  United States Court of Appeals
      for the Federal Circuit
                 ______________________

THERMOLIFE INTERNATIONAL LLC, BOARD OF
TRUSTEES OF THE LELAND STANFORD JUNIOR
               UNIVERSITY,
             Plaintiffs-Appellants

                            v.

   GNC CORPORATION, GENERAL NUTRITION
     CENTERS, INC., GENERAL NUTRITION
               CORPORATION,
                 Defendants

   HI-TECH PHARMACEUTICALS, INC., VITAL
          PHARMACEUTICALS, INC,
             Defendants-Appellees
            ______________________

                  2018-1657, 2018-1666
                 ______________________

   Appeals from the United States District Court for the
Southern District of California in Nos. 3:13-cv-00651-JLS-
MDD, 3:13-cv-00830-JLS-MDD, 3:13-cv-01015-JLS-MDD,
Judge Janis L. Sammartino.
                 ______________________

                  Decided: May 1, 2019
                 ______________________

    ROBERT J. GAJARSA, Latham & Watkins LLP, Washing-
ton, DC, argued for plaintiff-appellant ThermoLife Inter-
national LLC.     Also represented by GABRIEL BELL;
2        THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION




GREGORY BLAIN COLLINS, ERIC HULL, CARA MOLLY LOUISE
ROGERS, Kercsmar & Feltus PLLC, Scottsdale, AZ.

    WILLIAM P. ATKINS, Pillsbury Winthrop Shaw Pittman
LLP, McLean, VA, argued for plaintiff-appellant Board of
Trustees of the Leland Stanford Junior University. Also
represented by BENJAMIN LEE KIERSZ.

   ROBERT F. PARSLEY, Miller & Martin PLLC, Chatta-
nooga, TN, argued for defendant-appellee Hi-Tech Phar-
maceuticals, Inc. Also represented by DAVID M. BARNES.

   FRANCIS DIGIOVANNI, Drinker Biddle & Reath LLP,
Wilmington, DE, argued for defendant-appellee Vital Phar-
maceuticals, Inc. Also represented by MICHAEL CURT
LAMBERT, THATCHER RAHMEIER; MARC KESTEN, Vital Phar-
maceuticals, Inc., Parkland, FL.
                 ______________________

    Before TARANTO, BRYSON, and STOLL, Circuit Judges.
TARANTO, Circuit Judge.
     ThermoLife International, LLC exclusively licensed
four patents from the Board of Trustees of the Leland Stan-
ford Junior University. It filed infringement suits, assert-
ing selected claims of four patents, against numerous
defendants, including Hi-Tech Pharmaceuticals, Inc. and
Vital Pharmaceuticals, Inc. After Stanford became a co-
plaintiff of ThermoLife’s, a bench trial was held involving
Hi-Tech, Vital, and a trio of companies from the GNC fam-
ily as defendants (all other defendants having settled). The
district court held all asserted claims invalid. That ruling
ended the cases on the merits and is not at issue here.
     Before us is the court’s later grant of Hi-Tech’s and Vi-
tal’s motions for attorney’s fees under 35 U.S.C. § 285,
which authorizes an award of fees to a prevailing party
(like Hi-Tech and Vital) in “exceptional” cases. The district
THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION              3



court found the cases exceptional, but not based on an as-
sessment of the validity position taken by plaintiffs Ther-
moLife and Stanford or how they litigated validity. Rather,
the court relied on its conclusion that plaintiffs were unjus-
tified in alleging infringement in the first place, having
failed to do an adequate pre-filing investigation.
    ThermoLife and Stanford appeal the district court’s
award of fees, challenging the determination that these
were “exceptional” cases, not the amounts the court
awarded after finding the cases exceptional. We recognize
that these are unusual cases in that the basis for the fee
award had nothing to do with the only issues litigated to
reach the judgment on the merits: Infringement had not
been adjudicated in reaching the final judgment, and even
discovery on infringement had been postponed early in the
proceedings so that validity could be litigated first. Never-
theless, we see no abuse of discretion in the district court’s
determination of exceptionality based on plaintiffs’ inade-
quate pre-suit investigation of infringement in these and
related cases. We therefore affirm.
                              I
                              A
     Stanford owns U.S. Patent Nos. 5,891,459, 6,117,872,
6,646,006, and 7,452,916, which claim methods and compo-
sitions involving the amino acids arginine and lysine, to be
ingested to enhance vascular function and physical perfor-
mance. See, e.g., ’459 patent, Abstract. The ’459 patent,
the ’916 patent, and the relevant claims of the ’006 patent
share a priority date of June 11, 1993, and expired on June
11, 2013. The ’872 patent has a priority date of June 23,
1998, and expired on June 23, 2018. All asserted claims of
the ’459, ’872, and ’916 patents are method claims, whereas
all asserted claims of the ’006 patent are composition
claims.
4        THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION




     Claim 1 of the ’459 patent, the only claim of that patent
asserted against Hi-Tech and Vital, includes a requirement
of efficacy in producing physiological results. It recites:
        1. A method of improving vascular NO activity
    of the vascular system of a human host by enhanc-
    ing endothelial NO, said method comprising:
        administering orally as a dietary supplement
    to said host in accordance with a predetermined
    regimen a prophylactic dose in an amount suffi-
    cient to enhance endogenous endothelial NO, L-ar-
    ginine or L-arginine hydrochloride, as other than a
    natural food source and in the absence of other
    amino acids and polypeptides as other tha[n] die-
    tary supplements, to enhance the level of endoge-
    nous NO in the vascular system.
Id., col. 26, lines 39–49 (emphasis added). As originally
filed, claim 1 included L-arginine and all physiologically
acceptable salts thereof, but it was amended during prose-
cution to exclude salts other than L-arginine hydrochlo-
ride.
     Claim 1 of the ’872 patent requires particular amounts
of identified amino acids. It reads:
       1. A method for enhancing physical perfor-
    mance of a mammal prior to said physical perfor-
    mance, said method comprising:
        administering to said mammal prior to said
    physical performance as the active ingredient an
    amino acid composition consisting of at least one
    amino acid selected [from] the group consisting of
    arginine and lysine of at least about 60 mg/kg/day
    within 24 h of said physical performance.
THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION                 5



’872 patent, col. 11, line 55, through col. 12, line 6 (empha-
sis added). 1 Claims 4 and 5 depend on claim 1 and thus
also require at least about 60 mg/kg/day of arginine or ly-
sine. Id., col. 12, lines 11–16. Claims 7, 8, and 12 all re-
quire “at least about 2 g per day” of arginine or lysine. Id.,
col. 12, lines 19–31, 45–51. Claim 10 depends on claim 7
and additionally requires “about 2 to 12 g per day” of argi-
nine or lysine. Id., col. 12, lines 34–36.
    Claim 1 of the ’916 patent includes both efficacy and
amount requirements for L-arginine or any physiologically
acceptable salt (not just the hydrochloride salt). It reads:
         1. A method of enhancing nitric oxide produc-
    tion comprising orally administering to a human
    host in need thereof a composition comprising L-
    arginine or a physiologically acceptable salt
    thereof, wherein (i) said composition includes an
    amount of L-arginine or its physiologically accepta-
    ble salt sufficient to increase the level of nitric oxide
    production in said human host and (ii) said compo-
    sition is a dietary or food supplement or a pharma-
    ceutical composition in a form suitable for oral
    administration selected from the group consisting
    of a pill, a powder, a liquid, and a capsule, wherein
    said administering provides a daily amount rang-
    ing from 1 to 12 grams of L-arginine or its physio-
    logically acceptable salt and wherein the
    composition further comprises at least one addi-
    tional compound associated with production of ni-
    tric oxide other than L-arginine or a physiologically
    acceptable salt thereof.




