  United States Court of Appeals
      for the Federal Circuit
                 ______________________

HZNP MEDICINES LLC, HORIZON PHARMA USA,
                    INC.,
            Plaintiffs-Appellants

                            v.

        ACTAVIS LABORATORIES UT, INC.,
            Defendant-Cross-Appellant
              ______________________

2017-2149, 2017-2152, 2017-2153, 2017-2202, 2017-2203,
                      2017-2206
               ______________________

    Appeals from the United States District Court for the
District of New Jersey in Nos. 1:14-cv-07992-NLH-AMD,
1:15-cv-05025-NLH-AMD, 1:15-cv-06131-NLH-AMD, 1:15-
cv-06989-NLH-AMD, 1:15-cv-07742-NLH-AMD, 1:16-cv-
00645-NLH-AMD, Judge Noel Lawrence Hillman.
                 ______________________

                Decided: October 10, 2019
                 ______________________

    CARYN BORG-BREEN, Green, Griffith & Borg-Breen
LLP, Chicago, IL, argued for all plaintiffs-appellants. Also
represented by ROBERT FRITZ GREEN, JESSICA MACKAY.

    MICHAEL E. JOFFRE, Sterne Kessler Goldstein & Fox,
PLLC, Washington, DC, argued for defendant-cross-appel-
lant. Also represented by JOHN CHRISTOPHER ROZENDAAL,
KRISTINA CAGGIANO KELLY, WILLIAM H. MILLIKEN.
2         HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




                   ______________________

    Before PROST, Chief Judge, NEWMAN and REYNA, Circuit
                           Judges.
      Opinion for the court filed by Circuit Judge REYNA.
Opinion concurring in part and dissenting in part filed by
                Circuit Judge NEWMAN.
REYNA, Circuit Judge.
     HZNP Medicines LLC and Horizon Pharma USA, Inc.
(“Horizon”) appeal from the U.S. District Court for the Dis-
trict of New Jersey’s judgment of invalidity and nonin-
fringement. Actavis Laboratories UT, Inc. (“Actavis”)
cross-appeals the district court’s judgment of nonobvious-
ness. We affirm.
                        BACKGROUND
    Horizon 1 is the assignee of U.S. Patent Nos. 8,217,078
(“the ’078 patent”); 9,132,110 (“the ’110 patent”); 8,618,164
(“the ’164 patent”); 9,168,304 (“the ’304 patent”); 9,168,305
(“the ’305 patent”); 8,546,450 (“the ’450 patent”); 9,101,591
(“the ’591 patent”); 8,563,613 (“the ’613 patent”); 9,220,784
(“the ’784 patent”); 8,871,809 (“the ’809 patent”); 8,252,838
(“the ’838 patent”); and 9,066,913 (“the ’913 patent”) (col-
lectively, “the patents-at-issue” or “Horizon’s patents”).
The patents-at-issue generally relate to methods and com-
positions for treating osteoarthritis and can be divided into



      1 During the pendency of this appeal, HZNP Medi-
cines LLC substituted itself as plaintiff-appellant for Hori-
zon Pharma Ireland Limited and HZNP Limited,
explaining that it is now the lawful holder and owner of
New Drug Application No. 204623 and of U.S. Patent
Nos. 8,217,078; 8,252,838; 8,546,450; 8,563,613; 9,066,913;
9,101,591; 9,132,110; 9,168,304; 9,168,305; and 9,220,784.
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.         3



two groups, with the patents in each group sharing a sub-
stantially similar specification.
     The first group of patents consists of method-of-use pa-
tents, including the ’450, ’078, ’110, and ’164 patents. (the
“method-of-use patents”). Claim 10 of the ’450 patent is
illustrative of the asserted claims of the method-of-use pa-
tents:
    10. A method for applying topical agents to a knee
    of a patient with pain, said method comprising:
        applying a first medication consisting of a
        topical diclofenac preparation to an area of
        the knee of said patient to treat osteoar-
        thritis of the knee of said patient, wherein
        the topical diclofenac preparation com-
        prises a therapeutically effective amount of
        a diclofenac salt and 40–50% w/w dimethyl
        sulfoxide;
        waiting for the treated area to dry;
        subsequently applying a sunscreen, or an
        insect repellant to said treated area after
        said treated area is dry, wherein said step
        of applying a first medication does not en-
        hance the systemic absorption of the subse-
        quently applied sunscreen, or insect
        repellant; and
        wherein said subsequent application oc-
        curs during a course of treatment of said
        patient with said topical diclofenac prepa-
        ration.
’450 patent col. 73 l. 35–col. 74 l. 11.
    The second group of patents consists of formulation pa-
tents, including the ’838, ’591, ’304, ’305, ’784, ’613, ’809,
and ’913 patents. (the “formulation patents”). Claim 49 of
4       HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




the ’838 patent is illustrative of the asserted claims of the
formulation patents:
    49. A topical formulation consisting essentially of:
        1–2% w/w diclofenac sodium;
        40–50% w/w DMSO;
        23–29% w/w ethanol;
        10–12% w/w propylene glycol;
        hydroxypropyl cellulose; and
        water to make 100% w/w, wherein the top-
        ical formulation has a viscosity of 500–5000
        centipoise.
’838 patent col. 30 ll. 60–67.
    Both groups of patents are listed in the U.S. Food and
Drug Administration’s (“FDA”) Approved Drug Products
with Therapeutic Equivalence Evaluations (“Orange Book”)
for Horizon’s PENNSAID® 2% product. PENNSAID® 2%
is a nonsteroidal anti-inflammatory drug (“NSAID”) and
the first FDA-approved twice-daily topical diclofenac so-
dium formulation for the treatment of pain of osteoarthritis
of the knees.
    Relevant to the development of PENNSAID® 2% is
prior art PENNSAID® 1.5%. PENNSAID® 1.5% also
treats osteoarthritis knee pain but differs from
PENNSAID® 2% both in formulation and recommended
dosage. As to dosage, PENNSAID® 1.5% directs the user
to administer the formulation by applying 40 drops of
PENNSAID® 1.5% on each painful knee, four times a day.
J.A. 6923. PENNSAID® 2% improved upon this dosing
regimen by reducing the frequency of application to a rec-
ommended dose of 40 mg of the formulation, applied
through “2 pump actuations on each painful knee, 2 times
a day.” J.A. 6649–51.
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.          5



     Actavis sought to market a generic version of
PENNSAID 2% and filed Abbreviated New Drug Applica-
tion (“ANDA”) No. 207238. 2 The ANDA included a certifi-
cation under 21 U.S.C. § 355(j)(2)(A)(vii)(IV) (“Paragraph
IV certification”), stating that the patents-at-issue were in-
valid or would not be infringed by Actavis’s generic prod-
uct. The filing of an ANDA with a Paragraph IV
certification constitutes an act of artificial patent infringe-
ment under 35 U.S.C. § 271(e)(2)(A), which allows litiga-
tion to commence before actual sale of an accused product
has occurred. Vanda Pharm. Inc. v. West-Ward Pharm.
Int’l Ltd., 887 F.3d 1117, 1126 (Fed. Cir. 2018).
    On December 23, 2014, after receiving notice of Ac-
tavis’s Paragraph IV certification, Horizon filed suit in the
District of New Jersey, alleging infringement of the pa-
tents-at-issue under § 271(e)(2)(A).
                   I. Claim Construction
     At the district court, the parties disputed the construc-
tion of various terms in the asserted claims. Both sides
filed claim construction briefs. The district court conducted
Markman hearings on March 3, 2016, and June 7, 2016.
On August 17, 2016, the district court issued its Markman
order, finding three terms in the asserted claims of the for-
mulation patents to be indefinite.
    First, the district court found that the term “the topical
formulation produces less than 0.1% impurity A after 6
months at 25°C and 60% humidity” was indefinite because



    2   Watson Laboratories, Inc., (“Watson”) was the
holder of the ANDA when it was filed with the FDA. Wat-
son later changed its name to Actavis Laboratories UT, Inc.
Actavis is now the holder of the ANDA. For simplicity, we
refer to Watson and Actavis Laboratories, UT Inc. as Ac-
tavis.
6       HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




the identity of “impurity A” is unknowable to a person of
ordinary skill in the art (“POSITA”).
    Second, the district court found that the term “the for-
mulation degrades by less than 1% over 6 months” was in-
definite because neither the claims nor the specification
disclose the means to evaluate degradation.
    Third, the district court found that the term “consisting
essentially of” was indefinite. In that regard, the district
court began by recognizing that the phrase “consisting es-
sentially of,” when used in a formulation patent, reflects
that the recited formulation includes (a) the listed ingredi-
ents that follow the phrase, and (b) unlisted ingredients
that do not materially affect the basic and novel properties
of the invention. See J.A. 14–15 (citing PPG Indus. v.
Guardian Indus. Corp., 156 F.3d 1351, 1354 (Fed. Cir.
1998)). Because the parties disputed the basic and novel
properties, the district court determined that in this case
identification of those properties was required. The district
court therefore concluded that “[b]ecause the basic and
novel properties of an invention are part of the construction
of a claim containing the phrase ‘consisting essentially of,’
the Nautilus standard applies to the assessment of an in-
vention’s basic and novel properties.” J.A. 22–23 (citing
Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898, 910
(2014)).
    Turning to the basic and novel properties of the inven-
tion, the district court noted that the specification identi-
fied five properties: (1) better drying time; (2) higher
viscosity; (3) increased transdermal flux; (4) greater phar-
macokinetic absorption; and (5) favorable stability.
The district court focused on the “better drying time” prop-
erty and held that this basic and novel property was indef-
inite. In doing so, the district court emphasized that the
specification described two different methods for evaluat-
ing “better drying time.” Those two methods, however, did
not provide consistent results at consistent times. Faced
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.          7



with this inconsistency, the district court was persuaded by
expert testimony that a POSITA would not know under
which standard to evaluate the drying rate of the claimed
invention. According to the district court, this prevented a
POSITA from being able to have “reasonable certainty”
about the scope of the basic and novel properties of the in-
vention, thereby rendering the term “consisting essentially
of” indefinite. J.A. 27.
    On August 30, 2016, Horizon filed a motion for recon-
sideration of the claim construction. Horizon argued that
the district court erred by failing to consider indefiniteness
on a claim-by-claim basis. Horizon also contended that it
had been prevented from fully developing the record in re-
lation to the “better drying time” property. On January 4,
2017, the district court conducted a hearing on the motion
for reconsideration, and on January 6, 2017, it issued an
opinion denying Horizon’s motion for reconsideration and
maintaining its initial claim constructions and indefinite-
ness determinations.
     The district court concluded that Horizon’s arguments
on reconsideration lacked merit. As to the claim-by-claim
argument, the district court noted that Horizon chose to
address the issue in relation to the formulation patents as
a whole, and that this was a new argument raised for the
first time in a motion for reconsideration, which is im-
proper. The district court also found that Horizon had am-
ple notice and opportunity to present evidence and develop
the record during the two Markman hearings, the supple-
mental briefing in between those hearings, and during the
ten weeks between the second hearing and the Markman
order.
     The district court bolstered its conclusion that the basic
and novel properties were indefinite by analyzing the “fa-
vorable stability” property, which had not been addressed
in the initial Markman order. Because the specification
failed to provide the requisite guidance for a POSITA to
8       HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




