Court Opinion

ID: 4527799
Source: CourtListenerOpinion
Date Created: 2020-04-22 16:00:46.390148+00
Date Added: 2024-06-11T09:26:37.351625
License: Public Domain

Case: 19-2054     Document: 56    Page: 1    Filed: 04/22/2020

   United States Court of Appeals
       for the Federal Circuit
                   ______________________

  HOLOGIC, INC., CYTYC SURGICAL PRODUCTS,
                      LLC,
              Plaintiffs-Appellants

                             v.

                MINERVA SURGICAL, INC.,
                 Defendant-Cross-Appellant
                  ______________________

                    2019-2054, 2019-2081
                   ______________________

     Appeals from the United States District Court for the
 District of Delaware in No. 1:15-cv-01031-JFB-SRF, Senior
 Judge Joseph F. Bataillon.
                  ______________________

                   Decided: April 22, 2020
                   ______________________

     MATTHEW WOLF, Arnold & Porter Kaye Scholer LLP,
 Washington, DC, argued for plaintiffs-appellants. Also
 represented by JENNIFER SKLENAR, MARC A. COHN.

     ROBERT N. HOCHMAN, Sidley Austin LLP, Chicago, IL,
 argued for defendant-cross-appellant. Also represented by
 JILLIAN STONECIPHER, CAROLINE A. WONG; OLIVIA M. KIM,
 EDWARD POPLAWSKI, Wilson Sonsini Goodrich & Rosati,
 Los Angeles, CA; VERA ELSON, Palo Alto, CA.
                  ______________________
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 2                     HOLOGIC, INC. v. MINERVA SURGICAL, INC.

 Before WALLACH, CLEVENGER, and STOLL, Circuit Judges.
     Opinion for the court filed by Circuit Judge STOLL, in
     which WALLACH and CLEVENGER, Circuit Judges, join.
        Additional views filed by Circuit Judge STOLL.
 STOLL, Circuit Judge.
     These appeals require us to grapple with the doctrine
 of assignor estoppel, an equitable doctrine that prevents a
 party who assigned a patent to another from later challeng-
 ing the validity of the assigned patent in district court.
 There are two patents-in-suit and each presents a different
 assignor estoppel issue. For the first patent, we consider
 whether the district court erred in holding that assignor
 estoppel does not bar the assignor from relying on our
 court’s affirmance of the Patent Trial and Appeal Board’s
 final decision invalidating the asserted patent claims in an
 inter partes review proceeding. For the second patent, we
 review the district court’s summary judgment that as-
 signor estoppel bars the assignor from asserting invalidity
 of the assigned second patent in district court. Based on
 our precedent, which we are bound to follow, we conclude
 that the district court did not err in either respect.
                         BACKGROUND
                               I
      Hologic, Inc. and Cytyc Surgical Products, LLC (collec-
 tively, “Hologic”) sued Minerva Surgical, Inc. for infringe-
 ment of certain claims of its U.S. Patent Nos. 6,872,183 and
 9,095,348, which relate to procedures and devices for endo-
 metrial ablation. Endometrial ablation is a treatment
 wherein the lining of the uterus is destroyed in order to
 treat menorrhagia, or abnormally heavy menstrual bleed-
 ing.
     The ’183 patent is titled “System and Method for De-
 tecting Perforations in a Body Cavity,” and describes and
 claims methods for determining the presence of uterine
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 HOLOGIC, INC. v. MINERVA SURGICAL, INC.                    3

 perforations, or holes, prior to ablation. “[T]he presence of
 a perforation in the uterus could result in inadvertent pas-
 sage of the ablation device through the perforation and out
 of the uterus into the bowel.” ’183 patent col. 1 ll. 38–41.
 The ’183 patent solves this problem by “provid[ing] a mech-
 anism by which a physician can evaluate whether perfora-
 tions are present in [the uterus] before” ablation.
Id. at col. 1 ll. 43–46. Claim 9, the only asserted independ-
 ent claim of the ’183 patent, recites:
     9. A method of detecting a perforation in a uterus,
     comprising the steps of:
     passing an inflation medium into the uterus;
     monitoring for the presence of a perforation in the
     uterus using a pressure sensor;
     if no perforation is detected during the monitoring
     step, permitting ablation of the uterus using an ab-
     lation device; and
     if a perforation is detected during the monitoring
     step, preventing ablation of the uterus.
Id. at col. 8 ll. 39–48.
     The ’348 patent is titled “Moisture Transport System
 for Contact Electrocoagulation,” and describes and claims
 an ablation device. The claimed device eliminates the prob-
 lem of “steam and liquid buildup at the ablation site” asso-
 ciated with prior art devices, and also “allows the depth of
 ablation to be controlled” and “automatically discontinues
 ablation once the desired ablation depth has been reached.”
 ’348 patent col. 2 ll. 25–30. Claim 1, the only claim of the
 ’348 patent at issue in this appeal, recites:
     1. A device for treating a uterus comprising:
     an elongate member having a proximal portion and
     a distal portion, the elongate member comprising
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 4                    HOLOGIC, INC. v. MINERVA SURGICAL, INC.

     an outer sleeve and an inner sleeve slidably and co-
     axially disposed within the outer sleeve;
     an applicator head coupled to the distal portion,
     the applicator head defining an interior volume
     and having a contracted state and an expanded
     state, the contracted state being configured for
     transcervical insertion and the expanded state be-
     ing configured to conform to the shape of the
     uterus, the applicator head including one or more
     electrodes for ablating endometrial lining tissue of
     the uterus;
     a handle coupled to the proximal portion of the
     elongate member, wherein the handle comprises a
     frame, a proximal grip and a distal grip pivotally
     attached to one another at a pivot point and opera-
     bly coupled to the applicator head so that when the
     proximal grip and the distal grip are moved closer
     together, the applicator head transitions from the
     contracted state to the expanded state;
     a deflecting mechanism including flexures disposed
     within the applicator head, the flexures including
     first and second internal flexures and first and sec-
     ond external flexures, the first and second external
     flexures being coupled to the outer sleeve and the
     first and second internal flexures being coupled to
     the inner sleeve, wherein the deflecting mechanism
     is configured so that translating the inner sleeve
     relative to the frame causes the applicator head to
     transition from the contracted state to the ex-
     panded state; and
     an indicator mechanism operably coupled to the in-
     ner sleeve, the indicator mechanism configured to
     indicate a dimension of the uterus.
Id. at col. 19 ll. 9–42 (emphases added to highlight disputed
 claim terms on appeal).
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 HOLOGIC, INC. v. MINERVA SURGICAL, INC.                   5

