 (CL 11-47). The district court
 also did not make any finding regarding PMC’s January
 2003 reply, see J.A. 15-16 (FF 42-45), a reply which
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 10   PERSONALIZED MEDIA COMMUNICATIONS, LLC      v. APPLE INC.

 appears to have been timely, see J.A. 48136 (PMC request-
 ing three-month extension and paying fee, “thereby extend-
 ing the period for response to January 31, 2003”). The “give
 and take” between the examiner and PMC in and around
 the July 2002 office action and January 2003 reply is rou-
 tine, not unreasonable and inexcusable. See In re Buszard,
 504 F.3d 1364, 1366-67 (Fed. Cir. 2007) (“The patent exam-
 iner and the applicant, in the give and take of rejection and
 response, work toward defining the metes and bounds of
 the invention to be patented.”).
     In short, I do not see how PMC’s prosecution conduct
 in connection with the July 2002 office action constitutes
 unreasonable and inexcusable delay that could give rise to
 Apple developing intervening rights in the 2002 or 2003
 timeframe. And neither the district court nor the Majority
 explain how it could.
                               B
      The district court also found that PMC’s February 4,
 2003 amendment “was the first time that encryption, de-
 cryption, or decryption keys” appeared in the ’145 applica-
 tion’s claims. J.A. 22 (FF 61). The Majority finds no abuse
 of discretion in this finding. See Maj. Op. at 6-7, 15. I view
 the question of whether the amendment added encryption,
 decryption, and decryption keys to the claims as a matter
 of claim scope and, therefore, an issue of law. See Mark-
 man v. Westview Instruments, Inc., 517 U.S. 370, 391
 (1996). Moreover, I am persuaded that each of these limi-
 tations was within the scope of the pre-amendment claims
 and, therefore, the amendment was a routine narrowing
 amendment. See PPC Broadband, Inc. v. Corning Optical
 Commc’ns RF, LLC, 815 F.3d 734, 740 (Fed. Cir. 2016)
 (“[T]he patentee can amend the claim language during
 prosecution—and narrow it if necessary—to clarify the
 scope of the invention and avoid rejection or cancellation of
 the claims.”); see also In re Zletz, 893 F.2d 319, 321 (Fed.
 Cir. 1989) (“[D]uring patent prosecution . . . claims can be
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 PERSONALIZED MEDIA COMMUNICATIONS, LLC      v. APPLE INC.   11

 amended, ambiguities should be recognized, scope and
 breadth of language explored, and clarification imposed.”).
     As the Majority explains, the 2003 “amendment
 changed the claim from ‘[a] method of enabling a program-
 ming presentation at a receiver station’ to ‘[a] method of
 decrypting programming at a receiver station,’ and intro-
 duced various encryption and decryption steps.” Maj. Op.
 at 7 (internal emphasis omitted). The Majority, district
 court, and Apple all fail to provide any reason to view this
 amendment—to the claim’s preamble—as even a claim lim-
 itation, and certainly not one that broadens claim scope.
 See generally Symantec Corp. v. Comput. Assocs. Int’l, Inc.,
 522 F.3d 1279, 1288-89 (Fed. Cir. 2008) (“[I]n general, the
 purpose of a claim preamble is to give context for what is
 being described in the body of the claim; if it is reasonably
 susceptible to being construed to be merely duplicative of
 the limitations in the body of the claim (and was not clearly
 added to overcome a rejection), we do not construe it to be
 a separate limitation.”).
      The amendment additionally changed “enabling said
 disabled information” to “decrypting said encrypted infor-
 mation,” and similarly changed other instances of “ena-
 bling said disabled information” to “decrypting;” “disabled
 information” to “encrypted information;” and “enabling in-
 formation” to “decryption key.” J.A. 22 (FF 61). These
 amendments narrowed and limited the scope of the claims
 to encryption, decryption, and decryption keys, elements
 that were present in the claims at least as far back as 1997.
 See, e.g., J.A. 40125, 40139 (June 10, 1997 response to of-
 fice action, showing amendment and request for reconsid-
 eration in connection with U.S. Patent Application No.
 08/485,507 (“’507 application”), stating: “One place where
 the specification discloses enabling information and disa-
 bled (encrypted) information begins on page 297 line 20 and
 goes through to page 298, line 21.”) (emphasis added);
 J.A. 27711, 27734 (PMC designating certain pending
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 12   PERSONALIZED MEDIA COMMUNICATIONS, LLC    v. APPLE INC.