evaluate stability, the district court found that the “favor-
able stability” property was indefinite which in this case,
by extension, rendered the phrase “consisting essentially
of” indefinite.
                  II. Summary Judgment
     On January 27, 2017, after the district court reaffirmed
its claim constructions and related indefiniteness determi-
nations, Actavis filed a motion for summary judgment of
noninfringement. Actavis argued that there was no dis-
pute that Actavis did not directly infringe the patents-at-
issue, and that, while Horizon premised its allegations of
induced infringement upon the labeling of Actavis’s ANDA
product, there was also no material factual dispute that Ac-
tavis’s proposed label does not induce infringement.
    In evaluating the inducement argument, the district
court considered, among other things, the asserted claims
of the method-of-use patents and the respective labels for
both Horizon’s and Actavis’s products. As to the asserted
claims of the method-of-use patents, the district court
found that Horizon’s claimed methods required the follow-
ing steps: (1) application of the medication to knee, (2) wait-
ing for the area to dry, and (3) application of sunscreen,
insect repellant, or a second topical medication. To perform
Horizon’s claimed methods, all the steps must be con-
ducted.
     Turning to the parties’ respective labels, according to
the district court, both were essentially the same; the main
distinction being that Actavis’s proposed ANDA label re-
placed “PENNSAID” with “diclofenac sodium topical solu-
tion.” In relevant part, the parties’ labels warn to “[w]ait
until the treated area is dry” before applying a second top-
ical agent, such as sunscreen, insect repellant, or covering
the area with clothing. The district court held that this
warning was insufficient to show induced infringement be-
cause Horizon’s claimed method requires application of a
second topical agent whereas the label merely permits,
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.      9



without encouraging, post-product application of sun-
screen, insect repellant, or a second topical medication.
The district court thus granted summary judgment in Ac-
tavis’s favor, concluding that Horizon had not met its bur-
den to show that Actavis’s label induced infringement of
the method-of-use patents.
                         III. Trial
     The district court’s Markman and summary-judgment
orders disposed of most of the asserted claims of the pa-
tents-at-issue. At trial, only one claim remained—claim 12
of the ’913 patent. Actavis maintained that claim 12 of the
’913 patent was invalid as obvious. Actavis stipulated that
if the claim was found not invalid at trial, its ANDA prod-
uct would infringe the claim. The stipulation thus nar-
rowed the trial court’s focus to obviousness.
    Actavis’s obviousness theory was that the changes
made to PENNSAID® 1.5%, which resulted in the
PENNSAID® 2% formulation, would have been obvious to
a POSITA based upon the prior art available at the time of
the invention.
10       HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




    The formulation differences between PENNSAID®
1.5% and PENNSAID® 2% (as recited in claim 12 of the
’913 patent) 3 are as follows:




J.A. 15915 (table generated by the district court). Each of
the ingredients listed above performs a specific function.
Diclofenac sodium is the active ingredient. Dimethyl sul-
foxide (“DMSO”) is a penetration enhancer, which en-
hances absorption of the drug into the skin. Ethanol is both
a solvent, which dissolves the active ingredient for absorp-
tion of the drug into the skin, and a penetration enhancer.
Propylene glycol is a solvent. Hydroxypropyl cellulose
(“HPC”) is a thickening agent, which increases the viscosity
of a formulation. Glycerin is a humectant, which is a non-
volatile substance that holds water onto the skin. And wa-
ter is a solvent.
   Actavis contended that the drawbacks to PENNSAID®
1.5%—frequent application and vulnerability to run-off—




     3  Claim 12 of the ’913 patent recites a method for ap-
plying the formulation that is collectively recited in claims
1, 8, and 9.
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.        11



were known, and that a POSITA would have been moti-
vated to modify PENNSAID® 1.5% to address these draw-
backs by: (a) increasing the absorption to reduce
application frequency; (b) thickening the formulation; and
(c) reducing the drying time to prevent run-off. Actavis
proposed that a POSITA would have had a reasonable ex-
pectation that these modifications would address the
known drawbacks.         Actavis also pointed out that
PENNSAID® 1.5% included all of the ingredients required
by claim 12 of the ’913 patent except for a thickener (the
HPC), in addition to the claimed amounts of DMSO, pro-
pylene glycol, and water. As to the remaining limitations
in claim 12, Actavis maintained that they were disclosed in
the prior art. Actavis argued that all the changes were ob-
vious optimizations of result-effective variables that pro-
duced a predictable result in relation to absorption,
thickness, and drying times.
    Horizon, on the other hand, argued that the changes
made to PENNSAID® 1.5% were not routine optimiza-
tions, and that the results of the various changes could not
be predicted by the prior art. According to Horizon, the
prior art reflects that the field of topical pharmaceutical
formulations is complex and unpredictable. And to arrive
at the formulation recited in claim 12 of the ’913 patent,
Horizon maintains that a POSITA would have had to:
   (1) increase the diclofenac concentration from 1.5%
   to exactly 2%, (2) increase the concentration of eth-
   anol from 11% to exactly the range of 23–29%, (3)
   add a thickening agent, (4) choose the thickening
   agent to be HPC, (5) identify the concentration of
   HPC to be exactly 2.5%, (6) select a viscosity range
   of between 500 and 5000 cps, and then (7) decide
   not to change the concentrations of DMSO or pro-
   pylene glycol, but instead (8) remove or reduce glyc-
   erin and/or water to account for the increases in
   diclofenac, ethanol and thickening agent concen-
   trations and still total 100%, and the [POSITA]
12       HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




     would also have had to change the method of ad-
     ministration from 3–4 times per day to twice a day
     [despite knowing that increasing viscosity makes it
     harder for drug molecules to penetrate the skin.]
J.A. 15921–22.
   Trial began on March 21, 2017, and continued until
March 30, 2017. The parties filed post-trial submissions on
April 20, 2017.
    On May 12, 2017, the district court found that Actavis
had not shown, by clear and convincing evidence, that
claim 12 of the ’913 patent is invalid for obviousness. On
May 22, 2017, the district court entered a final judgment
consistent with its holdings and conclusions in the Mark-
man order, the summary-judgment order, and the post-
trial findings of fact and conclusions of law. Since claim 12
of the ’913 patent was found to be nonobvious and Actavis
had stipulated to infringement of that claim if it was
deemed not invalid at trial, the district court ordered that
Actavis be enjoined from engaging in the commercial use,
offer for sale, or sale of its ANDA product until the expira-
tion of the ’913 patent.
    Horizon appeals and Actavis cross-appeals the district
court’s final judgment. We have jurisdiction under 28
U.S.C. § 1295(a)(1).
                        DISCUSSION
    We first address Horizon’s appeal and then Actavis’s
cross-appeal.
                    I. Horizon’s Appeal
    Horizon’s appeal proceeds on two fronts. First, Horizon
contests the district court’s holding on claim construction
that the terms “impurity A”; “degrades at less than 1% over
6 months”; and “consisting essentially of” are indefinite.
Second, Horizon challenges the district court’s holding, on
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.        13



summary judgment, that Actavis’s ANDA label did not in-
duce infringement. For the reasons below, we affirm.
                     A. Indefiniteness
    We review indefiniteness determinations de novo. In-
terval Licensing LLC v. AOL, Inc., 766 F.3d 1364, 1370
(Fed. Cir. 2014). A claim is invalid for indefiniteness if its
language, read in light of the specification and prosecution
history, “fail[s] to inform, with reasonable certainty, those
skilled in the art about the scope of the invention.” Nauti-
lus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898, 901
(2014). General principles of claim construction apply to
indefiniteness allegations. Biosig Instruments, Inc. v. Nau-
tilus, Inc., 783 F.3d 1374, 1377–78 (Fed. Cir. 2015). Ac-
cordingly, we review a district court’s determinations of
subsidiary facts based upon extrinsic evidence for clear er-
ror, and those based upon intrinsic evidence (the patent
claims, specification, and prosecution history) de novo. Id.
    The district court found that a POSITA would not have
understood, with reasonable certainty, the scope of the
claims reciting (1) “impurity A,” (claim 4 of the ’913 pa-
tent); 4 (2) a formulation that “degrades at less than 1% over
6 months” (asserted claims of the ’613 patent and claims
10–11 and 19 of the ’591 patent); and (3) a formulation
“consisting essentially of” specified ingredients (asserted
claims of the ’838, ’304, ’305, and ’784 patents and claims
12–15, 17, 19, and 24–25 of the ’591 patent). It thus held
that those claims were indefinite. We address each of those
conclusions in turn.




    4   As noted above, claim 12 of the ’913 patent pro-
ceeded to trial. Of the asserted claims of the ’913 patent,
only claim 4 was implicated by the district court’s claim
construction and indefiniteness determination.
14      HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




                      1. “Impurity A”
    Claim 4 of the ’913 patent recites a “topical formulation
produc[ing] less than 0.1% [of] impurity A after 6 months
at 25° C[] and 60% humidity.” ’913 patent col. 30 ll. 22–24.
The district court concluded that “impurity A” is indefinite
because a POSITA would not know, with reasonable cer-
tainty, the identity of the substance as claimed. We agree.
     The term “impurity A” only appears in claim 4 and Ex-
ample 6 of the ’913 patent. Example 6 examines “the sta-
bility of the compositions of the present invention . . . at
room temperature over a six month period.” ’913 patent
col. 25 ll. 36–38. To do so, the example refers to a study
where samples were placed into sealed plastic screw cap
bottles and then stored at 25°C and 60% humidity for six
months. Id. col. 25 ll. 47–49. After six months of storage,
“the samples were tested for impurities by high perfor-
mance liquid chromatography (HPLC).” Id. col. 25 ll. 49–
51.
    According to Example 6, this test revealed two unex-
pected findings: (1) that the composition of the invention
contained a higher concentration of the active agent while
resulting in a “lower concentration of a degradation impu-
rity”; and (2) “that compositions using hydroxypropylcellu-
lose (HPC) as the gelling agent had a significantly lower
quantity of this impurity as compared to compositions
made using carbomer gelling agents.” Id. col. 25 ll. 38–46.
In discussing the results of the study, the example refers to
“an impurity, termed ‘impurity A,’ [which] was seen to
elute at about 6.6 minutes in varying amounts for the var-
ious [tested] compositions.” Id. col. 25 ll. 54–56. Table 13
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.        15



shows the percentage of “impurity A” in relation to the
tested compositions:




Id. col. 25 ll. 57–66.
     The example goes on to remark that the appearance of
“a lower percentage of ‘impurity A’” in the formulation
“containing 3.5% HPC shows a higher degree of stability.”
Id. col. 26 ll. 1–5. It also states that the “reduction in the
level of impurity A” in the HPC gel formulation, as com-
pared to the formulation containing 0.9% Carbopol, shows
that the former “is more stable than” the latter. Id. col. 26
ll. 7–11. Because of that, it concludes that “the present in-
vention provides improved stability,” which is evidenced by
the “degrad[ation of] less than 0.034% or 0.09%” over the
six-month period. Id. col. 26 ll. 11–16. Lastly, the example
notes that “the amount of ‘impurity A’ found [was] . . . well
below [the] limits that would require additional nonclinical
testing of the impurity.” Id. col. 26 ll. 16–19.
    Although the specification does not define “impurity
A,” Horizon argues that a POSITA would understand the
term to mean “USP Related Diclofenac Compound A.”
(“USP Compound A”). According to Horizon, a POSITA
versed in the pertinent prior art would be able to ascertain
the meaning of “impurity A” based on the intrinsic evi-
dence. It is undisputed that the intrinsic evidence does not
16      HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




explicitly refer to USP Compound A, or its chemical formu-
lation, in relation to “impurity A.” Still, Horizon maintains
that, consulting the available pharmacopeias at the time, a
POSITA would know “impurity A” refers to a specific im-
purity of diclofenac sodium. Horizon posits that because
the specification refers to “impurity A” as a degradation of
diclofenac sodium, which is the only component of the in-
ventive formulation with a known impurity, a POSITA
would know this term refers to “USP Related Diclofenac
Compound A RS.”
     Actavis argues that the specification does not provide
any clues as to the identity of “impurity A,” which implies
that “impurity A” is an unknown impurity. According to
Actavis’s expert, a POSITA reading the specification would
read “impurity A” as referring to an unknown impurity be-
cause the specification: (a) does not disclose the chemical
name of the impurity, which would be expected if such were
known; (b) uses quotes to refer to “impurity A,” suggesting
that it is not the formal name of a known impurity; and (c)
justifies not conducting additional tests to identify the im-
purity merely because it occurs in low amounts. Actavis
contends that the only relevant disclosure in the specifica-
tion about “impurity A” is in relation to Example 6. But,
citing to its expert’s declaration, Actavis maintains that
the information in Example 6 is insufficient to allow a
POSITA to determine the identity of “impurity A.” For in-
stance, Actavis’s expert opined that the specification offers
no information about the HPLC procedure used, including
the column type, mobile solvent, and temperature used for
the HPLC analysis reported. Moreover, Actavis contends
that Example 6’s observation that the amount of “impurity
A” is so low that no “additional nonclinical testing” is re-
quired implies further testing was necessary to ascertain
the identity of “impurity A.”
   As to Horizon’s reliance on pharmacopeias, Actavis ar-
gues that the district court did not clearly err in rejecting
Horizon’s view on what a POSITA would have surmised
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.        17



from those pharmacopeias. Actavis points out that the
specification never mentions USP Diclofenac Related Com-
pound A RS, which is a degradation of the active ingredi-
ent. Actavis also states that the claims refer to the
degradation of the entire formulation—including other ex-
cipients (inactive ingredients)—as opposed to the degrada-
tion of the diclofenac sodium, the active ingredient. Actavis
argues that even in light of the pharmacopeias, there is
considerable doubt as to whether a POSITA would read
“impurity A” to mean an impurity of the formulation as op-
posed to that of the active ingredient.
    We find no error in the district court’s conclusion that
“impurity A” is indefinite. First, we look to the language of
the claims to evaluate if the meaning of “impurity A” is rea-
sonably clear. Berkheimer v. HP Inc., 881 F.3d 1360, 1363
(Fed. Cir. 2018) (“We look first to the language of the claim
to determine whether the meaning of [the term] is reason-
ably clear.”). Claim 4 of the ’913 patent depends upon claim
1. Claim 1 recites:
    1. A topical formulation comprising:
        diclofenac sodium present at 2% w/w;
        DMSO present at about 40 to about 50%
        w/w;
        ethanol present at 23–29% w/w;
        propylene glycol present at 10–12% w/w;
        hydroxypropyl cellulose; and
        water to make 100% w/w,
        wherein the formulation has a viscosity of
        500–5000 centipoise.
’913 patent col. 30 ll. 9–17. Claim 4 then recites the topical
formulation of claim 1, wherein such formulation “produces
less than 0.1% impurity A after 6 months at 25° C[] and
18      HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




60% humidity.” Id. col. 30 ll. 22–24. Although Horizon at-
tempts to tie “impurity A” to diclofenac sodium, Actavis is
correct to point out that the claims do not support such a
result. Claim 4 refers to the entire topical formulation of
claim 1, which includes several other excipients. The
claims thus do not make clear that “impurity A” refers to
an impurity of diclofenac sodium.
    Looking beyond the language of the claims, it is also
undisputed that the written description contains no refer-
ences to USP Compound A or its chemical name. Indeed,
Horizon does not cite to any part of the specification, the
claims, or the prosecution history that defines or directly
connects “impurity A” to USP Compound A. The only part
of the specification that uses the term “impurity A” is Ex-
ample 6, which contains “[t]he only identity information
provided for ‘impurity A.’” J.A. 9. That information con-
sists of “retention times derived from a high performance
liquid chromatography (‘HPLC’).” Id. The specification,
however, is devoid of other information about the condi-
tions of the HPLC experiment, such as the column, the mo-
bile phase, and the flow rate. Thus, the written description
provides no clue as to the identity of “impurity A.”
    Next, we turn to extrinsic evidence. Horizon attempted
to connect “impurity A” to USP Compound A through phar-
macopoeias and its expert’s opinion. The district court con-
sidered that evidence but found that Horizon’s expert did
not explain why a POSITA would know that the HPLC test
in Example 6 was undertaken using a pharmacopoeia chro-
matographic system. The district court understood this to
mean that the basis upon which Horizon’s entire argument
rests—that a POSITA familiar with pharmacopoeias would
understand “impurity A,” as used in Example 6, to be USP
Compound A—is incorrect. We agree.
    The district court emphasized that none of the “refer-
ences relied upon by [Horizon’s expert] . . . that use [a]
pharmacopoeia chromatographic system omit the details of
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.        19



the HPLC experiment . . . or identify USP Compound A by
anything other than its actual chemical formula and/or
structure.” J.A. 11. Put differently, because the specifica-
tion omits the details of the HPLC experiment—such as the
column, the mobile phase, and the flow rate—a POSITA
faced with this specification would not reasonably presume
that Example 6 was undertaken using a pharmacopoeia
chromatographic system. This outcome undermines Hori-
zon’s reliance on the pharmacopoeias to extrapolate mean-
ing into “impurity A.”
     We see no clear error in the district court’s determina-
tion, based upon the extrinsic evidence, that “impurity A”
is indefinite when used in the context of Example 6, which
lacks sufficient information about the HPLC procedure to
enable a POSITA to ascribe meaning to “impurity A” with
reasonable certainty. See Eli Lilly & Co. v. Teva Parenteral
Medicines, Inc., 845 F.3d 1357, 1371–72 (Fed. Cir. 2017)
(finding that the district court did not clearly err in deter-
mining, based on extrinsic evidence, what a POSITA would
understand “vitamin B12” to mean in a medical context);
Akzo Nobel Coatings, Inc. v. Dow Chem. Co., 811 F.3d 1334,
1343–44 (Fed. Cir. 2016) (finding that the district court did
not clearly err in determining, based on extrinsic evidence,
that a POSITA would measure viscosity at room tempera-
ture if no other temperature is specified); Berkheimer, 881
F.3d at 1363–64 (affirming district court’s conclusion that
“minimal redundancy” limitation was indefinite because
the subsidiary finding of fact that a POSITA would not
have known what the term meant as used in claim was not
clearly erroneous). To be clear, we do not hold that a refer-
ence to an impurity is indefinite in all contexts, only that
on this record, the term “impurity A” is indefinite.
20       HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




                       2. “Degrades”
    Claims 1–5, 9–19, and 22–24 of the ’613 patent, and
claims 10–11 and 19 of the ’591 patent, recite a topical for-
mulation that “degrades [by/at] 5 less than 1% over 6
months” (the “degrades” term). 6 ’613 patent col. 27 l. 7–col.
28 l. 55; ’591 patent col. 27 l. 6–col. 28 l. 21. The district
court found this term indefinite because the specification
did not identify the means of degradation. We agree.
    The district court’s finding that the claims reciting the
“degrades” term are indefinite follows from the indefinite-
ness determination about “impurity A.” This is so because
Horizon’s proposed construction for the “degrades” term
was “[l]ess than 1% of Impurity A (USP Diclofenac Related
Compound A RS) present in a formulation sample after the
sample was maintained at 25°C and 60% humidity for 6
months.” J.A. 12, 883. Since “impurity A” is indefinite, it
logically follows that another term, such as the “degrades”
term, which relies on “impurity A” for its construction,
must also be indefinite. Based on the district court’s indef-
initeness determination about “impurity A,” which we af-
firm, we conclude that its finding about the “degrades”
term should also be affirmed.
               3. “Consisting Essentially Of”
    Several of the claims in the formulation patents recite,
either directly (via independent claims) or indirectly (via
dependent claims), a formulation “consisting essentially of”


     5   The ’613 patent recites “degrades by” while the ’591
patent recites “degrades at.”
    6    Claim 24 of the ’613 patent recites a formulation
that degrades by less than “0.5% over 6 months.” ’613 pa-
tent col. 28 ll. 50–51.
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.        21



various ingredients. 7 Claim 49 of the ’838 patent is illus-
trative. It recites:
    49. A topical formulation consisting essentially of:
        1–2% w/w diclofenac sodium;
        40–50% w/w DMSO;
        23–29% w/w ethanol;
        10–12% w/w propylene glycol;
        hydroxypropyl cellulose; and
        water to make 100% w/w, wherein the top-
        ical formulation has a viscosity of 500–5000
        centipoise.
’838 patent col. 30 ll. 60–67 (emphasis added).
       The dissent argues that the claimed formulation
cannot be indefinite in light of the expressly listed ingredi-
ents of the invention. Dissent Op. at 5. The dissent’s posi-
tion, however, would render the claim meaningless because
it would have us read the term “essentially” out of the
phrase “consisting essentially of,” resulting in the separate
and distinct claim phrase, “consisting of.” This reading
would be contrary to the well-established “principle that
claim language should not [be] treated as meaningless.”
Bicon, Inc. v. Straumann Co., 441 F.3d 945, 951 (Fed. Cir.
2006); Playtex Prods., Inc. v. Procter & Gamble Co., 400
F.3d 901, 908 (Fed. Cir. 2005) (rejecting the district court’s
construction of the claim because it “reads out the essence
of the claim limitation ‘substantially flattened’ as it