                              II
     In 1993, Csaba Truckai co-founded the company Nova-
 Cept, Inc. In the late 1990s, Mr. Truckai and his design
 team at NovaCept developed a medical device called the
 NovaSure system. NovaSure, which received approval for
 commercial distribution from the U.S. Food and Drug Ad-
 ministration in September 2001, detects perforations in the
 uterus by applying carbon dioxide gas to the uterus and
 measuring any flow of gas out of the uterus. NovaSure
 uses an application head with a triangular shape designed
 to conform to the shape of the uterus and which ablates the
 endometrial lining throughout the cavity in two minutes or
 less. NovaSure also provides a moisture transport function
 with a vacuum used to remove steam and moisture from
 the cavity during energy delivery. NovaSure is indicated
 for use in premenopausal women with menorrhagia due to
 benign causes for whom childbearing is complete. It is un-
 disputed that NovaSure incorporates the patented technol-
 ogy in this case.
     Both the ’183 and ’348 patents list Mr. Truckai as an
 inventor. In August 1998, Mr. Truckai assigned his inter-
 est in U.S. Patent Application No. 09/103,072, an applica-
 tion from which the ’348 patent claims priority, as well as
 all continuation applications, to NovaCept. In Febru-
 ary 2001, Mr. Truckai assigned his interest in U.S. Patent
 Application No. 09/710,102, an application from which the
 ’183 patent claims priority, as well as all continuation ap-
 plications, to NovaCept.
     In 2004, Cytyc Corporation acquired NovaCept for
 $325 million. NovaCept assigned its patent rights, includ-
 ing rights to continuation applications, to Cytyc. Hologic
 acquired Cytyc in 2007. The continuation application that
 issued as the ’183 patent was filed in May 2004 and issued
 in March 2005. The continuation application that issued
 as the ’348 patent was filed in August 2013 and issued in
 August 2015. Hologic is the current assignee of the
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 6                    HOLOGIC, INC. v. MINERVA SURGICAL, INC.

 ’183 and ’348 patents and markets and sells the NovaSure
 system throughout the United States.
     Mr. Truckai left NovaCept and, in 2008, founded the
 accused infringer in this case, Minerva. Mr. Truckai
 served as Minerva’s President, Chief Executive Officer,
 and a member of its Board of Directors. Mr. Truckai and
 others at Minerva developed the Endometrial Ablation
 System (EAS), which received FDA approval in 2015. Mi-
 nerva’s EAS is approved for the same indication as Ho-
 logic’s NovaSure system. Minerva began commercial
 distribution of the EAS in August 2015.
                              III
     In November 2015, Hologic sued Minerva in the
 U.S. District Court for the District of Delaware, alleging
 that Minerva’s EAS and the use thereof infringed certain
 claims of the ’183 and ’348 patents. In addition to asserting
 the invalidity defenses of lack of enablement and failure to
 provide an adequate written description in district court,
 Minerva also filed petitions for IPR in the Patent Office,
 challenging the patentability of the asserted ’183 patent
 claims, as well as those of the ’348 patent, in view of prior
 art. The Board instituted review of the ’183 patent, but
 denied review of the ’348 patent.
     Shortly after the district court issued its claim con-
 struction decision in April 2017, the Board issued its final
 written decision in the parallel IPR proceeding, holding the
 ’183 patent claims unpatentable as obvious. See generally
 Minerva Surgical, Inc. v. Hologic, Inc., No. IPR2016-00868,
 2017 WL 6404966 (P.T.A.B. Dec. 15, 2017). Hologic ap-
 pealed the Board’s decision to this court.
      Around the same time, Minerva requested that the dis-
 trict court dismiss as moot Hologic’s claim for infringement
 of asserted claims 7, 9, 11, 13, and 14 of the ’183 patent.
 The district court denied Minerva’s request, concluding
 that the “patent has not been cancelled” and the Board’s
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 HOLOGIC, INC. v. MINERVA SURGICAL, INC.                    7

 “finding is on appeal and does not have preclusive effect as
 to this action unless and until the appeal is resolved.” Ho-
 logic, Inc. v. Minerva Surgical, Inc., 325 F. Supp. 3d 507,
 519 (D. Del. 2018) (Summary Judgment Op.).
      Hologic, for its part, moved for summary judgment that
 the doctrine of assignor estoppel bars Minerva from chal-
 lenging the validity of the ’183 and ’348 patent claims in
 district court. The district court granted Hologic’s motion
 for both patents. After “[c]onsidering the balance of equi-
 ties and the relationship of Minerva and Truckai,” the dis-
 trict court found that “Truckai is in privity with Minerva”
 and that “assignor estoppel applies to Minerva’s defenses
 to Hologic’s patent infringement claims.” Summary Judg-
 ment Op., 325 F. Supp. 3d at 524–25. Specifically, the court
 relied on “[u]ndisputed evidence” that Mr. Truckai founded
 Minerva, he “used his expertise to research, develop, test,
 manufacture, and obtain regulatory approval for the Mi-
 nerva EAS,” his “job responsibilities as Minerva’s Presi-
 dent and CEO included bringing the accused product to
 market to directly compete with Hologic,” and he “executed
 broad assignments of his inventions to NovaCept, which
 was then sold to Hologic’s predecessor for $325 million.” Id.
 at 523. In addition, the district court granted summary
 judgment of no invalidity in Hologic’s favor. The district
 court also granted summary judgment of infringement of
 the asserted ’183 and ’348 patent claims.
     The case then proceeded to a jury trial on the issues of
 willful infringement, damages, and certain of Minerva’s
 state law counterclaims. The jury found, in relevant part,
 that Hologic was entitled to $4,200,529.75 in lost profits
 and $587,138.48 in royalties for sales not included in lost
 profits—for a total award of $4,787,668.23—based on Mi-
 nerva’s infringement of the ’183 and ’348 patent claims.
 Over Minerva’s objection, the jury was not asked to sepa-
 rately apportion damages between the two patents. The
 jury also found that Minerva’s infringement of claim 1 of
 the ’348 patent was not willful. On August 13, 2018, the
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 8                     HOLOGIC, INC. v. MINERVA SURGICAL, INC.

 district court entered judgment on the verdict, subject to
 revision pursuant to any rulings on post-trial motions. Af-
 ter trial, Hologic moved for a permanent injunction to en-
 join Minerva from further infringement of the asserted
 ’183 patent claims.
     The ’348 patent expired on November 19, 2018.
 Five months later, this court affirmed the Board’s decision
 that the ’183 patent claims are invalid as obvious under
 35 U.S.C. § 103. See generally Hologic, Inc. v. Minerva Sur-
 gical, Inc., 764 F. App’x 873 (Fed. Cir. 2019) (Hologic).
 Thereafter, the district court denied Hologic’s motion for a
 permanent injunction as moot in light of this court’s Ho-
 logic decision. Hologic, Inc. v. Minerva Surgical, Inc.,
 No. 15-1031, 2019 WL 1958020, at *4 (D. Del. May 2, 2019)
 (JMOL Op.). The district court also denied Hologic’s mo-
 tions for supplemental damages, enhanced damages, and
 ongoing royalties for infringement of the asserted ’183 pa-
 tent claims as moot. Id.
      With respect to the ’348 patent, the district court noted
 Minerva’s argument that the jury had not even found will-
 ful infringement, id. at *2, and denied Hologic’s motion for
 enhanced damages, finding that “the damages are ade-
 quate to compensate Hologic for infringement through the
 life of the patent,” id. at *10. It awarded Hologic supple-
 mental damages for Minerva’s continued infringement of
 claim 1 of the ’348 patent “from the last-produced date of
 sales (April 1, 2018) to the date the ’348 patent expired (No-
 vember 19, 2018),” determined that Hologic was “entitled
 to recover a 16.1% royalty for [those] infringing sales,” and
 ordered Minerva to submit an accounting of those infring-
 ing sales. Id. at *10–11. The court declined, however, to
 award an enhanced royalty for the post-verdict sales be-
 cause “Hologic has not shown that enhanced damages are
 warranted.” Id. at *10. The court also awarded Hologic
 $270,533 in pre-judgment interest on the jury’s damages
 award, and concluded that Hologic would be awarded post-
 judgment interest “at the legal rate from and after
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 HOLOGIC, INC. v. MINERVA SURGICAL, INC.                    9

