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-cv00645-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-appellant. 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 District of New Jersey’s judgment of invalidity and noninfringement. Actavis Laboratories UT, Inc. (“Actavis”) 

cross-appeals the district court’s judgment of nonobviousness. We affirm.

BACKGROUND

Horizon1 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”) (collectively, “the patents-at-issue” or “Horizon’s patents”). 

The patents-at-issue generally relate to methods and compositions for treating osteoarthritis and can be divided into 

 

1 During the pendency of this appeal, HZNP Medicines LLC substituted itself as plaintiff-appellant for Horizon 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 substantially similar specification. 

The first group of patents consists of method-of-use patents, 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 patents: 

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 osteoarthritis of the knee of said patient, wherein 

the topical diclofenac preparation comprises 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 enhance the systemic absorption of the subsequently applied sunscreen, or insect 

repellant; and

wherein said subsequent application occurs during a course of treatment of said 

patient with said topical diclofenac preparation.

’450 patent col. 73 l. 35–col. 74 l. 11. 

The second group of patents consists of formulation patents, 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 topical 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 sodium 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 recommended 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 Application (“ANDA”) No. 207238.2 The ANDA included a certification under 21 U.S.C. § 355(j)(2)(A)(vii)(IV) (“Paragraph 

IV certification”), stating that the patents-at-issue were invalid or would not be infringed by Actavis’s generic product. The filing of an ANDA with a Paragraph IV 

certification constitutes an act of artificial patent infringement under 35 U.S.C. § 271(e)(2)(A), which allows litigation 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 Actavis’s Paragraph IV certification, Horizon filed suit in the 

District of New Jersey, alleging infringement of the patents-at-issue under § 271(e)(2)(A). 

I. Claim Construction

At the district court, the parties disputed the construction 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 formulation 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. Watson 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 Actavis. 
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 formulation degrades by less than 1% over 6 months” was indefinite 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 essentially of,” when used in a formulation patent, reflects

that the recited formulation includes (a) the listed ingredients 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 invention’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 invention, the district court noted that the specification identified five properties: (1) better drying time; (2) higher 

viscosity; (3) increased transdermal flux; (4) greater pharmacokinetic absorption; and (5) favorable stability. 

The district court focused on the “better drying time” property and held that this basic and novel property was indefinite. In doing so, the district court emphasized that the 

specification described two different methods for evaluating “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 invention, thereby rendering the term “consisting essentially 

of” indefinite. J.A. 27.

On August 30, 2016, Horizon filed a motion for reconsideration 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 relation 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 indefiniteness 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 improper. The district court also found that Horizon had ample notice and opportunity to present evidence and develop 

the record during the two Markman hearings, the supplemental 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 “favorable 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 “favorable 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 determinations, Actavis filed a motion for summary judgment of 

noninfringement. Actavis argued that there was no dispute that Actavis did not directly infringe the patents-atissue, 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 Actavis’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 following steps: (1) application of the medication to knee, (2) waiting 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 conducted. 

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 replaced “PENNSAID” with “diclofenac sodium topical solution.” In relevant part, the parties’ labels warn to “[w]ait 

until the treated area is dry” before applying a second topical 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 because 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 sunscreen, insect repellant, or a second topical medication. 

The district court thus granted summary judgment in Actavis’s favor, concluding that Horizon had not met its burden 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 patents-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 product would infringe the claim. The stipulation thus narrowed 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 sulfoxide (“DMSO”) is a penetration enhancer, which enhances absorption of the drug into the skin. Ethanol is both 

a solvent, which dissolves the active ingredient for absorption 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 nonvolatile substance that holds water onto the skin. And water 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 applying 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 motivated to modify PENNSAID® 1.5% to address these drawbacks 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 expectation 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, propylene 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 obvious optimizations of result-effective variables that produced 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 optimizations, 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 ethanol 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 propylene glycol, but instead (8) remove or reduce glycerin and/or water to account for the increases in 

diclofenac, ethanol and thickening agent concentrations 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 administration 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 Markman order, the summary-judgment order, and the posttrial 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 expiration 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 induce infringement. For the reasons below, we affirm.