    7    The relevant claims of the formulation patents are
claims 49–52 and 55–61 of the ’838 patent; claims 12–15,
17, 19, and 24–25 of the ’591 patent; claims 2–5 and 8–11
of the ’304 patent; claims 2–5 and 9–12 of the ’305 patent;
and claims 2–5 and 9–12 of the ’784 patent.
22      HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




equates ‘flattened’ with ‘flat’”); Application of Sabatino,
480 F.2d 911, 913 (CCPA 1973). Here, the dissent reads
out the term “essentially” so as to render the claim term to
“consists of” or simply “consists.”
     The phrase “consisting essentially of” has a distinct
meaning within our jurisprudence. It is a transition
phrase often used to signal a partially open claim. PPG
Indus., 156 F.3d at 1354. The phrase serves as a middle
ground between closed-ended claims using the phrase “con-
sisting of” and open-ended claims using the phrase “com-
prising.” Id.; AK Steel Corp. v. Sollac & Ugine, 344 F.3d
1234, 1239 (Fed. Cir. 2003). Accordingly, a drafter will gen-
erally include the phrase “consisting essentially of” before
(a) a list of ingredients when dealing with a composition
claim, or (b) a series of steps when dealing with a process
claim. PPG Indus., 156 F.3d at 1354. By doing so, “the
drafter signals that the invention necessarily includes the
listed ingredients [but] is open to unlisted ingredients that
do not materially affect the basic and novel properties of
the invention.” Id. Put differently, “[t]he phrase ‘consist-
ing essentially of’ . . . permit[s] inclusion of components not
listed in the claim, provided that they do not ‘materially
affect the basic and novel properties of the invention.’” AK
Steel, 344 F.3d at 1239.
    In light of our case law, the district court considered
“consisting essentially of” in accordance with its legal
meaning: “consisting of only the specified materials and
those that do not materially affect the basic and novel prop-
erties of the claimed invention.” J.A. 17. The parties do
not dispute the legal meaning adopted by the district court
about the phrase “consisting essentially of.” Instead, the
parties’ dispute focuses on the basic and novel properties of
the formulation patents. These properties are implicated
by virtue of the phrase “consisting essentially of,” which al-
lows unlisted ingredients to be added to the formulation so
long as they do not materially affect the basic and novel
properties.
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.         23



    The district court held that the specification of the for-
mulation patents identified five basic and novel properties:
(1) better drying time; (2) higher viscosity; (3) increased
transdermal flux; (4) greater pharmacokinetic absorption;
and (5) favorable stability. J.A. 23. Although Actavis
maintains that the specification does not identify these
characteristics as important enough to be considered basic
and novel properties, we are unpersuaded.
     The specification adequately identifies each of these
properties by separate subheadings in the section titled
“Characteristics of the Gel Formulation.” ’838 patent col.
9 l. 1–col. 10 l. 47. That section includes five subheadings:
(a) “Transdermal Flux”; (b) “Viscosity”; (c) “Stability”; (d)
“Drying Time”; and (e) “Pharmacokinetics.” Id. Each sub-
heading not only identifies the specific characteristic but
also includes relevant discussion about its importance.
The specification further highlights these features as ad-
vantageous over prior art, stating that the inventive for-
mulation “display[s] a better drying time, higher viscosity,
increased transdermal flux, and greater pharmacokinetic
absorption,” in addition to providing other advantages such
as “favorable stability.” Id. col. 4 ll. 21–32. With these par-
ticular aspects noted, the specification then states that the
inventive formulation “provide[s] superior means for deliv-
ery of diclofenac sodium through the skin for the treatment
of osteoarthritis.” Id. col. 4 ll. 36–39. The district court
thus correctly concluded that the intrinsic record identifies
these characteristics as the basic and novel properties.
    Next, we turn to whether the Nautilus definiteness
standard applies to the basic and novel properties of an in-
vention. In Nautilus, the Supreme Court held that “a pa-
tent is invalid for indefiniteness if its claims, read in light
of the specification delineating the patent, and the prose-
cution history, fail to inform, with reasonable certainty,
those skilled in the art about the scope of the invention.”
572 U.S. at 901. The district court evaluated the basic and
24      HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




novel properties under this definiteness standard. Horizon
maintains that was legal error.
     Horizon argues that the Nautilus definiteness stand-
ard focuses on the claims and therefore does not apply to
the basic and novel properties of the invention. This argu-
ment, however, is misguided. By using the phrase “consist-
ing essentially of” in the claims, the inventor in this case
incorporated into the scope of the claims an evaluation of
the basic and novel properties. The use of “consisting es-
sentially of” implicates not only the items listed after the
phrase, but also those steps (in a process claim) or ingredi-
ents (in a composition claim) that do not materially affect
the basic and novel properties of the invention. Having
used the phrase “consisting essentially of,” and thereby in-
corporated unlisted ingredients or steps that do not mate-
rially affect the basic and novel properties of the invention,
a drafter cannot later escape the definiteness requirement
by arguing that the basic and novel properties of the inven-
tion are in the specification, not the claims. Indeed, this
contravenes the legal meaning associated with the phrase
“consisting essentially of.” And a holding to the contrary
would promote the innovation-discouraging “zone of uncer-
tainty” that the Supreme Court has warned against. See
Nautilus, 572 U.S. at 911 (rejecting the “not amenable to
construction or insolubly ambiguous” definiteness stand-
ard in favor of one that fosters the public-notice function of
the definiteness requirement); United Carbon Co. v. Binney
& Smith Co., 317 U.S. 228, 236 (1942) (“The statutory re-
quirement of particularity and distinctness in claims is met
only when they . . . clearly circumscribe what is foreclosed
from future enterprise. A zone of uncertainty which enter-
prise and experimentation may enter only at the risk of in-
fringement claims would discourage invention only a little
less than unequivocal foreclosure of the field.”). Notably,
the phrase “consisting essentially of” is not per se indefi-
nite. Indeed, a patentee can reap the benefit of claiming
unnamed ingredients and steps by employing the phrase
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.          25



“consisting essentially of” so long as the basic and novel
properties of the invention are definite.
    Horizon attempts to cast the issue about the bounds of
the basic and novel properties as one that should not be
addressed at the claim construction stage, arguing this
court considers those properties solely as factual determi-
nations of validity and infringement. See Appellant Br. 41–
42. But Horizon’s view about the role of the basic and novel
properties disregards one of the cornerstones of the defi-
niteness requirement: to afford clear notice of what is being
claimed so as to apprise the public of what is still open to
them. Nautilus, 572 U.S. at 909.
    The Supreme Court has repeatedly emphasized why
the definiteness requirement demands clear notice of what
is being claimed. In Festo Corp. v. Shoketsu Kinzoku Kogyo
Kabushiki Co., the Court explained:
    The patent laws “promote the Progress of Science
    and useful Arts” by rewarding innovation with a
    temporary monopoly. U.S. Const., Art. I, § 8, cl. 8.
    The monopoly is a property right; and like any
    property right, its boundaries should be clear. This
    clarity is essential to promote progress, because it
    enables efficient investment in innovation. A pa-
    tent holder should know what he owns, and the
    public should know what he does not. For this rea-
    son, the patent laws require inventors to describe
    their work in “full, clear, concise, and exact terms,”
    35 U.S.C. § 112, as part of the delicate balance the
    law attempts to maintain between inventors, who
    rely on the promise of the law to bring the inven-
    tion forth, and the public, which should be encour-
    aged to pursue innovations, creations, and new
    ideas beyond the inventor’s exclusive rights.
535 U.S. 722, 730–31 (2002). Accordingly, “[t]he limits of a
patent must be known” because the goal of the definiteness
requirement is “to guard against unreasonable advantages
26      HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




to the patentee and disadvantages to others arising from
uncertainty.” Gen. Elec. Co. v. Wabash Appliance Corp.,
304 U.S. 364, 369 (1938). That is why “inventor[s] must
inform the public [about] the limits of the monopoly as-
serted, [i.e., the patented invention,] so that it may be
known which features may be safely used or manufactured
without a license and which may not.” Id. (internal quota-
tion marks omitted).
     Having determined that the basic and novel properties
of an invention are part of the scope of the claims in this
case, it follows that those basic and novel properties, “when
read in light of the specification and the prosecution his-
tory, must provide objective boundaries for those of skill in
the art.” See Interval Licensing, 766 F.3d at 1371; see also
Datamize, LLC v. Plumtree Software, Inc., 417 F.3d 1342,
1350 (Fed. Cir. 2005) (“Some objective standard must be
provided in order to allow the public to determine the scope
of the claimed invention.”). That the basic and novel prop-
erties may not be precise does not automatically render
them indefinite. See Seattle Box Co. v. Indus. Crating &
Packing, Inc., 731 F.2d 818, 826 (Fed. Cir. 1984). Instead,
the basic and novel properties must be sufficiently definite
so as to inform, with reasonable certainty, a POSITA of
their scope within the context of the invention. Nautilus,
572 U.S. at 901.
     Two questions arise when claims use the phrase “con-
sisting essentially of.” One question focuses on definite-
ness: what are the basic and novel properties of the
invention? The other question focuses on infringement:
does a particular unlisted ingredient materially affect
those basic and novel properties? There certainly may be
circumstances where it will be up to a fact-finder to deter-
mine whether an unlisted ingredient has a material effect
on the basic and novel properties of the invention. Our
analyses in PPG Industries and AK Steel of patents using
the term “consisting essentially of” in the claims is instruc-
tive as to this distinction.
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.         27



    In PPG Industries, we evaluated a patent directed to a
green-tinted glass with specific light transmittance charac-
teristics. 156 F.3d at 1352. The patent claimed that the
composition of the glass “consist[ed] essentially of” a list of
chemical ingredients. Id. Iron sulfide was not listed in the
claims and was present in the accused product. Id. at 1354.
The alleged infringer defended on that basis. At trial, since
the claims used the phrase “consisting essentially of,” the
district court instructed the jury that the claimed glass in-
cluded other ingredients not specifically identified in the
claim so long as those unlisted ingredients did not have a
material effect on the basic and novel properties of the
glass. Id. at 1354. The parties had agreed that the basic
and novel properties of the claimed glass were color, com-
position, and light transmittance. Id. We held that, be-
cause “the patent is silent about iron sulfide and about
what constitutes a material effect on the properties of the
glass,” it was proper for “the jury to determine whether the
amounts of iron sulfide in [the accused glass] have a mate-
rial effect on the basic and novel characteristics of the
glass.” Id. at 1357.
     In AK Steel, we dealt with patents directed to hot-dip
aluminum-coated stainless steel. 344 F.3d at 1236. One of
the patents at issue used the phrase “consisting essentially
of aluminum” in the claims. Id. at 1237. The district court
construed the phrase to permit only up to about 0.5% sili-
con. Id. at 1238. Since the accused product included alu-
minum and 8.0%–8.5% silicon, the district court granted
summary judgment of noninfringement. Id. We affirmed,
noting that the patent clearly identified “good wetting” as
the goal of the invention and as the distinguishing feature
from the prior art. Id. at 1239–40. This was a basic and
novel property. The specification also stated that having
silicon in excess of 0.5% by weight in an aluminum coating
did not achieve the goal of “good wetting.” See id. In other
words, 0.5% silicon by weight served as a threshold, and
28      HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




anything above it would not achieve the goal of “good wet-
ting.” We held that PPG Industries did not compel the dis-
trict court to submit the issue of whether more than 0.5%
silicon materially alters the basic and novel properties of
the invention to the jury. Id. at 1240–41. We explained
that the specification in PPG Industries was silent about
iron sulfide and what constitutes a material effect on the
properties of the glass. Id. at 1240. But, unlike PPG In-
dustries, the specification at issue in AK Steel was far from
silent about silicon and its material effect on the properties
of the invention, particularly where the specification iden-
tified having silicon in excess of 0.5% by weight in alumi-
num coating as contravening the goal of “good wetting.” Id.
The district court was thus correct to construe the claims
as not encompassing steel coated with aluminum contain-
ing more than about 0.5% silicon, and then grant summary
judgment of noninfringement because the accused product
contained 8.0%–8.5% silicon. Id. at 1240–41.
    In relation to this case, the crucial teachings from both
PPG Industries and AK Steel is that courts evaluating
claims that use the phrase “consisting essentially of” may
ascertain the basic and novel properties of the invention at
the claim construction stage, and then consider if the in-
trinsic evidence establishes what constitutes a material al-
teration of those properties. The definiteness inquiry
focuses on whether a POSITA is reasonably certain about
the scope of the invention. Indeed, if a POSITA cannot as-
certain the bounds of the basic and novel properties of the
invention, then there is no basis upon which to ground the
analysis of whether an unlisted ingredient has a material
effect on the basic and novel properties. To determine if an
unlisted ingredient materially alters the basic and novel
properties of an invention, the Nautilus definiteness stand-
ard requires that the basic and novel properties be known
and definite. Accordingly, in this case, the district court
did not err in considering the definiteness of the basic and
novel properties during claim construction.
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.          29



