Hologic, Inc. v. Minerva Surgical, Inc.

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.
______________________
Case: 19-2054 Document: 56 Page: 2 Filed: 04/22/2020

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
Case: 19-2054 Document: 56 Page: 3 Filed: 04/22/2020

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
Case: 19-2054 Document: 56 Page: 4 Filed: 04/22/2020

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).
Case: 19-2054 Document: 56 Page: 5 Filed: 04/22/2020

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
Case: 19-2054 Document: 56 Page: 6 Filed: 04/22/2020

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
Case: 19-2054 Document: 56 Page: 7 Filed: 04/22/2020

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
Case: 19-2054 Document: 56 Page: 8 Filed: 04/22/2020

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
Case: 19-2054 Document: 56 Page: 9 Filed: 04/22/2020

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.
Case: 19-2054 Document: 56 Page: 10 Filed: 04/22/2020

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
Case: 19-2054 Document: 56 Page: 11 Filed: 04/22/2020

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
Case: 19-2054 Document: 56 Page: 12 Filed: 04/22/2020

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).
Case: 19-2054 Document: 56 Page: 13 Filed: 04/22/2020

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
Case: 19-2054 Document: 56 Page: 14 Filed: 04/22/2020

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
Case: 19-2054 Document: 56 Page: 15 Filed: 04/22/2020

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.
Case: 19-2054 Document: 56 Page: 16 Filed: 04/22/2020

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
Case: 19-2054 Document: 56 Page: 17 Filed: 04/22/2020

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
Case: 19-2054 Document: 56 Page: 18 Filed: 04/22/2020

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

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
Case: 19-2054 Document: 56 Page: 20 Filed: 04/22/2020

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
Case: 19-2054 Document: 56 Page: 21 Filed: 04/22/2020

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

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
Case: 19-2054 Document: 56 Page: 23 Filed: 04/22/2020

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.
Case: 19-2054 Document: 56 Page: 24 Filed: 04/22/2020

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
Case: 19-2054 Document: 56 Page: 25 Filed: 04/22/2020

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
Case: 19-2054 Document: 56 Page: 26 Filed: 04/22/2020

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).
Case: 19-2054 Document: 56 Page: 27 Filed: 04/22/2020

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
Case: 19-2054 Document: 56 Page: 28 Filed: 04/22/2020

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.
Case: 19-2054 Document: 56 Page: 29 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
______________________

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).