A. Indefiniteness

We review indefiniteness determinations de novo. Interval 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.” Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898, 901 

(2014). General principles of claim construction apply to 

indefiniteness allegations. Biosig Instruments, Inc. v. Nautilus, Inc., 783 F.3d 1374, 1377–78 (Fed. Cir. 2015). Accordingly, we review a district court’s determinations of 

subsidiary facts based upon extrinsic evidence for clear error, 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 patent);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 proceeded 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 certainty, the identity of the substance as claimed. We agree.

The term “impurity A” only appears in claim 4 and Example 6 of the ’913 patent. Example 6 examines “the stability 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 performance liquid chromatography (HPLC).” Id. col. 25 ll. 49–

51. 

According to Example 6, this test revealed two unexpected 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 impurity”; and (2) “that compositions using hydroxypropylcellulose (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 various [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 compared 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 invention 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 evidence. 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 formulation, 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 impurity 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 inventive 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 because 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 impurity merely because it occurs in low amounts. Actavis 

contends that the only relevant disclosure in the specification 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 instance, 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 required implies further testing was necessary to ascertain 

the identity of “impurity A.” 

As to Horizon’s reliance on pharmacopeias, Actavis argues 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 Compound A RS, which is a degradation of the active ingredient. Actavis also states that the claims refer to the 

degradation of the entire formulation—including other excipients (inactive ingredients)—as opposed to the degradation 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 opposed 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 reasonably 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 reasonably 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 attempts 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 references 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 Example 6, which contains “[t]he only identity information 

provided for ‘impurity A.’” J.A. 9. That information consists of “retention times derived from a high performance 

liquid chromatography (‘HPLC’).” Id. The specification, 

however, is devoid of other information about the conditions of the HPLC experiment, such as the column, the mobile 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 pharmacopoeias and its expert’s opinion. The district court considered 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 chromatographic 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 “references 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 specification 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 Horizon’s reliance on the pharmacopoeias to extrapolate meaning into “impurity A.” 

We see no clear error in the district court’s determination, 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 determining, 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 temperature 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 reference 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 formulation 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 indefiniteness 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 indefiniteness determination about “impurity A,” which we affirm, 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 patent col. 28 ll. 50–51. 
HZNP MEDICINES LLC v. ACTAVIS LABORATORIES UT, INC. 21

various ingredients.7 Claim 49 of the ’838 patent is illustrative. 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 topical 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 ingredients of the invention. Dissent Op. at 5. The dissent’s position, 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 “consisting of” and open-ended claims using the phrase “comprising.” Id.; AK Steel Corp. v. Sollac & Ugine, 344 F.3d 

1234, 1239 (Fed. Cir. 2003). Accordingly, a drafter will generally 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 ‘consisting 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 properties 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 allows 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 formulation 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 subheading not only identifies the specific characteristic but 

also includes relevant discussion about its importance. 

The specification further highlights these features as advantageous over prior art, stating that the inventive formulation “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 particular aspects noted, the specification then states that the 

inventive formulation “provide[s] superior means for delivery 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 invention. In Nautilus, the Supreme Court held that “a patent is invalid for indefiniteness if its claims, read in light 

of the specification delineating the patent, and the prosecution 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 standard focuses on the claims and therefore does not apply to 

the basic and novel properties of the invention. This argument, however, is misguided. By using the phrase “consisting 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 essentially of” implicates not only the items listed after the 

phrase, but also those steps (in a process claim) or ingredients (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 incorporated unlisted ingredients or steps that do not materially 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 invention 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 uncertainty” that the Supreme Court has warned against. See 

Nautilus, 572 U.S. at 911 (rejecting the “not amenable to 

construction or insolubly ambiguous” definiteness standard 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 requirement of particularity and distinctness in claims is met 

only when they . . . clearly circumscribe what is foreclosed 

from future enterprise. A zone of uncertainty which enterprise and experimentation may enter only at the risk of infringement claims would discourage invention only a little 

less than unequivocal foreclosure of the field.”). Notably, 

the phrase “consisting essentially of” is not per se indefinite. 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 determinations 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 definiteness 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 patent holder should know what he owns, and the 

