United States Court of Appeals 

for the Federal Circuit 

__________________________ 

IN RE CYCLOBENZAPRINE HYDROCHLORIDE 

EXTENDED-RELEASE CAPSULE PATENT 

LITIGATION 

---------------------------------------------------------------------------------

------------------------------------ 

EURAND, INC. (NOW KNOWN AS APTALIS 

PHARMATECH, INC.), CEPHALON, INC., AND 

ANESTA AG, 

Plaintiffs-Cross Appellants, 

v. 

MYLAN PHARMACEUTICALS INC. AND MYLAN 

INC., 

Defendants-Appellants, 

and 

PAR PHARMACEUTICAL, INC., 

Defendant-Appellee. 

__________________________ 

2011-1399, -1409 

__________________________ 

Appeals from the United States District Court for the 

District of Delaware in Case No. 09-MD-2118, Judge Sue 

L. Robinson. 

_____________________ 

Decided: April 16, 2012 

_____________________ 
EURAND v. MYLAN 2

JONATHAN E. SINGER Fish & Richardson, P.C., of Wilmington, Delaware, argued for plaintiff-cross appellant. 

With him on the brief were WILLIAM J. MARSDEN, JR. of 

Minneapolis, Minnesota, JUANITA R. BROOKS, of San 

Diego, California, and CHERYLYN ESOY MIZZO, of Washington, DC. 

JAMES H. WALLACE, JR., Wiley Rein LLP, of Washington, DC, argued defendants-appellants. With him on the 

brief were MARK A. PACELLA, ROBERT J. SCHEFFEL, 

MATTHEW J. DOWD, KEVIN P. ANDERSON and BRIAN H.

PANDYA. 

__________________________ 

Before NEWMAN, O’MALLEY, and REYNA, Circuit Judges. 

O’MALLEY, Circuit Judge. 

After a bench trial, the U.S. District Court for the District of Delaware found U.S. Patent Nos. 7,387,793 and 

7,544,372 invalid as obvious. Case No. 2011-1409 is an 

appeal from that judgment. We reverse and vacate the 

district court’s judgment of invalidity because the district 

court erred when it declared the patents in suit invalid as 

obvious. Specifically, by failing to consider the lack of a 

known pharmacokinetic/pharmacodynamic relationship 

for the claimed drug formulation, the trial court erred 

when it assessed the importance of the teachings of the 

prior art to the obviousness analysis. 

As an alternative ground in support of the district 

court’s judgment invalidating the ’793 and ’372 patents, 

the defendants argue that the district court erred when it 

found that the patents satisfy the best mode disclosure 

requirement. We affirm the district court’s best mode 

ruling. The evidence supports a finding that the patents 
3 EURAND v. MYLAN

in suit enable one of ordinary skill in the art to practice 

the inventor’s preferred dew points. 

After invalidating the ’793 and ’372 patents as obvious, the district court enjoined the defendants—the 

parties who prevailed at trial—from launching their 

generic product pending appeal to this court. That order 

is challenged in Case No. 2011-1399. We dismiss that 

appeal as premature because several outstanding issues 

in the district court leave uncertain whether the defendants could recover on their appeal bond. 

I. 

Plaintiff Aptalis Pharmatech, Inc. is the owner of the 

’793 and ’372 patents. Plaintiff Anesta AG, a wholly 

owned subsidiary of plaintiff Cephalon, Inc., is the exclusive licensee of the patents. We refer to the plaintiffs 

collectively as Cephalon. 

The ’793 patent covers a modified-release dosage form 

of skeletal muscle relaxants. The ’372 patent covers a 

method of relieving muscle spasms with the formulation 

disclosed in the ’793 patent. Cephalon markets a drug 

covered by the patents under the brand name Amrix. The 

active pharmaceutical ingredient in Amrix is cyclobenzaprine hydrochloride. A single dose of Amrix releases 

cyclobenzaprine hydrochloride in the body during a 

twenty-four-hour period. Immediate-release formulations, by contrast, release the drug in a shorter amount of 

time and require multiple daily doses. 

The ’793 and ’372 patents share the same specification and, as relevant to this appeal, have the same limitations in claims 1–3. Claim 1 recites a dosage form of a 

skeletal muscle relaxant (in the ’793 patent) and a 

method of relieving muscle spasms (in the ’372 patent), 

which, in relevant part, “provides [a] therapeutically 
EURAND v. MYLAN 4

effective plasma concentration over a period of 24 hours to 

treat muscle spasm associated with painful musculoskeletal conditions . . . .” ’793 patent col.10 ll.23, 43–46 (filed 

Nov. 14, 2003); ’372 patent col.10 ll.21, 43–46 (filed Feb. 6, 

2008). Claim 2 depends on claim 1 and specifies the 

claimed skeletal muscle relaxant as cyclobenzaprine 

hydrochloride. ’793 patent col.10 ll.62–64; ’372 patent 

col.10 ll.61–62. Claim 3 depends on claim 2 and specifies 

the following pharmacokinetic values: 

[A] maximum blood plasma concentration 

(Cmax) within the range of about 80% to 

125% of about 20 ng/mL of cyclobenzaprine HCl and an AUC0–168 within the 

range of about 80% to 125% of about 740 

ng·hr/mL and a Tmax within the range of 

80% to 125% of about 7 hours following 

oral administration . . . . 

’793 patent col.10 l.65–col.11 l.5; ’372 patent col.10 l.63–

col.11 l.3. 

Pharmacokinetics is the study of what a person’s body 

does to a drug after administration. The pharmacokinetic 

(“PK”) values recited in claim 3 measure various characteristics about the drug’s behavior in a patient’s blood 

plasma. Cmax, as claim 3 alludes, represents the maximum concentration of the drug in a person’s blood 

plasma. AUC0–168 represents the area under the blood 

plasma concentration curve, or, in other words, the body’s 

total exposure to the drug. Tmax represents the time after 

administration when the maximum concentration of the 

drug in the blood plasma (Cmax) occurs. 

To formulate a therapeutically effective, extendedrelease version of cyclobenzaprine hydrochloride, the 

inventors had to ascertain the correct pharmacokinetic/pharmacodynamic (“PK/PD”) profile. The PK side of 
5 EURAND v. MYLAN

the relationship—what a person’s body does to the drug—

includes the Cmax, AUC, and Tmax, as identified in claim 3. 

The PD side of the relationship describes the effect that a 

drug renders on a person’s body. The PD of cyclobenzaprine hydrochloride is the relief of muscle spasms. 

The determination of a PK profile is a quantitative 

exercise. The determination of PD, or therapeutic effectiveness, however, is a qualitative exercise. As one of 

Cephalon’s experts, Dr. Stanley Davis, explained, a 

therapeutically effective plasma concentration is “a concentration that the formulation provides when the formulation works.” The district court, likewise, construed the 

claim limitation “therapeutically effective plasma concentration” to mean “the amount of a drug required to produce the therapeutic result.” 

One of the patents’ inventors, Dr. Gopi Venkatesh, 

testified at trial about how he and his co-inventor, Dr. 

James Clevenger, ascertained the correct PK/PD profile 

for the patented formulation. First, they estimated PK 

values with computer models. They started by creating 

PK profiles for the immediate-release formulation. The 

immediate-release formulation is dosed at 10 mg. Using 

immediate-release PK data, the inventors created models 

for twice-a-day dosing and three-times-a-day dosing at 10 

mg per dose. Then, they drew on that data to create a 

model for a single, 30 mg dose. The inventors then created an in vitro dissolution profile, which modeled how 

much drug would be released over time if the formulation 

with the model PK values were placed in a solution such 

as water. Finally, the inventors tested a formulation with 

the model PK values and dissolution profile in a clinic. 

Clinical test results confirmed that the formulation was 

therapeutically effective. 
EURAND v. MYLAN 6

II. 

The defendants, Mylan Pharmaceuticals Inc. and Mylan Inc. (collectively, “Mylan”), and Par Pharmaceutical, 

Inc. (“Par”), filed abbreviated new drug applications 

(“ANDAs”) for generic versions of extended-release 

cyclobenzaprine hydrochloride. In support of their ANDAs, Mylan and Par filed “Paragraph IV” certifications, in 

which they alleged that their generic products would not 

infringe the ’793 patent, or that the patent was invalid or 

unenforceable. See 21 U.S.C. § 355(j)(2)(A)(vii)(IV) (2006). 

The U.S. Food and Drug Administration (“FDA”) approved both defendants’ applications. Because Mylan was 

the first party to file a Paragraph IV certification, the 

FDA granted Mylan a 180-day exclusive marketing period 

for its generic product. 

Cephalon sued Mylan and Par for patent infringement, claiming that the defendants’ filing of their ANDAs 

infringed the ’793 patent. See 35 U.S.C. § 271(e)(2) (2006 

& Supp. IV 2010). The FDA stayed Mylan’s exclusive 

marketing period for thirty months because of the litigation. The district court conducted a bench trial in September and October 2010. Rather than ruling from the 

bench, the district court took the matter under advisement to prepare a written opinion. The end of the FDA’s 

thirty-month stay approached as the parties waited for 

the district court’s opinion. On April 8, 2011, the district 

court, sua sponte, temporarily enjoined Mylan from 

launching its generic product pending the issuance of an 

opinion. The thirty-month stay expired on April 17, 2011. 

The district court issued its written opinion on May 

12, 2011. It ruled that Mylan’s and Par’s products infringed the ’793 and ’372 patents, but that Cephalon’s 

asserted patent claims were invalid as obvious. The 

district court entered judgment of invalidity in favor of 
7 EURAND v. MYLAN

Mylan and Par. The district court’s sua sponte injunction 

expired by its own terms upon entry of judgment. 

On May 13, 2011, the day after the district court entered judgment, Mylan launched its generic product. On 

May 15, 2011, Cephalon moved for an injunction to bar 

Mylan’s launch pending appeal and to recapture product 

already released. Cephalon argued that it was likely to 

prevail on appeal because it believed the district court 

had made a number of errors in its obviousness analysis. 

