United States Court of Appeals for the Federal Circuit 

 

04-1506 

WARNER-LAMBERT COMPANY, 

Plaintiff-Appellee, 

and 

SCHWARZ PHARMA, INC. and SCHWARZ PHARMA AG, 

Plaintiffs-Appellees, 

v. 

TEVA PHARMACEUTICALS USA, INC., 

Defendant-Appellant. 

Joseph M. O’Malley, Jr., Fitzpatrick, Cella, Harper & Scinto, of New York, New 

York, argued for plaintiff-appellee, Warner-Lambert Company. With him on the brief 

were Bruce M. Wexler, Herbert W. Rea, Joshua I. Rothman and Andrew M. Grodin. 

Brian M. Poissant, Jones Day, of New York, New York, for plaintiffs-appellees, 

Schwarz Pharma AG, et al. With him on the brief were Francis D. Cerrito and Daniel L. 

Malone. 

Henry C. Dinger, Goodwin Procter LLP, of Boston, Massachusetts, argued for 

defendant-appellant. With him on the brief were David M. Hashmall, Mark I. Koffsky

and Dominique T. Hussey, of New York, New York. Of counsel was Kenneth A. Cohen, 

of Boston, Massachusetts. 

Appealed from: United States District Court for the District of New Jersey 

Senior District Judge Dickinson R. Debevoise 
United States Court of Appeals for the Federal Circuit 

04-1506 

WARNER-LAMBERT COMPANY, 

Plaintiff-Appellee, 

and 

SCHWARZ PHARMA, INC. and SCHWARZ PHARMA AG, 

Plaintiffs-Appellees, 

v. 

TEVA PHARMACEUTICALS USA, INC., 

Defendant-Appellant. 

 __________________________

 DECIDED: August 11, 2005 

 __________________________

Before SCHALL, LINN, and PROST, Circuit Judges. 

SCHALL, Circuit Judge. 

 Teva Pharmaceuticals USA, Inc. (“Teva”) appeals from the final judgment of the 

United States District Court for the District of New Jersey that (1) U.S. Patent No. 

4,743,450 (“the ’450 patent”) owned by Warner-Lambert Company (“Warner-Lambert”) 

was not invalid by reason of non-enablement; (2) Teva infringes the ’450 patent; and (3) 

the ’450 patent is not unenforceable by reason of inequitable conduct. Warner-Lambert 

Co. v. Teva Pharm. USA, Inc., No. 99-922 (D.N.J. July 15, 2004) (“Final Judgment”); 

Warner-Lambert Co. v. Teva Pharm. USA, Inc., No. 99-922, 2004 WL 1498162 (D.N.J. 
June 29, 2004) (“Bench Trial Opinion”); Warner-Lambert Co. v. Teva Pharm. USA, Inc., 

289 F. Supp. 2d 515 (D.N.J. 2003) (“Summary Judgment”). The court granted summary 

judgment on the enablement and infringement issues. Its ruling on the inequitable 

conduct issue followed a bench trial. We see no error in the court’s ruling that the ’450 

patent is not unenforceable by reason of inequitable conduct. We conclude, however, 

that because there are genuine issues of material fact, the court erred in granting 

summary judgment in favor of Warner-Lambert on the issues of enablement and 

infringement. We thus affirm-in-part and reverse-in-part and remand the case to the 

district court for further proceedings. 

BACKGROUND 

I. 

The ’450 patent relates to angiotension converting enzyme (“ACE”) inhibitors and 

their methods of manufacture. ACE inhibitors comprise a class of chemical compounds

that have antihypertensive properties and are consequently useful in pharmaceuticals 

aimed at treating hypertension. There are numerous types of ACE inhibitors—such as

enalapril, quinapril, and captopril, to name a few—and different hypertension drugs 

incorporate different ACE inhibitors. The first drug to use an ACE inhibitor reached the 

market in the early 1980s. It was developed using the ACE inhibitor known as captopril.

The drug was expensive, however, and exhibited adverse side effects. Pharmaceutical

companies consequently continued searching for other suitable ACE inhibitor

formulations that did not have the same side effects as the captopril formulation. 

04-1506 2
Merck & Co. (“Merck”) and Warner-Lambert were two of these companies. Their

efforts to develop a suitable hypertension drug using an ACE inhibitor form the 

backdrop of this case. 

A. 

Merck directed its research efforts to drug formulations incorporating the ACE 

inhibitor known as enalapril. In its pure form, enalapril is a stable compound. However, 

Merck quickly discovered that enalapril becomes unstable when combined with various 

excipients commonly used in drug formulations.1

 In particular, Merck found that 

enalapril suffered from two forms of degradation, cyclization and hydrolysis. Although 

initially unsure of the particular reaction mechanism, the Merck scientists determined 

that the cyclization was caused by some type of intra-molecular nucleophilic attack, 

which resulted in the enalapril compound converting into an unusable byproduct known 

as diketopiperazine. Degradation by hydrolysis occurred when water reacted with the 

ACE inhibitor’s ester side chain. 