 August 13, 2018.” Id. The court denied Minerva’s motion
 for judgment as a matter of law of no damages or, alterna-
 tively, for a new trial on reasonable royalty damages. The
 court then ordered the parties to each submit a proposed
 final judgment consistent with its decision.
     Finally, the district court addressed the impact of this
 court’s Hologic decision on the jury’s damages award and
 the district court’s ruling on assignor estoppel. Specifi-
 cally, the district court determined that the Hologic deci-
 sion “d[id] not affect the jury verdict” because “a finding
 that the method claims [of the ’183 patent] are not valid
 does not affect the finding of infringement as to the appa-
 ratus claim” of the ’348 patent, and the “jury’s damages de-
 termination can be adequately supported by the finding of
 infringement of Claim 1 of the ’348 patent.” Id. at *3. The
 district court further held that this court’s “findings as to
 the ’183 patent (method claims) do not affect the [district
 court’s] findings of assignor estoppel on the asserted claim
 of the ’348 patent.” Id. at *4 (footnote omitted).
     In its final judgment, the district court awarded Ho-
 logic pre-judgment interest on the jury’s $4,787,668.23
 damages award “in the amount of $270,533, plus postjudg-
 ment interest at the statutory rate of 2.44% under
 35 U.S.C. § 1961(a)” in accordance with its ruling on post-
 trial motions. Final Judgment at 1, Hologic, Inc. v. Mi-
 nerva Surgical, Inc., No. 15-1031 (D. Del. June 3, 2019),
 ECF No. 621 (Final Judgment). The district court also
 awarded Hologic supplemental damages in the amount of
 $1,629,304.08—the amount proposed by Minerva in its pro-
 posed final judgment. The district court further awarded
 pre-judgment interest on the supplemental damages
 award calculated “from the date of infringement to Au-
 gust 13, 2018, (D.I. 520), plus post-judgment interest there-
 after at the legal rate under 28 U.S.C. § 1961 until such
 time as the judgment is paid.” Id. at 1–2.
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 10                    HOLOGIC, INC. v. MINERVA SURGICAL, INC.

    Hologic and Minerva appeal. We have jurisdiction pur-
 suant to 28 U.S.C. § 1295(a)(1).
                         DISCUSSION
     This case presents various issues on appeal and cross-
 appeal. We start by addressing the assignor estoppel is-
 sues. We then turn to Minerva’s challenge to the district
 court’s claim construction, Minerva’s challenge to the jury’s
 damages award, Hologic’s appeal of the district court’s sup-
 plemental damages award, and Hologic’s challenge to the
 district court’s award of pre- and post-judgment interest.
                               I
      We first address Hologic’s challenge to the district
 court’s application of collateral estoppel based on our affir-
 mance of the Board’s holding of invalidity of the ’183 patent
 claims in Hologic. Hologic asserts that assignor estoppel
 precludes Minerva from relying on this court’s Hologic de-
 cision to escape liability for infringement. It argues that
 “the final outcome of the IPR is irrelevant to the district
 court proceeding” and that “[t]o hold otherwise would be to
 hold that the America Invents Act (‘AIA’) abrogated the as-
 signor estoppel doctrine in a district court infringement ac-
 tion.” Appellant’s Br. 36. Based on our precedent, we
 disagree.
                               A
     This court first examined and affirmed the vitality of
 the doctrine of assignor estoppel in Diamond Scientific Co.
 v. Ambico, Inc., 848 F.2d 1220 (Fed. Cir. 1988). We defined
 assignor estoppel as “an equitable doctrine that prevents
 one who has assigned the rights to a patent (or patent ap-
 plication) from later contending that what was assigned is
 a nullity.” Diamond Sci., 848 F.2d at 1224. We explained
 that the “estoppel also operates to bar other parties in priv-
 ity with the assignor, such as a corporation founded by the
 assignor.” Id. (citation omitted). We also cited early Su-
 preme Court cases addressing the doctrine, including
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 HOLOGIC, INC. v. MINERVA SURGICAL, INC.                    11

 Westinghouse Electric & Manufacturing Co. v. Formica In-
 sulation Co., 266 U.S. 342 (1924) and Scott Paper Co.
 v. Marcalus Manufacturing Co., 326 U.S. 249 (1945). See
id. at 1222–23. In both Westinghouse and Scott Paper, the
 Supreme Court carved out exceptions to the general as-
 signor estoppel doctrine. But the Court did not abolish the
 doctrine.
      In Diamond Scientific, we recognized that some courts
 questioned the vitality of the assignor estoppel doctrine fol-
 lowing the Supreme Court’s decision abolishing licensee es-
 toppel in Lear, Inc. v. Adkins, 395 U.S. 653, 666 (1969). See
id. at 1223–24. We concluded, however, that nothing in
 Lear eliminated assignor estoppel and that an important
 distinction existed between assignors and licensees:
     The public policy favoring allowing a licensee to
     contest the validity of the patent is not present in
     the assignment situation. Unlike the licensee,
     who, without Lear might be forced to continue to
     pay for a potentially invalid patent, the assignor
     who would challenge the patent has already been
     fully paid for the patent rights.
Id. at 1224.
      We acknowledged the “public policy encouraging peo-
 ple to challenge potentially invalid patents” and “disfavor-
 ing the repression of competition by the enforcement of
 worthless patents,” but we nonetheless held that assignor
 estoppel serves important purposes. Id. at 1224–25. In do-
 ing so, we identified four common justifications for apply-
 ing the doctrine: “(1) to prevent unfairness and injustice;
 (2) to prevent one [from] benefiting from his own wrong;
 (3) by analogy to estoppel by deed in real estate; and (4) by
 analogy to a landlord-tenant relationship.” Id. at 1224 (al-
 teration in original) (quoting Cooper, Estoppel to Challenge
 Patent Validity: The Case of Private Good Faith vs. Public
 Policy, 18 Case W. Res. L. Rev. 1122 (1967)). We also em-
 phasized the longstanding reasoning behind the doctrine
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 12                   HOLOGIC, INC. v. MINERVA SURGICAL, INC.