    Lastly, we address whether the district court erred in
determining that the basic and novel property of “better
drying time” was indefinite. We conclude that it did not.
    The section of the specification listing the basic and
novel properties of the invention includes a subheading for
“Drying Time.” ’838 patent col. 10 l. 5. Under that sub-
heading, the specification explains that the compositions of
the invention “dry quicker” than previously disclosed com-
positions. Id. col. 10 ll. 6–10. In support, the specification
discloses results from two tests: an in vivo test and an in
vitro test.
    As to the in vivo test, the specification states that “[t]he
drying time difference is evident when equal amounts of
the two products are tested on opposite limbs. Within
thirty (30) minutes the compositions of the invention are
almost completely dry whereas a significant amount of the
previously described liquid formulation remains.” Id. col.
10 ll. 15–21. No other data is provided about the test.
     As to the in vitro test, the specification notes that “dry-
ing times” were compared “more quantitatively” by con-
ducting side-by-side comparisons. Id. col. 10 ll. 22–23. To
do so, the inventors “measured the residual weight of for-
mulations by placing equal amounts (100 mg) of a prior art
formulation and compositions of the invention in weighing
dishes . . . and weighing the amount remaining over time.”
Id. col. 10 ll. 23–27. According to the specification, under
this methodology “a difference is immediately noticeable,
and becomes dramatically different by 4 hours.” Id. col. 10
ll. 27–29. The in vitro test corresponds with Example 5,
and Table 12 reflects the data from the test. Example 5,
entitled “Comparison of Drying Time/Residual Weight of a
Comparative Liquid Formulation Solution Versus the Cor-
responding Gel,” reveals that the prior art formulation was
compared to three gel compositions which are embodi-
ments of the invention. See id. col. 21 l. 38–col. 22 l. 49.
30       HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




Table 12 provides information about the percentage of the
remaining weight as follows:




Id. col. 23 ll. 17–27.
    The district court found that the two different methods
for evaluating “better drying time” do not provide con-
sistent results at consistent times. J.A. 26. On the one
hand, the in vivo test noted that after thirty minutes the
compositions of the invention are “almost completely dry”
while a “significant amount” of the prior art formulation
remained. J.A. 24–27. But on the other hand, when the
results of the in vitro test are reviewed at the thirty-minute
mark, only two of the formulations exhibit “better drying
time.” Id. As reflected in Table 12, at thirty minutes the
prior art liquid comparative showed 95.6% of its weight re-
maining, whereas the “F971” inventive formulation
showed 100% of its weight remaining. J.A. 25–26. After
highlighting these inconsistencies, the district court noted
that the prosecution history failed to inform as to the ap-
propriate time frame under which to evaluate the drying
rate. J.A. 27. The district court also found persuasive the
testimony of Actavis’s expert that a POSITA would not
know under what standard to evaluate the drying rate. Id.
Accordingly, the district court concluded that the basic and
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.         31



novel property of “better drying rate” was indefinite, and
consequently, that the term “consisting essentially of” was
likewise indefinite. Id.
    On appeal, Horizon argues that the district court im-
properly conflated “drying rate” with “better drying time.”
According to Horizon, “drying rate” refers to “how quickly
[a formulation] dries” while “drying time” refers to “how
long [a formulation] takes to dry.” Appellant Br. 49. In
light of this distinction, Horizon maintains that the speci-
fication’s descriptions of the results of the in vivo test and
in vitro test are not in conflict. Horizon asserts that a
POSITA would understand that the time points earlier
than 4 hours in the in vitro test do not reflect drying time,
and instead, they reflect drying rates that can change over
time. Horizon argues that the district court failed to com-
prehend the differences between the two tests.
    In response, Actavis contends that the patent uses the
concepts of “drying time” and “drying rate” interchangea-
bly, with both terms apparently intended to refer to the re-
sidual weight of the formulation left as time progresses.
But Horizon challenges that assertion, stating that the
“specification differentiates these two concepts, referencing
‘drying time’ as a characteristic of the inventive formula-
tions, and then separately discussing drying rate in rela-
tion to the speed (‘more rapid,’ ‘quicker,’ or ‘faster’) of
drying.” Appellant Reply Br. 61. We find Horizon’s pro-
posed distinction unpersuasive in light of the specification.
    Example 5, the in vitro test, compared “drying time” in
relation to the residual weight of a given formulation. Its
stated purpose was to “evaluate . . . drying time.” ’838 pa-
tent col. 21 l. 45. Throughout Example 5, the specification
tethers a “dryness” evaluation to the residual weight of a
formulation in order to show the improved characteristic
over the prior art. See id. col. 22 ll. 7–10 (stating that “one
would have expected the liquid formulation to lose weight
32      HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




more quickly, and thus have a shorter drying time”). Be-
yond that, the basic point raised by the district court re-
mains: the results are inconsistent. Referring to the
results in Example 5, the specification states that “even
within the first five minutes, the three gel formulations dis-
played more rapid drying than the liquid formulation.” Id.
col. 21 ll. 63–65 (emphasis added). Regardless of the dis-
tinction Horizon attempts to draw, this statement stands
for the proposition that, at the five-minute mark, the three
inventive formulations are drier than the prior art formu-
lation. So, it follows that according to the specification’s
clear language, the inventive formulations displayed better
drying time when compared at five minutes. But, as the
district court pointed out, the data is inconsistent with the
specification’s statement about better drying at five
minutes (as stated in the in vitro test) or at thirty minutes
(as compared to the in vivo test). At both of those marks,
Table 12 reflects that inventive gel “F971” retained a larger
percentage weight than the prior art. Only at the four-hour
mark does the inventive gel “F971” reflect a lower percent-
age than the prior art comparator.
    “[A] claim is indefinite if its language might mean sev-
eral different things and no informed and confident choice
is available among the contending definitions.” Media
Rights Techs., Inc. v. Capital One Fin. Corp., 800 F.3d
1366, 1371 (Fed. Cir. 2015) (internal quotations marks
omitted). Here, an evaluation of the specification reveals
inconsistencies about the basic and novel property of “bet-
ter drying time.” Two tests are disclosed, but those tests
do not provide consistent results upon which a POSITA
would be able to evaluate “better drying time.” Conse-
quently, we conclude that the district court did not err in
its determination that a POSITA would not know under
what standard to evaluate the drying rate of the invention,
thus rendering the basic and novel property of “better dry-
ing rate” indefinite.
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.        33



     In sum, we hold that the district court did not err in:
(a) defining the basic and novel properties of the formula-
tion patents; (b) applying the Nautilus definiteness stand-
ard to the basic and novel properties of the formulation
patents; and (c) concluding that the phrase “consisting es-
sentially of” was indefinite based on its finding that the
basic and novel property of “better drying time” was indef-
inite on this record. To be clear, we do not hold today that
so long as there is any ambiguity in the patent’s description
of the basic and novel properties of its invention, no matter
how marginal, the phrase “consisting essentially of” would
be considered indefinite. Nor are we requiring that the pa-
tent owner draft claims to an untenable level of specificity.
We conclude only that, on these particular facts, the dis-
trict court did not err in determining that the phrase “con-
sisting essentially of” was indefinite in light of the
indefinite scope of the invention’s basic and novel property
of a “better drying time.” 8



    8    The dissent states that “[i]t is hard to imagine a
clearer statement than a list of the ingredients that the
claimed formulation ‘consists essentially of.’” Dissent Op.
at 5. It is not. A clearer statement would be a list of ingre-
dients that the claimed formulation “consists of,” which, as
we previously noted, is a “closed claim” confined to the
listed ingredients or steps in a claim. PPG Indus., 156 F.3d
at 1354.
     Here, the patentee, however, chose to use the distinct
and separate phrase, “consisting essentially of.” In so
choosing, the patentee can now assert its claim against
products containing ingredients nowhere listed in the pa-
tent claim, an option foreclosed under the phrase “consist-
ing of.” See, e.g., AK Steel, 344 F.3d at 1239 (“consisting
34      HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




                 B. Induced Infringement
    We review the district court’s grant of summary judg-
ment de novo. Frolow v. Wilson Sporting Goods Co., 710
F.3d 1303, 1308 (Fed. Cir. 2013) (citing Nicini v. Morra,
212 F.3d 798, 805 (3d Cir. 2000) (en banc)). Summary judg-
ment is appropriate when there are no genuine issues of
material fact and the moving party is entitled to judgment
as a matter of law. Fed. R. Civ. P. 56; Anderson v. Liberty
Lobby, Inc., 477 U.S. 242, 247–48 (1986). The nonmovant’s
evidence is to be believed and all justifiable inferences are
to be drawn in his favor. Frolow, 710 F.3d at 1308.
    The district court granted summary judgment in rela-
tion to the asserted claims of the method-of-use patents 9 on
the basis that Horizon failed to show that Actavis’s label
induces a use of its ANDA product that directly infringes
those claims. We review Actavis’s ANDA label in relation
to the asserted claims of the methods-of-use patents to
evaluate if the district court erred in concluding that Ac-
tavis’s label does not induce infringement of those particu-
lar claims.
    Actavis’s ANDA product, diclofenac sodium topical so-
lution 2%, is a generic version of Horizon’s PENNSAID®




essentially of aluminum” asserted against product contain-
ing aluminum and silicon). This flexibility afforded to pa-
tentee underscores the importance of our holding today:
that when the patentee choses to use the phrase “consisting
essentially of,” the underlying basic and novel properties of
that invention should be sufficiently definite in scope in or-
der to afford clear notice of the claim’s bound. Nautilus,
572 U.S. at 909.
    9   Claims 10, 11, 15, and 17 of the ’450 patent, claim
14 of the ’078 patent, and claims 3, 11, and 13 of the ’110
patent.
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.         35



