  United States Court of Appeals
      for the Federal Circuit
                ______________________

              GILEAD SCIENCES, INC.,
               Plaintiff-Cross-Appellant

                           v.

  MERCK & CO., INC., MERCK SHARP & DOHME
    CORP., IONIS PHARMACEUTICALS, INC.,
              Defendants-Appellants
             ______________________

                 2016-2302, 2016-2615
                ______________________

   Appeals from the United States District Court for the
Northern District of California in No. 5:13-cv-04057-BLF,
Judge Beth Labson Freeman.
                ______________________

                Decided: April 25, 2018
                ______________________

    JUANITA ROSE BROOKS, Fish & Richardson, PC, San
Diego, CA, argued for plaintiff-cross-appellant. Also
represented by CRAIG E. COUNTRYMAN, JONATHAN ELLIOT
SINGER; ELIZABETH M. FLANAGAN, DEANNA JEAN REICHEL,
Minneapolis, MN; ROBERT M. OAKES, Wilmington, DE;
EDMUND HIRSCHFELD, E. JOSHUA ROSENKRANZ, Orrick,
Herrington & Sutcliffe LLP, New York, NY.

   JEFFREY A. LAMKEN, MoloLamken LLP, Washington,
DC, argued for defendants-appellants. Also represented
by JAMES A. BARTA, SARAH JUSTINE NEWMAN, MICHAEL
2                  GILEAD SCIENCES, INC.   v. MERCK & CO., INC.



GREGORY PATTILLO, JR.; SARA MARGOLIS, New York, NY;
JESSAMYN SHELI BERNIKER, STANLEY E. FISHER, BRUCE
GENDERSON, JESSICA PALMER RYEN, Williams & Connolly
LLP, Washington, DC; MITCHELL EPNER, STEPHEN S.
RABINOWITZ, Hughes Hubbard & Reed LLP, New York,
NY.
               ______________________

 Before TARANTO, CLEVENGER, and CHEN, Circuit Judges.
TARANTO, Circuit Judge.
    This case involves two patents relating to treatments
for Hepatitis C. Merck & Co., Inc. and Ionis Pharmaceu-
ticals, Inc. (formerly Isis Pharmaceuticals, Inc.) collabo-
rated on research in the area and eventually obtained
U.S. Patent Nos. 7,105,499 and 8,481,712. The patents,
whose specifications are materially the same for present
purposes, describe and claim classes of compounds, identi-
fied by structural formulas, and the administration of
therapeutically effective amounts of such compounds.
Gilead Sciences, Inc., developed its own Hepatitis C
treatments—marketed now as Solvadi® and Harvoni®,
both based on the compound sofosbuvir.
    Gilead filed this action against Merck & Co., its sub-
sidiary Merck Sharp & Dohme Corp., and Ionis (collec-
tively, “Merck” unless the context indicates reference just
to Merck & Co. and/or Merck Sharp). Gilead sought a
declaratory judgment that Merck’s ’499 and ’712 patents
are invalid and that Gilead is not infringing by its activi-
ties involving its sofosbuvir products. Merck counter-
claimed for infringement.
    Gilead eventually stipulated to infringement based on
the district court’s claim construction, which is not chal-
lenged on appeal. A jury trial was held on Gilead’s chal-
lenges to the patents as invalid for lack of both an
adequate written description and enablement of the
asserted claims (claims 1–2 of the ’499 patent and claims
GILEAD SCIENCES, INC.   v. MERCK & CO., INC.              3



1–3, 5, 7, and 9-11 of the ’712 patent) as well as Gilead’s
closely related defense that Merck did not actually invent
the subject matter but derived it from another inventor,
employed by Gilead’s predecessor. The jury ruled for
Merck and awarded damages.
    The district court then held a bench trial on Gilead’s
equitable defenses, including unenforceability against
Gilead based on the allegation that Merck had unclean
hands regarding the patents. The district court ruled for
Gilead, finding both pre-litigation business misconduct
and litigation misconduct attributable to Merck, and it
barred Merck from asserting the patents against Gilead.
Gilead Scis., Inc. v. Merck & Co., No. 13-cv-04057-BLF,
2016 WL 3143943, at *39 (N.D. Cal. June 6, 2016). Hav-
ing so concluded, the district court subsequently deemed
moot Gilead’s motion for judgment as a matter of law of
invalidity for lack of adequate written description and
enablement. The court also awarded attorney’s fees,
relying on the finding of unclean hands.
    Merck appeals the unenforceability judgment based
on unclean hands. Gilead cross-appeals the denial of
judgment as a matter of law of invalidity, but it asks us to
reach that issue only if we set aside the unenforceability
judgment.     We have jurisdiction under 28 U.S.C.
§ 1295(a)(1). We affirm the judgment based on unclean
hands, concluding that it is sufficiently supported by
findings that withstand review for clear error. We there-
fore do not reach the issues raised by Gilead’s conditional
cross-appeal.
                                I
                               A
    In 1998, Merck and Isis began collaborating on find-
ing a way to block propagation of the Hepatitis C virus
(HCV) by impeding the synthesis of its RNA. J.A. 20291.
The collaborators sought a molecule that would have two
4                  GILEAD SCIENCES, INC.   v. MERCK & CO., INC.



properties. First, an enzyme involved in RNA assembly
(NS5B polymerase) would recognize the molecule as a
building block and add it to the growing RNA chain
during replication of the virus’s RNA. Second, the addi-
tion of this molecule would effectively stop further RNA
assembly before completion and, hence, end RNA replica-
tion and prevent viral propagation.
    Starting in 2001, the two collaborators filed a series of
patent applications related to antiviral agents for Hepati-
tis C. Dr. Phillipe Durette, a Merck chemist who had
become a patent attorney, was central to their initial
patenting efforts. J.A. 20301. A provisional patent appli-
cation dated January 22, 2001, summarizes the invention
as “a method for inhibiting hepatitis C virus (HCV) NS5B
polymerase, a method for inhibiting HCV replication,
and/or a method for treating HIV infection” by adminis-
tering a “therapeutically effective amount of a compound
of structural formula I.” J.A. 25808. It sets forth and
claims large families of possible structures in Markush
format: it displays a number of configurations of nucleic
acid derivatives and shows variables at a number of
locations in the structures (e.g., different bases, different
molecules attached to the sugar ring), the variables each
stated to represent any of a substantial number of possi-
ble constituents. J.A. 25803–980.
    The same is true of Merck’s two January 2002 appli-
cations under the Patent Cooperation Treaty (PCT appli-
cations). J.A. 24832, 26913. One of those became Merck’s
July 2003 U.S. application 10/250,873, which issued as
the ’499 patent. J.A. 150, 27227. A non-provisional U.S.
application filed in January 2002 led to the 2007 applica-
tion that issued as the ’712 patent. J.A. 223. The number
of possible combinations within the Markush groups is
very large.
GILEAD SCIENCES, INC.   v. MERCK & CO., INC.               5