    1    For a 150-pound person, 60 mg/kg/day is about 4
grams per day. Unlike claim 1 of the ’459 patent, this claim
is not limited to L-arginine or its hydrochloride salt.
6        THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION




’916 patent, col. 26, lines 38–53 (emphases added). Claim
2, another independent claim, and claim 6, which depends
on claim 2, likewise require both “an amount of L-arginine
or its physiologically acceptable salt sufficient to increase
the level of nitric oxide production” and “a daily amount
ranging from 1 to 12 grams of L-arginine or its physiologi-
cally acceptable salt.” See id., col. 26, lines 54–67; id., col.
28, lines 6–8.
    Standing apart from the other asserted claims are
three claims of the ’006 patent, which claim compositions
comprising L-arginine and any physiologically acceptable
salt but do not include either amount or efficacy require-
ments. Claim 3 reads:
        3. A composition comprising L-arginine or a
    physiologically acceptable salt thereof and at least
    one additional compound associated with produc-
    tion of nitric oxide other than L-arginine or a phys-
    iologically acceptable salt thereof, said composition
    excluding other amino acids which are not precur-
    sors of nitric oxide, wherein said composition is in
    a form suitable for oral administration selected
    from the group consisting of a pill, a powder, a liq-
    uid, and a capsule.
’006 patent, col. 27, lines 40–47 (emphasis added). Claim
5, another independent claim, and claim 14, which depends
on claim 5, similarly do not, on their face, contain any
amount or efficacy limitations. See id., col. 27, lines 52–61;
id., col. 28, lines 20–22.
                               B
     Stanford originally granted exclusive licenses to the
’459, ’872, ’006, and ’916 patents to Cooke Pharma, Inc.,
which eventually became Unither Pharma, Inc. In 2002
and 2003, Unither and Stanford filed several infringement
suits involving some of those patents in the Northern Dis-
trict of California. One of those cases resulted in a
THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION              7



November 2005 district court decision that construed
“amount sufficient” in the ’459 patent to mean “an amount
typically administered to a subset of mammalian organ-
isms for the purpose of the administration.” Unither
Pharma, Inc. v. Daily Wellness Co., No. 02-cv-05284, 2005
WL 6220096, at *10 (N.D. Cal. Nov. 30, 2005). Unither ter-
minated its license with Stanford in September 2012.
    Some months later, in February 2013, Stanford exclu-
sively licensed the four patents to ThermoLife. From
March 19, 2013, to December 11, 2013, ThermoLife filed a
total of eighty-one infringement suits, including suits
against Hi-Tech and Vital, in the Southern District of Cal-
ifornia. Although separate suits were filed, see 35 U.S.C.
§ 299 (broadly requiring separate filings), the district
court, beginning in August 2013, consolidated the cases be-
fore it for pre-trial purposes. Eventually, in January 2015,
Stanford was added as a plaintiff, through the filing of an
amended complaint against all defendants, to resolve a dis-
pute about ThermoLife’s standing to proceed alone.
     ThermoLife alleged that Hi-Tech and Vital each di-
rectly infringed the four patents—for the composition
claims, by making or selling the accused products, and for
the method claims, by administering the accused products
to end users—and also indirectly infringed, by inducing or
contributing to end users’ directly infringing use of the ac-
cused products. ThermoLife pointed to Hi-Tech’s and Vi-
tal’s labels and advertisements in support of its allegations.
ThermoLife sought damages, including enhanced dam-
ages, and injunctive relief. The January 2015 amended
complaint is similar.
    Pursuant to applicable local rules for patent cases,
ThermoLife notified the defendants of specific infringe-
ment contentions shortly after the suits were filed. In its
December 12, 2013 amended infringement contentions,
ThermoLife identified specific Hi-Tech products and the
corresponding allegedly infringed patent claims: Anavar
8        THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION




(’459 patent—claim 1); NO Overload (’459 patent—claim 1;
’872 patent—claims 1, 4, 5, 7, 8, 10, 12; ’916 patent—claims
1, 2, 6); Zencore Plus (’459 patent—claim 1; ’006 patent—
claims 3, 5); Mesomorph (APS Nutrition) (’006 patent—
claim 3); SizeMatters (HealthSource) (’459 patent—claim
1; ’006 patent—claims 3, 5, 14); and StaminaRx (’459 pa-
tent—claim 1; ’006 patent—claims 3, 5, 14). The same day,
ThermoLife made more limited allegations against Vital
products: AEX NO (’872 patent—claim 12; ’916 patent—
claims 1, 2, 6); and NO Shotgun V3, NO Shotgun MHF-1,
and NO Synthesize (’459 patent—claim 1).
     By January 2014, with dozens of cases before it, the
district court had set a schedule in which discovery was to
begin for claim construction, invalidity, unenforceability,
and standing—but not for infringement. In March 2014,
the parties filed a joint report stating that they had agreed
to “phased discovery”: “discovery should be coordinated and
initially limited to issues concerning standing, claim con-
struction, patent invalidity and/or unenforceability.” J.A.
215. “If necessary,” the report added, “discovery should
then proceed as issues unique to each Defendant and each
case, namely[,] infringement and damages.” Id. The report
explained that “[t]his will facilitate the fair and efficient
conduct of discovery and dispositive motion practice in this
matter, and will alleviate the burden of excessive and po-
tentially unnecessary discovery on all parties in this mat-
ter.” Id. The district court was aware of the agreed-on
procedure.
    In December 2014, the district court construed several
terms in the asserted claims. ThermoLife Int’l, LLC v. My-
ogenix Corp., No. 13-cv-651, 2014 WL 12160740 (S.D. Cal.
Dec. 2, 2014). It did not construe “an amount sufficient to
enhance endogenous endothelial NO,” as used in claim 1 of
the ’459 patent, or any other limitations of the asserted
claims regarding the amount of arginine to be adminis-
tered. See id. at *11–12.
THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION              9