 that “an assignor should not be permitted to sell something
 and later to assert that what was sold is worthless, all to
 the detriment of the assignee.” Id. Stated another way, “it
 is the implicit representation by the assignor that the pa-
 tent rights that he is assigning (presumably for value) are
 not worthless that sets the assignor apart from the rest of
 the world and can deprive him of the ability to challenge
 later the validity of the patent.” Id. Thus, it “could work
 an injustice against the assignee” to “allow the assignor to
 make that representation at the time of the assignment (to
 his advantage) and later to repudiate it (again to his ad-
 vantage).” Id.
      Since Diamond Scientific, this court has continued to
 apply the doctrine in a variety of circumstances, often cit-
 ing prevention of “unfairness and injustice” as the primary
 justification for its application. See, e.g., Mentor Graphics
 Corp. v. EVE-USA, Inc., 851 F.3d 1275, 1280–83 (Fed. Cir.
 2017) (affirming grant of summary judgment that a com-
 pany founded by the patent’s inventors was barred from
 challenging the validity of the patent asserted by the in-
 ventors’ former employer and assignee); Pandrol USA, LP
 v. Airboss Ry. Prods., Inc., 424 F.3d 1161, 1166–67
 (Fed. Cir. 2005) (affirming the district court’s exclusion of
 an assignor-inventor’s testimony as to the invalidity of his
 own patent on the ground of assignor estoppel); Mentor
 Graphics Corp. v. Quickturn Design Sys., Inc., 150 F.3d
 1374, 1377–80 (Fed. Cir. 1998) (affirming grant of a pre-
 liminary injunction where the assignee showed a likelihood
 of success on validity based on the district court’s grant of
 summary judgment that the original assignor and its
 wholly owned subsidiary were barred from challenging va-
 lidity); Shamrock Techs., Inc. v. Med. Sterilization, Inc.,
 903 F.2d 789, 793–96 (Fed. Cir. 1990) (affirming grant of
 summary judgment that the patent’s inventor and the com-
 pany he joined as “Vice President in charge of Operations”
 were barred from challenging the validity of the patent as-
 serted by the inventor’s former employer and assignee).
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 HOLOGIC, INC. v. MINERVA SURGICAL, INC.                     13

      Consistent with the Supreme Court’s guidance in West-
 inghouse and Scott Paper, however, we have recognized
 certain limits to the doctrine. For instance, although es-
 topped parties “cannot challenge the validity of” the patent
 at issue, “assignor estoppel does not limit their ability to
 defend themselves in other ways,” including “arguing that
 the patentee is itself collaterally estopped from asserting a
 patent found invalid in a prior proceeding.” Mentor
 Graphics, 150 F.3d at 1379 (first citing Blonder–Tongue
 Lab., Inc. v. Univ. of Ill. Found., 402 U.S. 313 (1971); then
 citing Foster v. Hallco Mfg. Co., 947 F.2d 469, 481–83
 (Fed. Cir. 1991)). In addition, an estopped party “may also
 argue for a narrow claim construction, or that the accused
 devices are within the prior art and therefore cannot in-
 fringe.” Id. at 1380 (first citing Westinghouse, 266 U.S.
 at 351; then citing Scott Paper, 326 U.S. at 257–58).
                               B
     Based on our precedent and the limits it places on the
 assignor estoppel doctrine, we conclude that assignor es-
 toppel does not preclude Minerva from relying on the Ho-
 logic decision to argue that the ’183 patent claims are void
 ab initio.
     We are mindful of the seeming unfairness to Hologic in
 this situation. Although Minerva would have been es-
 topped from challenging the validity of the ’183 patent
 claims in district court, it was able to challenge their valid-
 ity in an IPR proceeding and, hence, circumvent the as-
 signor estoppel doctrine. Minerva had the right to do so
 under the AIA and this court’s precedent. This court has
 held that the doctrine of assignor estoppel does not bar an
 assignor from filing a petition for IPR. Arista Networks,
 Inc. v. Cisco Sys., Inc., 908 F.3d 792, 804 (Fed. Cir. 2018).
 In Arista, the patent owner argued that assignor estoppel
 barred the assignor-petitioner’s IPR challenge to the pa-
 tent’s validity. Id. at 798. We interpreted the statute at
 issue, 35 U.S.C. § 311(a)—which provides that “a person
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 14                    HOLOGIC, INC. v. MINERVA SURGICAL, INC.

 who is not the owner of a patent” may file an IPR—to de-
 termine whether Congress intended for assignor estoppel
 to apply in an IPR proceeding. Id. at 802–03. We con-
 cluded that the plain language of the statute was unambig-
 uous and provided that “an assignor, who is no longer the
 owner of a patent, may file an IPR petition as to that pa-
 tent.” Id. at 803.
      While we understand Hologic’s predicament, we never-
 theless conclude that the district court did not abuse its
 discretion in denying Hologic its requested injunctive and
 monetary relief following a finding of patent infringement.
 See Robert Bosch LLC v. Pylon Mfg. Corp., 659 F.3d 1142,
 1147 (Fed. Cir. 2011) (denial of a permanent injunction is
 reviewed for abuse of discretion). Generally, “when a [pa-
 tent] claim is cancelled, the patentee loses any cause of ac-
 tion based on that claim, and any pending litigation in
 which the claims are asserted becomes moot.” Fresenius
 USA, Inc. v. Baxter Int’l, Inc., 721 F.3d 1330, 1340
 (Fed. Cir. 2013). Because the ’183 patent claims are inva-
 lid, Hologic cannot assert those claims or seek ongoing
 monetary or injunctive relief based on infringement. Our
 affirmance of the Board’s invalidity decision in Hologic is
 dispositive of the validity of the ’183 patent claims, regard-
 less of how the validity question came to this court, and
 regardless of whether assignor estoppel bars Minerva from
 challenging the patent’s validity in this district court case.
     Our conclusion is further supported by XY, LLC
 v. Trans Ova Genetics, L.C., 890 F.3d 1282 (Fed. Cir. 2018),
 in which we addressed the impact of our concurrent affir-
 mance of invalidity on other pending actions involving the
 same patent. XY involved an appeal from a district court’s
 judgment following a jury trial. Id. at 1285–86. Similar to
 this case, there was a parallel IPR proceeding involving the
 same patent, in which the Board had held the asserted
 claims invalid. Id. at 1294. This court held sua sponte that
 the patent owner was collaterally estopped from asserting
 the patent “in any further proceedings” in view of the
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 HOLOGIC, INC. v. MINERVA SURGICAL, INC.                    15

 court’s concurrent affirmance of the Board’s invalidity de-
 cision. Id. at 1294–95. As in XY, this court’s affirmance of
 the Board’s invalidity decision in Hologic “renders final a
 judgment on the invalidity of the [’183 patent], and has an
 immediate issue-preclusive effect on any pending or co-
 pending actions involving the patent,” including the in-
 stant action. Id. at 1294.
     Hologic cites American Fence Co. v. MRM Security Sys-
 tems, Inc., 710 F. Supp. 37 (D. Conn. 1989), as an example
 of how “district courts have suggested that assignor estop-
 pel would control” in district court even when there is a de-
 termination of invalidity in an IPR. Appellant’s Br. 37.
 Similar to this case, the assignee in American Fence sued
 the assignor and the company the assignor created for pa-
 tent infringement. 710 F. Supp. at 39. The district court
 held that assignor estoppel prevented the defendants from
 challenging the validity of the patents-in-suit. Id. at 42.
 The district court also denied the defendants’ request to
 stay the proceedings pending reexamination of one of the
 patents, stating that “[e]ven if upon reexamination the
 U.S. Patent Office finds that the . . . patent is invalid, the
 defendants will be unable to assert that finding” because of
 assignor estoppel. Id. But American Fence is not binding
 on this court, and the section of the opinion on which Ho-
 logic relies is contrary to Mentor Graphics. There, we held
 that even an estopped assignor may argue that “the pa-
 tentee is itself collaterally estopped from asserting a patent
 found invalid in a prior proceeding.” Mentor Graphics,
 150 F.3d at 1379 (citations omitted).
     Accordingly, we affirm the district court’s denial of Ho-
 logic’s motions for a permanent injunction, enhanced dam-
 ages, and ongoing royalties for Minerva’s infringement of
 the ’183 patent claims because Hologic is collaterally es-
 topped from asserting infringement of these claims.
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 16                    HOLOGIC, INC. v. MINERVA SURGICAL, INC.