    One instance of the formulas in the written descrip-
tion, from the 2003 application that issued as the ’499
patent, is:
   structural formula III which is of the stereochemi-
   cal configuration:




   wherein B is




   D is N, CH, C—CN, C—NO2, C—C1-3 alkyl, C—
       NHCONH2, C—CONR11R11, C—CSNR11R11,
       C—COOR11, C-hydroxy, C—C1-3 alkoxy, C-
       amino, C—C1-4 alkylamino, C-di(C1-4 al-
       kyl)amino, C-halogen, C-(1,3-6oxazol-2-yl), C-
       (1,3-thiazol-2-yl), or C-(imidazol-2-yl); wherein
       alkyl is unsubstituted or substituted with one
       to three groups independently selected from
       halogen, amino, hydroxy, carboxy, and
   C1-3 alkoxy;
   W is O or S;
   Y is H, C1-10 alkylcarbonyl, P3O9H4, P2O6H3, or
      P(O)R9R10;
   R1 is hydrogen, CF3, or C1-4 alkyl and one of R2
       and R3 is OH or C1-4 alkoxy and the other of R2
       and R3 is selected from the group consisting of
6                    GILEAD SCIENCES, INC.   v. MERCK & CO., INC.



       hydrogen,
       hydroxy,
       fluoro,
       C1-3 alkyl,
       trifluoromethyl,
       C1-8 alkylcarbonyloxy,
       C1-3 alkoxy, and
       amino; or
    R2 is hydrogen, CF3, or C1-4 alkyl and one of R1 and
    R3 is OH or C1-4 alkoxy and the other of R1 and R3
    is selected from the group consisting of
       hydrogen,
       hydroxy,
       fluoro,
       C1-3 alkyl,
       trifluoromethyl,
       C1-8 alkylcarbonyloxy,
       C1-3 alkoxy, and
       amino; or
    R1 and R2 together with the carbon atom to which
        they are attached form a 3- to 6-membered
        saturated monocyclic ring system optionally
        containing a heteroatom selected from O, S,
        and NC0-4 alkyl;
    R6 is H, OH, SH, NH2, C1-4 alkylamino, di(C1-4 al-
        kyl)amino, C3-6 cycloalkylamino, halogen, C1-4
        alkyl, C1-4 alkoxy, or CF3;
GILEAD SCIENCES, INC.   v. MERCK & CO., INC.                7



    R5 is H, C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, C1-4
        alkylamino, CF3, or halogen;
    R7 is hydrogen, amino, C1-4 alkylamino, C3-6 cyclo-
        alkylamino, or di(C1-4 alkyl)amino;
    each R11 is independently H or C1-6 alkyl;
    R8 is H, halogen, CN, carboxy, C1-4 alkyloxycar-
        bonyl, N3, amino, C1-4 alkylamino, di(C1-4 al-
        kyl)amino, hydroxy, C1-6 alkoxy, C1-6 alkylthio,
        C1-6 alkylsulfonyl, or (C1-4 alkyl)0-2 aminome-
        thyl; and
    R9 and R10 are each independently hydroxy,
       OCH2CH2SC(═O)t-butyl, or OCH2O(C═O)iPr;
    with the provisos that (a) when R1 is hydrogen and
        R2 is fluoro, then R3 is not hydrogen, trifluo-
        romethyl, fluoro, C1-3 alkyl, amino, or C1-3
        alkoxy; (b) when R1 is hydrogen and R2 is fluo-
        ro, hydroxy, or C1-3 alkoxy, then R3 is not hy-
        drogen or fluoro; and (c) when R1 is hydrogen
        and R2 is hydroxy, then R3 is not β-hydroxy.
’499 Patent, col. 13, line 5 through col. 14, line 17 (empha-
ses added to highlight terms of particular interest for this
case); J.A. 27245–47. 1
    Various claims appeared in Merck’s patent applica-
tions based on that structural formula or related ones,
including claims 6 and 8 of the January 2001 provisional,
J.A. 25954–56, claims 6 and 8 of the PCT application that



    1   The top figure shows the key elements of the nu-
cleoside. B is the base, shown in the next two figures in
single-ring (pyrimidine) and double-ring (purine) versions.
R1 and R2 are located at the 2′ (carbon) position on the
ring, with R1 at the 2′ “up” location and R2 at the 2′
“down” location. R3 is at the 3′ position.
8                 GILEAD SCIENCES, INC.   v. MERCK & CO., INC.



issued as the ’499 patent, J.A. 25036–38, and claim 44 of
that same application, which was added, substituting for
earlier claims, immediately upon filing the U.S. version in
July 2003, J.A. 27482–83. The 2003-added claim 44 of the
2003 application, for example, recites the above structural
formula but is limited to the single-ring bases shown
above (pyrimidine bases, such as cytosine and uracil). It
therefore omits the above-quoted language concerning D,
R7, and R8, which appear only on the double-ring bases
shown above (purine bases, such as adenine and guanine).
Id.
    Claim 44 of the 2003 application and its PCT counter-
part, like the structural formula III, encompasses, among
the large number of possible combinations of values of the
variables, structures having (i) a single-ring base, (ii) a
methyl (C1 alkyl) in the R1 position, and (iii) a fluoro in
the R2 or R3 position. J.A. 25036–38, 27482–83. A subge-
nus with those characteristics—which embraces both a
metabolite of Gilead’s sofosbuvir and an earlier identified
compound that was modified to arrive at sofosbuvir, and
which Merck eventually focused on in new claims in
2005—is central in this case.
                            B
    In 2002, a pharmaceutical company called Pharmas-
set, which was later acquired by Gilead, was researching
Hepatitis C treatments. When one of Merck’s early
applications was published that year, Pharmasset re-
viewed the application, looking for “loopholes.” J.A. 20048
(533). After reviewing Merck’s application, Jeremy Clark,
a chemist at Pharmasset, proposed the compound PSI-
6130 (the compound that led to sofosbuvir). Id. (533–534).
PSI-6130 had a single-ring base (cytosine), a methyl in
the 2′ up position, and a fluoro in the 2′ down position.
J.A. 24619, 24826. Pharmasset synthesized and tested
PSI-6130 by May 2003. J.A. 20040 (504). It was the first
compound made by Pharmasset that was active against
GILEAD SCIENCES, INC.   v. MERCK & CO., INC.              9