In response, the district court conceded certain errors and 

modified some of its findings, but reaffirmed its obviousness ruling. Notwithstanding that it affirmed Mylan’s 

victory, the district court granted Cephalon’s motion for 

injunctive relief and issued an injunction pending appeal 

to this court. The district court expressed uncertainty 

about whether this court would affirm its invalidity ruling 

and found that Cephalon was “just as likely as not” to 

succeed on appeal. The district court then found that the 

potential harm to Cephalon and a lack of a corresponding 

threat of harm to Mylan weighed in favor of an injunction. 

Mylan appealed the injunction. Cephalon appealed 

the district court’s invalidity ruling. Mylan moved this 

court to stay the injunction pending resolution of the 

appeal, and this court did so temporarily, pending full 

briefing of Mylan’s motion. In re Cyclobenzaprine Hydrochloride Extended-Release Capsule Patent Litig., No. 

2011-1399 (Fed. Cir. May 25, 2011) (order granting immediate stay of preliminary injunction). After briefing 

from the parties, this court lifted the temporary stay, but 

declined to require that Mylan recall any product it had 

sold while the stay was in place. In re Cyclobenzaprine 

Hydrochloride Extended-Release Capsule Patent Litig., 

Nos. 2011-1399, 2011-1409 (Fed. Cir. July 7, 2011) (order 

granting temporary stay in part). We now consider both 

appeals on their merits. 
EURAND v. MYLAN 8

III. 

We address the district court’s obviousness ruling 

first. A patent may not issue “if the differences between 

the subject matter sought to be patented and the prior art 

are such that the subject matter as a whole would have 

been obvious at the time the invention was made to a 

person having ordinary skill in the art to which said 

subject matter pertains.” 35 U.S.C. § 103(a) (2006). 

Obviousness is a question of law based on underlying 

factual findings: (1) the scope and content of the prior art; 

(2) the differences between the claims and the prior art; 

(3) the level of ordinary skill in the art; and (4) objective 

considerations of nonobviousness. Graham v. John Deere 

Co., 383 U.S. 1, 17–18 (1966). Generally, a party seeking 

to invalidate a patent as obvious must “demonstrate ‘by 

clear and convincing evidence that a skilled artisan would 

have had reason to combine the teaching of the prior art 

references to achieve the claimed invention, and that the 

skilled artisan would have had a reasonable expectation 

of success from doing so.’” Procter & Gamble Co. v. Teva 

Pharms. USA, Inc., 566 F.3d 989, 994 (Fed. Cir. 2009) 

(quoting Pfizer, Inc. v. Apotex, Inc., 480 F.3d 1348, 1361 

(Fed. Cir. 2007)). See also Amgen, Inc. v. F. Hoffmann-La 

Roche Ltd., 580 F.3d 1340, 1362 (Fed. Cir. 2009) (“An 

obviousness determination requires that a skilled artisan 

would have perceived a reasonable expectation of success 

in making the invention in light of the prior art.”) (citations omitted). The Supreme Court has warned, however, 

that, while an analysis of any teaching, suggestion, or 

motivation to combine known elements is useful to an 

obviousness analysis, the overall obviousness inquiry 

must be expansive and flexible. KSR Int’l Co. v. Teleflex, 

Inc., 550 U.S. 398, 415, 419 (2007). 

In reviewing a district court’s obviousness ruling after 

a bench trial, we review its legal conclusion de novo, but 
9 EURAND v. MYLAN

we review its underlying factual findings for clear error. 

Proctor & Gamble, 566 F.3d at 993–94. The clear-error 

standard of review applied to a district court’s factual 

findings demands that we defer to those findings unless 

we are left with “a definite and firm conviction that a 

mistake has been committed.” United States v. U.S. 

Gypsum Co., 333 U.S. 364, 395 (1948). While we afford 

deference to a district court’s factual findings, however, 

we retain plenary review to determine whether, as a legal 

matter, the evidence satisfies the clear-and-convincing 

standard of proof. Proctor & Gamble, 566 F.3d at 993–

94. Indeed, the Supreme Court recently confirmed that a 

party asserting an obviousness claim bears that high 

burden of persuasion. Microsoft Corp. v. i4i Ltd., 131 S. 

Ct. 2238, 2242 (2011). 

A. 

We find that the district court’s legal conclusion that 

bioequivalence alone was sufficient to render the claims 

at issue obvious was in error. We also find clear error in a 

number of the district court’s factual findings, as identified below. 

The obviousness inquiry in this case is focused on bioequivalence. The concept of bioequivalence means the 

body is exposed to the same amount of active pharmaceutical ingredient at the same rate after administration of 

either an immediate-release or extended-release formulation. The district court found the asserted claims obvious 

because it believed the claimed extended-release PK 

profile is bioequivalent to the immediate-release PK 

profile. Mylan agrees with the district court’s approach of 

resting its obviousness finding on bioequivalence. Cephalon, however, argues that the district court placed undue 

weight on bioequivalence and, as a result, misinterpreted 

the proffered prior art references. 
EURAND v. MYLAN 10

We agree with Cephalon. The district court treated 

bioequivalence as the end of its inquiry when the court 

found that it would have been obvious to a person having 

ordinary skill in the art to target extended-release PK 

values “mirroring”—in other words, bioequivalent to—

those of the immediate-release cyclobenzaprine formulation. The district court, however, was also required to 

consider the asserted claims’ limitation requiring therapeutic effectiveness, and whether it would have been 

obvious to one of ordinary skill in the art at the time of 

the invention that a bioequivalent PK value would satisfy 

that limitation. Graham, 383 U.S. at 17–18 (making clear 

that “differences between the prior art and the claims at 

issue are to be ascertained”) (emphasis added). 

Mylan and Par argued, and the district court agreed, 

that the undisputed fact that cyclobenzaprine lacked a 

known PK/PD relationship at the time of invention was 

irrelevant. Without such a known relationship, however, 

skilled artisans could not predict whether any particular 

PK profile, including a bioequivalent one, would produce a 

therapeutically effective formulation. Dr. Davis, Cephalon’s expert, testified that cyclobenzaprine’s “mode of 

action was not really well known and there [was] certainly no clear relationship between a given pharmacokinetic profile and the pharmacodynamic effect, what it 

actually does to the body.” One of the defendants’ experts, 

Dr. Gordon Amidon, acknowledged that there was nothing 

in the prior art or published literature “that would help a 

person skilled in the art determine a therapeutically 

effective plasma concentration over a 24-hour period.” 

Mylan and Par did not dispute that cyclobenzaprine 

lacked a known PK/PD relationship. Rather, they attempted to avoid that fact in two ways. First, they asserted the truism that skilled artisans would need only a 

reasonable expectation of success and would not need to 
11 EURAND v. MYLAN

be certain of what a particular PK profile would yield. 

See Defs.’ Resp. & Reply Br. 26. Second, Mylan and Par 

argued to the district court that the patents in suit lack 

sufficient written description to support the “therapeutically effective” limitation. Lack of written description, 

however, is a separate defense, which the defendants do 

not advance on appeal. For purposes of obviousness, 

therefore, we must accept as true that cyclobenzaprine 

lacked a known PK/PD relationship at the time of invention, and that the asserted claims contain a valid “therapeutically effective” limitation. 

The district court misapprehended the importance of 

the lack of a known PK/PD relationship. The district 

court stated that “[t]he lack of a PK/PD relationship is of 

no moment . . . given that one of ordinary skill in the art 

would expect the extended release formulation to have the 

same PD effect on the body if it has the immediate release 

formulation’s PK profile.” That statement contains an 

inherent contradiction. By stating that skilled artisans 

would assume that the immediate-release and extendedrelease PK profiles produce the same PD effect, the district court was assuming that a known PK/PD relationship existed for the immediate-release formulation. 

Because all experts and parties agree, however, that 

skilled artisans did not know the PK/PD relationship even 

for the immediate-release formulation, there was no way 

to match the dosage for the extended-release formulation 

to achieve a known therapeutic effect. The district court, 

therefore, could not find obviousness without finding that 

the prior art would have taught or suggested a therapeutically effective formulation to one of ordinary skill in the 

art. The record lacks any such evidence. While it may 

have been obvious to experiment with the use of the same 

PK profile when contemplating an extended-release 

formulation, there is nothing to indicate that a skilled 
EURAND v. MYLAN 12

artisan would have had a reasonable expectation that 

such an experiment would succeed in being therapeutically effective. See Proctor & Gamble, 566 F.3d at 994 

(requiring a reasonable expectation of success to prove 

obviousness). 

This distinction is important. Where a skilled artisan 

merely pursues “known options” from “a finite number of 

identified, predictable solutions,” the resulting invention 

is obvious under Section 103. KSR, 550 U.S. at 421. 

Where, however, a defendant urges an obviousness finding by “merely throw[ing] metaphorical darts at a board” 

in hopes of arriving at a successful result, but “the prior 

art gave either no indication of which parameters were 

critical or no direction as to which of many possible 

choices is likely to be successful,” courts should reject 

“hindsight claims of obviousness.” In re Kubin, 561 F.3d 

1351, 1359 (Fed. Cir. 2009) (quoting In re O’Farrell, 853 

F.2d 894, 903 (Fed. Cir. 1988)). 

B. 

The district court’s failure to appreciate the lack of a 

known PK/PD relationship for any formulation of 

cyclobenzaprine rendered deficient its analysis of the 

evidence that Mylan and Par offered to prove the claimed 

PK values obvious and its analysis of the implications of 

that evidence on its legal conclusion of obviousness. We 

explain below why the district court’s analysis was deficient. 

1. 

The district court found that a skilled artisan could 

calculate the claimed AUC and Tmax by conducting what it 

called “routine experimentation”: creating computer 

models based on data from articles by Winchell and 

Hucker, and PK data for Flexeril, the branded immediate-
13 EURAND v. MYLAN

release formulation. The district court relied on the 

testimony of Dr. Amidon in interpreting those prior art 

references.1 Mylan and Par agree with the district court, 

arguing that the evidence shows that “one of ordinary 

skill in the art could readily convert the known pharmacokinetic data for Flexeril® administered 10 mg three 

times a day to an equivalent pharmacokinetic profile for a 

single daily 30 mg administration.” Defs.’ Resp. & Reply 

Br. 40. 

Dr. Amidon’s testimony, however, was insufficient to 

support the conclusion that a skilled artisan would reasonably expect to achieve a therapeutically effective AUC 

and Tmax. Indeed, it was actually inconsistent with that 

conclusion. As Dr. Amidon explained, Winchell reveals 

that cyclobenzaprine is linear, which means that blood 

plasma concentration increases proportionally to dosage. 