                               II
     We next consider Minerva’s assertion that the district
 court erred in holding that assignor estoppel precludes Mi-
 nerva from challenging the validity of claim 1 of the
 ’348 patent. We review a district court’s application of the
 equitable doctrine of assignor estoppel for an abuse of dis-
 cretion. MAG Aerospace Indus., Inc. v. B/E Aerospace,
 Inc., 816 F.3d 1374, 1376 (Fed. Cir. 2016) (citing Pandrol,
 424 F.3d at 1165). We conclude that the district court did
 not abuse its discretion in applying assignor estoppel here.
      As an initial matter, we decline Minerva’s invitation to
 “abandon the doctrine” of assignor estoppel entirely.
 Cross-Appellant’s Br. 67. Minerva contends that the doc-
 trine is inconsistent with Lear, in which the Supreme
 Court abolished the doctrine of licensee estoppel. Minerva
 argues that “[a]n assignee who seeks protection against fu-
 ture competition from an assignor need simply negotiate a
 covenant not to compete in their agreement.” Id. When
 addressing this same argument in EVE-USA, we declined
 to read Lear as “demolish[ing] the doctrinal underpinnings
 of assignor estoppel.” EVE-USA, 851 F.3d at 1283 (citation
 omitted). In EVE-USA, we noted that our Diamond Scien-
 tific decision “emphasized the continued vitality of the doc-
 trine of assignor estoppel after Lear.” Id. (citing Diamond
 Sci., 848 F.2d at 1222–26); see also Arista, 908 F.3d at 802.
 We similarly decline at this time to read Lear as eliminat-
 ing the doctrine of assignor estoppel.
     Although we recognize that assignor estoppel is not a
 “broad equitable device susceptible of automatic applica-
 tion,” Diamond Sci., 848 F.2d at 1225–26, we agree with
 the district court that the equities weigh in favor of its ap-
 plication in this case. The facts here are analogous to those
 in Diamond Scientific, Shamrock, and other cases in which
 an inventor executes broad assignments to his employer,
 leaves his employer, founds or takes on a controlling role
 at a competing company, and is directly involved in the
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 HOLOGIC, INC. v. MINERVA SURGICAL, INC.                   17

 alleged infringement. Minerva disputed none of the perti-
 nent facts below or on appeal. Mr. Truckai “executed a
 broad assignment of his patent rights to NovaCept and
 later sold NovaCept to Hologic’s predecessor for $325 mil-
 lion.” Summary Judgment Op., 325 F. Supp. 3d at 524.
 Thus, NovaCept “received appreciable value” for the pa-
 tents at issue. Mentor Graphics, 150 F.3d at 1378.
 Mr. Truckai then “founded Minerva” and “used his exper-
 tise to research, develop, test, manufacture, and obtain reg-
 ulatory approval for the Minerva EAS.”             Summary
 Judgment Op., 325 F. Supp. 3d at 523. Mr. Truckai’s “job
 responsibilities as Minerva’s President and CEO included
 bringing the accused product to market to directly compete
 with Hologic.” Id.
     Minerva also does not challenge the district court’s
 finding that Minerva is in privity with Mr. Truckai—the
 original assignor and Minerva’s founder, President, and
 CEO. See Diamond Sci., 848 F.2d at 1224 (“[E]stoppel also
 operates to bar other parties in privity with the assignor,
 such as a corporation founded by the assignor.” (citation
 omitted)). Instead, Minerva contends that “Hologic is de-
 ploying assignor estoppel to shield its unwarranted expan-
 sion of the patent’s scope from the invalidity arguments
 created by its own overreach.” Cross-Appellant’s Br. 68.
 Minerva emphasizes that Hologic, not Mr. Truckai, prose-
 cuted claim 1 of the ’348 patent. The continuation applica-
 tion from which the ’348 patent issued was filed in 2013,
 after Mr. Truckai had left NovaCept and founded Minerva.
 Minerva asserts that Hologic broadened the claims during
 prosecution and after Mr. Truckai’s assignment, and that
 it would be unfair to block Mr. Truckai (or Minerva) from
 challenging the breadth of those claims.
     We find Minerva’s argument unpersuasive. In Dia-
 mond Scientific, we considered it “irrelevant that, at the
 time of the assignment,” the inventor’s “patent applications
 were still pending” and that assignee Diamond “may have
 later amended the claims in the application process (a very
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 18                   HOLOGIC, INC. v. MINERVA SURGICAL, INC.

 common occurrence in patent prosecutions), with or with-
 out [the inventor’s] assistance.” 848 F.2d at 1226. It is
 true, as Minerva observes, that in Diamond Scientific we
 noted that the Supreme Court “observed that the scope of
 the right conveyed in the assignment of patent rights be-
 fore the granting of the patent ‘is much less certainly de-
 fined than that of a granted patent, and the question of the
 extent of the estoppel against the assignor of such an in-
 choate right is more difficult to determine than in the case
 of the patent assigned after its granting.’” Id. (quoting
 Westinghouse, 266 U.S. at 352–53). We also noted, how-
 ever, that the Supreme Court “found it unnecessary to de-
 cide the question” and “merely suggested that ‘[t]his
 difference might justify the view that the range of relevant
 and competent evidence in fixing the limits of the subse-
 quent estoppel should be more liberal than in the case of
 an assignment of a granted patent.’” Id. (alteration in orig-
 inal) (quoting Westinghouse, 266 U.S. at 353).
      To the extent Hologic “may have broadened the claims”
 in the application that issued as the ’348 patent after
 Mr. Truckai’s assignment “beyond what could be validly
 claimed in light of the prior art,” the Supreme Court’s and
 this court’s precedents allow Minerva to “introduce evi-
 dence of prior art to narrow the scope of” claim 1 so as to
 bring its accused product “outside the scope of” claim 1. Id.
 (citing Westinghouse, 266 U.S. at 350). Thus, “[t]his excep-
 tion to assignor estoppel also shows that estopping [Mi-
 nerva] from raising invalidity defenses does not necessarily
 prevent [it] from successfully defending against [Hologic’s]
 infringement claims.” Id.
     Because the district court did not abuse its discretion
 in applying the doctrine of assignor estoppel, we affirm the
 district court’s grant of summary judgment of no invalidity
 as to claim 1 of the ’348 patent.
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 HOLOGIC, INC. v. MINERVA SURGICAL, INC.                      19