     On July 29, 2015, defendants moved for summary judg-
ment on invalidity, contending that all asserted claims of
all four patents were invalid. In December 2015, the dis-
trict court denied summary judgment, concluding that
there were genuine disputes of material fact as to the inva-
lidity of all asserted claims. ThermoLife Int’l, LLC v. My-
ogenix Corp., No. 13-cv-651, 2015 WL 11237635, at *20
(S.D. Cal. Dec. 8, 2015). Shortly thereafter, with the par-
ties’ agreement, the court bifurcated the proceedings: A
consolidated trial on invalidity and unenforceability would
be held; and if necessary, separate proceedings on infringe-
ment would follow. 2
    The district court held a bench trial on invalidity from
August 1 to August 8, 2016. 3 In September 2016, the court
held that all asserted claims of all four patents were invalid
for anticipation or obviousness. ThermoLife Int’l, LLC v.
Myogenix Corp., No. 13-cv-651, 2016 WL 5118525, at *25
(S.D. Cal. Sept. 21, 2016). For instance, the court found
that claim 1 of the ’459 patent was anticipated by U.S. Pa-
tent No. 5,217,997 (Levere), which discloses using L-argi-
nine to treat high-vascular-resistance disorders such as
hypertension. Id. at *9 (citing J.A. 5306–16).




    2   The “Defendants” listed in the jointly filed agree-
ment to that process are Hi-Tech, Vital, and three GNC en-
tities, plus eight more firms: Kingfisher Media LLC;
NBTY, Inc.; Novex Biotech, LLC; Nutrex Research, Inc.;
Solgar, Inc.; United States Nutrition, Inc.; Vitamin World,
Inc.; and 6S, Inc. d/b/a Bodystrong.
     3  By the time of trial, the only remaining defendants
were Hi-Tech, Vital, and the three GNC entities. Only va-
lidity was tried, as unenforceability was dropped before
trial.
10       THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION




                             C
     On October 12, 2016, Hi-Tech and Vital (but not the
GNC entities) moved for attorney’s fees under 35 U.S.C.
§ 285. Rhetoric aside, they made two related arguments
for exceptionality that are relevant here. 4 Their main ar-
gument was that plaintiffs did not conduct an adequate
pre-suit investigation into infringement, an investigation
that would have revealed that the accused products did not
infringe claim 1 of the ’459 patent, the only claim Hi-Tech
and Vital specifically discussed. One premise of the argu-
ment was that the accused products all contained less than
one gram of L-arginine (or its hydrochloride salt) per serv-
ing. 5 The other premise was that plaintiffs’ own validity
expert made clear in his 2015 deposition testimony and



     4  Hi-Tech and Vital also made two other arguments
for exceptionality: They briefly relied on their victory on
validity; and as to infringement, they asserted that some
accused products fell outside claim 1 of the ’459 patent be-
cause those products contained amino acids prohibited by
the claim. The district court did not rest its exceptional-
case determination on either of those bases. We note that
Hi-Tech and Vital generally adopted each other’s argu-
ments, though certain contentions were product-specific.
    5   Specifically, Hi-Tech submitted a declaration stat-
ing that its accused products do not “contain 1 gram or
more of L-Arginine or L-Arginine hydrochloride.” J.A.
10716–17. Vital submitted two such declarations, the first
stating that one of its accused products “never contained L-
arginine or L-arginine hydrochloride” and that two of its
accused products “always contained less than 500 milli-
grams of L-arginine per serving.” J.A. 10506–07. Vital’s
second declaration revised that figure downward, stating
that the latter two accused products “always contained[]
less than 5 milligrams of L-arginine” or L-arginine salts
per serving. J.A. 11586.
THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION            11



2016 trial testimony that studies published before these
suits were filed showed that amounts of L-arginine less
than one gram were ineffective to enhance nitric oxide pro-
duction (being too small an increase over the regular hu-
man intake of arginine). See J.A. 10456, 10461−63. Based
on those premises, Hi-Tech and Vital argued that plaintiffs
would have discovered that the accused products did not
infringe had they read the labels on the accused products
and conducted simple tests before suing. In their second-
ary argument, Hi-Tech and Vital broadened their focus and
accused plaintiffs of filing many suits, without adequate in-
vestigation, simply to try to extract nuisance-value settle-
ments.
    Plaintiffs ThermoLife and Stanford jointly responded.
They did not deny that the accused products were publicly
available, and they neither denied the existence of simple
tests to determine the accused products’ composition nor
asserted that they had conducted any such tests. While
noting that Hi-Tech and Vital focused entirely on claim 1
of the ’459 patent, to the exclusion of the other patents at
issue, plaintiffs did not discuss any other claims to show
why they differed as to the adequacy of the pre-suit inves-
tigation. Plaintiffs denied the accusation that they sued
just to extract settlements and argued that there was in-
sufficient record information to support the speculation
that the settlements were for mere nuisance values. 6
    The district court held oral argument on the attorney’s
fees motions on February 9, 2017. After Hi-Tech argued
the inadequacy of the pre-filing investigation by plaintiffs’
counsel, plaintiffs sought permission to file a declaration to


    6   Plaintiffs did not contend before the district court
that Stanford should be distinguished from ThermoLife
with respect to whether there was a reasonable pre-filing
investigation. We therefore treat them the same, and we
focus on the filing of the cases in 2013.
12       THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION




address the argument, which they said was new. The court
provisionally allowed plaintiffs to file such a declaration,
but said that Hi-Tech and Vital, in responding, could argue
that the declaration should be stricken. On February 16,
2017, plaintiffs submitted a declaration from their lead
counsel, Mr. Woods, who described the pre-filing investiga-
tion that he and his co-counsel undertook. Hi-Tech and Vi-
tal jointly responded.
     In April 2017, the district court issued its decision on
the motions for attorney’s fees. ThermoLife Int’l, LLC v.
Myogenix Corp., No. 13-cv-651, 2017 WL 1235766 (S.D.
Cal. Apr. 4, 2017) (Fees Op.). The court began by striking
the Woods declaration. The court explained that plaintiffs
could have presented the same information in their initial
opposition to the attorney’s fees motions, that the declara-
tion went beyond providing facts about their counsel’s pre-
filing investigation, and that Hi-Tech and Vital had no op-
portunity to conduct discovery regarding the new state-
ments and arguments. Id. at *2–3.
     On the merits of the attorney’s fees requests, the court
first found that plaintiffs had conducted an inadequate pre-
filing investigation, resulting in objectively unreasonable
infringement contentions. Id. at *4–7. The court focused
entirely on claim 1 of the ’459 patent, as the parties had
done in their filings. It found that plaintiffs’ validity expert
testified that less than one gram of arginine would not en-
hance NO production. Id. at *6. The court found that ei-
ther plaintiffs did not examine the accused products’ labels
before filing or, if they did, they ignored clear label indica-
tions of less than one gram of L-arginine (or its hydrochlo-
ride salt) for some of the accused products. Id. at *5. The
court found that, aside from any (unclear) reliance on la-
bels, plaintiffs relied only on the defendants’ advertising
statements, even while disparaging the statements as
“bombastic.” Id. at *6 (quoting J.A. 11060, 11062 (plain-
tiffs’ response)). At least in light of the label information
and the tension between such information and defendants’
THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION              13