2%. Both products are directed to the treatment of osteo-
arthritis pain on the knees. In relevant part, Actavis’s la-
bel includes the following:
   The recommended dose is 2 pump actuations on
   each painful knee, 2 times a day. (2)
   •   Apply diclofenac sodium topical solution, to
       clean, dry skin. (2.1)
   •   Dispense 40 mg (2 pump actuations) directly
       onto the knee or first into the hand and then
       onto the knee. Spread evenly around front, back
       and sides of the knee. (2.1)
   ....
   •   Wait until area is completely dry before covering
       with clothing or applying sunscreen, insect re-
       pellent, cosmetics, topical medications, or other
       substances. (2.2)
   ....
   •   Avoid wearing clothing over the diclofenac so-
       dium topical solution-treated knee(s) until the
       treated knee is dry.
   •   Protect the treated knee(s) from natural and ar-
       tificial sunlight.
   •   Wait until the treated area is dry before applying
       sunscreen, insect repellant, lotion, moisturizer,
       cosmetics, or other topical medication to the
       same knee you have just treated with diclofenac
       sodium topical solution.
   •   Until the treated knee(s) is completely dry,
       avoid skin-to-skin contact between other people
       and the treated knee(s).
J.A. 5873, 5876 (emphasis added) (numbers in parentheses
indicating cross references: e.g., 2.1 indicating “general
36       HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




dosing instructions” and 2.2. indicating “special precau-
tions”).
    It is undisputed that Actavis’s label is substantially
similar to Horizon’s; the primary difference between the
two labels is that Horizon’s label refers to “PENNSAID” in-
stead of “diclofenac sodium topical solution” or “diclofenac
sodium.”
    Turning to the method-of-use patents, claim 10 of the
’450 patent is illustrative of the asserted method-of-use
claims. It recites:
     10. A method for applying topical agents to a knee
     of a patient with pain, said method comprising:
        applying a first medication consisting of a
        topical diclofenac preparation to an area of
        the knee of said patient to treat osteoar-
        thritis of the knee of said patient, wherein
        the topical diclofenac preparation com-
        prises a therapeutically effective amount of
        a diclofenac salt and 40–50% w/w dimethyl
        sulfoxide;
        waiting for the treated area to dry;
        subsequently applying a sunscreen, or an
        insect repellant to said treated area after
        said treated area is dry, wherein said step
        of applying a first medication does not en-
        hance the systemic absorption of the subse-
        quently applied sunscreen, or insect
        repellant;
        and wherein said subsequent application
        occurs during a course of treatment of said
        patient with said topical diclofenac prepa-
        ration.
’450 patent col. 73 l. 36–col. 74 l. 10.
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.        37



    The district court evaluated Actavis’s label vis-à-vis the
claims of the method-of-use patents and noted that the dis-
pute between the parties centered around the warning in
Actavis’s label to wait until the treated area is dry before
covering it or applying another substance. Because Hori-
zon alleged that the warning in Actavis’s label would in-
duce infringement of its method-of-use patents, the district
court evaluated the claims, stating that Horizon’s claimed
methods provide three sequential instructions. J.A. 52–53.
First, the user applies the medication to the knee. Second,
the user waits for the treated area to dry. And third, the
user subsequently applies sunscreen or insect repellant. 10
With this framework in mind, the district court found that
“Actavis’s proposed label does [no] more than simply per-
mit, rather than require or direct, the post-product appli-
cation of sunscreen, insect repellant, or a second topical
medication.” J.A. 58. So even if at some point a user ap-
plies one of the items claimed in step three of the method-
of-use claims to his or her knee, the district court explained
that “permission does not amount to encouragement be-
cause those items are just three examples of what a patient
might wish to apply to his knee after treatment, if anything
is to be applied at all.” J.A. 59. The district court thus
concluded that Actavis’s label was insufficient to create a
material dispute of fact as to whether the label suggests an
infringing use. J.A. 59–60.
     On appeal, Horizon argues that the district court erred
in finding that Actavis’s labeling did not induce infringe-
ment of the method-of-use patents. Horizon maintains
that Actavis’s labeling tracks closely with the asserted
claims, thereby reflecting Actavis’s specific intent to induce



    10   For the ’078 patent, the third step consists of ap-
plying a second medication, and for the ’110 patent it con-
sists of applying sunscreen, an insect repellant, or a second
medication. J.A. 53.
38        HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




infringement. Although Horizon recognizes that not every
user will need to apply sunscreen, insect repellant, or an-
other topical medication, it contends that, when such need
arises, Actavis’s instruction will lead to an infringing use.
Horizon also points to a warning in Actavis’s labeling that
cautions patients to avoid exposure to natural or artificial
sunlight on the treated knees, 11 arguing this reflects that
application of sunscreen is medically necessary. Lastly,
Horizon contends that material issues of fact preclude sum-
mary judgment. Specifically, Horizon cites to its expert’s
testimony and states that the district court should have
viewed it in Horizon’s favor and thus denied Actavis’s mo-
tion.
    Actavis disputes Horizon’s proposition that there are
material issues of fact that precluded summary judgment.
Actavis argues that its proposed label does not induce in-
fringement because, unlike the method-of-use patents, its
label does not promote the application of a second topical
agent after application of the diclofenac sodium gel. Ac-
tavis maintains that its label never affirmatively instructs
the patient to apply anything after the diclofenac sodium
gel; the label merely permits applying a second topical
agent after the patient waits for the diclofenac sodium to
dry. Its label, therefore, does not contain any instruction
that induces infringement. Instead, Actavis states that the
label warns patients that if they choose to apply a second
topical agent, they should take the precaution of waiting



     11 Section 5.14 of Actavis’s labeling, entitled “Sun Ex-
posure,” provides: “Instruct patients to avoid exposure to
natural or artificial sunlight on treated knee(s) because
studies in animals indicated topical diclofenac treatment
resulted in an earlier onset of ultraviolet light-induced skin
tumors. The potential effects of diclofenac sodium topical
solution on skin response to ultraviolet damage in humans
are not known.” J.A. 5881.
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.       39



for the diclofenac sodium gel to dry. Because Horizon’s only
evidence of inducement depends upon Actavis’s label, Ac-
tavis contends that there are no material issues of fact and
that the district court correctly resolved the matter on sum-
mary judgment.
    “Whoever actively induces infringement of a patent
shall be liable as an infringer.” 35 U.S.C. § 271(b). To
prove inducement, a plaintiff must present evidence of ac-
tive steps taken to encourage direct infringement; mere
knowledge about a product’s characteristics or that it may
be put to infringing uses is not enough. Takeda Pharm.
U.S.A., Inc. v. West-Ward Pharm. Corp., 785 F.3d 625, 630–
31 (Fed. Cir. 2015). The focus is not on whether the in-
structions describe the mode of infringement, but rather on
whether the “instructions teach an infringing use of the de-
vice such that we are willing to infer from those instruc-
tions an affirmative intent to infringe the patent.” Id. at
631 (emphasis omitted). In ANDA cases, when a plaintiff
attempts to draw intent from the label, we examine
whether the proposed label “encourage[s], recommend[s],
or promote[s] infringement.” Id. Merely describing the in-
fringing use, or knowing of the possibility of infringement,
will not suffice; specific intent and action to induce in-
fringement must be shown. Id.
    The patented method here requires three distinct
steps. The user must: (1) apply the inventive formulation,
(2) wait for the area to dry, and (3) apply sunscreen, insect
repellant, or a second topical medication. The instructions
in Actavis’s label, however, only require the first step of
this method, nothing else. Moreover, Actavis’s label is
broader than step three of Horizon’s claimed method. For
example, beyond warning the user about waiting for the
treated area to be completely dry before covering it with
sunscreen, insect repellent, or another topical medication,
Actavis’s label also warns about clothing, cosmetics, lotion,
water, moisturizer, and other substances. J.A. 5873, 5876,
5898. The warning, then, operates in an “if/then” manner:
40      HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




if the user wants to cover the treated area with clothing or
apply another substance over it, then the patient should
wait until the area is dry. J.A. 53. This does not encourage
infringement, particularly where the label does not require
subsequent application of sunscreen, insect repellant, or a
second medication.
     We are also unpersuaded by Horizon’s reliance on its
expert’s opinion to maintain that there are material issues
of fact that prevent summary judgment. Horizon concedes
that its expert recognized that not all patients who follow
the instructions in Actavis’s label will engage in an infring-
ing use by applying sunscreen, insect repellant, or a second
medication. See Appellant Br. 29–30. And the “mere ex-
istence of direct infringement . . . is not sufficient for in-
ducement.” Takeda, 785 F.3d at 631. Instead, our inquiry
focuses on whether the instructions reflect an “affirmative”
or “specific intent to encourage infringement.” Vita-Mix
Corp. v. Basic Holding, Inc., 581 F.3d 1317, 1329 n.2 (Fed.
Cir. 2009). The district court examined Actavis’s label in
detail and concluded that there can be no material dispute
that the instructions do not reflect specific intent to induce.
The district court found that the label merely provided
guidance to patients about what to do if the patent desired
to have anything come into contact with the knee after ap-
plication of the medication.
     The fact that Actavis’s label does not require subse-
quent application of other products reflects that the prod-
uct has “substantial noninfringing uses, [and] intent to
induce infringement cannot be inferred even [if Actavis]
has actual knowledge that some users of its product may
be infringing the patent.” Warner-Lambert Co. v. Apotex
Corp., 316 F.3d 1348, 1365 (Fed. Cir. 2003). Horizon’s evi-
dence, viewed in the light most favorable to it, establishes
that some users might infringe. The evidence, however,
does not establish that “the proposed label instructs users
to perform the patented method.” AstraZeneca LP v. Apo-
tex, Inc., 633 F.3d 1042, 1060 (Fed. Cir. 2010).
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.        41



    The district court did not err in granting summary
judgment of noninfringement in Actavis’s favor.
        II. Actavis’s Cross-Appeal on Obviousness
    After a seven-day bench trial, the district court held
that Actavis did not show, by clear and convincing evi-
dence, that claim 12 of the ’913 patent is invalid for
obviousness. Actavis cross-appeals the nonobviousness de-
termination. We review the ultimate legal conclusion
about obviousness de novo and the underlying factual find-
ings for clear error. Novo Nordisk A/S v. Caraco Pharm.
Labs., Ltd., 719 F.3d 1346, 1354 (Fed. Cir. 2013).
    Actavis’s cross-appeal centers around the district
court’s statement that claim 12 of the ’913 patent “was not
a result of routine optimization of PENNSAID®
1.5% . . . because general principles and ranges of permis-
sible concentrations would not have predicted the exact for-
mulation and dosing frequency that resulted in
PENNSAID® 2%.” J.A. 15923 (emphasis added). Actavis
argues that the district court erred by requiring that the
prior art predict the exact formulation of the asserted
claim.
    To explain its obviousness theory, Actavis relied on a
stereo receiver analogy drawn by its expert. Under that
analogy, the various components of PENNSAID® 2% are
like bass, treble, fade, and volume, among other things.
Cross-Appellant Br. 69. In the analogy, the knobs of the
stereo receiver correspond to various aspects of the formu-
lation, such as the thickener that adjusts viscosity, the dis-
clofenac sodium concentration that adjusts permeation
rate/absorption, or the glycerine that adjusts drying rate.
According to Actavis, if a POSITA wants to change one as-
pect of the formulation in a particular way, she may adjust
the knobs upwards or downwards for the parameter corre-
sponding to the desired change.
42        HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