                               III
     We next consider Minerva’s challenge to the district
 court’s constructions of two terms in claim 1 of the ’348 pa-
 tent. Claim construction based on the intrinsic evidence is
 a question of law that this court reviews de novo. Trustees
 of Columbia Univ. v. Symantec Corp., 811 F.3d 1359, 1362
 (Fed. Cir. 2016) (“The construction of claim terms based on
 the claim language, the specification, and the prosecution
 history are legal determinations.” (citing Teva Pharms.
 USA, Inc. v. Sandoz, Inc., 574 U.S. 318, 328 (2015))). Mi-
 nerva contends that the district court erred in its construc-
 tions of “applicator head” and “indicator mechanism” and
 further that Minerva’s accused EAS product does not in-
 fringe under the proper constructions. Minerva requests
 that this court remand to the district court with instruc-
 tions to enter a judgment of noninfringement. Because we
 discern no error in either of the court’s constructions, we
 deny Minerva’s request.
      The district court construed the term “applicator head”
 in claim 1 of the ’348 patent to mean “[a] distal end portion
 of an ablation device that applies energy to the uterine tis-
 sue.” Hologic, Inc. v. Minerva Surgical, Inc., No. 15-1031,
 2017 WL 1483305, at *2 (D. Del. Apr. 24, 2017) (Claim Con-
 struction Op.). The court rejected Minerva’s proposed con-
 struction of “applicator head” to require “an applicator
 having a permeable or absorbent tissue contacting surface
 into which moisture is drawn.” Id. at *2 n.6. It noted that
 Minerva “presented extensive argument for reading [cer-
 tain] limitations from the specification into the claims” re-
 lating to “shortcomings of the prior art methods” with
 respect to permeability, but concluded that “such disclo-
 sures do not rise to the level of disclaimer, sufficient to nar-
 row the disputed claim limitation as desired by” Minerva.
 Id. We agree. Neither the claim nor the specification de-
 scribes the “applicator head” as being permeable or requir-
 ing moisture removal. To be certain, the specification
 emphasizes the importance of moisture removal. But
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 20                   HOLOGIC, INC. v. MINERVA SURGICAL, INC.

 neither the plain claim language “applicator head” nor the
 specification includes a moisture removal requirement in
 the applicator head. Minerva emphasizes that an embodi-
 ment of the invention includes an “electrode carrying
 means” formed of a material that is “permeable to mois-
 ture,” ’348 patent col. 5 ll. 52–57, but this appears to be a
 component of the ablation device other than the claimed
 “applicator head.” For all these reasons, we agree with the
 district court’s claim construction.
     The district court construed the term “indicator mech-
 anism” in claim 1 of the ’348 patent to mean “[a] mecha-
 nism configured to indicate a dimension.”              Claim
 Construction Op., 2017 WL 1483305, at *3. Minerva ar-
 gues, as it did below, that the court’s construction is too
 broad and that the term requires displaying uterine widths
 in “units of measure.” Id. at *3 n.10. To support its broader
 construction, the district court relied on the second embod-
 iment described in the specification, wherein the “ablation
 device . . . includes a measurement device for easily meas-
 uring the uterine width and for displaying the measured
 width on a gauge.” Id. at *3 (emphasis added) (quoting
 ’348 patent col. 14 ll. 33–36). The district court also cited
 Figure 32b of the ’348 patent, which shows a “dial face”
 that “includes calibration markings corresponding to an
 appropriate range of uterine widths.” Id. (emphasis added)
 (quoting ’348 patent col. 14 ll. 47–49).
     We adopt the district court’s construction of “indicator
 mechanism.” Like the district court, we are unpersuaded
 by Minerva’s attempt to narrow the claim scope to require
 a dimension. First of all, Minerva’s proposed construction
 is inconsistent with the plain language of claim 1. See
 ’348 patent col. 19 ll. 40–42 (reciting “an indicator mecha-
 nism operably coupled to the inner sleeve, the indicator
 mechanism configured to indicate a dimension of the
 uterus”). Moreover, we agree with the district court that
 “[n]othing in the specification suggests that applicant in-
 tended to limit ‘an indicator mechanism’ to devices that
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 HOLOGIC, INC. v. MINERVA SURGICAL, INC.                   21

 solely display uterine widths in ‘units of measure.’” Claim
 Construction Op., 2017 WL 1483305, at *3 n.10. Accord-
 ingly, we discern no error in the district court’s claim con-
 struction.
      We have considered Minerva’s additional arguments in
 support of its proposed claim constructions, but do not find
 them persuasive. Because the district court correctly con-
 strued the disputed terms in claim 1 of the ’348 patent, we
 affirm the district court’s grant of summary judgment of
 infringement.
                              IV
     We turn to Minerva’s assertion that the district court
 erred in awarding damages to Hologic based on Minerva’s
 infringement of claim 1 of the ’348 patent alone, where the
 jury verdict did not apportion damages between the
 ’348 and ’183 patents and where the ’183 patent claims
 were held invalid following the jury verdict. We discern no
 reversible error in the district court’s decision.
     “The general rule is that when a ‘jury was told it could
 rely on any of two or more independent legal theories, one
 of which was defective,’ the general verdict must be set
 aside.” WesternGeco L.L.C. v. ION Geophysical Corp.,
 913 F.3d 1067, 1073 (Fed. Cir. 2019) (citations omitted).
 “In a situation—such as this one—where the jury rendered
 a single verdict on damages, without breaking down the
 damages attributable to each patent, the normal rule
 would require a new trial as to damages.” Verizon Servs.
 Corp. v. Vonage Holdings Corp., 503 F.3d 1295, 1310
 (Fed. Cir. 2007) (citing Memphis Cmty. Sch. Dist. v. Sta-
 chura, 477 U.S. 299, 312 (1986)); see also DDR Holdings,
 LLC v. Hotels.com, L.P., 773 F.3d 1245, 1262 (Fed. Cir.
 2014) (vacating the damages award upon holding the
 claims of one of the two patents-in-suit invalid as antici-
 pated and noting that its decision “could warrant a new
 trial on damages” (citing Verizon, 503 F.3d at 1310)).
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 22                   HOLOGIC, INC. v. MINERVA SURGICAL, INC.

      We have recognized, however, an exception to this gen-
 eral rule. A single damages award “can be sustained” if,
 despite the fact that some of the asserted claims were held
 invalid or not infringed subsequent to the award, “undis-
 puted evidence” demonstrated that the sustained patent
 claim was necessarily infringed by all of the accused activ-
 ity on which the damages award was based. WesternGeco,
 913 F.3d at 1074. In such cases, “we apply a harmlessness
 analysis similar to our approach in the case of erroneous
 jury instructions.” Id. (citation omitted); see also Chrimar
 Holding Co., LLC v. ALE USA Inc., 732 F. App’x 876, 886
 (Fed. Cir. 2018) (holding that a new trial to determine dam-
 ages on a patent-by-patent basis was unnecessary because
 the same royalty damages applied whether the claims of
 one or three asserted patents were infringed). For the rea-
 sons that follow, we conclude that a departure from the
 general rule is warranted in this case.
      In each of WesternGeco, Verizon, and DDR, this court
 vacated the damages award and remanded to the district
 court to determine in the first instance whether a new trial
 on damages was warranted based on this court’s invalidity
 or noninfringement ruling. See WesternGeco, 913 F.3d
 at 1075; Verizon, 503 F.3d at 1310; DDR, 773 F.3d at 1262.
 By contrast, the district court in this case addressed the
 issue of apportionment and determined that the jury ver-
 dict on damages was “adequately supported by the finding
 of infringement of Claim 1 of the ’348 patent.” JMOL Op.,
 2019 WL 1958020, at *3. The district court’s determination
 is supported by undisputed evidence. Hologic’s damages
 expert explained to the jury that the same royalty rate he
 used in his damages calculation would apply to either the
 ’183 patent or ’348 patent, “individually or the two patents
 collectively,” since they “both cover the entire procedure
 and device respectively.” J.A. 30439 at 1084:7–25. The ex-
 pert was then cross-examined about his reasoning. Thus,
 Hologic presented evidence to the jury that the damages
 award could be supported if either or both of the ’183 and
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 HOLOGIC, INC. v. MINERVA SURGICAL, INC.                    23