advertising statements, the court concluded, this was a
case in which it was unreasonable to dispense with (undis-
putedly available) testing to identify ingredients and their
amounts in the accused products, which were “publicly
available.” Id. at *5−6. And although plaintiffs noted that
some accused products contain compounds that are not
themselves L-arginine (or its hydrochloride salt), as recited
in claim 1 of the ’459 patent, but result in L-arginine when
dissolved in water pursuant to label instructions, the court
found that even those products did not lead to the one gram
required for efficacy. Id. at *6 (citing, e.g., J.A. 11586). The
court thus found “strong evidence that had Plaintiffs con-
ducted any reasonable pre-filing investigation, they would
have been on notice that at least some of the products in
this litigation could not have infringed.” Id. at *7.
    When the court turned to Hi-Tech and Vital’s second-
ary argument, it found that plaintiffs “only list one mar-
keted product, sales of which never amounted to more than
300 units,” and “brought suit under three patents that ex-
pired several months after ThermoLife agreed to purchase
the licenses.” Id. The court also found that plaintiffs “set-
tled early with many of the defendants in this lawsuit for
seemingly small dollar amounts” and “have filed numerous
infringement suits.” Id. The court then built into its find-
ing on this aspect of the matter a notion of irresponsibility
in the bringing of the many suits: “[T]he pattern of action
here is indeed one that strongly suggests Plaintiffs brought
suit against many defendants without carefully reviewing
their claims as a calculated risk that might yield nuisance-
value settlements.” Id. (emphasis added).
     The court summarized its conclusions: Plaintiffs’ “pre-
filing investigation was severely lacking, thus resulting in
frivolous claims and the objective unreasonableness of cer-
tain infringement contentions”; plaintiffs’ “motivation was
seemingly to extract nuisance-value settlements from a
large number of defendants”; and “awarding fees here will
advance compensation- and deterrence-oriented goals.” Id.
14       THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION




at *8. Under the totality of the circumstances, the court
ruled, “this case is exceptional,” justifying a fee award. Id.
     Plaintiffs filed a motion for reconsideration of the dis-
trict court’s decision, including new evidentiary material.
The district court struck the new material, which could
have been supplied earlier, and rejected each of plaintiffs’
arguments for changing the result of the April 2017 fees
opinion. ThermoLife Int’l, LLC v. Myogenix Corp., No. 13-
cv-651, 2017 WL 4792426, at *9 (S.D. Cal. Oct. 24, 2017)
(Reconsideration Op.). In February 2018, the district court
awarded $903,890.13 to Hi-Tech and $406,131.76 to Vital
for attorney’s fees and expenses, including pre- and post-
judgment interest.
    ThermoLife and Stanford appeal the district court’s ex-
ceptional-case determination. We have jurisdiction under
28 U.S.C. § 1295(a)(1).
                              II
    A court “in exceptional cases may award reasonable at-
torney fees to the prevailing party.” 35 U.S.C. § 285. An
exceptional case is one that, under the totality of the cir-
cumstances, “stands out from others with respect to the
substantive strength of a party’s litigating position” or “the
unreasonable manner in which the case was litigated.” Oc-
tane Fitness, LLC v. ICON Health & Fitness, Inc., 572 U.S.
545, 554 (2014).
     We review a district court’s grant of attorney’s fees un-
der § 285 for abuse of discretion. Highmark Inc. v. Allcare
Health Mgmt. Sys., Inc., 572 U.S. 559, 561 (2014). A dis-
trict court abuses its discretion when it makes “a clear er-
ror of judgment in weighing relevant factors or in basing
its decision on an error of law or on clearly erroneous fac-
tual findings.” Bayer CropScience AG v. Dow AgroSciences
LLC, 851 F.3d 1302, 1306 (Fed. Cir. 2017) (citing High-
mark, 572 U.S. at 563 n.2). A district court must “provide
a concise but clear explanation of its reasons for the fee
THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION            15



award.” Hensley v. Eckerhart, 461 U.S. 424, 437 (1983); see
In re Rembrandt Techs. LP Patent Litig., 899 F.3d 1254,
1276 (Fed. Cir. 2018); see also AFGE Local 3599 v. EEOC,
920 F.3d 794, 799–800 (Fed. Cir. 2019) (discussing fees in
agency context). We generally “give great deference to the
district court’s exercise of discretion in awarding fees.” En-
ergy Heating, LLC v. Heat On-The-Fly, LLC, 889 F.3d 1291,
1307 (Fed. Cir. 2018).
    We conclude that the district court in this case acted
within its discretion in determining, on the limited argu-
ments plaintiffs made in response to the fee motions, that
plaintiffs did not conduct an adequate pre-suit investiga-
tion into infringement by Hi-Tech and Vital. That deter-
mination would suffice to support the exceptional-case
determination. And we read the district court’s additional
discussion of plaintiffs’ filing of numerous suits on the pa-
tents at issue here as itself ultimately resting on the same
lack of adequate pre-suit investigation, not simply on Ther-
moLife’s limited product sales, the expiration dates of three
of the four patents, the number of suits filed, or the
amounts of the settlements. For those reasons, we affirm
the exceptional-case determination.
                              A
     We begin with three issues that confirm the propriety
of the district court’s focus on the inadequate-investigation
question.
                              1
     We see no abuse of discretion in the district court’s
striking of the Woods Declaration. The district court ex-
plained that the declaration was untimely: plaintiffs were
on notice of the need to address the adequacy of their pre-
filing investigation, an issue that does not neatly segregate
counsel from client, and so plaintiffs could and should have
put forth the information contained in the Woods Declara-
tion in their initial opposition to the motions for attorney’s
16       THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION




fees. The court also explained that Hi-Tech and Vital did
not have an opportunity to conduct additional discovery in
response to the facts and arguments raised in the declara-
tion. Fees Op., 2017 WL 1235766, at *2–3. Those are suf-
ficient reasons for striking the declaration.
                              2
     Nor do we see an abuse of discretion in the district
court’s resting its exceptional-case determination on an ex-
amination of an issue—infringement, and specifically the
basis for alleging infringement—that was neither fully ad-
judicated nor even fully litigated before the judgment on
the merits.       In Lumen View Technology LLC v.
Findthebest.com, Inc., we held that a district court did not
abuse its discretion in finding the case exceptional because
“[t]he allegations of infringement were ill-supported,” even
though non-infringement had not been adjudicated before
the asserted claims were invalidated. 811 F.3d 479, 481–
83 (Fed. Cir. 2016). This is an unusual basis for fees, and
we have emphasized the wide latitude district courts have
to refuse to add to the burdens of litigation by opening up
issues that have not been litigated but are asserted as ba-
ses for a fee award. Spineology, Inc. v. Wright Med. Tech.,
Inc., 910 F.3d 1227, 1230 (Fed. Cir. 2018). As a practical
matter, moreover, one stated rationale for deference—the
district court’s distinctive familiarity with the issues rele-
vant to fees due to its extensive work on the merits of the
case—is weaker when the award of fees rests on a basis not
meaningfully considered before fees were sought after the
merits were resolved. Also, a fuller explanation of the
court’s assessment of a litigant’s position may well be
needed when a district court focuses on a freshly consid-
ered issue than one that has already been fully litigated.
But we have been given no persuasive reason for holding
that such a basis for fees is a legally impermissible one.
   To be sure, due process and other procedural rights
must be respected in deciding the exceptional-case
THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION              17



question as a precondition to awarding fees against a losing
party. In re Rembrandt Techs., 899 F.3d at 1275−76. And
more process may well be needed on a fees motion when
the issue presented as a basis for fees has not previously
been litigated. But we have been pointed to no denial of
plaintiffs’ procedural rights in adjudicating the excep-
tional-case question in this matter. Plaintiffs did not re-
quest a hearing, they had an opportunity to meet the
contentions made in the fees motion, and they have made
no concrete persuasive argument for what discovery was
needed and requested but denied.
                               3
     Nor are we prepared to say that Hi-Tech and Vital
must be denied a fee award, if one is otherwise justified,
just because they did not give early notice of the defects in
plaintiffs’ infringement assertions that later became the
basis for the fee award. Recently, we have stressed that
one consideration that can and often should be important
to an exceptional-case determination is whether the party
seeking fees “provide[d] early, focused, and supported no-
tice of its belief that it was being subjected to exceptional
litigation behavior.” Stone Basket Innovations, LLC v.
Cook Med. LLC, 892 F.3d 1175, 1181 (Fed. Cir. 2018).
Here, the record before us does not reflect Hi-Tech’s or Vi-
tal’s provision of that kind of notice with respect to the
amount-of-arginine issue, whether by filing a motion under
Federal Rule of Civil Procedure 11 or otherwise. Cf. J.A.
11051 n.2 (plaintiffs noting in opposing fees: “If Defendants
thought Plaintiffs’ infringement case was meritless from
day one, they likely would have sent Rule 11 notices at
some point in the last three-and-a-half years, rather than
wait until the case was closed . . . .”). 7 Nevertheless, we see


    7   Suggesting that it gave such notice, Vital points to
a December 2014 email from ThermoLife’s counsel, appar-
ently responding to an assertion by Vital that three of its
18       THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION




no basis for finding the fee award in this matter to be an
abuse of discretion because such notice was missing.
    The § 285 standard is a flexible one within the frame-
work and guidelines established by governing precedents.
We have held that the lack of the early notice described in
Stone Basket can support a denial of attorney’s fees, see
Stone Basket, 892 F.3d at 1181–83, and that the presence
of such notice, followed by continuation of litigation, can be
a factor in justifying an award of attorney’s fees, see Nat’l
Oilwell Varco, L.P. v. Omron Oilfield & Marine, Inc., 676
F. App’x 967, 973 (Fed. Cir. 2017). But we have not held
that such notice is rigidly required. And here, there is rea-
son to avoid what would amount to a retroactive imposition
of a rigid notice requirement. Plaintiffs’ suits against a
large number of defendants, involving numerous products
and several patents and claims, reasonably led not only to
coordination among numerous defendants but to the agree-
ment of all parties, for efficiency, to give priority to the com-
mon issue of validity so that even discovery as to party-
specific issues like infringement could be postponed. In
these circumstances, we think that the district court did
not abuse its discretion in not treating lack of early notice
by Hi-Tech and Vital as a bar to fees if, as the court deter-
mined, plaintiffs failed to undertake an adequate pre-filing




accused products did not infringe the asserted claims of the
’459 patent because they contained citrulline malate, a salt
of another amino acid, as an active ingredient. See J.A.
11589. But that observation does not concern the amount-
of-arginine issue on which the fee award rested here. It
concerned the separate claim limitation forbidding certain
other amino acids, which raised an issue—subject to a
claim construction that presents an obstacle to Vital’s po-
sition, see J.A. 4275—that the district court did not decide
in its fees decision. See supra note 4.
THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION            19



investigation to support their infringement allegations
against Hi-Tech and Vital.
                              B
    We see no abuse of discretion in the inadequate-inves-
tigation determination.
                              1
    Although plaintiffs now contend that the district court
improperly restricted its attention to claim 1 of the ’459 pa-
tent, we see no reversible error in that respect. As we have
noted, plaintiffs in the district court made only a couple of
passing references to the fact that Hi-Tech and Vital fo-
cused their fees motion entirely on that one claim, but they
made no argument showing how the basis for their in-
fringement allegations was stronger for the other asserted
claims than for the ’459 patent’s claim 1. In the absence of
any such showing, we cannot fault the district court for not
separately assessing the reasonableness of plaintiffs’ pre-
suit investigation as to the other asserted claims.
    In this regard, it is worth noting that plaintiffs accused
three of Vital’s products of infringing only the ’459 patent’s
claim 1 and a single Vital product of infringing the asserted
’872 and ’916 patent claims. The latter all contain amount
and/or efficacy requirements. As to Hi-Tech, plaintiffs al-
leged that most of the accused products infringed the ’459
patent’s claim 1, one infringed the asserted ’872 and ’916
patent claims, and several infringed the ’006 patent’s
claims 3, 5, or 14 (one product was not accused of any in-
fringement outside the ’006 patent). Although the ’006 pa-
tent claims stand out from the others at issue (in not
containing amount or efficacy limitations), plaintiffs made
no showing in the district court, and make no showing in
this court, that even if assertion of the ’006 patent claims
was justified, the burdens of this litigation were materially
unaffected by the inclusion of all the other claims in this
20       THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION




case. The district court thus acted properly in limiting its
focus to claim 1 of the ’459 patent.
                              2
     The district court committed no error in finding that
one gram of L-arginine (or its hydrochloride salt) was re-
quired for infringement of that claim. To begin with, con-
trary to plaintiffs’ contention in this court, that finding is
not a matter of claim construction, but of infringement.
The claim requires L-arginine or L-arginine hydrochloride
in “an amount sufficient to enhance endogenous endothe-
lial NO.” ’459 patent, col. 26, lines 44–45. The claim
phrase, which was not construed in this case, requires an
amount that produces a specified effect, so the question of
infringement for that limitation was simply whether a par-
ticular amount being administered by the alleged direct in-
fringer sufficed to produce the effect. 8
    That question is a factual one about how human bodies
operate. It is not a question about what was believed about
the body’s operation at the time of issuance of or applica-
tion for the patent. Contrary to plaintiffs’ contention, it is
immaterial that claim 20 of the ’459 patent, which depends
on claim 1, adds a restriction that the dosage be “in the
range of 0.5−10 g.” ’459 patent, col. 28, lines 43−47. All