The fact that a skilled artisan could have predicted a 

particular blood plasma concentration, however, does not 

mean that such knowledge would have provided a skilled 

artisan a reasonable expectation of success in calculating 

a blood plasma concentration that was therapeutically 

effective. As Dr. Amidon also explained, Winchell suggests that cyclobenzaprine is well absorbed in the body. 

That information, however, pertains to the body’s physical 

absorption of the drug rather than the correct PK/PD 

relationship. As Dr. Amidon further explained, Winchell 

provides PK values for immediate-release cycloben-

 1 The district court also relied upon the testimony 

of another defense expert, Dr. Courtney Fletcher, to find 

that the Tmax can be calculated when the other parameters of the model are known. Because Cephalon is correct 

that Dr. Fletcher was not qualified to testify to that point, 

any reliance on Dr. Fletcher for this proposition was clear 

error. Indeed, the district court seemed to concede this 

point when responding to the errors that Cephalon identified in the court’s trial opinion. 
EURAND v. MYLAN 14

zaprine, and Hucker provides plasma concentration time 

curves for the immediate-release formulation. Without a 

known PK/PD relationship, however, immediate-release 

PK values are of little use in calculating extended-release 

values, because there is no proof that a skilled artisan 

would expect the extended-release values to produce a 

therapeutic effect solely because they are drawn from 

immediate-release values. 

The evidence on which the district court relied to find 

the claimed Cmax obvious similarly focuses on bare PK 

values rather than the PD effect that the PK values could 

be expected to produce. The district court found that 

Winchell “undisputably [sic]” disclosed the claimed Cmax. 

Winchell indicates that, after subjects are dosed every 

eight hours for seven days at 10 mg/dose, subjects have a 

Cmax of 25.9 ng/ml. That value is 129.5% of 20 ng/ml. 

Claim 3 of the patents in suit claims a Cmax range of about 

80% to 125% of about 20 ng/ml. The district court, however, cited no evidence specifically indicating that a 

cyclobenzaprine PK profile with a Cmax of 129.5% of 20 

ng/ml would be expected to yield the same therapeutic 

effect as that with a Cmax range of about 80% to 125% of 

about 20 ng/ml. 

The district court, moreover, cited nothing to support 

a finding that the claimed Cmax range of about 80% to 

125% of about 20 ng/ml even encompasses Winchell’s Cmax

of 129.5% of 20 ng/ml. Claim 3 does specify that the 

claimed range is about 80% to 125% of about 20 ng/ml. 

The district court construed the term “about” to mean 

“approximately,” but failed to cite any evidence indicating 

that 129.5% of 20 ng/ml is approximately 125% of 20 
15 EURAND v. MYLAN

ng/ml. The parties have not directed us to any such 

proof.2

The district court found persuasive Dr. Amidon’s ultimate opinion that a skilled artisan could expect to 

achieve efficacy by relying on the Winchell and Hucker 

articles to estimate a PK profile for an extended-release 

formulation by using computer software. While we would 

normally afford the district court deference in crediting 

such an opinion, we cannot do so here because Dr. Amidon 

failed to discuss why, in the specific context of cyclobenzaprine, a skilled artisan would expect PK values drawn 

from the prior art to yield a therapeutically effective 

formulation. Indeed, the portion of Dr. Amidon’s testimony on which the district court relied conflicts with his 

acknowledgement that the prior art and published literature lacked any guidance to help a skilled artisan determine a therapeutically effective, extended-release plasma 

concentration. Dr. Amidon’s own computer modeling, 

moreover, failed to generate PK values within the claimed 

ranges. 

Mylan and Par rely extensively on Dr. Amidon’s testimony about the prior art in arguing that it would have 

been obvious to try to develop extended-release cycloben-

 2 While it might appear to a layperson that 129.5% 

is “about” 125%, expert testimony is necessary to establish how a person having ordinary skill in the art would 

perceive those figures. We have no way of knowing the 

importance of even small differences in these percentages 

in the absence of some evidence in the record addressing 

that point. See Ortho-McNeil Pharm., Inc. v. Caraco 

Pharm. Labs., Inc., 476 F.3d 1321, 1326 (Fed. Cir. 2007) 

(“The use of the word “about,” avoids a strict numerical 

boundary to the specified parameter. Its range must be 

interpreted in its technological and stylistic context.” 

(quoting Pall Corp. v. Micron Separations, Inc., 66 F.3d 

1211, 1217 (Fed. Cir. 1995))). 
EURAND v. MYLAN 16

zaprine bioequivalent to the immediate-release PK profile, and that skilled artisans would have had a reasonable expectation of success in doing so. The insufficiency 

of that evidence demonstrates why the defendants’ argument stands on a weak foundation. Evidence of obviousness, especially when that evidence is proffered in support 

of an “obvious-to-try” theory, is insufficient unless it 

indicates that the possible options skilled artisans would 

have encountered were “finite,” “small,” or “easily traversed,” and that skilled artisans would have had a reason 

to select the route that produced the claimed invention. 

Ortho-McNeil Pharm., Inc. v. Mylan Labs., Inc., 520 F.3d 

1358, 1364 (Fed. Cir. 2008) (citing KSR, 550 U.S. at 421). 

While it is true that Section 103 bars patentability unless 

“the improvement is more than the predictable use of 

prior art elements according to their established functions,” KSR, 550 U.S. at 417, where the prior art, at best, 

“[gives] only general guidance as to the particular form of 

the claimed invention or how to achieve it,” relying on an 

“obvious-to-try” theory to support an obviousness finding 

is “impermissible.” In re Kubin, 561 F.3d at 1359 (quoting 

In re O’Farrell, 853 F.2d at 903). Nothing in Dr. Amidon’s 

testimony sheds light on why a skilled artisan would have 

chosen a bioequivalent PK profile in the absence of a 

known PK/PD relationship for cyclobenzaprine. Thus, the 

absence of such testimony suggests that skilled artisans 

would not have encountered finite, small, or easily traversed options in developing a therapeutically effective, 

extended-release formulation. See id. And, there is 

nothing in the record to support the conclusion that what 

the co-inventors did here was no more than a “predictable 

use of known prior art elements.” KSR, 550 U.S. at 417. 

The Winchell and Hucker articles, the Flexeril data, 

and the defense experts’ interpretation of those references, fail to indicate that a skilled artisan would have 
17 EURAND v. MYLAN

reasonably expected to calculate therapeutically effective 

PK values based on those references. While the district 

court’s assessment of this evidence may be understandable given its predicate mistake regarding the absence of 

a known PK/PD profile for the immediate-release formulation, it was, nonetheless, clear error.

2.

The district court also relied on other evidence to support its obviousness analysis. The district court’s factual 

conclusions from this evidence again were clearly erroneous, however, and the weight given to them in the court’s 

obviousness conclusion was undue. 

The district court noted that Dr. Clevenger, coinventor of the patents in suit, created computer models 

of the claimed PK values after he reviewed the Flexeril 

PK data. The district court cited Dr. Clevenger’s approach when it concluded that the claimed AUC and Tmax

could be obtained by “routine experimentation.” In relying on Dr. Clevenger’s testimony, the district court merely 

retraced the inventor’s steps. This hindsight analysis is 

inappropriate because obviousness must be assessed at 

the time the invention was made. See Ortho-McNeil, 520 

F.3d at 1364 (noting that 35 U.S.C. § 103(a) directs an 

inquiry into whether the subject matter as a whole “would 

have been obvious at the time the invention was made”). 

Like the district court, Mylan and Par rely on Dr. 

Clevenger’s testimony for the proposition that “one of 

ordinary skill could use the available software . . . and 

estimate the parameters identified by Mylan’s experts.” 

Defs.’ Resp. & Reply Br. 41. Like the district court, 

however, Mylan and Par employ hindsight analysis. 

Dr. Clevenger’s testimony, moreover, does not support 

the proposition for which the district court cited it. The 

district court found significant Dr. Clevenger’s testimony 
EURAND v. MYLAN 18

that “[i]t can be assumed that the [immediate-release 

product] produced a therapeutic effect . . .” and that “if we 

get something similar to those blood levels . . . then we, 

too, will have a product that will produce a therapeutic 

effect.” The district court, however, omitted the next 

exchange in Dr. Clevenger’s examination: “[Question:] . . . 

So the idea is that if the blood levels were similar to 

Flexeril, then hopefully, the effect would be similar—the 

therapeutic effect would be similar to Flexeril? [Answer:] 

Hopefully. Depends on the relationship between blood 

levels and therapeutic effect.” The district court later 

attempted to minimize the importance of Dr. Clevenger’s 

omitted testimony, concluding that “this testimony simply 

shows that the inventor needed to verify his results in the 

lab. Obviousness calls for an expectation of success, not a 

guarantee.” A plain reading of the testimony, however, 

indicates that Dr. Clevenger never expressed even an 

expectation of success. He merely testified that, whether 

blood levels similar to those produced by Flexeril would 

produce a therapeutic effect similar to that of Flexeril, 

depended on the relationship between blood levels and 

therapeutic effectiveness—a relationship that all concede 

was unknown. 

The district court also relied on an FDA guidance 

document, which it found directed skilled artisans to 

pursue bioequivalence when formulating extended-release 

formulations. The title of the document the district court 

cited is “Guidance for Industry.” The district court found 

that the document sets forth an FDA directive that an 

extended-release dosage form have the same AUC and 

Cmax of an already-approved immediate-release formulation. The FDA document, however, states that its purpose is “to provide recommendations to sponsors and/or 

applicants planning to include . . . bioequivalence information” in applications. The document provides advice on 
19 EURAND v. MYLAN

what they should do if they plan to pursue bioequivalence. 

The document provides little support for an obviousness 

finding here, because, in the absence of a known PK/PD 

relationship for cyclobenzaprine, there is no evidence that 

a skilled artisan would have targeted bioequivalence in 

the first instance. 

One judge of our court has observed that the FDA’s 

publishing of approval requirements for extended-release 

formulations does not necessarily render obvious a drug 

that meets those requirements, because “knowledge of the 

goal does not render its achievement obvious.” Abbott 

Labs., Inc. v. Sandoz, Inc., 544 F.3d 1341, 1352 (Fed. Cir. 