 ’348 patents’ claims were infringed and valid. Minerva did
 not present any contrary evidence. Accordingly, we con-
 clude that a departure from the general rule requiring a
 new trial is warranted in this case.
      Minerva asserts that it asked for a jury instruction on
 apportionment but that its request was denied. The dis-
 trict court reasoned, however, that Minerva had not pre-
 sented any evidence to the jury explaining why
 apportionment was necessary.           See J.A. 31961–64
 at 2298:4–2301:5. When asked during oral argument on
 appeal whether there was any evidence on apportionment
 other than the testimony by Hologic’s expert, Minerva’s
 counsel could not identify anything in the record. Oral Arg.
 at 17:35–21:19, http://oralarguments.cafc.uscourts.gov/de-
 fault.aspx?fl=2019-2054.mp3. Likewise, following oral ar-
 gument, this court did not receive any supplemental
 briefing identifying any testimony or other evidence to re-
 but Hologic’s expert’s testimony.
      Because Hologic’s expert’s testimony remains undis-
 puted, we see no error in the district court’s conclusion that
 the jury’s royalty award should stand. We have considered
 Minerva’s additional arguments concerning the jury’s dam-
 ages award, including its award of lost profits, but we do
 not find them persuasive. Accordingly, we affirm the dis-
 trict court’s denial of Minerva’s motion for judgment as a
 matter of law of no damages or, alternatively, for a new
 trial on reasonable royalty damages.
                               V
     We next consider Hologic’s assertion that the district
 court erred in denying Hologic’s requests for: (1) supple-
 mental damages based on all of Minerva’s infringing sales
 prior to the expiration of the ’348 patent; (2) an increase in
 the royalty rate for post-verdict infringing sales; and (3) an
 enhancement of that rate under 35 U.S.C. § 284. We re-
 view a district court’s decision to award or deny supple-
 mental or enhanced damages for an abuse of discretion.
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 24                   HOLOGIC, INC. v. MINERVA SURGICAL, INC.

 Presidio Components, Inc. v. Am. Tech. Ceramics Corp.,
 875 F.3d 1369, 1382 (Fed. Cir. 2017) (citing WBIP, LLC
 v. Kohler, Co., 829 F.3d 1317, 1339 (Fed. Cir. 2016)); see
 also Prism Techs. LLC v. Sprint Spectrum L.P., 849 F.3d
 1360, 1377–79 (Fed. Cir. 2017). We conclude that the dis-
 trict court did not abuse its discretion in its award of sup-
 plemental damages.
      Hologic argues that the district court undercounted the
 number of infringing sales and, specifically, that the court
 should have included $4.011 million from the sales of a cer-
 tain “design-around” product that Minerva began selling in
 June 2018. Appellant’s Br. 58–59. We disagree. Hologic
 is not entitled to supplemental damages based on sales of
 products that Hologic did not accuse of infringement. In-
 deed, the district court on summary judgment stated that
 it “need not address whether Minerva’s ‘new’ handle design
 would infringe Hologic’s ’348 Patent” because the new
 product “is not alleged to be infringing Hologic’s patent.”
 Summary Judgment Op., 325 F. Supp. 3d at 529. The jury
 was not asked to consider the design-around product for
 purposes of either infringement or determining the dam-
 ages award. Thus, the district court correctly excluded
 sales of Minerva’s design-around product from its supple-
 mental damages award.
      Hologic next contends that the district court should
 have increased the royalty rate from 16.1% to 20% for in-
 fringing sales made after August 13, 2018—the date the
 district court entered judgment on the jury’s verdict. “[A]n
 assessment of prospective damages for ongoing infringe-
 ment should ‘take into account the change in the parties’
 bargaining positions, and the resulting change in economic
 circumstances, resulting from the determination of liabil-
 ity.’” ActiveVideo Networks, Inc. v. Verizon Commc’ns, Inc.,
 694 F.3d 1312, 1343 (Fed. Cir. 2012) (quoting Amado v. Mi-
 crosoft Corp., 517 F.3d 1353, 1362 (Fed. Cir. 2008)). Here,
 the jury did not make any “determination of liability.” Id.
 Instead, the district court entered summary judgment of
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 HOLOGIC, INC. v. MINERVA SURGICAL, INC.                     25

 infringement and thus it, rather than the jury, made the
 “determination of liability.” We agree with Minerva that
 no change in the parties’ bargaining positions or economic
 circumstances could have “result[ed] from the determina-
 tion of liability” between the jury’s verdict and the district
 court’s ruling on post-trial motions because no determina-
 tion of liability occurred during that time period. Id. Thus,
 the district court did not abuse its discretion in declining to
 increase the royalty rate for ongoing royalties for infringe-
 ment of claim 1 of the ’348 patent.
      Lastly, Hologic contends that the district court should
 have enhanced the royalty rate for the supplemental dam-
 ages from 20% to 30% pursuant to § 284. District courts
 have discretion to “increase the damages up to three times
 the amount found or assessed.” 35 U.S.C. § 284. “En-
 hanced damages are generally only appropriate in egre-
 gious cases of misconduct, such as willful, wanton, or
 malicious behavior.” Presidio, 875 F.3d at 1382 (citing
 Halo Elecs., Inc. v. Pulse Elecs., Inc., 136 S. Ct. 1923, 1932
 (2016)). An award of enhanced damages, however, “does
 not necessarily flow from a willfulness finding.” Id. (first
 citing Halo, 136 S. Ct. at 1932; then citing WBIP, 829 F.3d
 at 1341 n.13). Rather, “[d]iscretion remains with the court
 to determine whether the conduct is sufficiently egregious
 to warrant enhanced damages,” and “courts should con-
 sider the overall circumstances of the case.” Id. (first citing
 WBIP, 829 F.3d at 1341 n.13; then citing Halo, 136 S. Ct.
 at 1933).
     Here, the jury determined that Minerva did not will-
 fully infringe claim 1 of the ’348 patent. Additionally, there
 was neither a finding by the district court of any post-ver-
 dict willful infringement, nor a request by Hologic that the
 district court make such a finding. Contrary to Hologic’s
 assertion, a district court is not required to award en-
 hanced damages absent a finding of willful infringement.
 Nor is it required to discuss the factors set forth in Read
 Corp. v. Portec, Inc., 970 F.2d 816 (Fed. Cir. 1992), in
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 26                    HOLOGIC, INC. v. MINERVA SURGICAL, INC.