public should know what he does not. For this reason, 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 invention forth, and the public, which should be encouraged 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 asserted, [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 quotation 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 history, 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 properties 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 “consisting essentially of.” One question focuses on definiteness: 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 determine 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 instructive 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 characteristics. 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 included 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, composition, and light transmittance. Id. We held that, because “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 material 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% silicon. Id. at 1238. Since the accused product included aluminum 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 wetting.” We held that PPG Industries did not compel the district 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 Industries, 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 identified having silicon in excess of 0.5% by weight in aluminum 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 containing 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 intrinsic evidence establishes what constitutes a material alteration 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 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 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 standard 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 subheading, the specification explains that the compositions of 

the invention “dry quicker” than previously disclosed compositions. 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 “drying times” were compared “more quantitatively” by conducting side-by-side comparisons. Id. col. 10 ll. 22–23. To 

do so, the inventors “measured the residual weight of formulations 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 Corresponding Gel,” reveals that the prior art formulation was 

compared to three gel compositions which are embodiments 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 consistent 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 remaining, 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 appropriate 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 improperly 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 specification’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 comprehend the differences between the two tests. 

In response, Actavis contends that the patent uses the 

concepts of “drying time” and “drying rate” interchangeably, with both terms apparently intended to refer to the residual 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 formulations, and then separately discussing drying rate in relation to the speed (‘more rapid,’ ‘quicker,’ or ‘faster’) of 

drying.” Appellant Reply Br. 61. We find Horizon’s proposed 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 patent 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”). Beyond that, the basic point raised by the district court remains: 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 displayed more rapid drying than the liquid formulation.” Id.

col. 21 ll. 63–65 (emphasis added). Regardless of the distinction 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 formulation. 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 percentage than the prior art comparator. 

“[A] claim is indefinite if its language might mean several 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 “better 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.” Consequently, 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 drying 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 formulation patents; (b) applying the Nautilus definiteness standard to the basic and novel properties of the formulation 

patents; and (c) concluding that the phrase “consisting essentially of” was indefinite based on its finding that the 

basic and novel property of “better drying time” was indefinite 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 patent owner draft claims to an untenable level of specificity. 

We conclude only that, on these particular facts, the district court did not err in determining that the phrase “consisting 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 ingredients 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 patent claim, an option foreclosed under the phrase “consisting 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 judgment 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 judgment 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 relation to the asserted claims of the method-of-use patents9 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 Actavis’s label does not induce infringement of those particular claims.

Actavis’s ANDA product, diclofenac sodium topical solution 2%, is a generic version of Horizon’s PENNSAID®

 

essentially of aluminum” asserted against product containing aluminum and silicon). This flexibility afforded to patentee 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 order 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 osteoarthritis pain on the knees. In relevant part, Actavis’s label 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 repellent, cosmetics, topical medications, or other 

substances. (2.2)

. . . .

• Avoid wearing clothing over the diclofenac sodium topical solution-treated knee(s) until the 

treated knee is dry. 

• Protect the treated knee(s) from natural and artificial 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 precautions”). 

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” instead 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 osteoarthritis of the knee of said patient, wherein 

the topical diclofenac preparation comprises 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 enhance the systemic absorption of the subsequently applied sunscreen, or insect 

repellant; 

and wherein said subsequent application 

occurs during a course of treatment of said 

patient with said topical diclofenac preparation.

’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 dispute 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 Horizon alleged that the warning in Actavis’s label would induce 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 permit, rather than require or direct, the post-product application of sunscreen, insect repellant, or a second topical 

medication.” J.A. 58. So even if at some point a user applies one of the items claimed in step three of the methodof-use claims to his or her knee, the district court explained 

that “permission does not amount to encouragement because 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 infringement 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 applying a second medication, and for the ’110 patent it consists 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 another 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 summary 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 motion. 

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 infringement 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. Actavis 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 Exposure,” 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, Actavis contends that there are no material issues of fact and 

that the district court correctly resolved the matter on summary 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 active 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 instructions describe the mode of infringement, but rather on 

whether the “instructions teach an infringing use of the device such that we are willing to infer from those instructions 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 infringing use, or knowing of the possibility of infringement, 

will not suffice; specific intent and action to induce infringement 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 infringing use by applying sunscreen, insect repellant, or a second 

medication. See Appellant Br. 29–30. And the “mere existence of direct infringement . . . is not sufficient for inducement.” 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 application of the medication. 