2009). That observation is particularly salient here 

because Mylan and Par fail to demonstrate that skilled 

artisans would have even viewed bioequivalence as the 

goal when creating an extended-release cyclobenzaprine 

formulation. Indeed, while there might have been a 

desire for an extended-release formulation, there is no 

evidence that skilled artisans would have known how to 

achieve it. See Cardiac Pacemakers, Inc. v. St. Jude Med., 

Inc., 381 F.3d 1371, 1377 (Fed. Cir. 2004) (“Recognition of 

a need does not render obvious the achievement that 

meets that need. . . . Recognition of an unsolved problem 

does not render the solution obvious.”). 

3.

Finally, the district court relied on two other prior art 

references, neither of which supports a finding that the 

“therapeutically effective” limitation is obvious. Those 

references—U.S. Patent No. 6,344,215 and European 

Patent Application No. 518,263A1 (“Urban”)—disclose 

formulation technology and dissolution profiles rather 

than pharmacokinetics. The Urban reference discloses a 

micropellet that can be used for an extended-release 

formulation. It lists cyclobenzaprine as a suitable me-
EURAND v. MYLAN 20

dicament for the formulation. The ’215 patent—Dr. 

Venkatesh is the named inventor—discloses a multiparticulate dosage form, for use with methylphenidate, that 

features the same dissolution profile claimed in the patents in suit. The district court believed that it would have 

been obvious to use the same drug delivery system because it had already been proven effective with methylphenidate. Mylan and Par, likewise, argue that “[t]he 

only meaningful structural difference between the asserted claims of the ’793 patent and ’215 patent was the 

active ingredient, cyclobenzaprine versus methylphenidate.” Defs.’ Resp. & Reply Br. 8. 

Even if the ’215 patent and Urban teach the claimed 

physical drug delivery system and dissolution profile, they 

reveal nothing about the critical limitation at issue here: 

a therapeutically effective PK profile. Cephalon has 

acknowledged that the structure of the drug delivery 

system and the dissolution profile are not novel aspects of 

the claimed invention. Oral Argument at 22:40, available 

at http://www.cafc.uscourts.gov/oral-argumentrecordings/2011-1399/all. Urban and the ’215 patent 

provide no support for the district court’s obviousness 

finding with respect to pharmacokinetics. 

 C.

After the district court found that Mylan and Par 

proved the asserted claims obvious, it considered Cephalon’s proof of objective considerations of nonobviousness to 

determine whether Cephalon’s proofs were sufficient to 

“rebut” that obviousness determination. Specifically, the 

district court considered Cephalon’s evidence of the failure of others to make the patented invention; longfelt but 

unsolved needs fulfilled by the patented invention; commercial success of the patented invention; and unexpected 

results produced by the patented invention. See Graham, 
21 EURAND v. MYLAN

383 U.S. at 17–18; Pfizer, Inc. v. Apotex, Inc., 480 F.3d 

1348, 1369 (Fed. Cir. 2007). The district court found 

Cephalon’s evidence insufficient to rebut Mylan’s and 

Par’s showing. The district court erred, however, by 

making its finding that the patents in suit were obvious 

before it considered the objective considerations and by 

shifting the burden of persuasion to Cephalon. In doing 

so, the district court contravened this court’s precedent 

requiring that a fact finder consider all evidence relating 

to obviousness before finding a patent invalid on those 

grounds, and the court imposed a burden-shifting framework in a context in which none exists. 

1.

The premature nature of the court’s obviousness finding is apparent. Before it reached the objective considerations, the district court stated that the claimed PK profile 

“would have been obvious to one of skill in the art at the 

time of the invention” and that “a person of ordinary skill 

in the art would have been motivated to take a group of 

known elements to create an extended release version of 

cyclobenzaprine, and [would have had] a reasonable 

expectation of success in doing so.” It was not until after 

the district court found the asserted claims obvious that it 

proceeded to analyze the objective considerations, or what 

it called the “secondary considerations.” 

2. 

The district court’s error is understandable because 

this court has inconsistently articulated the burden of 

proof applicable to an obviousness defense in district court 

litigation. It was error nonetheless. 

In Stratoflex, Inc. v. Aeroquip Corp., we held that a 

fact finder in district court litigation may not defer ex-
EURAND v. MYLAN 22

amination of the objective considerations until after the 

fact finder makes an obviousness finding: 

It is jurisprudentially inappropriate to 

disregard any relevant evidence on any issue in any case, patent cases included. 

Thus evidence rising out of the so-called 

“secondary considerations” must always 

when present be considered en route to a 

determination of obviousness. . . . Indeed, 

evidence of secondary considerations may 

often be the most probative and cogent 

evidence in the record. It may often establish that an invention appearing to have 

been obvious in light of the prior art was 

not. It is to be considered as part of all the 

evidence, not just when the decisionmaker 

remains in doubt after reviewing the art. 

713 F.2d 1530, 1538–39 (Fed. Cir. 1983) (citations omitted). Many subsequent cases have expressly followed 

Stratoflex’s directive that courts consider all objective 

evidence before reaching an obviousness conclusion. See

Ruiz v. A.B. Chance Co., 234 F.3d 654, 663 (Fed. Cir. 

2000) (“Our precedent clearly establishes that the district 

court must make Graham findings before invalidating a 

patent for obviousness.”); Cable Elec. Prods. v. Genmark, 

Inc., 770 F.2d 1015, 1026 (Fed. Cir. 1985) (quoting Stratoflex, 713 F.2d at 1539) (“The opinions of this court have 

suggested that evidence on these secondary considerations is to be taken into account always, ‘not just when 

the decisionmaker remains in doubt after reviewing the 

art.’”); Simmons Fastener Corp. v. Illinois Tool Works, 

Inc., 739 F.2d 1573, 1575 (Fed. Cir. 1984); (“The section 

103 test of nonobviousness set forth in Graham is a four 

part inquiry comprising, not only the three familiar 

elements (scope and content of the prior art, differences 
23 EURAND v. MYLAN

between the prior art and the claims at issue, and level of 

ordinary skill in the pertinent art), but also evidence of 

secondary considerations when such evidence is, of course, 

present”); Richardson-Vicks Inc. v. Upjohn Co., 122 F.3d 

1476, 1483 (Fed. Cir. 1997) (holding that “we must consider all of the evidence under the Graham factors before 

reaching our decision”); Rockwell Int’l Corp. v. United 

States, 147 F.3d 1358, 1366 (Fed. Cir. 1998) (following 

Richardson-Vicks); and Kan. Jack, Inc. v. Kuhn, 719 F.2d 

1144, 1150–51 (Fed. Cir. 1983) (finding that a district 

court’s consideration of commercial success complied with 

“the basic requirement that all evidence touching the 

obvious-nonobvious issue be fully considered before a 

conclusion is reached on that issue” (citing In re Sernaker, 

702 F.2d 989, 996 (Fed. Cir. 1983))). 

While many panels of this court have adhered to Stratoflex’s directive, some instead have spoken of the obviousness analysis in terms of a “prima facie” case which 

must then be “rebutted” by the patentee. Under that 

framework, a court inquires whether the party challenging validity has proven a “prima facie” case of obviousness, based only on reference to the patent and the 

proffered prior art, and only then considers objective 

evidence, asking whether such evidence is sufficient to 

overcome the prima facie case.3

 3 See, e.g., Innovention Toys, L.L.C. v. MGA Entm’t, 

Inc., 637 F.3d 1314, 1323 (Fed. Cir. 2011) (“[S]hould the 

district court conclude [on remand] that [defendant] has 

made out a prima facie case of obviousness based on the 

[prior art], the court must then determine whether [plaintiff’s] secondary considerations overcome [defendant’s] 

prima facie case”); Transocean Offshore Deepwater Drilling, Inc. v. Maersk Contractors USA, Inc., 617 F.3d 1296, 

1305 (Fed. Cir. 2010) (“If all of the factual disputes regarding the objective evidence resolve in favor of [plaintiff], it has presented a strong basis for rebutting the 
EURAND v. MYLAN 24

Despite this language, however, those cases should 

not be interpreted as establishing a formal burdenshifting framework. This is so for a number of reasons. 

First, a review of those cases indicates that in none was 

the placement of the burden with respect to evidence of 

objective considerations, or the timing of the fact finder’s 

consideration of that evidence, determinative. See supra

n.3. 

Second, even panels that have used the “prima facie” 

and “rebuttal” language generally have made clear that a 

fact finder must consider all evidence of obviousness and 

nonobviousness before reaching a determination. For 

example, in Iron Grip Barbell Co. v. USA Sports, Inc., 

while the panel did hold that “there is no objective evidence to rebut the strong showing of obviousness based on 

 

prima facie case [of obviousness].”); Muniauction, Inc. v. 

Thomson Corp., 532 F.3d 1318, 1327 (Fed. Cir. 2008) 

(“Under the foregoing analysis, we conclude that [defendant] has clearly and convincingly established a prima 

facie case that claims 1 and 31 of the ’099 patent are 

obvious as a matter of law. Accordingly, we turn to 

[plaintiff’s] attempt to rebut this prima facie case with 

secondary considerations of nonobviousness.”); Eli Lilly & 

Co. v. Zenith Goldline Pharms., Inc., 471 F.3d 1369, 1380 

(Fed. Cir. 2006) (“[Plaintiff] overcame any prima facie 

case of obviousness . . . [because it] proved extensive 

secondary considerations to rebut obviousness”); Ormco 

Corp. v. Align Tech., Inc., 463 F.3d 1299, 1311 (Fed. Cir. 

2006) (“A nonmovant may rebut a prima facie showing of 

obviousness with objective indicia of nonobviousness.”); 

Iron Grip Barbell Co. v. USA Sports, Inc., 392 F.3d 1317, 

1325 (Fed. Cir. 2004) (“[W]e conclude that there is no 

objective evidence to rebut the strong showing of obviousness based on the prior art.”); and WMS Gaming Inc. v. 