 deciding whether to award enhanced damages absent a
 finding of willful infringement. See Presidio, 875 F.3d
 at 1382. Moreover, we are not persuaded by Hologic’s un-
 supported assertion, raised for the first time during oral
 argument, that the Read factors supplant a willfulness
 finding in the post-verdict context. See Oral Arg. at 8:26–
 9:33. Thus, the district court did not abuse its discretion
 in declining to enhance the royalty rate for ongoing royal-
 ties for infringement of claim 1 of the ’348 patent.
      For all these reasons, we affirm the district court’s de-
 cision regarding supplemental damages.
                              VI
     Finally, we hold that the district court erred by using
 an incorrect judgment date in its calculation of pre- and
 post-judgment interest on the supplemental damages
 award.
     We apply regional circuit law in reviewing a determi-
 nation of pre- and post-judgment interest on a damages
 award. Taltech Ltd. v. Esquel Enters. Ltd., 604 F.3d 1324,
 1335 (Fed. Cir. 2010). The Third Circuit reviews such de-
 terminations de novo. Addie v. Kjaer, 836 F.3d 251, 258
 (3d Cir. 2016). The relevant statutory provision, 28 U.S.C.
 § 1961(a), provides that “[i]nterest shall be allowed on any
 money judgment in a civil case recovered in a district
 court,” and that “[s]uch interest shall be calculated from
 the date of the entry of the judgment, at a rate equal to the
 weekly average 1-year constant maturity Treasury yield,
 as published by the Board of Governors of the Federal Re-
 serve System, for the calendar week preceding[ ] the date
 of the judgment.” 28 U.S.C. § 1961(a). Generally, “post-
 judgment interest on a particular award only starts run-
 ning when a judgment quantifying that award has been en-
 tered.” Travelers Cas. & Sur. Co. v. Ins. Co. of N. Am.,
 609 F.3d 143, 175 (3d Cir. 2010) (citation omitted).
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 HOLOGIC, INC. v. MINERVA SURGICAL, INC.                    27

      In its May 2, 2019 ruling on post-trial motions, the dis-
 trict court determined that Hologic was entitled to supple-
 mental damages and ordered Minerva to “submit an
 accounting of infringing sales from April 1, 2018, to Novem-
 ber 19, 2018.” JMOL Op., 2019 WL 1958020, at *10–11. In
 its opinion, however, the court did not quantify the amount
 of supplemental damages to which Hologic was entitled.
 Pursuant to § 1961(a), both parties then submitted pro-
 posed final judgments requesting that interest on the sup-
 plemental damages award be calculated from the “date of
 entry of this Final Judgment.” J.A. 36251, 36259. Con-
 trary to Minerva’s assertion, in its submission to the dis-
 trict court, Hologic did not propose an August 13, 2018 date
 as the relevant date for interest on the supplemental dam-
 ages award. Instead, it proposed August 13, 2018 as the
 relevant date for interest on the jury’s damages award. See
 J.A. 36251.
     The district court’s final judgment specifies August 13,
 2018 as the date for awarding pre- and post-judgment in-
 terest for supplemental damages for the ’348 patent. Final
 Judgment at 1–2 (entering judgment in favor of Hologic for
 “supplemental damages for Minerva’s infringing sales from
 April 1, 2018, through August 13, 2018, plus prejudgment
 interest on that amount at the prime rate compounded
 quarterly from the date of infringement to August 13, 2018,
 (D.I. 520), plus post-judgment interest thereafter at the le-
 gal rate under 28 U.S.C. § 1961 until such time as the judg-
 ment is paid” (emphasis added)).            The “judgment
 quantifying [the supplemental damages] award,” however,
 was not entered until June 3, 2019—the date of the final
 judgment. Travelers, 609 F.3d at 175. We agree with Ho-
 logic that the district court should have used June 3, 2019
 as the relevant date for awarding pre- and post-judgment
 interest.
     We conclude that the district court erred in determin-
 ing the relevant date for calculating pre- and post-judg-
 ment interest on the supplemental damages award. We
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 28                    HOLOGIC, INC. v. MINERVA SURGICAL, INC.

 therefore vacate the district court’s interest award and re-
 mand for the district court to award pre-judgment interest
 on the supplemental damages award from the date of in-
 fringement to June 3, 2019, and post-judgment interest
 thereafter.
                         CONCLUSION
      For the foregoing reasons, we affirm the district court’s
 denial of Hologic’s motions for a permanent injunction, en-
 hanced damages, and ongoing royalties for infringement of
 the asserted ’183 patent claims. We also affirm its denial
 of Hologic’s requests for supplemental damages to include
 Minerva’s redesigned product, and for increased and en-
 hanced supplemental damages. Finally, we affirm the dis-
 trict court’s summary judgment of no invalidity and
 infringement, summary judgment that assignor estoppel
 bars Minerva from challenging the validity of the asserted
 ’348 patent claim, and denial of Minerva’s motion for judg-
 ment as a matter of law of no damages or, alternatively, for
 a new trial on reasonable royalty damages.
     We vacate the district court’s award of pre- and post-
 judgment interest on the supplemental damages award,
 and remand for the district court to calculate the interest
 award in accordance with this decision.
      AFFIRMED-IN-PART, VACATED-IN-PART, AND
                    REMANDED
                            COSTS
       No costs.
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    United States Court of Appeals
        for the Federal Circuit
                   ______________________

   HOLOGIC, INC., CYTYC SURGICAL PRODUCTS,
                       LLC,
               Plaintiffs-Appellants

                              v.

                MINERVA SURGICAL, INC.,
                 Defendant-Cross-Appellant
                  ______________________

                    2019-2054, 2019-2081
                   ______________________

 STOLL, Circuit Judge, additional views.
      I write separately to highlight and question the pecu-
 liar circumstance created in this case by this court’s prece-
 dent, which the panel is bound to follow. In Arista, we held
 that the judge-made doctrine of assignor estoppel does not
 apply in the context of an inter partes review. In other
 words, an assignor who sold his patent rights may file a
 petition for IPR challenging the validity of that patent.
 Arista Networks, Inc. v. Cisco Sys., Inc., 908 F.3d 792, 803–
 04 (Fed. Cir. 2018). At the same time, we continue to bar
 assignors from challenging in district court the validity of
 the patents they assigned. See, e.g., Mentor Graphics Corp.
 v. EVE-USA, Inc., 851 F.3d 1275, 1280–83 (Fed. Cir. 2017).
 Our precedent thus presents an odd situation where an as-
 signor can circumvent the doctrine of assignor estoppel by
 attacking the validity of a patent claim in the Patent Office,
 but cannot do the same in district court. Do the principles
 underlying assignor estoppel—unfairness in allowing one
Case: 19-2054    Document: 56     Page: 30    Filed: 04/22/2020

 2                    HOLOGIC, INC. v. MINERVA SURGICAL, INC.

 who profited from the sale of the patent to attack it—apply
 in district court but not in Patent Office proceedings?
 Should we change the application of the doctrine in district
 court, or should we revisit our construction of the America
 Invents Act and reevaluate our interpretation of the stat-
 ute as prohibiting the doctrine of assignor estoppel?
     Given the odd circumstance created in this case, I sug-
 gest that it is time for this court to consider en banc the
 doctrine of assignor estoppel as it applies both in district
 court and in the Patent Office. We should seek to clarify
 this odd and seemingly illogical regime in which an as-
 signor cannot present any invalidity defenses in district
 court but can present a limited set of invalidity grounds in
 an IPR proceeding. 1

     1   A petitioner in an IPR proceeding may request to
 cancel as unpatentable one or more claims of a patent, but
 “only on a ground that could be raised under section 102 or
 103 and only on the basis of prior art consisting of patents
 or printed publications.” 35 U.S.C. § 311(b).