Hepatitis C. J.A. 20050–51 (544–45). PSI-6130 led to
sofosbuvir, which has the same methyl and fluoro sub-
stituents as PSI-6130 but contains uracil, rather than
cytosine, as its base. J.A. 19913–17, 19951 (401).
    Pharmasset filed a patent application for Mr. Clark’s
invention in May 2003. J.A. 20042 (511–12). The appli-
cation was published in January 2005. The published
application, the “Clark Application,” described and
claimed (in 129 claims) a range of structures, including
both single-ring (pyrimidine) and double-ring (purine)
bases, and methods of using them for treatment of various
conditions, including Hepatitis C. J.A. 23709–86. Among
the many specifically described and claimed structures
was PSI-6130. J.A. 23727 (application ¶ 168), 23756
(claim 26). The application issued in September 2008 as
U.S. Patent No. 7,429,572, with only 19 claims, which
cover PSI-6130. J.A. 29947–87.
                               C
    In February 2005, the month after the January 2005
publication of the Clark Application, Merck, through Dr.
Durette, filed a narrowing amendment in the 2003 appli-
cation that eventually issued as the ’499 patent. J.A.
28318–21. Merck canceled all pending claims and substi-
tuted two narrower claims (claims 53 and 54). The claims
issued as claims 1 and 2 of the ’499 patent on September
12, 2006.
   Claim 1 of the ’499 patent is representative. It states:
   1. A method of treating hepatitis C virus (HCV)
   infection comprising administering to a mammal
   in need of such treatment a therapeutically effec-
   tive amount of a compound of structural formula
   III, or a pharmaceutically acceptable salt or acyl
   derivatives thereof,
10                  GILEAD SCIENCES, INC.   v. MERCK & CO., INC.




     wherein B is




     W is O or S;
     Y is H, C1-10 alkylcarbonyl, P3O9H4, P2O6H3, or
         P(O)R9R10;
     R1 is CF3, or C1-4 alkyl and one of R2 and R3 is OH
         or C1-4 alkoxy and the other of R2 and R3 is
         fluoro;
     R6 is H, OH, SH, NH2, C1-4 alkylamino, di(C1-4 al-
         kyl)amino, C3-6 cycloalkylamino, halogen, C1-4
         alkyl, C1-4 alkoxy, or CF3;
     R5 is H, C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, C1-4
         alkylamino, CF3, or halogen; and
     R9 and R10 are each independently hydroxy,
        OCH2CH2SC(═O)t-butyl, or OCH2O(C═O)iPr.
’499 Patent, col. 137, line 2 through col. 138, line 16.
Merck seems to accept that the ’499 patent claims include
PSI-6130. Merck Br. 18. Gilead characterizes the claim
as “target[ing]” PSI-6130. Gilead Br. 16, 18.
    We will elaborate below on the connection of Phar-
masset’s work on PSI-6130 with Dr. Durette, Merck, and
Merck’s 2005 claim amendments for what became the ’499
patent. Those connections, together with Dr. Durette’s
eventual testimony about those connections, came to be
the basis of the district court’s ultimate determination
GILEAD SCIENCES, INC.   v. MERCK & CO., INC.             11



that Merck had unclean hands, precluding patent en-
forcement against Gilead.
                               D
     In February 2007, a few months after the ’499 patent
issued, Merck’s Dr. Durette filed the application that
ultimately issued as the ’712 patent. J.A. 24147. The
original claims of that application were quite different
from PSI-6130, J.A. 24336–41, and Dr. Durette immedi-
ately substituted two claims that were closer, but that the
parties here do not contend covered PSI-6130, J.A. 24150–
53. It appears undisputed that after April 2007 Dr.
Durette did not participate in prosecuting the ’712 appli-
cation. Merck Br. 18; see e.g., J.A. 24369–70 (April 2007
filing by the attorney who took over responsibility for
prosecuting the application from Dr. Durette).
    In 2010, Pharmasset published an article in the Jour-
nal of Medicinal Chemistry describing “sofosbuvir” (PSI-
7977) to treat HCV. J.A. 31990–2007. In 2011, attorney
Jeffrey Bergman took over prosecuting the ’712 applica-
tion for Merck. J.A. 32383. Merck amended the ’712
application to include new claims. J.A. 24394–410. The
’712 patent issued on July 9, 2013.
   Claim 1 of the ’712 patent is representative. It states:
   1. A compound having the formula:




   or a pharmaceutically acceptable salt thereof,
   wherein:
       B is:
12                    GILEAD SCIENCES, INC.   v. MERCK & CO., INC.




     L is CH or N;
     E is N or CR5;
     W is O or S;
     R1 is C2-4 alkenyl, C2-4 alkynyl, or C1-4 alkyl option-
         ally substituted with amino, hydroxy, or 1 to 3
         fluorine atoms; R3 is hydroxy or C1-4 alkoxy;
         and R2 is selected from the group consisting of
         halogen,
         C1-4 alkyl, optionally substituted with 1 to 3
         fluorine atoms,
         C1-10 alkoxy, optionally substituted with C1-3
         alkoxy or 1 to 3 fluorine atoms,
         C2-6 alkenyloxy,
         C1-4 alkylthio,
         C1-8 alkylcarbonyloxy,
         aryloxycarbonyl,
         azido,
         amino,
         C1-4 alkylamino, and
         di(C1-4 alkyl)amino;
     R4 and R6 are each independently H, OH, SH,
        NH2, C1-4 alkylamino, di(C1-4 alkyl)amino, C3-6
        cycloalkylamino, halogen, C1-4 alkyl, C1-4
        alkoxy, or CF3;
GILEAD SCIENCES, INC.   v. MERCK & CO., INC.               13