Int’l Game Tech., 184 F.3d 1339, 1359 (Fed. Cir. 1999) 

(“The objective evidence of non-obviousness may be used 

to rebut a prima facie case of obviousness based on prior 

art references.”). 
25 EURAND v. MYLAN

the prior art,” 392 F.3d 1317, 1325 (Fed. Cir. 2004), it also 

cautioned that, in “determining the question of obviousness, inquiry should always be made into whatever objective evidence of nonobviousness there may be.” Id. at 

1323 (quoting Vandenberg v. Dairy Equip. Co., 740 F.2d 

1560, 1567 (Fed. Cir. 1984)). In Transocean Offshore 

Deepwater Drilling, Inc. v. Maersk Contractors USA, Inc., 

while the panel observed that, “[i]f all of the factual 

disputes regarding the objective evidence resolve in favor 

of [plaintiff], it has presented a strong basis for rebutting 

the prima facie case [of obviousness],” the panel stated, 

“[t]o be clear, a district court must always consider any 

objective evidence of nonobviousness presented in a case.” 

617 F.3d 1296, 1305 (Fed. Cir. 2010). And in WMS Gaming Inc. v. International Game Technology, while the 

panel stated that “[t]he objective evidence of nonobviousness may be used to rebut a prima facie case of 

obviousness based on prior art references,” it also stated 

that “[t]he consideration of the objective evidence presented by the patentee is a necessary part of the obviousness determination.” 184 F.3d 1339, 1359 (Fed. Cir. 

1999). Thus, a reading of these cases that permits a fact 

finder to reach a conclusion of obviousness before considering all relevant evidence, including evidence of objective 

considerations, would not only conflict with Stratoflex’s 

directive that objective considerations are “to be considered as part of all the evidence, not just when the decisionmaker remains in doubt after reviewing the art,” 713 

F.2d at 1538, but would ignore their actual holdings. 

Next, the Supreme Court has never imposed nor even 

contemplated a formal burden-shifting framework in the 

patent litigation context.4 It has, instead, required that 

 4 The Court’s treatment of the burden of persuasion 

in the obviousness context markedly differs from its 

treatment of the burden of persuasion in other contexts, 
EURAND v. MYLAN 26

all evidence relevant to obviousness or nonobviousness be 

considered, and be considered collectively. In Graham, 

the Court stated that “[s]uch secondary considerations as 

commercial success, long felt but unsolved needs, failure 

of others, etc., might be utilized to give light to the circumstances surrounding the origin of the subject matter 

sought to be patented,” along with the scope and content 

of the prior art, the differences between the prior art and 

the claims at issue, and the level of ordinary skill in the 

pertinent art. 383 U.S. at 17–18. Notably, the Court did 

 

such as employment discrimination claims under Title VII 

of the Civil Rights Act of 1964. In McDonnell Douglas 

Corp. v. Green, the Court established the well-known 

formal, three-part burden-shifting framework that a 

plaintiff must satisfy to prove a discrimination claim with 

circumstantial evidence. 411 U.S. 792 (1973). Several 

differences are apparent between the Court’s burdenshifting framework under McDonnell Douglas and its 

treatment of the burden of proof with respect to obviousness. First, the term “prima facie,” as used in the 

McDonnell Douglas context, means “the establishment of 

a legally mandatory, rebuttable presumption,” as opposed 

to “the plaintiff’s burden of producing enough evidence to 

permit the trier of fact to infer the fact at issue.” Tex. 

Dep’t of Cmty. Affairs v. Burdine, 450 U.S. 248, 254 n.7 

(1981). As discussed above, the Court has never spoken 

in terms of a legally rebuttable presumption with respect 

to obviousness. Second, the Court’s rationale for fashioning a formal burden-shifting framework in employment 

discrimination cases is to facilitate inquiry into an employer’s intent: “the allocation of burdens and the creation 

of a presumption by the establishment of a prima facie 

case is intended progressively to sharpen the inquiry into 

the elusive factual question of intentional discrimination.” 

Burdine, 256 F.3d at 256 n.8. While the obviousness 

inquiry undoubtedly demands precision, the Court has 

never identified a problem in its application such that 

“sharpening” by way of a burden-shifting scheme is necessary. 
27 EURAND v. MYLAN

not characterize the objective factors as after-the-fact 

considerations or relegate them to “secondary status.” 

The Court, rather, indicated that the objective considerations have broader applicability, noting that, “[a]s indicia 

of obviousness or nonobviousness, these inquiries may 

have relevancy.” Id. The Court recently reaffirmed this 

approach to objective considerations when it described the 

obviousness inquiry as “expansive and flexible” and noted 

that Graham “invite[s] the courts, where appropriate, to 

look at any secondary considerations that would prove 

instructive.” KSR, 550 U.S. at 415. And, in i4i, the Court 

reaffirmed both the scope and placement of the burden of 

proof in these circumstances. 131 S. Ct. at 2245, n.4. 

In i4i, the Court was asked to articulate the standard 

of proof a party must satisfy to prove an invalidity defense. 131 S. Ct. at 2242. The Court held that the standard of proof is proof by clear and convincing evidence. 

Id. In explaining that holding, the Court differentiated 

between the concepts of burden of proof, burden of production, burden of persuasion, and standard of proof. Id.

at 2245. As the Court explained, the commonly used term 

“burden of proof” encompasses the concepts of “burden of 

persuasion” and “burden of production.” Id. at 2245 n.4. 

The burden of persuasion specifies “which party loses if 

the evidence is balanced,” while the burden of production 

specifies “which party must come forward with evidence 

at various stages in the litigation.” Id. at 2245 n.4. The 

standard of proof, the court further explained, specifies 

“how difficult it will be for the party bearing the burden of 

persuasion to convince the jury of the facts in its favor.” 

Id. at 2245 n.4. 

The Court resorted to common-law principles to determine that the standard of proof is proof by clear and 

convincing evidence because the Patent Act does not 

explicitly articulate the standard of proof. Id. at 2245–
EURAND v. MYLAN 28

46. By contrast, the Court noted, the Patent Act specifies 

that the burden of proof is placed on the party challenging 

validity: “The burden of establishing invalidity of a patent 

or any claim thereof shall rest on the party asserting such 

invalidity.” Id. at 2245 (quoting 35 U.S.C. § 282). The 

Court provided no indication that it believes the burden of 

persuasion should shift to the patentee at some point to 

prove nonobviousness. 5

Finally, not only is Stratoflex the law, it is sound in 

requiring that a fact finder consider the objective evidence 

before reaching an obviousness determination. The 

objective considerations, when considered with the balance of the obviousness evidence in the record, guard as a 

check against hindsight bias. Graham, 383 U.S. at 36 

(quoting Monroe Auto Equip. Co. v. Heckethorn Mfg. & 

Supply Co., 332 F.2d 406, 412 (6th Cir. 1964)). In Graham, the Court recognized the danger of hindsight bias 

and the ameliorative effect that the objective considerations might offer. In discussing the utility of the objective 

considerations, the Court cited a law review note published after the nonobviousness requirement was enacted 

in the 1952 Patent Act. Id. at 18 (citing Richard L. Rob-

 5 It is true that, in most cases, it is a patentee who 

chooses to offer proof of objective considerations as evidence of nonobviousness. It is also true that district 

courts will often impose a discovery obligation on patentees to be the first to produce evidence relating to objective 

considerations. And, it is true that district courts also 

often require patentees to present their objective evidence 

during their case in chief to make an efficient use of time 

and resources during trial, relying on their authority 

under Federal Rule of Evidence 611(a) to structure the 

presentation of evidence. Those realities do not change 

the fact that the party challenging validity bears the 

burden of persuasion throughout the litigation. i4i, 131 S. 

Ct. at 2245 & n.4. 
29 EURAND v. MYLAN

bins, Subtests of “Nonobviousness”: A Nontechnical Approach to Patent Validity, 112 U. Pa. L. Rev. 1169 (1964) 

(“Robbins”)). In that note, the author argued that the 

instruments of decision-making applied in patent cases at 

the time were inadequate and allowed judges to rely on 

“judicial hunches,” thereby deciding cases on extralegal 

grounds. Robbins, 112 U. Pa. L. Rev. at 1170 & n.11 

(citing Joseph C. Hutcheson, Jr., The Judgment Intuitive: 

The Function of the “Hunch” in Judicial Decisions, 14 

Cornell L.Q. 274, 278 (1929)). Such “judicial hunches” are 

encouraged by hindsight bias. As one commentator 

recently observed, “decision-makers unconsciously let 

knowledge of the invention bias their conclusion concerning whether the invention was obvious in the first instance.” Gregory N. Mandel, Patently Non-Obvious: 

Empirical Demonstration that the Hindsight Bias Renders 

Patent Decisions Irrational, 67 Ohio St. L.J. 1391, 1393 

(2006). In other words, knowing that the inventor succeeded in making the patented invention, a fact finder 

might develop a hunch that the claimed invention was 

obvious, and then construct a selective version of the facts 

that confirms that hunch. This is precisely why the 

Supreme Court explained that objective considerations 

might prevent a fact finder from falling into such a trap, 

observing that objective considerations might serve to 

“resist the temptation to read into the prior art the teachings of the invention in issue.” 383 U.S. at 36.6 And, it is 

 6 To be sure, courts must exercise care in assessing 

proffered evidence of objective considerations, giving such 

evidence weight only where the objective indicia are 

“attributable to the inventive characteristics of the discovery as claimed in the patent.” See Rochelle Cooper 

Dreyfuss, The Federal Circuit: A Case Study in Specialized Courts, 64 N.Y.U. L. Rev. 1, 10 (1989) (noting that 

this court has imposed such a “nexus” requirement on the 

objective considerations). See also Ormco Corp. v. Align 
EURAND v. MYLAN 30

precisely why fact finders must withhold judgment on an 

obviousness challenge until it considers all relevant 

evidence, including that relating to the objective considerations. 

In sum, opinions of this court should not be read to 

require a burden-shifting framework in derogation of 

Stratoflex’s directive that objective evidence be considered 

before making an obviousness determination and in 

disregard of where the burdens of proof and persuasion 

are properly placed in district court litigation.7 Such a 

 

Tech., Inc., 463 F.3d 1299, 1311–12 (Fed. Cir. 2006) 

(noting that a nexus must exist between a product’s 

commercial success and the claimed invention). 