The fact that Actavis’s label does not require subsequent application of other products reflects that the product 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 evidence, 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. Apotex, 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 evidence, that claim 12 of the ’913 patent is invalid for 

obviousness. Actavis cross-appeals the nonobviousness determination. We review the ultimate legal conclusion 

about obviousness de novo and the underlying factual findings 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 permissible concentrations would not have predicted the exact formulation 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 formulation, such as the thickener that adjusts viscosity, the disclofenac sodium concentration that adjusts permeation 

rate/absorption, or the glycerine that adjusts drying rate. 

According to Actavis, if a POSITA wants to change one aspect of the formulation in a particular way, she may adjust 

the knobs upwards or downwards for the parameter corresponding 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 material effect on other variables and a system where the 

change to one variable must result in changes to the others.” Id. While a drug formulator could be inspired by general knowledge and the prior art to adjust a certain 

variable, the district court found that the variables here interacted 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 further highlighted the unpredictability of the results by crediting Dr. Bunge’s testimony that Fick’s law12—an 

established concept about drug permeation—could not predict what happens under the facts of this case, which involve 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 obvious 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 concentration of the drug in the topical formulation results in

a larger concentration gradient, and leads to a greater permeation—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 involved in this case, including the components of the inventive 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 teachings from the prior art. In light of the district court’s factual findings, we hold that claim 12 of the ’913 patent was 

nonobvious. We thus affirm the district court’s nonobviousness 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-cv00645-NLH-AMD, Judge Noel Lawrence Hillman.

______________________

NEWMAN, Circuit Judge, concurring-in-part, dissenting-inpart.

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 formulation of the drug diclofenac sodium for topical application 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 challenges the validity and infringement of the Horizon patents. 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 persons 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-understood 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, except for one claim, Actavis cannot be liable for induced infringement 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 osteoarthritis 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 “consisting essentially of” is today held to invalidate the composition 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 conclude 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 “consisting 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 topical 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 indefiniteness, 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 incorporated 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 application of section 112(b).

Definiteness of claiming requires that the subject matter 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 formidable 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.” (quoting 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 essentially of,’ and thereby incorporated unlisted ingredients or 

steps that do not materially 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 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 Nautilus, 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 Kabushiki Co., 535 U.S. 722, 741 (2002) (prosecution history).”

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 composition 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 Drying Time/Residual Weight of a Comparative Liquid Formulation Solution Versus the Corresponding Gel.” ’838 

patent, col. 21, l. 38–col. 22, l. 49. Example 5 presents experimental 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 drying time were in Example 5, “a POSA would not know under 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, stating 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 advantage of the claimed composition, recitation and measurement of this property in the specification does not 

convert the composition claims into invalidating indefiniteness 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 essentially 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 Example 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 chromatography.” Id., col. 25, ll. 47–51. Example 6 tabulates the results, 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 details of the chromatography procedure. Horizon responds 

that impurity A is described in the US Pharmacopoeia as 

impurity A of diclofenac (USP Diclofenac Related Compound 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 conditions. 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 diclofenac sodium,” Maj. Op. at 18. This does not comport with 

the presentation in Example 6, or with the US Pharmacopoeia 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 required to be written as a comprehensive tutorial and treatise 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 always 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 always 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 diclofenac 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 ‘favorable stability’ property was indefinite which in this 

case, by extension, rendered the phrase ‘consisting essentially 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 material 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 erroneous premise that the basic and novel properties are required to be included in claims to compositions that are 

described in “consisting essentially of” form.

The majority’s distinction between “consisting 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 “consisting 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 invention.” Id. at 1360.

The panel majority states that this meaning of “consisting of” is available only to “consisting essentially of,” and 

that “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, op. cit. The court in Conoco recognized the difference 

between “consisting of” and “consisting essentially of,” stating 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 “consisting 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 permits, the courts can demand no more.” (quoting GeorgiaPacific Corp. v. U.S. Plywood Corp., 258 F.2d 124, 136 (2d 

Cir. 1958))).

The usage “consisting essentially of” states the essential 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 ingredients. 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 specification.”).

Here no other components are asserted to be present, 

no “unnamed ingredients and steps.” Even on my colleagues’ 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 several 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 omitted). There was no evidence that persons of ordinary skill 

in the field of this invention would not understand the components of the composition claims with reasonable certainty.

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 induces 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 label 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 instructions. 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 incorrect in law. From my colleagues’ contrary ruling on this 

aspect, I again respectfully dissent.