   R5 is H, C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, C1-4
       alkylamino, CF3, or halogen;
   R12 and R13 are each independently hydrogen or
       methyl.
’712 Patent, col. 143, lines 2–54. The parties characterize
these claims, which embrace a single-ring base with
methyl up and fluoro down at the 2′ position in the sugar,
as covering metabolites of sofosbuvir, produced in the
body after administration of sofosbuvir. Merck Br. 18;
Gilead Br. 19. As noted above, in this case Gilead ulti-
mately stipulated to infringement of the asserted claims
of the ’712 and ’499 patents based on the district court’s
claim construction.
                               II
    After a bench trial on Gilead’s equitable defenses, the
district court held that Merck could not enforce the two
patents at issue here against Gilead because its conduct
gave it unclean hands. Gilead, 2016 WL 3143943, at *39.
The court rested that determination on its findings of
both pre-litigation business misconduct and litigation
misconduct attributable to Merck. Id. at *27. The court
balanced the equities and applied its determination to
both patents. Id. at *37–39.
     The Supreme Court has articulated the governing le-
gal standard. In Keystone Driller Co. v. General Excava-
tor Co., the Court explained that a determination of
unclean hands may be reached when “misconduct” of a
party seeking relief “has immediate and necessary rela-
tion to the equity that he seeks in respect of the matter in
litigation,” i.e., “for such violations of conscience as in
some measure affect the equitable relations between the
parties in respect of something brought before the court.”
290 U.S. 240, 245 (1933). In Precision Instrument Manu-
facturing Co. v. Automotive Maintenance Machinery Co.,
the Court stated that the doctrine “closes the doors of a
14                 GILEAD SCIENCES, INC.   v. MERCK & CO., INC.



court of equity to one tainted with inequitableness or bad
faith relative to the matter in which he seeks relief,
however improper may have been the behavior of the
defendant,” and requires that claimants “have acted fairly
and without fraud or deceit as to the controversy in is-
sue.” 324 U.S. 806, 814–15 (1945). The Court added that
the doctrine “necessarily gives wide range to the equity
court’s use of discretion in refusing to aid the unclean
litigant.” Id. at 815; see also Northbay Wellness Grp., Inc.
v. Beyries, 789 F.3d 956, 960 (9th Cir. 2015) (explaining
need for equitable balancing). 2
    Merck invokes the term “material” to describe the
kind of connection between misconduct and the litigation
that the Supreme Court’s formulations require. But
Merck has not identified how that term helpfully refines
the Supreme Court’s standard in a way that is relevant to
this case. See Merck Br. 39–43. For purposes of this case,
which involves clear misconduct in breaching commit-
ments to a third party and clear misconduct in litigation,
the “immediate and necessary relation” standard, in its
natural meaning, generally must be met if the conduct
normally would enhance the claimant’s position regarding
legal rights that are important to the litigation if the
impropriety is not discovered and corrected. Merck cites
no authority holding such misconduct to be outside Key-
stone’s scope. Nor does Merck deny that the standard can
cover at least some misconduct that ultimately fails to
affect the litigation, as when it is discovered before it



     2   The doctrine of unclean hands is not patent-
specific, but its application to patents has some distinctive
features affecting the patent system. We need not choose
between Ninth Circuit and Federal Circuit law on the
subject here. The parties have identified no differences
pertinent to this case, and they have not identified what
law they contend controls in this appeal.
GILEAD SCIENCES, INC.   v. MERCK & CO., INC.                15



bears fruit, as long as its objective potential to have done
so is sufficient.
    Significantly, this is not a case in which it is clear that
the identified misconduct could not reasonably have
enhanced the claimant’s legal position as to either the
creation or the enforcement of the legal rights at issue.
Nor is this a case involving alleged deficiencies in com-
munications with the PTO during patent prosecution, for
which this court’s inequitable-conduct decisions, e.g.,
Therasense, Inc. v. Becton, Dickinson & Co., 649 F.3d
1276 (Fed. Cir. 2011) (en banc), set important limits on
conclusions of unenforceability through that doctrine. 3 In
the circumstances present in this case, we see no genuine
issue about the governing legal standard, but only its
application.
     We conclude that the district court made findings that
have adequate support in the evidence and that, taken
together, justify the equitable determination of unclean
hands as a defense to enforcement in this case. In so
concluding, we apply deferential standards of review, as
Merck itself urges. We review the district court’s ruling
for abuse of discretion, which means that we review
factual findings only for clear error. See Merck Br. 37
(citing Northbay, 789 F.3d at 959).
    Our decision rests only on the totality of the evidence-
supported misconduct we summarize, not individual
elements alone and not every finding of the district court.
We are conscious, as any court presented with a defense



    3   We therefore have no occasion in this case to con-
sider issues that may arise in seeking to ensure that the
unclean-hands doctrine operates in harmony with, and
does not override, this court’s inequitable-conduct stand-
ards governing unenforceability challenges based on
prosecution communications with the PTO.
16                GILEAD SCIENCES, INC.   v. MERCK & CO., INC.



of unclean hands must be, both of the judicial system’s
vital commitment to the standards of probity protected by
the doctrine and, also, of the potential for misuse of this
necessarily flexible doctrine by parties who would prefer
to divert attention away from dry, technical, and complex
merits issues toward allegations of misconduct based on
relatively commonplace disputes over credibility. Having
those considerations in mind, we do not find a sufficient
basis to set aside the district court’s determination of
unclean hands under the applicable deferential standard
of review.
                            A
     The district court found, with adequate evidentiary
support, two related forms of pre-litigation business
misconduct attributable to Merck. First, Dr. Durette
learned of Pharmasset’s PSI-6130 structure by participat-
ing, at Merck’s behest, in a conference call with Pharmas-
set representatives, violating a clear “firewall”
understanding between Pharmasset and Merck that call
participants not be involved in related Merck patent
prosecutions. Second, Merck continued to use Dr. Durette
in the related patent prosecutions even after the call. The
district court also found, with adequate evidentiary
support, a direct connection to the ultimate patent litiga-
tion involving sofosbuvir. Thus, Dr. Durette’s knowledge
of PSI-6130, acquired improperly, influenced Merck’s
filing of narrowed claims, a filing that held the potential
for expediting patent issuance and for lowering certain
invalidity risks. Those findings establish serious miscon-
duct, violating clear standards of probity in the circum-
stances, that led to the acquisition of the less risky ’499
patent and, thus, was immediately and necessarily relat-
ed to the equity of giving Merck the relief of patent en-
forcement it seeks in this litigation.
GILEAD SCIENCES, INC.   v. MERCK & CO., INC.             17