7 It appears that the language discussing a twopart, burden-shifting inquiry may have originated in and 

been borrowed from the test employed in appeals from the 

Board of Patent Appeals and Interferences. In Iron Grip 

Barbell, for example, we stated that a “presumption of 

obviousness” that exists when a claimed invention falls 

within a range disclosed in the prior art could be “rebutted if it can be shown: (1) That the prior art taught away 

from the claimed invention . . . or (2) that there are new 

and unexpected results.” 392 F.3d at 1322. For that 

proposition, we cited In re Geisler, 116 F.3d 1465, 1471 

(Fed. Cir. 1997), and In re Woodruff, 919 F.2d 1575, 1578 

(Fed. Cir. 1990). Both of those cases were appeals from 

obviousness rejections during prosecution. In re Geisler, 116 F.3d at 1467; In re Woodruff, 919 F.2d at 1575.

Unlike in district court litigation, a burden-shifting 

framework makes sense in the prosecution context. The 

prima facie case furnishes a “procedural tool of patent 

examination, allocating the burdens of going forward as 

between examiner and applicant.” In re Oetiker, 977 F.2d 

1443, 1445 (Fed. Cir. 1992). During prosecution, a patent 

applicant, as a practical matter, may not have the opportunity to present objective evidence unless and until an 

examiner reviews the application and issues an obvious-
31 EURAND v. MYLAN

reading disregards our own precedent and is inconsistent 

with Supreme Court case law, including very recent case 

law. 

3. 

The district court appears to have fallen into the understandable but improper trap of constructing a selective 

version of the facts relating to the objective considerations 

so as to confirm its hunch that the asserted claims were 

obvious. The district court focused on objective evidence 

that supported its obviousness determination, but ignored 

 

ness rejection. This is because “the examiner bears the 

initial burden, on review of the prior art or on any other 

ground, of presenting a prima facie case of unpatentability. If that burden is met, the burden of coming forward 

with evidence or argument shifts to the applicant.” Id. 

Courts should not apply the burden-shifting framework 

for patentability appeals to invalidity determinations 

appealed from a district court, however, because the 

prosecution and litigation contexts are distinct. 

In the prosecution context, not only are the decision 

maker and the patent holder the only two parties involved, but that decision maker—the examiner—is required to determine patentability by a preponderance of 

the evidence. Id. Evidence of objective considerations 

also may not be available until years after an application 

is filed, and until long after the examiner first considers 

the prior art. Litigation differs significantly from the 

examination process. First, in the litigation context, 

validity, rather than patentability, is the issue. The 

challenged patent enjoys a presumption of validity, and 

the challenger must convince a third-party decision 

maker of the patent’s invalidity by clear and convincing 

evidence. 35 U.S.C. § 282; i4i, 131 S. Ct. at 2242. And, in 

litigation, all relevant evidence is presented to the fact 

finder in a single proceeding. There is simply no practical 

need to impose a burden-shifting framework in litigation.
EURAND v. MYLAN 32

other evidence that cast the objective considerations in a 

light favorable to Cephalon. And, it is clear that the 

district court assumed that it was Cephalon’s burden to 

disprove the court’s initial obviousness finding. 

Had the district court, instead, considered the objective evidence in its entirety before making an obviousness 

finding, and considered that evidence in light of the actual 

burden imposed upon a patentee and a patent challenger, 

much of that evidence would have encouraged the district 

court to question the claim that the mere existence of an 

immediate-release formulation of cyclobenzaprine made 

an extended-release version of that drug obvious. Specifically, we find that evidence of a longfelt need for an 

extended-release formulation and the failure of others to 

formulate one strongly support a conclusion of nonobviousness. We address each of these considerations.8

 8 We find no error in the district court’s conclusion 

that Cephalon failed to offer adequate proof of reduced 

sedation through its formulation and, thus, could not rely 

on unexpected results to support its contention that 

Mylan and Par failed to prove obviousness by clear and 

convincing evidence. While we question the trial court’s 

interpretation of Eurand’s evidence of commercial success, 

moreover, we cannot find clear error therein. That these 

objective criteria do not strongly support a finding of 

nonobviousness does not affect our conclusions, however. 

On both points, we find the evidence to be neutral; while 

they do not support a finding of nonobviousness, they add 

little to Mylan and Par’s claim of obviousness. While 

evidence of reduced sedation may not have been strong, 

the patents in suit do not claim that benefit; they claim 

only therapeutic effectiveness. And, while Amrix’s commercial success may be slow in coming, it is clear its 

success is increasing, as its benefits—particularly greater 

compliance—become known. 
33 EURAND v. MYLAN

a.

Cephalon claims that another pharmaceutical company, ALZA, tried but failed to develop an extendedrelease cyclobenzaprine formulation.9 The district court 

rejected this claim, because, in its view, ALZA’s goals 

were different than Cephalon’s. Mylan and Par endorse 

the district court’s reasoning. The district court, however, 

ignored the fact that Cephalon and ALZA shared a common goal: to make a therapeutically effective product. 

This was clear error. 

Evidence that others tried but failed to develop a 

claimed invention may carry significant weight in an 

obviousness inquiry. “While absolute certainty is not 

necessary to establish a reasonable expectation of success, 

there can be little better evidence negating an expectation 

of success than actual reports of failure.” Boehringer 

Ingelheim Vetmedica, Inc. v. Schering-Plough Corp., 320 

F.3d 1339, 1354 (Fed. Cir. 2003). This is particularly true 

when the evidence indicates that others found development of the claimed invention difficult and failed to 

achieve any success. Advanced Display Sys. v. Kent State 

Univ., 212 F.3d 1272, 1285 (Fed. Cir. 2000). In such 

circumstances, “evidence of failed attempts by others 

could be determinative on the issue of obviousness.” Id. 

The evidence of ALZA’s failure to develop an extended-release formulation strongly supports a nonobviousness finding. In the late 1990s, ALZA performed 

pharmacokinetic modeling and created a PK profile for 

immediate-release cyclobenzaprine dosed three times a 

 9 Cephalon also claims that Merck and ScheringPlough tried but failed to develop an extended-release 

formulation. The evidence of Merck’s and ScheringPlough’s alleged failures, however, is weak, and the 

district court did not clearly err in disregarding it. 
EURAND v. MYLAN 34

day. This approach was similar to the manner in which 

Drs. Venkatesh and Clevenger modeled their PK profile. 

The immediate-release PK profile that ALZA modeled 

represented “peaks and valleys” on a graph, with blood 

plasma concentrations undulating as time passed. ALZA 

then hypothesized a PK profile for an extended-release 

cyclobenzaprine product based on its model for the immediate-release product. For its extended-release PK profile, 

ALZA chose a straight line that cut through the immediate-release profile, staying below the peaks and above the 

valleys. ALZA hoped that staying below the peaks would 

avoid side effects and that staying above the valleys 

would maintain therapeutic effectiveness. Clinical trials, 

however, revealed that ALZA’s product was not therapeutically effective. ALZA lost $10 million in its unsuccessful 

attempt to develop an extended-release formulation. 

At trial, Cephalon called a former ALZA vice president, Dr. Samuel Saks. Cephalon’s counsel showed Dr. 

Saks Cephalon’s PK profile. That profile indicated that 

Cephalon had departed from ALZA’s attempt to cut 

through the immediate release PK profile’s peaks and 

valleys. Rather, Cephalon had chosen a PK profile in 

which the Cmax rose higher and the minimum blood 

plasma concentration (Cmin) dipped lower than those of the 

immediate-release profile. After reviewing Cephalon’s PK 

profile, Dr. Saks expressed surprise that Cephalon succeeded, because he believed a lower Cmin would be less 

effective. Thus, where ALZA failed to develop a therapeutically effective product, Cephalon took a materially 

different approach and succeeded. Evidence that others 

were “‘going in different ways’ is strong evidence that the 

[inventor’s] way would not have been obvious.” Panduit 

Corp. v. Dennison Mfg. Co., 774 F.2d 1082, 1099 (Fed. Cir. 

1985), vacated and remanded on other grounds, 475 U.S. 

809 (1986). 
35 EURAND v. MYLAN

The district court disregarded ALZA’s failures. ALZA 

intended to make a formulation that was not only therapeutically effective, but one that also reduced side effects. 

Cephalon’s patents do not cover a formulation that reduces side effects. The district court noted that an alleged 

failure must be directed to the problem that a patent 

purports to solve. Symbol Techs., Inc. v. Opticon, Inc., 935 

F.2d 1569, 1578 (Fed. Cir. 1991). Because ALZA had the 

additional goal of reducing side effects, the district court 

believed that ALZA’s failure was not directed to the 

problem that Cephalon’s patents purport to solve. 

The district court clearly erred because it disregarded 

that Cephalon and ALZA did share a central common 

goal: to create a therapeutically effective product. There 

is no dispute that AZLA sought to create a product that 

worked. The patents in suit, of course, cover a therapeutically effective PK profile. The district court was not 

required to disregard Cephalon and ALZA’s common goal 

simply because ALZA had an additional goal not encompassed by the patents in suit. The purpose of evidence of 

failure of others is to show “indirectly the presence of a 

significant defect in the prior art, while serving as a 

simulated laboratory test of the obviousness of the solution to a skilled artisan.” Symbol Techs., 935 F.2d at 

1578–79 (quoting Robbins, 112 U. Pa. L. Rev. at 1173). 

ALZA’s failure accomplishes that purpose, confirming 

that a therapeutically effective PK profile was lacking in 

the prior art and that skilled artisans struggled to attain 

it. Such a scenario is classic evidence of nonobviousness. 

See, e.g., Advanced Display Sys., 212 F.3d at 1285 (holding that the objective evidence supported an obviousness 

finding where others had “tried for a long time” to develop 

the claimed invention but found it “very hard” and “were 

all not successful”). ALZA’s failure to develop a therapeutically effective product, in sum, is keyed to the problem 
EURAND v. MYLAN 36

that the patents in suit purport to solve, and it supports a 

finding that Cephalon’s accomplishment was not obvious 

to those skilled in the art. 

b.

Cephalon also claimed that a longfelt need existed for 

an extended-release cyclobenzaprine formulation and that 

Amrix satisfied that need. The district court rejected that 

argument because it believed Cephalon failed to offer any 

expert testimony to support it. The district court’s assessment of this factor was inadequate. 

Longfelt need is closely related to the failure of others. 