     8  Under the 2005 construction in Unither, the ques-
tion for infringement would be whether an administered
amount is “an amount typically administered . . . for the
purpose of” achieving the specified effect. Unither, 2005
WL 6220096, at *10. That question, too, focuses on an
amount to achieve the effect, and it is generally to be ex-
pected that typical administration would come to reflect
what science revealed as the amount needed for the effect.
Plaintiffs have not shown that the Unither construction ap-
plies here or would make a material and favorable differ-
ence to the analysis.
THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION            21



that dependent-claim language covers, by its terms, is any
amount that both falls within the specified range and also
meets the efficacy requirement: it does not declare that all
amounts in the range meet the requirement. Plaintiffs
suggest that the language tends to suggest that applicants
believed in 1993 that, as a matter of science, the low end of
the claimed range would have the required efficacy. But
applicants’ belief, when applying for the patent or later,
does not control the answer to the efficacy question posed
directly by the claim language. Science does.
     The district court thus properly focused on whether,
when plaintiffs sued in 2013, they had done an adequate
investigation of whether the accused products were being
administered in amounts that would produce the claimed
effect. The district court found that one gram was needed
for that purpose. That finding had adequate support in the
record.
    The deposition and trial testimony given by Ther-
moLife’s validity expert provides such support. In the dep-
osition, the expert described knowledge available before
the 2013 filing of these cases:
    [A]ll the studies that were performed after Dr.
    Cooke’s initial study and that showed an increase
    in nitric oxide utilized doses higher than 1.5 to 2
    grams per day in a chronic dosing, whereas several
    studies that have been published and claimed that
    L-arginine is ineffective in increasing nitric oxide
    were using doses of 1 to 1.5 grams and below.
J.A. 10456. Asked “[y]ou said showed 1 gram was ineffec-
tive; is that correct?,” he replied, “1 gram and below was
ineffective.” Id. “Q: According to studies? A: Yes.” Id. At
trial, he was asked: “And administering 1 gram or less of a
supplement is not going to affect the arginine—excuse me,
is not going to meaningfully affect the arginine level in
one’s plasma, correct?” J.A. 10463. He answered: “That’s
22       THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION




correct.” Id. The district court committed no clear error in
finding one gram necessary for the claimed efficacy.
     Finally, given this evidence, we see no error in the dis-
trict court’s attribution to plaintiffs of knowledge of the
one-gram minimum. Their expert testified that this mini-
mum was revealed in the public literature. It is not an
abuse of discretion in these circumstances to fault plaintiffs
for failing to learn this public-literature information before
bringing suit, whether by hiring an expert or otherwise.
                              3
    The district court also committed no reversible error in
determining that plaintiffs did not conduct adequate inves-
tigations to apply the one-gram minimum to the accused
products. Importantly, it was not disputed in the district
court that “all the relevant products were publicly availa-
ble.” Fees Op., 2017 WL 1235766, at *5. Nor was it dis-
puted that plaintiffs could have determined the amounts of
L-arginine or its hydrochloride salt (in the recommended
servings of the accused products) by performing what Vital
characterized as a “simple test.” J.A. 10537; see also J.A.
10710 (Hi-Tech’s motion). Nor, finally, does the record re-
veal that plaintiffs performed such a test.
    We have explained that testing of an accused product
is not necessarily a required part of an adequate pre-filing
investigation. See Intamin Ltd. v. Magnetar Techs., Corp.,
483 F.3d 1328, 1338 (Fed. Cir. 2007) (testing not required
where high obstacles to testing); Q-Pharma, Inc. v. Andrew
Jergens Co., 360 F.3d 1295, 1302−03 (Fed. Cir. 2004) (test-
ing unnecessary for purposes of Rule 11 and § 285 where
the product labels, among other things, supported infringe-
ment). Whether testing is necessary for a responsible ac-
cusation of infringement necessarily depends on the
availability of the products at issue, the existence and costs
of testing, and whether other sufficiently reliable infor-
mation exists. Here, given the deficiencies of the two pos-
sible alternatives to testing (product label ingredient lists
THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION             23



and product advertising), we see no error in the district
court’s determination that this matter was one in which
there was no adequate substitute for simple testing of pub-
licly available products.
    The district court noted that there was some, though
slim, evidence that plaintiffs examined the labels of the ac-
cused products. Fees Op., 2017 WL 1235766, at *5; Recon-
sideration Op., 2017 WL 4792426, at *6; see J.A. 10187
(deposition testimony of ThermoLife’s president). But the
court agreed with Vital and Hi-Tech that the labels of at
least some, perhaps many, of the accused products made
clear that they did not contain one gram of L-arginine or
its hydrochloride salt in a serving. Fees Op., 2017 WL
1235766, at *5–7. The evidence supports that determina-
tion.
     The label of Vital’s NO Synthesize does not list L-argi-
nine or its hydrochloride salt as an ingredient at all. J.A.
10509. 9 The labels of other accused products list L-argi-
nine but in amounts that preclude one gram per serving.
For instance, Hi-Tech’s Stamina Rx, Zencore Plus, and
SizeMatters products list L-arginine as an ingredient, but
all the listed ingredients together total 550, 325, and 550