 applications—including ’507 and ’145—as “relat[ing] to de-
 cryption of broadcast information,” also known as “DECR”).
     Prior to the 2003 amendment, one could practice the
 claims by disabling information using mechanisms other
 than encryption, and enabling information could be of a
 type other than decryption keys. Moreover, disabled infor-
 mation could be enabled without specifically decrypting it
 via a decryption key. After the 2003 amendment, by con-
 trast, the claims were narrowed to encryption, decryption,
 and decryption keys. There was nothing unreasonable, in-
 excusable, or even unusual about this routine amendment.
 Therefore, Apple has not shown that any prejudice it suf-
 fered in 2003 is attributable to PMC’s prosecution delay.
                              C
     Apple portrays PMC’s conduct in 2011, which had the
 effect of amending the ’091 patent’s independent claim 13,
 as “one of its more egregious tactics.” Appellee’s Br. 76.
 The Majority “find[s] no clear error in the district court’s
 determination that PMC engaged in conduct causing de-
 lays at least through 2011.” Maj. Op. at 17. But PMC’s
 2011 claim amendment was permitted by the Consolida-
 tion Agreement reached between PMC and the PTO. I do
 not believe PMC’s compliance with the Consolidation
 Agreement justifies a finding that PMC’s unreasonable and
 inexcusable delay persisted until 2011.
     As the parties stipulated in the district court, a key
 component of the Consolidation Agreement was: “Appli-
 cants and the PTO agreed that, in order to expedite allow-
 ance of patentable claims, if there were claims that
 remained finally rejected in an application, those claims
 were to be moved to the ‘B’ Application for further action,
 and the ‘A’ Application would be allowed to issue.”
 J.A. 8082 (Stip. ¶ 50). Consistent with this Agreement, in
 or around 2000, PMC designated the ’145 application an
 “A” application and the ’507 application as the correspond-
 ing “B” application. J.A. 18 (FF 54). Pursuant to the
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 PERSONALIZED MEDIA COMMUNICATIONS, LLC      v. APPLE INC.   13

 Consolidation Agreement, PMC “[m]aintain[ed] applica-
 tion B as a potential application for any claims not allowed”
 in the A application. J.A. 27725. When, in April 2011,
 PMC reintroduced via the ’507 “B” application claim 45—
 which is identical to claim 22 of the ’145 “A” application as
 it existed after its February 4, 2003 amendment—it was
 acting in accordance with the Consolidation Agreement to
 which the PTO had agreed. After minimal further amend-
 ments, claim 45 of the ’507 application issued as independ-
 ent claim 13 of the ’091 patent, and the jury later found
 Apple infringed “at least one of claims 13, 14, 15, and 16 of
 the ’091 patent.” J.A. 27 (FF 73).
     PMC explained to the examiner exactly what it was do-
 ing with its 2011 submissions, writing: “Consistent with
 the consolidation agreement between the Applicants and
 the Office, Applicants now wish to pursue the subject mat-
 ter within the scope of the ‘A’ claims of the DECR 87 group
 ‘A’ application (U.S. Patent Application Serial No.
 08/474,145) by claiming such subject matter that was not
 patented in the ‘A’ application in the instant ‘B’ applica-
 tion.” J.A. 16864. PMC also sought to “aid the Examiner
 in understanding the amendments to the claim[s]” by “at-
 tach[ing] a marked up copy of the claims (Appendix A) in-
 dicating the differences between the ‘A’ Claims and the
 amended form submitted herein.” Id. Furthermore, PMC
 signed a terminal disclaimer that “disclaim[ed] the termi-
 nal portion of any patent granted on [the ’507] application
 which would extend beyond the expiration date of [the ’169
 patent].” Apple Inc. v. Personalized Media Commc’ns.,
 LLC., No. IPR2016-00755, Ex. 1040, at 6 (P.T.A.B. March
 14, 2016) (March 2012 Notice of Allowance for ’507 appli-
 cation).
     As the Majority points out, “[t]he record does not ex-
 plain how PMC and the PTO decided on” the provisions of
 the Consolidation Agreement, including the “A” and “B” ap-
 plication provisions. Maj. Op. at 5 n.3. While the Consoli-
 dation Agreement does not necessarily render all actions
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 14       PERSONALIZED MEDIA COMMUNICATIONS, LLC   v. APPLE INC.