Evidence is particularly probative of obviousness when it 

demonstrates both that a demand existed for the patented 

invention, and that others tried but failed to satisfy that 

demand. See, e.g., In re Piasecki, 745 F.2d 1468, 1475 

(Fed. Cir. 1984) (finding nonobviousness where the evidence demonstrated a failure of others to provide a feasible solution to a longstanding problem); Alco Standard 

Corp. v. Tenn. Valley Auth., 808 F.2d 1490, 1500 (Fed. 

Cir. 1986) (affirming a nonobviousness finding where the 

evidence showed that the relevant industry had searched 

for more than a decade for a reliable solution and that 

major manufacturers in the industry had tried but failed 

to develop such a solution). 

Cephalon’s proof indicates that a longfelt need existed 

for a therapeutically effective, extended-release cyclobenzaprine formulation. The immediate-release formulation 

existed for decades, but that formulation’s regimen of 

multiple daily doses led to poor patient compliance. As 

discussed above, moreover, others tried but failed to 

develop an extended-release version. In addition to these 

facts, Cephalon called Dr. David Steiner, a physician who 

has practiced in pain management for more than a decade. Dr. Steiner discussed his experiences treating his 
37 EURAND v. MYLAN

patients’ pain in the clinic. He testified that patient 

compliance with a medical regimen is important and that 

he began prescribing Amrix, in part, because of the prospect of more convenient dosing for his patients. 

Not only was the district court wrong that Cephalon 

produced no expert testimony on this issue, but the district court was wrong to ignore the non-expert evidence 

proffered on this point. In combination with compelling 

evidence of the failure of others to produce an extendedrelease formulation, this factor further supports a nonobviousness finding. 

4. 

Where, as here, the obviousness determination turns 

on whether one of ordinary skill in the art would have 

expected that a particular formulation of an extendedrelease drug would be successful—in other words, would 

render a therapeutically effective treatment—objective 

indicia of failure of others and longfelt need are particularly telling. The district court would have encountered a 

different landscape had it examined the objective evidence 

in light of the absence of a known PK/PD relationship. 

ALZA’s failure to develop a therapeutically effective, 

extended-release formulation suggests that skilled artisans would not have reasonably expected to succeed in 

developing the claimed formulation. The long delay 

between the marketing of an immediate-release formulation and Amrix, and Dr. Steiner’s testimony of longfelt 

need, moreover, supports the inference that it was difficult for researchers to create a therapeutically effective, 

extended-release product. Because a desire existed for 

such a product, researchers, presumably, would have 

created one if they were able to do so. 

Rather than supporting a finding of obviousness, the 

most relevant objective considerations, when considered 
EURAND v. MYLAN 38

as part of the totality of the evidence, support a nonobviousness finding. 

D. 

The record, in sum, is insufficient to support a conclusion of obviousness by clear and convincing evidence. At 

its core, Mylan and Par’s proof of obviousness is that the 

claimed PK profile is bioequivalent to the immediaterelease profile. In rejecting the sufficiency of Mylan and 

Par’s proof, we do not hold that bioequivalence can never 

serve as evidence of obviousness. Indeed, it is most 

certainly relevant to that inquiry. We only hold that, on 

the facts of this case—in which therapeutic effectiveness 

is a claimed limitation and the parties do not dispute that 

cyclobenzaprine lacked a known PK/PD relationship—

Mylan and Par cannot rely on bioequivalence as the sole 

basis for an obviousness finding, particularly given the 

heavy burden of proof imposed on them in this context. 

Indeed, defense counsel acknowledged at oral argument 

that Mylan and Par are not requesting a categorical rule 

that it is always obvious to try to target bioequivalence 

when formulating an extended-release formulation. See

Oral Argument at 8:54, available at

http://www.cafc.uscourts.gov/oral-argumentrecordings/2011-1399/all. If we were to affirm the district 

court’s obviousness ruling on the basis of this record, we 

effectively would announce such a rule.10

 10 The parties have not cited any cases in which the 

presence or absence of a known PK/PD relationship was 

determinative. Indeed, in other cases, it appears that the 

parties and the court assumed bioequivalence would 

produce a therapeutically effective result. See Abbott 

Labs. v. Andrx Pharms., Inc., 452 F.3d 1331, 1340–43 

(Fed Cir. 2006) (finding a substantial question of validity 

on a preliminary injunction motion where the prior art 

disclosed substantially bioequivalent PK values, but 
39 EURAND v. MYLAN

The district court erred in finding that Mylan and Par 

proved that the asserted claims are obvious by clear and 

convincing evidence. 

IV. 

We address next Mylan and Par’s best mode defense. 

The district court rejected Mylan and Par’s claim that the 

patents in suit are invalid for failure to disclose the best 

mode. Although the district court applied the incorrect 

test for a best mode disclosure violation, the district 

court’s findings support its ultimate conclusion that no 

best mode disclosure violation existed. 

A patent’s specification must “set forth the best mode 

contemplated by the inventor of carrying out his invention.” 35 U.S.C. § 112 ¶ 1 (2006). The version of the 

Patent Act currently in effect provides that, although an 

applicant must disclose the best mode to register a patent, 

a party to a lawsuit may not rely on an alleged best mode 

disclosure violation to cancel, invalidate, or hold a patent 

otherwise unenforceable. Id.; Leahy-Smith America 

Invents Act, Pub. L. No. 112-29, sec. 15(a), 125 Stat. 284, 

328 (2011) (to be codified at 35 U.S.C. § 282 ¶ 2(3)(A)). 

That provision, however, is inapplicable to this case 

because it is the product of amendments made to the 

Patent Act that became effective after this action was 

filed. Leahy-Smith America Invents Act, Pub. L. No. 112-

29, sec. 15(c), 125 Stat. 284, 328 (2011) (providing that the 

best mode amendments apply only to actions commenced 

 

failing to address whether bioequivalent PK values would 

produce a therapeutically effective result); Adams Respiratory Therapeutics, Inc. v. Perrigo Co., 616 F.3d 1283, 

1289 (Fed. Cir. 2010) (reversing a district court’s grant of 

summary judgment because a fact finder could reasonably 

find infringement based on the accused ANDA product’s 

having a Cmax equivalent to that of a standard immediaterelease product). 
EURAND v. MYLAN 40

on or after the effective date of the amendments). The 

version of the Patent Act applicable to this case permits 

an accused infringer to assert a best mode disclosure 

violation as a defense. 35 U.S.C. § 282 ¶ 2(3) (2006). 

A defense of failure to disclose the best mode is a 

question of fact. Zygo Corp. v. Wyko Corp., 79 F.3d 1563, 

1566–67 (Fed. Cir. 1996). We review a lower court’s 

finding of no best mode disclosure violation for clear error. 

Id. 

Mylan and Par claim that the specification fails to 

disclose the best mode because it omits a particular range 

of dew points. The claimed cyclobenzaprine formulation 

is made with a coated bead. During the formulation 

process, the bead is placed in a fluid bed machine, which 

sprays a layer of the drug and a layer of extended-release 

coating on the bead. The dew point of the air entering the 

fluid bed must be controlled. Mylan and Par claim that 

Dr. Venkatesh preferred dew points of 6–12oC for immediate-release coating and 7–16oC for extended-release 

coating, with target dew points of 8oC and 10oC, respectively. The specification does not disclose those dew 

points. 

To determine whether a best mode disclosure violation exists, a fact finder applies a two-prong test. First, 

the fact finder determines whether, at the time the application was filed, the inventor possessed a best mode for 

practicing the invention. Eli Lilly & Co. v. Barr Labs., 

Inc., 251 F.3d 955, 963 (Fed. Cir. 2001) (citations omitted). A subjective inquiry, the first prong focuses on “the 

inventor’s state of mind at the time he filed the patent 

application, and asks whether the inventor considered a 

particular mode of practicing the invention to be superior 

to all other modes at the time of filing.” Teleflex, Inc. v. 
41 EURAND v. MYLAN

Ficosa N. Am. Corp., 299 F.3d 1313, 1330 (Fed. Cir. 2002) 

(citation omitted). 

The district court found that Dr. Venkatesh preferred 

particular dew points at the time the applications were 

filed. In March 2003, before the patent applications were 

filed, Dr. Venkatesh told the FDA that, during scale-up 

experiments, “the dew point of the incoming air was 

monitored by setting the control at a very low target of 

8°C (6–12)°C” and that “[d]ecreasing the dew point of the 

incoming process air reduced the tackiness of the beads 

and reduced the tendency of the coated beads from clumping together.” Dr. Venkatesh acknowledged that dew 

points could affect dissolution: “If you don’t use the proper 

optimization, then you may not get good yield or you may 

not get the proper coating . . . [t]hen the product will not 

be good . . . .” While Cephalon argued to the district court 

that Dr. Venkatesh did not have a subjective belief in a 

best mode, Cephalon does not contest on appeal the 

district court’s finding that he did have such a belief, and 

we do not find that finding to have been clearly erroneous 

in any event. 

If the inventor possessed a best mode at the time of 

filing, as the district court found Dr. Venkatesh did, the 

second prong of the inquiry requires the fact finder to 

determine whether the specification discloses sufficient 

information such that one reasonably skilled in the art 

could practice the best mode. Eli Lilly, 251 F.3d at 963 

(citations omitted). Because the second prong focuses on 

what the specification teaches to a person of ordinary skill 

in the art, the inquiry is objective. Id.

Mylan and Par mistakenly attempt to cast the second 

prong as an inquiry concerning whether Dr. Venkatesh 

“concealed” his best mode. Defs.’ Resp. & Reply Br. 50. 

That characterization is inaccurate. Concealment impli-
EURAND v. MYLAN 42

cates an inventor’s state of mind, which is inconsistent 

with an objective inquiry focused on what the specification teaches to a skilled artisan. U.S. Gypsum Co. v. Nat’l 

Gypsum Co., 74 F.3d 1209, 1215–16 (Fed. Cir. 1996). As 

we explained in U.S. Gypsum, this court has used the 

term “concealment” as a shorthand way of inquiring about 

the adequacy of the disclosure: 

The “concealment” language of our case 

law originated in In re Gay, 309 F.2d 769 

(CCPA 1962). In Gay, the Court of Customs and Patent Appeals (CCPA) explained that “the sole purpose of [the best 

mode] requirement is to restrain inventors 

from applying for patents while at the 

same time concealing from the public preferred embodiments of their inventions 

which they have in fact conceived.” . . . 