                                1
    The business misconduct found in this case grows out
of Merck’s dealings with Pharmasset. In the early 2000s,
the two companies discussed possible business arrange-
ments that would include work on “discovery and devel-
opment of antiviral agents against . . . hepatitis C virus.”
Gilead, 2016 WL 3143943, at * 6. They entered into a
non-disclosure agreement in January 2001. Id.
    In September 2003, Pharmasset gave Merck certain
information about Pharmasset’s NS5B Nucleoside Inhibi-
tor, i.e., PSI-6130. Id.; J.A. 32161–81. In October 2003,
the companies signed a Material Transfer Agreement
under which Pharmasset would give Merck the “Phar-
masset HCV NS5B Nucleoside Inhibitor” for Merck to
evaluate. Gilead, 2016 WL 3143943, at *7; J.A. 30077–83.
The Agreement allowed Merck to test PSI-6130 as long as
it did not try to discern the compound’s chemical struc-
ture. Gilead, 2016 WL 3143943, at *7; J.A. 30078 ¶ 3.1.
    In January 2004, Merck asked Pharmasset to furnish
more information to a “firewalled” Merck medicinal
chemist—meaning that the chemist was “firewalled” from
Merck’s own Hepatitis C program. Gilead, 2016 WL
3143943, at *7–8; J.A. 32183–86. Pharmasset agreed to
provide information to Merck’s chemist, Dr. Ashton, on
the conditions that the information was subject to the
2001 non-disclosure agreement and, what is critical here,
that it was to be shared only on a “‘fire walled’ basis.”
J.A. 22921–22; Gilead, 2016 WL 3143943, at *7–8. In
February 2004, Merck’s “firewalled” chemist determined
that “PSI6130 and its relatives represent a potentially
good fit with Merck’s existing anti-HCV portfolio arising
from the Isis collaboration.” J.A. 22918–19.
    Merck and Pharmasset then scheduled, for March 17,
2004, a conference call during which Pharmasset would
disclose the structure of PSI-6130. J.A. 23706–07; see
Gilead, 2016 WL 3143943, at *8. Merck planned to have
18                 GILEAD SCIENCES, INC.   v. MERCK & CO., INC.



Dr. Durette, Merck’s patent prosecutor for what became
the ’499 patent, “view the structure” during the call. J.A.
23706–07; Gilead, 2016 WL 3143943, at *8; see also J.A.
19945 (375) (Dr. Durette’s supervisor asked him to partic-
ipate in the call). The district court found that Dr. Du-
rette knew before the call “that any information he
learned about Pharmasset’s PSI-6130 nucleoside analog
compound would overlap with the subject matter of his
patent prosecution docket for Merck, thereby creating a
conflict.” Gilead, 2016 WL 3143943, at *9.
    On the March 17, 2004 call, before disclosing the com-
pound’s structure, Pharmasset confirmed the importance
of the firewall to it by asking whether the two participat-
ing Merck employees (Dr. Durette and Dr. Pon) were
within the firewall separating Merck call participants
from related Merck HCV patenting efforts. Id.; J.A.
31544–45; J.A. 19947 (382). At some point in the call, the
Merck participants said that they were within the fire-
wall. Gilead, 2016 WL 3143943, at *9–10; J.A. 31544–45;
J.A. 19960 (435). Pharmasset’s notes from the call, how-
ever, also indicate some disclosure by Dr. Durette of a
conflict issue for him: “It’s a problem for Phil Durette; he
needs to have a conversation with his supervisor; ‘seems
quite related to things that I’m involved with.’ . . . [H]e is
personally conflicted; not the company.” J.A. 31545; see
Gilead, 2016 WL 3143943, at *9–10. The PSI-6130 struc-
ture was disclosed during the call. Id. at *9.
    After the March 17, 2004 call, Dr. Durette stopped
participating in the work of the Merck team dealing with
Pharmasset. J.A. 19944 (373). But Merck kept him
working as the prosecuting attorney for its patent appli-
cations related to nucleosides that inhibit Hepatitis C
virus replication. Gilead, 2016 WL 3143943, at *10
(“Instead of withdrawing from prosecution, Dr. Durette
continued to prosecute Merck’s HCV patent applications
and write new claims that targeted Pharmasset’s work.”).
The court found that neither Merck nor Dr. Durette
GILEAD SCIENCES, INC.   v. MERCK & CO., INC.              19



provided any explanation as to why he was not removed
from further prosecution of the Merck patent applications.
Id.
     Those facts support the district court’s findings of se-
rious business misconduct. Merck sent Dr. Durette to
participate in the March 2004 call despite the clear fire-
wall and the fact that “Merck . . . knew that Pharmasset’s
compound was an NS5B polymerase inhibitor just like its
own compounds from the Merck-Isis collaboration.” Id. at
*28. “Dr. Durette’s involvement with Merck’s HCV pa-
tents violated the understanding the parties had about
their firewall obligations, which excluded anyone involved
with Merck’s internal HCV program.” Id. And after the
call, it was “wrong for Merck to allow Dr. Durette to
continue to prosecute” the Merck applications: he contin-
ued prosecution of the application that became the ’499
patent, and in 2007 he filed (and immediately amended)
the application that became the ’712 patent. Id. 4



    4    The court added that Merck’s own “corporate poli-
cy forb[ade] Merck’s patent prosecutors from participating
in licensing discussions in an area related to their prose-
cution work.” Id. at *9 (citing J.A. 22341 (38–39)); see id.
at *28; J.A. 22374 (170–71). That policy, as we note
below, confirms the connection between (a) Merck’s patent
prosecutor learning the structure of PSI-6130 during the
March 2004 call and (b) Merck’s patenting and the result-
ing litigation. To the extent that the district court sug-
gested that the violation of Merck’s internal policy was an
independent basis for finding wrongful conduct, even
apart from the violation of the firewall understanding, we
see no basis for such a suggestion. A patent-obtaining
firm may legitimately have such a policy simply to avoid
having its later litigation position weakened by exposure
to information gained from licensing discussions. Viola-
tion of such a policy would be a wrong to the firm but not
20                 GILEAD SCIENCES, INC.   v. MERCK & CO., INC.