     The district court found the analogy to be inconsistent
with the complexity of the art, and more specifically, with
the particular components of the formulation. J.A. 15925.
The district court explained that Actavis’s analogy failed to
“differentiate between a system that allows independent
change of one variable with little or no predictable or ma-
terial effect on other variables and a system where the
change to one variable must result in changes to the oth-
ers.” Id. While a drug formulator could be inspired by gen-
eral knowledge and the prior art to adjust a certain
variable, the district court found that the variables here in-
teracted with each other in unpredictable ways. See id.
    The district court credited Horizon’s expert’s (Dr.
Bunge’s) testimony that the inventive formulation was
complex and that a POSITA would be challenged to predict
relative ratios in order to achieve the desired goal of
PENNSAID® 2%. J.A. 15926–27. The district court fur-
ther highlighted the unpredictability of the results by cred-
iting Dr. Bunge’s testimony that Fick’s law 12—an
established concept about drug permeation—could not pre-
dict what happens under the facts of this case, which in-
volve a complex topical formulation that attempts to drive
an active ingredient through human skin (a “formidable
barrier” according to the district court’s findings). J.A.
15929–32.
    The district court also found that the combination of
changes to the PENNSAID® 1.5% formulation were not ob-
vious optimizations of result-effective “variables that
would produce a predictable result, particularly as to the
formulation’s absorption, thickness, and drying time.”


     12 “Under Fick’s First Law of Diffusion, a larger con-
centration of the drug in the topical formulation results in
a larger concentration gradient, and leads to a greater per-
meation—or flux—rate of the drug through the skin.”
J.A. 15909.
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.        43



J.A. 15933. The district court found that the variables in-
volved in this case, including the components of the in-
ventive formulation, interact in an unpredictable or
unexpected way, such that the results emanating into
PENNSAID® 2% were not obvious. J.A. 15933–36. The
district court found that nothing in the prior art allowed a
POSITA to find “the schematic or roadmap to a diclofenac
gel effective at two doses a day.” J.A. 15934. The district
court thus held that “the combination of adjustments
needed to change PENNSAID® 1.5% into PENNSAID® 2%
was not predictable from the prior art.” J.A. 15933.
    We hold that the district court did not clearly err in its
factual findings about the lack of predictability in relation
to the changes made to PENNSAID® 1.5% and the teach-
ings from the prior art. In light of the district court’s fac-
tual findings, we hold that claim 12 of the ’913 patent was
nonobvious. We thus affirm the district court’s nonobvious-
ness conclusion and its determination that PENNSAID®
2% was not the result of routine experimentation such that
a POSITA would have reasonably predicted the changes
made to PENNSAID® 1.5%.
                        CONCLUSION
    We have considered all remaining arguments but find
them unpersuasive. For the foregoing reasons, we affirm
the judgment of the district court.
                        AFFIRMED
                           COSTS
    No costs.
  United States Court of Appeals
      for the Federal Circuit
                ______________________


HZNP MEDICINES LLC, HORIZON PHARMA USA,
                    INC.,
            Plaintiffs-Appellants

                           v.

        ACTAVIS LABORATORIES UT, INC.,
            Defendant-Cross-Appellant
              ______________________


2017-2149, 2017-2152, 2017-2153, 2017-2202, 2017-2203,
                      2017-2206
                ______________________


    Appeals from the United States District Court for the
District of New Jersey in Nos. 1:14-cv-07992-NLH-AMD,
1:15-cv-05025-NLH-AMD, 1:15-cv-06131-NLH-AMD, 1:15-
cv-06989-NLH-AMD, 1:15-cv-07742-NLH-AMD, 1:16-cv-
00645-NLH-AMD, Judge Noel Lawrence Hillman.
                ______________________
NEWMAN, Circuit Judge, concurring-in-part, dissenting-in-
part.
    This suit was brought pursuant to the Hatch-Waxman
Act, based on Actavis’ ANDA challenge to the HZNP
2       HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




(Horizon) patents on the product PENNSAID® 2%, a for-
mulation of the drug diclofenac sodium for topical applica-
tion to treat osteoarthritis of the knee. Actavis stated to
the FDA that its generic ANDA composition and method
are within the Horizon patents, and Actavis’ Paragraph IV
certification led to this litigation in which Actavis chal-
lenges the validity and infringement of the Horizon pa-
tents. Trial was held in the district court.
    On the issue of patent validity, the district court held
the composition claims invalid, holding that the claim term
“consisting essentially of” rendered the claims indefinite,
in violation of 35 U.S.C. § 112(b). The panel majority
agrees. The majority also holds that the knowledge of per-
sons of skill in the field of the invention cannot fill any gap
in proving the properties of compositions claimed in the
“consisting essentially of” form. I respectfully dissent from
these departures from long-established law and long-un-
derstood practice.
    The district court held the method-of-use claims valid
but not infringed. On the issue of infringement of these
claims, Actavis conceded that the instructions in its ANDA
label are identical to the method-of-use claimed in the
Horizon patents. However, the district court held that, ex-
cept for one claim, Actavis cannot be liable for induced in-
fringement because the user might not follow the
instructions on the label. The panel majority agrees.
Again I respectfully dissent, for this holding is contrary to
statute and precedent.
    On Actavis’ cross-appeal, the district court sustained
the validity of claim 12 of U.S. Patent No. 9,066,913 (“the
’913 patent”), and found infringement. The panel majority
sustains that judgment. I join that aspect of the court’s
decision.
    I start with brief reference to Actavis’ cross-appeal, for
the court’s correct ruling on claim 12 of the ’913 patent
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.        3



points up the inconsistency and uncertainty spawned by
today’s decision.
                              I
                  ACTAVIS’ CROSS-APPEAL
    Following is claim 12 of the ’913 patent, shown with the
claims whose subject matter is incorporated by reference:
         12. A method for treating pain due to osteoar-
    thritis of a knee of a patient in need thereof, said
    method comprising:
         administering to the knee a topical formulation
    of claim 9,
         wherein the administration of the formulation
    is twice daily.
        9. The topical formulation of claim 8, wherein
    the hydroxypropyl cellulose is present at 2.5% w/w.
        8. The topical formulation of claim 1, wherein
    the DMSO is present at 45.5% w/w.
       1. A topical formulation comprising:
       diclofenac sodium present at 2% w/w;
       DMSO present at about 40 to about 50% w/w;
       ethanol present at 23–29% w/w;
       propylene glycol present at 10–12% w/w;
       hydroxypropyl cellulose; and
       water to make 100% w/w,
       wherein the formulation has a viscosity of 500–
    5000 centipoise.
In the district court the only challenge to validity of claim
12 was on the ground of obviousness. Actavis stipulated to
infringement. I flag the usage “comprising” in claim 1
above, for this is the identical composition for which “con-
sisting essentially of” is today held to invalidate the com-
position claims on the ground of indefiniteness.
4       HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




                              II
                       INDEFINITENESS
   The claim definiteness requirement is codified at 35
U.S.C. § 112(b):
    § 112(b) Conclusion.—The specification shall con-
    clude with one or more claims particularly pointing
    out and distinctly claiming the subject matter
    which the inventor or a joint inventor regards as
    the invention.
An illustrative claim held invalid based on the usage “con-
sisting essentially of” is claim 49 of Horizon’s U.S. Patent
No. 8,252,838 (“the ’838 patent”):
    49. A topical formulation consisting essentially of:
        1–2% w/w diclofenac sodium;
        40–50% w/w DMSO;
        23–29% w/w ethanol;
        10–12% w/w propylene glycol;
        hydroxypropyl cellulose; and
        water to make 100% w/w, wherein the top-
        ical formulation has a viscosity of 500–5000
        centipoise.
’838 patent, col. 30, ll. 60–67; Maj. Op. at 4, 21.
       The usage “consisting essentially of” is
    not a ground of invalidity
    The panel majority holds that the phrase “consisting
essentially of” invalidates the composition claims for indef-
initeness, Maj. Op. at 33, because the claims are rendered
“open to unlisted ingredients that do not materially affect
the basic and novel properties of the invention,” id. at 22.
The majority holds that “By using the phrase ‘consisting
essentially of’ in the claims, the inventor in this case incor-
porated into the scope of the claims an evaluation of the
basic and novel properties.” Id. at 24. That is not correct
as a matter of claim construction, it is not the law of
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.         5



patenting novel compositions, and it is not the correct ap-
plication of section 112(b).
     Definiteness of claiming requires that the subject mat-
ter for which patent protection is sought is clearly stated in
the claim. See Vitronics Corp. v. Conceptronic, Inc., 90 F.3d
1576, 1582 (Fed. Cir. 1996) (“[W]e look to the words of the
claims themselves . . . to define the scope of the patented
invention.”); Halliburton Energy Servs., Inc. v. M-I LLC,
514 F.3d 1244, 1249 (Fed. Cir. 2008) (“If the meaning of the
claim is discernible, even though the task may be formida-
ble and the conclusion may be one over which reasonable
persons will disagree, we have held the claim sufficiently
clear to avoid invalidity on indefiniteness grounds.” (quot-
ing Exxon Research & Eng’g Co. v. United States, 265 F.3d
1371, 1375 (Fed. Cir. 2001))). It is hard to imagine a clearer
statement than a list of the ingredients that the claimed
formulation “consists essentially of.”
     Both sides agree that there are no unlisted ingredients
in the formulations claimed in these patents. However, the
majority states: “Having used the phrase ‘consisting essen-
tially of,’ and thereby incorporated unlisted ingredients or
steps that do not materially affect the basic and novel prop-
erties of the invention, a drafter cannot later escape the
definiteness requirement by arguing that the basic and
novel properties of the invention are in the specification,
not the claims.” Maj. Op. at 24. This statement is contrary
to long-standing law and practice, as summarized in Nau-
tilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898, 908
(2014): “[I]n assessing definiteness, claims are to be read in
light of the patent’s specification and prosecution history.
See, e.g., United States v. Adams, 383 U.S. 39, 48–49 (1966)
(specification); Festo Corp. v. Shoketsu Kinzoku Kogyo Ka-
bushiki Co., 535 U.S. 722, 741 (2002) (prosecution his-
tory).”
    When the properties of a composition are described in
the specification, the usage “consisting essentially of” the
6       HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