Subsequently, the CCPA clarified that 

“only evidence of concealment (whether 

accidental or intentional) is to be considered. That evidence, in order to result in 

affirmance of a best mode rejection, must 

tend to show that the quality of an applicant’s best mode disclosure is so poor as to 

effectively result in concealment.” In re 

Sherwood, 613 F.2d 809, 816 (CCPA 

1980). 

Id. Thus, the proper inquiry focuses on the adequacy of 

the disclosure rather than motivation for any nondisclosure. See also Bayer AG v. Schein Pharms., Inc., 301 F.3d 

1306, 1320 (Fed. Cir. 2002) (explaining that the inquiry is 

objective). 

The district court did not directly address whether the 

specification adequately disclosed the best mode. Rather, 
43 EURAND v. MYLAN

the district court found that the dew points did not need 

to be disclosed because they amounted to routine details. 

We have recognized that routine details apparent to one 

of ordinary skill in the art need not be disclosed to satisfy 

the best mode disclosure requirement. E.g., Teleflex, 299 

F.3d at 1331–32; Eli Lilly, 251 F.3d at 963; and Young 

Dental Mfg. Co. v. Q3 Special Prods., Inc., 112 F.3d 1137, 

1144 (Fed. Cir. 1997). 

To conclude that the optimal dew points were routine 

details exempt from disclosure, the district court was 

required to find that the dew points would be apparent to 

a person of ordinary skill in the art. Teleflex, 299 F.3d at 

1331–32. The district court found the following: (1) it 

would be routine to control humidity during product 

fabrication; (2) the allegedly concealed dew points were 

within the normal operating range of a commonly used 

fluid-bed coating device; (3) Dr. Venkatesh’s optimal dew 

point was within the normal operating range; and (4) the 

defendants’ own technicians were able to optimize the 

dew point in just a few days. That evidence does not 

indicate that the optimal dew points would actually be 

apparent to one of ordinary skill in the art. If they were, 

the evidence, presumably, would indicate that skilled 

artisans would know the optimal dew points and program 

the fluid bed accordingly before commencing production. 

The district court’s findings indicate, rather, that some, 

albeit minimal, work was required to ascertain the optimal dew points. 

Rather than finding that the dew points were routine 

details apparent to one of ordinary skill in the art, the 

district court could, and should, have made a more fundamental finding: that the specification need not disclose 

the optimal dew points to enable skilled artisans to practice the best mode. See U.S. Gypsum, 74 F.3d at 1215–16 

(focusing the inquiry on the adequacy of the disclosure). 
EURAND v. MYLAN 44

As one expert, Dr. Robert Williams, explained, skilled 

artisans do not begin the fabrication process by attempting to attain a particular dew point in the fluid bed. 

Rather, they attempt to manipulate and harmonize a 

number of parameters, including, for example, air humidity, inlet air quantity, inlet air temperature, and spray 

rate. Dew point is a function of the other parameters. 

The totality of these parameters, when harmonized, 

creates the optimal condition for fabricating product. 

Thus, as the district court’s findings suggest, skilled 

artisans would expect to attain the optimal dew points 

during the ordinary harmonization process by employing 

routine steps such as controlling the humidity and operating the fluid bed within the normal operating range. 

Because harmonization—a process known to skilled 

artisans—would produce the optimal dew points, the 

specification need not disclose them to enable skilled 

artisans to practice the best mode. The disclosure is 

adequate without them. 

Mylan and Par argue that, because the dew points 

materially affect the claimed invention, express disclosure 

in the specification was required. For this proposition, 

they cite Bayer, 301 F.3d at 1312. Mylan and Par misread Bayer. There, we held that, to prove inadequate 

disclosure of the best mode, an accused infringer must 

prove that the undisclosed information affects the properties of the claimed invention. Id. at 1319. The panel also 

held that an accused infringer may prove a best mode 

disclosure violation if the undisclosed subject matter 

materially affects the properties of the claimed invention, 

even if the undisclosed subject matter is not strictly 

within the bounds of the patent claims. Id. at 1316. 

Bayer created an exception to the general rule that “the 

best mode disclosure requirement only refers to the 

invention defined by the claims.” Id. at 1315–16. Bayer is 
45 EURAND v. MYLAN

inapposite here because there is no dispute that the dew 

points are within the bounds of the asserted claims: The 

claims cover a particular dissolution profile, and dew 

point affects dissolution. The only issue here is whether 

the disclosure is adequate to enable a person of ordinary 

skill in the art to practice the invention incorporating the 

optimal dew points. Mylan and Par cannot avoid that 

issue merely by claiming that the dew points are material 

to the claimed invention. 

Invalidation as a result of a best mode disclosure violation requires proof by clear and convincing evidence. 

Teleflex, 299 F.3d at 1330. Mylan and Par cannot meet 

that burden because the record indicates that skilled 

artisans could readily obtain the optimal dew points using 

a common fluid bed. We find, therefore, that the district 

court did not err in rejecting Mylan and Par’s best mode 

defense. 

V. 

We address next Mylan’s appeal in Case No. 2011-

1399. Mylan appeals from the district court’s order 

entering an injunction against launch of its generic version of Amrix. Mylan argues that it is virtually always 

improper to enjoin a prevailing party from acting in a 

manner authorized by a district court’s own judgment; 

that it is particularly inappropriate to enter an injunction 

pending appeal against a prevailing generic in an ANDA 

action; and that, even if such an injunction is permissible 

in the abstract, the district court abused its discretion 

when it entered an injunction in this case. Mylan contends that it is entitled to recapture damages, capped by 

the amount of the bond imposed, regardless of the outcome on appeal. 

Given our ruling today, Mylan is no longer a prevailing party or a prevailing generic, however. We have 
EURAND v. MYLAN 46

reversed the judgment of invalidity upon which Mylan 

predicates its objections in this appeal. If our resolution 

of the appeal in Case No. 2011-1409 resulted in an order 

directing judgment in favor of Cephalon and a permanent 

injunction, Mylan’s own appeal would certainly be moot. 

See Grupo Mexicano de Desarrollo, S.A. v. Alliance Bond 

Fund, Inc., 527 U.S. 308, 314 (1998). In Grupo Mexicano 

de Desarrollo, the Supreme Court explained: 

[I]f [a plaintiff’s] lawsuit turns out to be 

meritorious—if he is found to be entitled 

to the permanent injunction that he 

seeks—even if the preliminary injunction 

was wrongly issued (because at that stage 

of the litigation the plaintiff’s prospects of 

winning were not sufficiently clear, or the 

plaintiff was not suffering irreparable injury) its issuance would in any event be 

harmless error. The final injunction establishes that the defendant should not 

have been engaging in the conduct that 

was enjoined. 

Id. at 314–15. See also Global NAPs, Inc. v. Verizon New 

England, Inc., 489 F.3d 13, 22 (1st Cir. 2007) (“[A] party 

is wrongfully enjoined when it had a right all along to do 

what it was enjoined from doing.“); Blumenthal v. Merrill 

Lynch, Pierce, Fenner & Smith, Inc., 910 F.2d 1049, 1054 

(2d Cir. 1990) (“A party has been ‘wrongfully enjoined’ . . . 

if it is ultimately found that the enjoined party had at all 

times the right to do the enjoined act.”) Thus, if Mylan 

was simply enjoined from engaging in conduct in which it 

had no right to engage, Mylan’s complaints about that 

injunction become meaningless. This simple principle 

may or may not ultimately apply in this case, however. It 

is unclear at this stage what the ultimate resolution of 

this matter will be and whether launch of Mylan’s generic 
47 EURAND v. MYLAN

will be deemed unauthorized. See, e.g., Grupo Mexicano 

de Desarrollo, 527 U.S. at 314–15 (indicating that where a 

permanent injunction either does not ultimately issue or 

is narrower in scope than a preliminary injunction, a 

claim against the bond could lie). 

Here, it is unclear whether a final judgment against 

Mylan will be entered and, if so, what the scope of an 

injunctive remedy, if any, might be. There is much litigation that is yet to occur—both as to Cephalon’s claims for 

relief and as to Mylan’s currently stayed counterclaims. 

For these reasons, we find it premature to address Mylan’s claim on the appeal bond or to resolve the questions 

Mylan poses regarding the circumstances under which, or 

the standards by which, an injunction pending appeal 

may be imposed on a prevailing party in an ANDA action. 

We dismiss Mylan’s appeal without prejudice to reassert a 

claim for damages against the appeal bond if and when 

such a claim might be ripe and appropriate. In the interim, the appeal bond will remain in place unless the 

parties stipulate to its release. 

VI. 

On a final matter, we note that, because Mylan’s patent misuse and antitrust claims remained unresolved at 

the time of appeal, the parties did not appeal from a final 

judgment, which normally precludes an appellate court 

from exercising jurisdiction. See Fed. R. Civ. P. 54. After 

the appeals were filed, the parties moved the district 

court for entry of a certificate pursuant to Rule 54(b) of 

the Federal Rules of Civil Procedure, which would allow 

the disposed issues to be immediately appealed. The 

district court granted the motion and entered the Rule 

54(b) certificate. We have permitted parties to establish 

appellate jurisdiction with a nunc-pro-tunc Rule 54(b) 

certificate. Storage Tech. Corp. v. Cisco Sys., Inc., 329 
EURAND v. MYLAN 48

F.3d 823, 829–30 (Fed. Cir. 2003); State Contracting & 

Eng’g Corp. v. Fla., 258 F.3d 1329, 1334–35 (Fed. Cir. 

2001). While the parties should have moved for entry of a 

Rule 54(b) certificate before filing their appeals, the latefiled certificate is sufficient to establish appellate jurisdiction under our precedent. 

VII. 

We reverse and vacate the district court’s invalidity 

judgment and affirm its best mode ruling. We dismiss as 

premature Mylan’s appeal from the district court’s entry 

of the injunction. To allow the district court an opportunity to assess the propriety of a preliminary injunction 

pending further proceedings, the injunction will remain in 

place for forty-five days post-mandate, or until further 

order of the district court, whichever occurs sooner. 

AFFIRMED IN PART, REVERSED IN PART, 

VACATED IN PART, DISMISSED IN PART