                              2
     The district court found, with sufficient basis, that the
wrongful business conduct had the required connection to
this patent litigation. Id. at *29. As laid out above, in
February 2005, a month after the publication of Pharmas-
set’s Clark Application, Dr. Durette amended the Merck
application that ultimately issued as the ’499 patent by
canceling the broad genus claims and substituting claims
that narrowed the scope to a subgenus focused on the key
features of PSI-6130. Id. at *11. The district court found
that “Dr. Durette would not have written new claims to
cover PSI-6130 in February 2005 but for his improper
participation on the March 17, 2004 patent due diligence
call and learning the structure of PSI-6130 ahead of the
structure being published.” Id.
    Given that Dr. Durette learned of the PSI-6130 struc-
ture in March 2004 (as is now conceded), the district court
could readily find that his knowledge from the call played
a significant role in his actual process of decision-making
that led him to file claims focusing on that and similar
structures. Dr. Durette admitted during his deposition
that participation in the March 2004 call, which he at the
time denied, “would have tainted [his] judgment as to
what claims to pursue in the Merck/Isis collaboration.”
J.A. 22341 (38). The timing of Merck’s February 2005
amendment, which occurred just one month after the
structure of PSI-6130 was published in January 2005,
supports the inference, as the district court put it, that
Merck was deliberately “wait[ing].” Gilead, 2016 WL
3143943, at *11 (“Dr. Durette waited to amend the
claims . . . until Clark application was published”). Dr.
Durette provided support for the inference of a taint when


to the potential licensee, or the judicial system, in the
absence of other understandings, such as the firewall
understanding here.
GILEAD SCIENCES, INC.   v. MERCK & CO., INC.            21



he stated in his deposition that failing to keep partici-
pants in the March 2004 call separate from the patent
prosecutors “could raise issues down the road on the
patent that would issue based on the attorneys prosecut-
ing of those patents.” J.A. 22374 (171). 5
    The additional finding that Dr. Durette would not
otherwise have made the February 2005 amendment is
not clearly erroneous. Dr. Durette’s testimony at his
deposition greatly downplayed the role of the sole promi-
nent candidate for an independent cause of the February
2005 amendment, namely, the January 2005 Clark Appli-
cation. In doing so, Dr. Durette gave testimony that is
capable of being read as suggesting that the Clark Appli-
cation alone would not have led him to amend the claims.
J.A. 22344–46. Significantly, Merck did not present
evidence that would compel a finding, or even meaningful-
ly argue for a finding, that even if Dr. Durette personally
had not made the February 2005 amendment, others at
Merck lacking the earlier knowledge of PSI-6130 would
have done something equivalent so as to break any causal
connection between the business misconduct and the
patent-rights benefits associated with the amendment.
See Defs.’ [Proposed] Findings of Fact and Conclusions of
Law Regarding Gilead’s Equitable Defenses, Gilead Scis.,
Inc. v. Merck & Co., Inc., et al., Case No. 5:13-cv-04057-



   5    The timing of the amendment undermines a dif-
ferent, but ultimately immaterial, finding of the district
court—that Merck violated the non-disclosure agreement
with Pharmasset. E.g., Gilead, 2016 WL 3143943, at *10,
*27, *29. The only identified forbidden use of information
covered by the agreement—Dr. Durette’s February 2005
claim amendment focusing on PSI-6130—did not occur
until the information was publicly disclosed in the Clark
Application.    The disclosure ended the information’s
protection by the agreement. J.A. 32152 ¶ 3(ii).
22                 GILEAD SCIENCES, INC.   v. MERCK & CO., INC.



BLF, D.I. 407 at 27–28 (¶¶ 113–15) (N.D. Cal. Apr. 22,
2016) (brackets in document name in original).
      Although Merck stresses that even the pre-February
2005 claims included PSI-6130 and similar structures, Dr.
Durette explained the benefits to a patentee’s legal posi-
tion from a narrowing amendment of this sort. “It would
expedite prosecution.” J.A. 22347 (62); see J.A. 19945
(376) (“the Examiner would have less subject matter to
. . . search”). Relatedly, “limiting the scope” of the claims
would mean “fewer opportunities for prior art to . . .
present an issue of patentability” under 35 U.S.C. §§ 102
and 103. J.A. 22347 (62). That would be so during prose-
cution and also in a litigation challenge. And a narrowing
amendment can reduce a patentee’s risk on other invalidi-
ty issues, such as the risk that breadth can create under
the requirement that the “full scope” of a claim be ena-
bled. See, e.g., Amgen Inc. v. Sanofi, 872 F.3d 1367, 1375
(Fed. Cir. 2017). Such risks can be reduced even if, as
here, the resulting claim still covers a large, though less
large, number of compounds.
    In these circumstances, we see no error in the district
court’s determination that the pre-litigation business
misconduct we have summarized was immediately and
necessarily related to the equity of Merck’s obtaining
enforcement of its patent in this litigation.
                             B
    The district court also found, with adequate eviden-
tiary support, essentially two forms of litigation miscon-
duct involving Dr. Durette as a witness and attributable
to Merck. First, in his deposition, where he appeared
partly as Merck’s corporate witness on issues to which the
March 2004 call was relevant, Dr. Durette gave testimony
that he did not participate in the March 2004 call—
testimony that was later conceded to be false and that the
court found to be intentionally so. Second, both in the
deposition and then at trial, Dr. Durette, in support of
GILEAD SCIENCES, INC.   v. MERCK & CO., INC.            23



Merck’s validity positions, gave testimony about the role
the January 2005 Clark Application played in Dr. Du-
rette’s filing of the February 2005 amendment that the
court found so incredible as to be intentionally false. The
intentional testimonial falsehoods qualify as the kind of
misconduct that can, in these circumstances, support a
determination of unclean hands. The court also found,
with adequate evidentiary support, that the false testi-
mony, in both respects, bore on the origin story of the
February 2005 amendment, which was relevant to the
invalidity issues in the litigation and hence immediately
and necessarily related to the equity of the patent-
enforcement relief Merck seeks in this case.
                                1
    In 2015, during the discovery phase of this case,
Merck designated Dr. Durette as its corporate witness
under Fed. R. Civ. P. 30(b)(6) on certain issues, even
though he had retired from Merck in 2010. Gilead, 2016
WL 3143943, at *12; J.A. 22335 (15–16), 22377 (181–84);
J.A. 22214. In particular, Merck designated him to repre-
sent the corporation regarding the prosecution of the
application that issued as the ’499 patent. Gilead, 2016
WL 3143943, at *12; J.A. 22214–16 (¶¶ 15–21). Dr.
Durette was not Merck’s representative regarding the
2007 application that issued as the ’712 patent, id.
(¶¶ 20–21), though he filed that application.
    On May 8, 2015, Gilead deposed Dr. Durette in both
his personal and his representative capacities. J.A.
22331–83. Near the end of the deposition, Dr. Durette
stated that his answers regarding the ’499 patent would
not differ according to the capacity in which he was testi-
fying. J.A. 22377 (183–84). Merck’s counsel represented
both Merck and Dr. Durette at the deposition. Gilead,
2016 WL 3143943, at *12; J.A. 22333 (7). Dr. Durette
testified that, in preparation for his deposition, he met
with Merck’s outside counsel for six to seven hours on
24                 GILEAD SCIENCES, INC.   v. MERCK & CO., INC.