    9    In the fees proceeding, plaintiffs observed that the
label lists di-L-arginine malate, a non-hydrochloride salt of
L-arginine, though without listing an amount, J.A. 10509,
and plaintiffs asserted that this ingredient would dissoci-
ate to form L-arginine “when the powder product is mixed
with liquid as instructed on the label,” J.A. 11065. But
there is no evidence that plaintiffs had this view of in-
fringement in mind before suing: it is not reflected even in
the amended infringement contentions. See J.A. 6257−58.
Had plaintiffs investigated, they might have found, as
stated in Vital’s evidence credited by the district court, that
the amount was less than 5 milligrams per serving. See
Fees Op., 2017 WL 1235766, at *6 (citing J.A. 11586).
24       THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION




milligrams per serving, respectively. See J.A. 10721; J.A.
10736; J.A. 10739. The Zencore Plus and SizeMatters la-
bels instruct users to take one or two servings, but reaching
the one-gram minimum of L-arginine is impossible (325
milligrams times 2, total ingredients for Zencore Plus) or
quite unlikely (550 milligrams times 2, total ingredients for
SizeMatters) with two servings. Those deficiencies in la-
bels either preclude an accusation of infringement or, at a
minimum, strongly suggest a need for testing.
    To be sure, other accused products have labels that do
not arithmetically preclude more than one gram of L-argi-
nine or its hydrochloride salt per serving. See, e.g., J.A.
10513 (Vital’s NO Shotgun V3 product contained L-argi-
nine as one of several ingredients totaling 9660 milligrams
per serving). Those product labels, however, do not identify
the amount of L-arginine or its hydrochloride salt, so they
can reasonably be deemed insufficient to support an alle-
gation of infringement where, as here, a simple test on eas-
ily acquired products was available to resolve the issue.
Moreover, even if some allegations of infringement were
made with an adequate basis, inclusion of numerous alle-
gations not made with such a basis might so increase de-
fense costs, and alter the litigation or settlement of the
responsible allegations, that such inclusion may weigh in
favor of exceptionality when the defendants end up fully
prevailing.
     Ingredient lists on the labels aside, plaintiffs also relied
for their pre-filing investigation on what may be described
as advertising by the defendants for their products—in-
cluding the non-ingredient portions of labels. In some cir-
cumstances, a potential infringer’s public assertions about
its products may supply, or help to supply, a reliable basis
for a patent owner to allege infringement. See Q-Pharma,
360 F.3d at 1302−03 (“Because Q-Pharma obtained a sam-
ple of the accused product, reviewed Jergens’ statements
made in the advertising and labeling of the accused prod-
uct, and, most importantly, compared the claims of the
THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION             25



patent with the accused product, we conclude that its claim
of infringement was supported by a sufficient factual ba-
sis.”). But the nature and setting of the assertions can sig-
nificantly affect their reliability for that purpose. Here, the
district court properly found that defendants’ advertising
claims were no substitute for simple testing.
     Plaintiffs have not pointed to advertisements that as-
sert the inclusion of more than one gram of L-arginine or
its hydrochloride salt. Advertisement claims to NO-
enhancement effects, made in disregard or ignorance of the
knowledge (available by 2013) that one gram was needed,
may properly be found not to be a reliable basis for plain-
tiffs, justifiably charged with such knowledge, to assert in-
fringement in 2013. In addition, in the fees proceeding,
plaintiffs themselves characterized Hi-Tech’s statements
in the non-ingredient portions of its labels as “bombastic.”
J.A. 11060; see J.A. 11062; Fees Op., 2017 WL 1235766, at
*6. Plaintiffs also attacked the probity of Hi-Tech’s presi-
dent, J.A. 11063−64, and stated that Vital was warned by
the Food and Drug Administration about product adulter-
ation, J.A. 11067 n.8. See Fees Op., 2017 WL 1235766, at
*6. In these circumstances, we see no reversible error in
the district court’s determination that plaintiffs could not
reasonably rely on the advertising at issue for these prod-
ucts as a substitute for simple testing.
                              4
    At oral argument in this court, ThermoLife’s counsel
sought to undermine the one-gram-minimum premise of
the district court’s decision by pointing to statements in the
defendants’ January 2015 invalidity contentions that “any
amount of L-arginine inherently enhances nitric oxide
26        THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION




production.” Oral Arg. at 12:58–13:56 (citing J.A. 10421). 10
We note that those contentions are preceded by extensive
disclaimers that some or all invalidity contentions are
made on a mere assumption of the truth of plaintiffs’ in-
fringement contentions (i.e., the December 2013 amended
infringement contentions). See J.A. 10209. But we do not
further address this argument, which is either an assertion
that defendants are barred from disputing what plaintiffs
should have known about required L-arginine amounts be-
fore filing or an invocation of evidence that plaintiffs never
cited to the district court on that issue, much less said was
significant. No matter how characterized, the argument
comes too late, not having been made to this court in plain-
tiffs’ opening briefs and not having been presented to the
district court. See, e.g., Polara Eng’g Inc. v. Campbell Co.,
894 F.3d 1339, 1355 (Fed. Cir. 2018); SmithKline Beecham
Corp. v. Apotex Corp., 439 F.3d 1312, 1319 (Fed. Cir. 2006).
We will not disturb the district court’s exercise of discretion
on such a basis.
    For those reasons, we find no abuse of discretion in the
district court’s determination that plaintiffs failed to con-
duct an adequate investigation into infringement before fil-
ing suit.
                              B
    Had the district court deemed the matter exceptional
on that basis, considering compensation and deterrence in-
terests, we would find no abuse of discretion. See Inventor
Holdings, LLC v. Bed Bath & Beyond, Inc., 876 F.3d 1372,
1377 (Fed. Cir. 2017) (affirming attorney’s fees award
based on the exceptional weakness of the patentee’s argu-
ments, citing deterrence policy); Lumen View, 811 F.3d at



     10  Vital attached the invalidity contentions to its fees
motion to support its brief argument that plaintiffs’ valid-
ity position made this matter exceptional. J.A. 10532.
THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION           27



481, 483 (affirming fee award based on “ill-supported” alle-
gations of infringement). The district court, however, did
not draw a bottom-line exceptionality conclusion after fin-
ishing its discussion of the Hi-Tech and Vital cases. It con-
tinued with its analysis, addressing the full range of cases
filed by plaintiffs and finding a “pattern of action”—specif-
ically, a pattern of misconduct—that, together with the dis-
cussion tied to the Hi-Tech and Vital cases, supported the
ultimate exceptional-case determination. Fees Op., 2017
WL 1235766, at *7.
     Plaintiffs challenge the significance of four enumerated
findings made by the district court in reaching its pattern-
of-misconduct determination. Considered alone, those
findings would not support a pattern-of-misconduct find-
ing. But those findings do not stand alone. The district
court’s “pattern” determination ultimately is tied to the
finding that plaintiffs failed to conduct an adequate pre-
suit investigation into infringement. Because, as we have
explained, we see no reversible error in that finding, we re-
ject plaintiffs’ challenge to the ultimate “pattern” determi-
nation and affirm the exceptional-case ruling.
    In the first two findings at issue, the district court
noted that plaintiff ThermoLife was at best a very small
seller of nutritional-supplement products (we assume that
Stanford is not a seller of such products at all) and that
plaintiffs brought these suits just a few months before
three of the patents were to expire. Id. We do not consider
what role such facts might play in resolving other patent-
law issues, such as the appropriate remedy where infringe-
ment is found, or even whether they might bear on an ex-
ceptional-case determination resting on a different basis
from the one the district court in this case adopted. Here,
what the district court found was a pattern of misconduct,
and these two facts do not tend to support such a finding.
One of the four patents had five years left on its term, and
even for the three that would soon expire, six years’ worth
of damages for past infringement were potentially
28       THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION




available under 35 U.S.C. § 286. Moreover, the patent stat-
ute does not restrict enforceable patent rights to those who
practice the patent, to the exclusion of research institutions
and their exclusive licensees engaged to perform needed
enforcement activities in which the inventors, or research
institutions, may lack expertise or experience. See Conti-
nental Paper Bag Co. v. Eastern Paper Bag Co., 210 U.S.
405, 424−25 (1908); Broadcom Corp. v. Qualcomm Inc., 543
F.3d 683, 703 (Fed. Cir. 2008); Rite-Hite Corp. v. Kelley Co.,
Inc., 56 F.3d 1538, 1547 (Fed. Cir. 1995); cf. eBay Inc. v.
MercExchange, L.L.C., 547 U.S. 388, 393 (2006) (rejecting
categorical exclusion of non-practitioners from injunctive
remedy).
    The more significant findings by the district court were
that plaintiffs brought many suits and settled many for
“seemingly small” amounts. Fees Op., 2017 WL 1235766,
at *7. But even those findings do not show misconduct
without the additional evidence of inadequate pre-suit in-
vestigation.
    “[A] pattern of litigation abuses characterized by the
repeated filing of patent infringement actions for the sole
purpose of forcing settlements, with no intention of testing
the merits of one’s claims, is relevant to a district court’s
exceptional case determination under § 285.” SFA Sys.,
LLC v. Newegg Inc., 793 F.3d 1344, 1350 (Fed. Cir. 2015)
(emphases added); see Eon-Net LP v. Flagsar Bancorp, 653
F.3d 1314, 1324−28 (Fed. Cir. 2011) (relying on litigation
misconduct and baseless infringement assertions). We
have emphasized, however, that filing a large number of
suits does not, by itself, justify an inference of such an im-
proper motive. SFA Sys., 793 F.3d at 1351 (“The mere ex-
istence of these other suits does not mandate negative
inferences about the merits or purpose of this suit.”). A pa-
tent might apply in similar fashion to the activities of nu-
merous persons, such as numerous sellers of similar
products, and a patentee may have a legitimate interest in
pressing reasonably grounded claims against all or many
THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION             29



of them, whether to obtain compensation or to deter disre-
gard of these or other patent rights or for other reasons.
See Checkpoint Sys., Inc. v. All-Tag Sec. S.A., 858 F.3d
1371, 1375 (Fed. Cir. 2017) (distinguishing legitimate “mo-
tivation to implement the statutory patent right by bring-
ing suit based on a reasonable belief in infringement” from
motivation “to harass or burden an opponent”); King In-
struments Corp. v. Perego, 65 F.3d 941, 950 (Fed. Cir. 1995)
(recognizing deterrence value of enforcement actions). As
a procedural matter, moreover, Congress has required sep-
arate suits in circumstances like the one before us. 35
U.S.C. § 299. 11
      Similarly, “there is no minimum damages requirement
to file a patent infringement case,” and “[a]sserting seem-
ingly low damages against multiple defendants—or set-
tling with defendants for less than the cost of litigation—
does not necessarily make a case ‘exceptional’ under § 285.”
AdjustaCam, LLC v. Newegg, Inc., 861 F.3d 1353, 1361
(Fed. Cir. 2017). A patent plaintiff may be able to distrib-
ute common costs over many suits, making each suit
worthwhile even on its terms, let alone as a deterrent to
others who might disregard the plaintiff’s patent rights.
The economics of such cost-distribution is familiar from the
related context of class actions. See, e.g., Epic Sys. Corp. v.
Lewis, 138 S. Ct. 1612, 1632 (2018) (“[C]lass actions can
enhance enforcement by spreading the costs of litigation
. . . .” (internal quotation marks and alteration omitted)).
    As for settlement amounts, a low figure might simply
reflect the small size of an individual defendant’s potential
liability. Indeed, the figure may result from what the


    11  To the extent that the district court here referred
to plaintiffs’ filing of suits on other patents, see Fees Op.,
2017 WL 1235766, at *7 (noting that ThermoLife filed 117
cases in 2013), it cited nothing to suggest the unreasona-
bleness of any of those other suits.
30       THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION




Supreme Court has recognized as the normal, legitimate
settlement calculus, which includes consideration of litiga-
tion costs: a prediction of the amount of liability, “dis-
counted by its probability, plus the transaction costs of
further litigation.” Evans v. Jeff D., 475 U.S. 717, 734
(1986); see Prism Techs. LLC v. Sprint Spectrum L.P., 849
F.3d 1360, 1369 (Fed. Cir. 2017). A court must therefore
be cautious in inferring bad faith from the “small dollar
amounts” of settlements, which is all the district court in
this case found, without further findings about, for exam-
ple, the value of the claims. Fees Op., 2017 WL 1235766,
at *7.
    For those reasons, and noting the fact that plaintiffs
pressed their claims to judgment through extensive litiga-
tion on the merits, we agree with plaintiffs that the four
findings whose significance plaintiffs criticize on appeal
would not, standing alone, show “litigation abuses” or “the
repeated filing of patent infringement actions for the sole
purpose of forcing settlements, with no intention of testing
the merits of [the] claims.” SFA Sys., 793 F.3d at 1350. In
other words, those findings would not themselves establish
misconduct in the form of imposing burdens solely to ex-
tract “nuisance-value settlements.” Fees Op., 2017 WL
1235766, at *7.
     We nevertheless reject plaintiffs’ argument that the
“pattern” portion of the district court’s opinion infects the
ultimate determination of exceptionality. The four find-
ings we have discussed do not stand alone. What the dis-
trict court found is a “pattern of action” by plaintiffs of
bringing “suit against many defendants without carefully
reviewing their claims.” Id. (emphasis added). The district
court, which oversaw the full group of more than six dozen
suits, thus viewed the inadequacy of plaintiffs’ pre-filing
investigation as extending beyond the two suits against Hi-
Tech and Vital to the group more generally. Plaintiffs have
not shown reversible error in that finding if, as we have
THERMOLIFE INTERNATIONAL LLC v. GNC CORPORATION             31



concluded, there is no reversible error in the inadequate-
investigation finding as to the Hi-Tech and Vital suits.
    The “pattern” part of the district court’s opinion thus
rests on a finding, which we accept, that plaintiffs’ irre-
sponsible filing of infringement allegations extended
widely beyond the two cases before us. The remainder of
the discussion in the “pattern” portion of the district court’s
opinion may add nothing significant to that finding, but it
does not undermine the finding. On that basis, which en-
hances the force of the deterrence policy as applied here,
we see no abuse of discretion in the ultimate determination
of exceptionality.
                              III
    For the foregoing reasons, we affirm the district court’s
judgment.
                        AFFIRMED