ingredients of the composition does not invalidate the
claims when the properties are not repeated in the claims.
        The property of better drying time and its
    measurement need not be included in compo-
    sition claims “consisting essentially of” the
    listed ingredients
    The panel majority affirms that “the phrase ‘consisting
essentially of’ was indefinite based on [the district court’s]
finding that the basic and novel property of ‘better drying
time’ was indefinite on this record.” Maj. Op. at 33. The
majority criticizes Example 5, headed “Comparison of Dry-
ing Time/Residual Weight of a Comparative Liquid Formu-
lation Solution Versus the Corresponding Gel.” ’838
patent, col. 21, l. 38–col. 22, l. 49. Example 5 presents ex-
perimental details and the results of measuring drying
time of samples in vitro in weighing dishes, and in vivo as
applied directly to the knees.
    The district court held that since two measures of dry-
ing time were in Example 5, “a POSA would not know un-
der what standard to evaluate the drying rate of the
claimed invention.” Dist. Ct. Op. at 27 (J.A. 27). On this
reasoning, the district court invalidated the composition
claims for indefiniteness. The panel majority agrees, stat-
ing that “this prevented a POSITA from being able to have
‘reasonable certainty’ about the scope of the basic and novel
properties of the invention, thereby rendering the term
‘consisting essentially of’ indefinite.” Maj. Op. at 7.
    Whatever the significance of drying time as an ad-
vantage of the claimed composition, recitation and meas-
urement of this property in the specification does not
convert the composition claims into invalidating indefinite-
ness because the ingredients are listed in the claims as
“consisting essentially of.”
       The property of improved stability and its
    measurement need not be included in
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.         7



    composition claims “consisting essentially of”
    the listed ingredients
    The majority also finds indefiniteness of “consisting es-
sentially of” claims based on the property of stability of the
claimed formulations. Longer shelf-life is stated to be an
advantage of these products, and is demonstrated in Ex-
ample 6 entitled “Comparison of Stability Characteristics
of a Comparative Liquid Formulation Versus Diclofenac
Sodium Gel Formulations.” ’913 patent, col. 25, l. 29–col.
26, l. 20. In Example 6, samples were stored for 6 months
at 60% humidity and 25º C, and “the samples were tested
for impurities by high performance liquid chromatog-
raphy.” Id., col. 25, ll. 47–51. Example 6 tabulates the re-
sults, and concludes: “It was found that upon 6 months of
storage, an impurity, termed ‘impurity A’, was seen to elute
at about 6.6 minutes in varying amounts for the various
compositions as shown in Table 13 below.” ’913 patent, col.
25, ll. 53–56; U.S. Patent No. 8,563,613, col. 22, ll. 52–55.
    The majority holds that the “consisting essentially of”
claims are indefinite because Example 6 does not state the
chemical name of impurity A and does not provide full de-
tails of the chromatography procedure. Horizon responds
that impurity A is described in the US Pharmacopoeia as
impurity A of diclofenac (USP Diclofenac Related Com-
pound A RS), and that persons of skill in this field would
know of this resource; an expert witness so testified.
     Despite Example 6 and its detailed measurement of the
degradation product impurity A, the majority states that
“neither the claims nor the specification disclose the means
to evaluate degradation,” Maj. Op at 6. The specification
describes and exemplifies the stability to degradation by
measuring the appearance of Impurity A in various condi-
tions. The criticism is untenable. See One-E-Way, Inc. v.
Int’l Trade Comm’n, 859 F.3d 1059, 1063 (Fed. Cir. 2017)
(“As long as claim terms satisfy this test [of understanding
8       HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




by persons of skill in the field], relative terms and words of
degree do not render patent claims invalid.”).
    My colleagues also state that “[t]he claims . . . do not
make clear that ‘impurity A’ refers to an impurity of diclo-
fenac sodium,” Maj. Op. at 18. This does not comport with
the presentation in Example 6, or with the US Pharmaco-
poeia identification of this impurity and this method of
analysis. Patents are written for persons in the field of the
invention. See Verve, LLC v. Crane Cams, Inc., 311 F.3d
1116, 1119 (Fed. Cir. 2002) (“Patent documents are written
for persons familiar with the relevant field; the patentee is
not required to include in the specification information
readily understood by practitioners, lest every patent be re-
quired to be written as a comprehensive tutorial and trea-
tise for the generalist, instead of a concise statement for
persons in the field.”).
    The majority further holds that the information in the
US Pharmacopoeia cannot be considered when the claim is
in the form “consisting essentially of.” Maj. Op. at 16–19.
However, knowledge in the field of the invention must al-
ways be considered. See Energizer Holdings, Inc. v. Int’l
Trade Comm’n, 435 F.3d 1366, 1370 (Fed. Cir. 2006)
(“Claim definiteness is analyzed not in a vacuum, but al-
ways in light of the teachings of the prior art and of the
particular application disclosure as it would be interpreted
by one possessing the ordinary level of skill in the pertinent
art.” (internal quotation marks omitted)).
    The Court guided in Nautilus, 572 U.S. at 908, that
“definiteness is to be evaluated from the perspective of
someone skilled in the relevant art.” See also Energizer
Holdings, 435 F.3d at 1370 (claim definiteness is viewed as
the claim would be understood by a person of ordinary skill
in the field of the invention). The Actavis expert conceded
that impurity A is a known degradation product of diclo-
fenac sodium. Nonetheless, my colleagues hold that “Since
‘impurity A’ is indefinite, it logically follows that another
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.         9



term, such as the ‘degrades’ term, which relies on ‘impurity
A’ for its construction, must also be indefinite.” Maj. Op.
at 20. From this flawed premise the court holds: “[T]he ‘fa-
vorable stability’ property was indefinite which in this
case, by extension, rendered the phrase ‘consisting essen-
tially of’ indefinite.” Id. at 8. “Indeed, if a POSITA cannot
ascertain the bounds of the basic and novel properties of
the invention, then there is no basis upon which to ground
the analysis of whether an unlisted ingredient has a mate-
rial effect on the basic and novel properties.” Id. at 28. I
repeat, there are no unlisted ingredients.
    The majority illustrates this flaw in its holding in claim
19 of U.S. Patent No. 9,101,591, that includes both the
term “consisting essentially of,” Maj. Op. at 21 n.7, and the
property “degrades [at] less than 1% over 6 months,” id. at
20. The majority holds the claim invalid for indefiniteness
although the advantageous property is actually stated in
the claim.
    The majority’s conclusion is flawed, even on its errone-
ous premise that the basic and novel properties are re-
quired to be included in claims to compositions that are
described in “consisting essentially of” form.
        The majority’s distinction between “con-
    sisting of” and “consisting essentially of” is
    unsupported in precedent
     The panel majority holds that the consequence of
claiming a composition as “consisting essentially of” the
named ingredients, compared with “consisting of” the
named ingredients, Maj. Op. at 33–34 n.8, is that the “con-
sisting essentially of” claims are invalid for indefiniteness
unless the claims include the “basic and novel properties”
of the composition and how these properties are measured.
This new rule is not in conformity with precedent. See, e.g.,
Conoco, Inc. v. Energy & Envtl. Int’l, L.C., 460 F.3d 1349
(Fed. Cir. 2006), where this court explained that
10      HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




“consisting of” permits “aspects unrelated to the inven-
tion.” Id. at 1360.
     The panel majority states that this meaning of “consist-
ing of” is available only to “consisting essentially of,” and
that “a drafter cannot later escape the definiteness require-
ment by arguing that the basic and novel properties of the
invention are in the specification, not the claims.” Maj. Op.
at 24, op. cit. The court in Conoco recognized the difference
between “consisting of” and “consisting essentially of,” stat-
ing that “while ‘consisting of’ limits the claimed invention,
it does not limit aspects unrelated to the invention.” 460
F.3d at 1360. However, no precedent has held that “con-
sisting essentially of” composition claims are invalid unless
they include the properties of the composition in the
claims.
    In the cases cited by the panel majority, Maj. Op. at 19,
the properties of the novel compositions were recited in the
specification or adduced in extrinsic evidence. In no case
did the court hold that unless the properties were included
in claims written as “consisting essentially of”" the claims
are invalid. The majority’s new ruling sows conflict and
confusion.
        This new rule of claiming compositions
     casts countless patents into uncertainty
    The role of the claims is to state the subject matter for
which patent rights are sought. See In re Packard, 751
F.3d 1307, 1313 (Fed. Cir. 2014) (“If the claims, read in the
light of the specifications, reasonably apprise those skilled
in the art both of the utilization and scope of the invention,
and if the language is as precise as the subject matter per-
mits, the courts can demand no more.” (quoting Georgia-
Pacific Corp. v. U.S. Plywood Corp., 258 F.2d 124, 136 (2d
Cir. 1958))).
     The usage “consisting essentially of” states the essen-
tial ingredients of the claimed composition. There are no
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.         11



fuzzy concepts, no ambiguous usages in the listed ingredi-
ents. There is no issue in this case of the effect of other
ingredients, as in In re Hitachi Metals, Ltd., 603 F. App’x
976, 979 (Fed. Cir. 2015) (“[B]ecause the claims were
drafted in the ‘consisting essentially of’ format, the scope of
the claims can include those additional elements which do
not materially affect the basic and novel characteristics of
the claimed invention as specified in the ’368 patent speci-
fication.”).
    Here no other components are asserted to be present,
no “unnamed ingredients and steps.” Even on my col-
leagues’ flawed construction, the claims are not subject to
invalidity for indefiniteness.
       The requirement of clear and convincing
    evidence
    Invalidity for indefiniteness must be established by
clear and convincing evidence. Microsoft Corp. v. i4i Ltd.
P’ship, 564 U.S. 91, 95 (2011). This standard plainly is not
met. “[A] claim is indefinite if its language might mean sev-
eral different things and no informed and confident choice
is available among the contending definitions.” Media
Rights Techs., Inc. v. Capital One Fin. Corp., 800 F.3d
1366, 1371 (Fed. Cir. 2015) (internal quotation marks omit-
ted). There was no evidence that persons of ordinary skill
in the field of this invention would not understand the com-
ponents of the composition claims with reasonable cer-
tainty.
    Applying statute and precedent, the claims at issue
have not been proved invalid for indefiniteness. From my
colleagues’ contrary ruling, I respectfully dissent.
                              III
                  INDUCEMENT TO INFRINGE
   35 U.S.C. § 271(b) provides that “Whoever actively in-
duces infringement of a patent shall be liable as an
12      HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC.




infringer.” The Actavis ANDA label instructs the method
of use that is identical to the patented use. However, my
colleagues hold that there can be no liability for induced
infringement because some patients may not follow the la-
bel instructions. Thus the court holds that the provider of
the product with instructions to use it in accordance with
the infringing method cannot be liable for inducement to
infringe.
    To be sure, patients may not always comply with in-
structions. However, this does not insulate the provider
from infringement liability. See Vanda Pharm. Inc. v.
West-Ward Pharm. Int’l Ltd., 887 F.3d 1117, 1129 (Fed.
Cir. 2018) (“The contents of the label itself may permit the
inference of specific intent to encourage, recommend, or
promote infringement.”). It is not disputed that the Actavis
label “instructs users to perform the patented method.”
AstraZeneca LP v. Apotex, Inc., 633 F.3d 1042, 1060 (Fed.
Cir. 2010).
    The summary judgment of non-infringement is incor-
rect in law. From my colleagues’ contrary ruling on this
aspect, I again respectfully dissent.