each of two days and spent eight to ten additional hours
on his own. Gilead, 2016 WL 3143943, at *12; J.A. 22334
(10–11).
     Dr. Durette gave two different answers about whether
he participated in the March 17, 2004 call with Pharmas-
set. Near the start of the deposition, J.A. 22336 (19), and
toward the end of the deposition, J.A. 22374–75 (172–73),
he repeatedly said that he did not recall participating.
But during a portion of the deposition not long after it
started (corresponding to about nine pages of the tran-
script), Dr. Durette repeatedly stated, definitively, that he
did not participate. J.A. 22339–41 (30–38); see, e.g., J.A.
22339 (31) (“sure” that he was not involved in any discus-
sion with Pharmasset in March 2004 where he was told of
PSI-6130’s structure); J.A. 22341 (37) (“I never participat-
ed in a due diligence meeting on March 17 . . . . I did not
participate in any meeting of due diligence on March 17”).
One reason that he was so sure, he said, was that it would
have violated Merck policy to allow his participation and
to keep him on the related patent prosecutions. J.A.
22341 (38–39), 22373–74 (168–72); 22382 (202). On the
basis of those definitive denials, the district court found
that “[w]hen asked about the March 17, 2004, call at the
deposition, Dr. Durette denied ever having been on such a
call. When asked whether he was sure that he was not on
the March 17, 2004, call, Dr. Durette unequivocally
answered yes.” Gilead, 2016 WL 3143943, at *12.
    That denial of participation was false, as came to be
undisputed by Merck, and acknowledged by Dr. Durette,
at trial. See id. at *14; J.A. 19937–38 (344–47). The
district court found the falsity of the deposition denial of
participation to be intentional. Gilead, 2016 WL 3143943,
at *29–31. We cannot deem that state-of-mind finding to
be clearly erroneous, given the district court’s direct
observation of Dr. Durette at the trial; the documentary
evidence of his participation, including pre-participation
emails (some that he reviewed during his deposition); and
GILEAD SCIENCES, INC.   v. MERCK & CO., INC.             25



the sufficiently supported findings that aspects of his
testimony were “inconsistent, contradictory, and untruth-
ful.” Id. at *29; see id. at *12–16.
    Regarding the role of the January 2005 Clark Appli-
cation in Dr. Durette’s decision to file new claims in
February 2005, Dr. Durette downplayed that role in ways
that the district court reasonably found incredible. Most
starkly, at his deposition, he stated that he simply did not
recall whether he saw the Clark Application before filing
the February 2005 amendment and hence could not state
that it played a role in the amendment. See id. at *16;
J.A. 22343–44 (48–52), 22348–49 (66–69).
    Before trial, the court denied Merck’s motion to ex-
clude all evidence post-dating 2002 from the jury trial
regarding invalidity—a denial not separately challenged
as incorrect here. J.A. 19220–22 (denying exclusion
because the information was relevant to invalidity issues).
Once that motion was denied, Merck itself indicated that
it would call Dr. Durette as a witness. J.A. 19404 (42)
(Merck explaining that Dr. Durette is “planning to come
and testify in our case”). Gilead then took the opportunity
to call Dr. Durette first, cross-examining him before
Merck conducted its direct examination regarding validity
issues, including the origin of the February 2005 amend-
ment.
     In his trial testimony, Dr. Durette continued to down-
play the role of the Clark Application, though to a lesser
extent than during the deposition. See Gilead, 2016 WL
3143943, at *16. Explaining his decision to file the
amendment, he stressed that he narrowed the claims to
“expedite” examination, id. at *17; J.A. 19944–45 (371–
75), and said that “he amended the ’499 claims to focus on
‘get[ting] allowance on the subject matter that was most
important to the [Merck-Isis] collaboration,’” Gilead, 2016
WL 3143943, at *17; J.A. 19952 (404). He also testified,
however, that he had “bec[o]me convinced that it was the
26                GILEAD SCIENCES, INC.   v. MERCK & CO., INC.



publication of the [Clark] [A]pplication that led [him] to
reexamine” the prosecution of the application that became
the ’499 patent and file the February 2005 amendment.
J.A. 19949 (390–91); Gilead, 2016 WL 3143943, at *16.
The district court could reasonably find that, by stating
that it was surrounding circumstances that so convinced
him, not his own recollection, Dr. Durette was continuing
to minimize the actual role of the Clark Application and
what he learned in the March 2004 call, i.e., the role of
Pharmasset’s work, in his amendment decision for Merck.
As already noted above, the court reasonably found that
he had in mind the information he learned in the March
2004 call, that he was waiting for publication of PSI-
6130’s structure to avoid violating the non-disclosure
agreement, and that he filed the February 2005 amend-
ment once publication of the Clark Application occurred.
In light of those findings, it was also reasonable for the
district court to find Dr. Durette’s trial testimony a mis-
leading effort to downplay the role of Pharmasset’s work
in the February 2005 amendment.
     The district court found that “Dr. Durette’s changing
and evasive explanations for why he narrowed the claims
undermine his testimony” and that “his testimony [was]
not credible.” Id. at *17. It found that Dr. Durette’s
testimony that “he amended the ’499 claims to focus on
‘get[ting] allowance on the subject matter that was most
important to the [Merck-Isis] collaboration’ is contrary to
the evidence and is not credible because Merck never
tested any of the claimed compounds” until after the
Clark Application was published. Id. The testimony
downplaying the role of Pharmasset’s work—published in
the Clark Application, first disclosed to Dr. Durette in
March 2004—the court found “not credible” and “false.”
Id.
GILEAD SCIENCES, INC.   v. MERCK & CO., INC.               27