 taken by PMC pursuant to it reasonable and excusable, I
 would find that, under the totality of circumstances, Apple
 failed to show PMC’s 2011 conduct, which is consistent
 with the Consolidation Agreement, renders 2011 a perti-
 nent time during which Apple could have suffered preju-
 dice attributable to PMC’s delay. 7
                               III
      Today’s holding, which allows Apple to prevail on
 laches by proving it suffered prejudice in and around 2003,
 due to the ongoing impact of prosecution delays PMC
 caused primarily between 1987 and 1995, implies that
 PMC was doomed to procure unenforceable patents regard-
 less of how well it conducted itself after 1995, and no mat-
 ter how egregious Apple’s infringement might be. This
 outcome, which renders irrelevant years of PMC’s conduct
 (i.e., 1995 to 2003 and beyond), is inconsistent with the to-
 tality of circumstances analysis required for assessing ap-
 plication of prosecution laches. See Lemon v. Kurtzman,
 411 U.S. 192, 200 (1973) (“[E]quitable remedies are a spe-
 cial blend of what is necessary, what is fair, and what is
 workable.”) (internal footnote omitted); see also Symbol
 Techs., Inc. v. Lemelson Med., Educ. & Rsch. Found., LP,
 422 F.3d 1378, 1385-86 (Fed. Cir. 2005). It is also in ten-
 sion with our holding in Hyatt, in which we suggested that,
 even decades into the prosecution, when the PTO “notified
 Hyatt of its own obligations and requirements and thereby
 gave him the opportunity to avoid prosecution laches,” 998

      7    We stated in Hyatt, 998 F.3d at 1369, that a “clear
 abuse of the patent system” can exist even if the prosecu-
 tion tactics do “not literally violate regulations or statutory
 provisions.” This does not mean, however, that the permis-
 sibility of the patentee’s conduct, including if it was under-
 taken pursuant to an agreement the PTO chose to enter
 into, is irrelevant to weighing the equities of the overall sit-
 uation.
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 PERSONALIZED MEDIA COMMUNICATIONS, LLC       v. APPLE INC.   15

 F.3d at 1366 (emphasis added), Hyatt’s subsequent cooper-
 ation with the PTO could, even then, have saved his pa-
 tents. In Hyatt, we “remand[ed] to the district court for the
 limited purpose of affording Hyatt the opportunity to pre-
 sent evidence on the issue of prosecution laches,” id. at
 1371, which we would not have done had the ongoing im-
 pact of Hyatt’s delays already conclusively established that
 his patents were unenforceable.
     In my view, Apple failed to prove it obtained interven-
 ing rights in the accused technology any sooner than 2000,
 as that is the earliest date it was possibly working on what
 became the infringing FairPlay product. Apple also failed
 to prove that PMC unreasonably and inexcusably delayed
 prosecution in or after 2000. As Apple did not establish
 any time during which there was both delay and prejudice,
 Apple did not demonstrate it suffered prejudice “attributa-
 ble to” PMC’s delay. Therefore, Apple did not meet its bur-
 den to prevail on its prosecution laches counterclaim. The
 district court’s contrary finding, which I believe is based on
 an incorrect reading of the law—one which wrongly per-
 mitted Apple to persuade the court that PMC’s delay had
 material lingering effects as late as 2011—should be re-
 versed. 8 Accordingly, I respectfully dissent.

     8    The prejudice prong of the prosecution laches test
 received very little attention in the parties’ appellate
 briefs, covering just 11 of the 167 pages of briefing we re-
 ceived. See Appellant’s Br. 59-60; Appellee’s Br. 71-77; Ap-
 pellant’s Reply Br. 29-30. The parties seem to have taken
 the same approach in the district court. Near the conclu-
 sion of the bench trial on equitable issues, the district judge
 was left to ask Apple’s counsel to “in one sentence, tell me
 what the prejudice to your client is,” to which the response
 was: “Well, the prejudice is that, had these applications
 been prosecuted diligently as they should have been, that
 the invention that is being claimed in the ’091 patent would
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 have been long since in the public domain.” Personalized
 Media Commc’ns, LLC v. Apple, Inc., No. 2:15-cv-01366,
 ECF No. 645 (Bench Trial Transcript), at 239-40; see also
 id. at 261 (“[Apple] has been prejudiced the same way the
 public has been prejudiced, that the term of the patent mo-
 nopoly was shifted.”). The parties’ decision to devote scant
 consideration to prejudice undoubtedly increased the chal-
 lenge confronted by the district court.