                                2
    The district court properly charged Merck with the
consequences of the testimony, at the deposition and at
the trial, that the court found to be intentionally false. Id.
at *29 (“[T]he record shows that . . . [Dr. Durette’s] testi-
mony was sponsored by Merck.”). As already noted, not
only did Merck’s counsel appear as counsel for Dr. Du-
rette at his deposition, and prepare him for it, but Dr.
Durette was Merck’s official corporate representative on
matters (the origin of the ’499 patent) to which the testi-
mony at issue was relevant. As also already noted, Dr.
Durette appeared at trial after Merck indicated that it
was going to call him to testify about invalidity matters,
to which the testimony at issue here had been held rele-
vant.
    The testimony, relevant to issues in the case and rea-
sonably found to be intentionally false, had an immediate
and necessary relation to the equity of the patent-
enforcement relief Merck seeks in this litigation. The
district court held that the origin of the February 2005
amendment, and hence Dr. Durette’s testimony about
that, was relevant to the invalidity issues to be tried. Id.
at *14 (“At trial, Dr. Durette provided key testimony for
Merck on validity issues, including written description of
the ’499 Patent.”); id. at *32 (determining that the testi-
mony was “directed at and supported Merck’s validity
arguments, and went to the heart of significant issues in
this case”). The verdict form made explicit that lack of
written description and lack of enablement were tied to
the defense of “derivation from Jeremy Clark” (the Phar-
masset inventor of PSI-6130)—the latter to be addressed
only if the jury found either lack of an adequate written
description or lack of enablement.         J.A. 21066–75.
Merck’s own policy of separating patent prosecutors from
discussions like the ones held with Pharmasset is confir-
mation that Merck recognized, as Dr. Durette testified,
that the origin of patent claims could matter in eventual
28                 GILEAD SCIENCES, INC.   v. MERCK & CO., INC.



litigation over those claims. See J.A. 22341 (39–40). In
this case, downplaying the role of the Clark Application
(and the March 2004 call) naturally served to aid Merck’s
case that it did not derive the claimed inventions from
Pharmasset’s Jeremy Clark. In these circumstances, the
district court could reasonably determine that the testi-
mony at issue here held a significant potential to give
Merck an advantage in the litigation, satisfying the
Keystone standard.
                             C
    We see no reversible error in the district court’s bal-
ancing of the equities. Gilead, 2016 WL 3143943, at *37–
39. As to the ’499 patent, the equity balance follows
directly from the determinations already described: the
misconduct leading to the February 2005 amendment and
the misconduct involved in the litigation defense of the
resulting patent claims. On appeal, we have relied on a
more limited set of wrongful conduct than recited in the
district court’s opinion, see supra nn.4–5, but we do not
think that the equitable balance is altered by that nar-
rowing. The conduct we have affirmed as wrongful is so
clearly the core of the district court’s analysis that we
have no doubt that the equitable balancing by the district
court would have been the same if it had limited its
wrongful-conduct findings to those we have recited. On
these facts, there is no abuse of discretion.
    As the district court recognized, the question for the
’712 patent is closer, but we also see no abuse of discretion
in the district court’s ultimate conclusion that the unclean
hands defense extends to that patent as well. The district
court connected the ’712 patent to one portion of Merck’s
improper conduct: once Dr. Durette improperly learned
PSI-6130’s structure through participating in the March
2004 call at Merck’s behest, Merck kept him in his patent-
prosecution role—which, as noted, included filing the
2007 application that issued as the ’712 patent, as well as
GILEAD SCIENCES, INC.   v. MERCK & CO., INC.             29



the initial substitute claims, after the (tainted) ’499
patent had already issued. Id. at *10–11. While the
district court said that its “finding of improper business
conduct related to the March 2004 call was not considered
by the Court in determining whether unclean hands
prevented enforcement of the ’712 Patent,” id. at *36 n.5,
that statement does not refer to the retention of Dr.
Durette as the lead prosecutor of HCV applications,
including the one that eventually issued as the ’712
patent, and the court relied on that improper retention.
E.g., id. at *10–11. The district court relied on the con-
nection between the two patents: “Dr. Durette played a
key role in the prosecution of both the ’499 and ’712
Patents. He was responsible for filing the application
that eventually matured as the ’712 Patent and this
application shares the same specification as the ’499
Patent.” Id. at *36.
    More importantly, the district court, turning from the
business misconduct to the litigation misconduct, reason-
ably concluded that “Merck’s litigation misconduct infects
the entire lawsuit, including the enforceability of the ’712
Patent.” Id. at *32. “[T]he untruthful testimony offered
by Dr. Durette in his deposition and at trial was not
incidental, but rather was directed at and supported
Merck’s validity arguments, and went to the heart of
significant issues in this case.” Id. The validity issues
were largely the same for the two patents, focused on the
common specification of the two patents and how that
specification bore on written-description support for and
enablement of claims in the two patents that have closely
related scope. As indicated above, the jury verdict form
tied both of those issues, for both patents, to the question
of “derivation from Jeremy Clark” (the Pharmasset inven-
tor of PSI-6130, disclosed in March 2004 and published in
the Clark Application). J.A. 21066–75. Thus, the litiga-
tion misconduct “infected this entire case, covering both
patents-in-suit.” Gilead, 2016 WL 3143943, at *36. We
30                 GILEAD SCIENCES, INC.   v. MERCK & CO., INC.



conclude that, contrary to Merck’s suggestion, the district
court set forth a sufficient explanation of the ’712 patent’s
connection to Merck’s misconduct.
     Merck argues that even where there is misconduct re-
lated to one patent, “that does not defeat claims under
another patent simply because they were ‘brought . . . in
the same lawsuit.’” Merck Br. 69. We agree; but the
assertion does not undermine the district court’s ruling
here. The Supreme Court’s decisions in Keystone and
Precision Instruments, dealing with findings of unclean
hands when multiple patents were at issue in the litiga-
tion and the alleged misconduct related to a subset of the
patents, are instructive. In both cases, the Supreme
Court applied the finding of unclean hands to all of the
patents. Keystone, 290 U.S. at 246–47; Precision Instru-
ments, 324 U.S. at 819. The district court in the present
case had sufficient reason to find that both patents were
tainted by the patentee’s misconduct, especially the
litigation misconduct. Thus, we see no abuse of discretion
with respect to either the ’499 patent or the ’712 patent.
                             III
    Because the district court did not abuse its discretion
in applying the doctrine of unclean hands, we affirm.
     Costs awarded to Gilead.
                       AFFIRMED