The Merck formulation team was most concerned with the cyclization problem 

because, in addition to no team member ever having confronted it prior to working with

enalapril, no documentation of the problem could be found in the pertinent literature. In 

search of a solution to the cyclization problem, Merck’s formulation team first turned to

pH investigations.2

 This basically consisted of adjusting the pH of enalapril in solution 

and then determining whether there were any corresponding improvements in stability, 

 1 Excipients are substances other than the active ingredient that, for a 

variety of reasons, are added to the formulation in manufacturing the drug. 

2 pH is a measure of a solution’s acidity. A solution with a pH below 7.0 is 

considered acidic, while a solution with a pH above 7.0 is considered basic. Acidity

increases as pH decreases. 

04-1506 3
i.e., whether the amount of degradation by cyclization decreased. The team found that

cyclization decreased at higher (more basic) pH levels. For commercial viability,

however, the end product had to be in a solid state. When the team tried adding 

appropriate pH buffers to solid enalapril, they found that the buffers did not have the 

same stabilizing effect. 

Merck’s formulation team consequently abandoned the pH studies and undertook 

the much more time-consuming task of figuring out how to chemically block the 

cyclization reaction. The team eventually hypothesized that it might be possible to block

the reaction by converting enalapril, which is an acid, to its sodium salt. The leader of

the team—Dr. Gerald S. Brenner—explained the hypothesis as follows: 

Our feeling was that we could inhibit the cyclization by 

converting OH, which is a fairly good leading group[,] to a 

much poorer leading group, and that poor leading group 

would be ONA. In other words, converting enalapril, which is

an acid, to its sodium salt. So that was our working 

hypothesis that we could inhibit cyclization by converting the 

acid group to an ONA group, a sodium salt. 

Bench Trial Opinion, 2004 WL 1498162, at *4. Implementing this idea proved to be 

both complicated and time consuming, but Merck eventually devised a successful 

method in which sodium bicarbonate was used to convert enalapril into its sodium salt. 

As hypothesized, Merck found that the cyclization of enalapril was significantly reduced

in its sodium salt form.3

 

In total, it took Merck somewhere between three and four years to develop a 

stable enalapril salt. The stabilized formulation consisted of, among other things, 

 3 The Merck formulation team also stabilized enalapril from degradation by

hydrolysis. This was presumably achieved by the addition of some excipient, but the 

record is not clear. In any event, it appears that degradation by cyclization presented

Merck with much more of a problem than degradation by hydrolysis. 

04-1506 4
enalapril maleate, sodium bicarbonate, and lactose. Merck obtained approval from the 

Food and Drug Administration (“FDA”) to market this formulation on December 24, 

1985. Shortly thereafter, in January of 1986, Merck began selling it as Vasotec®. 

Merck’s next decision was whether to seek patent protection for its process or to 

maintain it as a trade secret. It appeared at this point that all of the ingredients of 

Vasotec® were in the public domain. However, Merck concluded that competitors

would not be able to figure out the process for making Vasotec® from its ingredients 

alone—namely, the process used to stabilize enalapril against cyclization. Merck 

therefore chose to retain the sodium bicarbonate stabilization process as a trade secret

and to forgo patent protection. 

B. 

Around the same time that Merck was investigating the viability of an enalaprilbased drug formulation, Warner-Lambert was investigating drug formulations using the

ACE inhibitor known as quinapril. Warner-Lambert’s initial experiences with quinapril in 

many respects paralleled Merck’s experiences with enalapril. In particular, the 

scientists at Warner-Lambert discovered that quinapril suffered from degradation by

both cyclization and hydrolysis. The Warner-Lambert team also discovered that 

quinapril suffered from an additional form of oxidative degradation, marked by 

discoloration of the quinapril. Apparently, over time, a white quinapril tablet would 

discolor by changing to a pink or purple color. However, as with Merck, the WarnerLambert scientists were most concerned with figuring out how to minimize the 

degradation caused by cyclization. 

04-1506 5
Warner-Lambert’s quinapril formulation team, as had Merck’s enalapril 

formulation team, initially looked to pH solutions to the cyclization problem. They did 

this by dissolving quinapril in solution and then adjusting the pH of the resulting solution 

to determine if it affected stability. The formulation team discovered that, in solution, 

cyclization was reduced at higher pH levels. Quinapril, like enalapril, is an acid, and so

the team needed to add alkaline excipients in order to reach these higher pH levels.

One of the alkaline excipients used was sodium bicarbonate. During this time, the 

Warner-Lambert scientists were aware of Vasotec® and had even conducted some pH 

tests on it. In fact, a Warner-Lambert memorandum dated May 7, 1986, stated that 

Vasotec® had a pH of 6.5 in solution and that it was obtained through the inclusion of 

sodium bicarbonate. However, the Warner-Lambert scientists soon learned the same 

thing with respect to quinapril as the Merck scientists had learned earlier with respect to 

enalapril—namely, that while pH adjustments worked to stabilize the ACE inhibitor in

solution, the stability did not carry over to the solid form. Therefore, sometime around 

May of 1986, the Warner-Lambert formulation team abandoned pH adjustment studies 

and began looking for other solutions to the cyclization stability problem. 

This led Warner-Lambert into the second stage of its cyclization investigation. 

However, unlike the Merck team, the Warner-Lambert team did not open an 

investigation at this time into the reaction pathway of the cyclization degradation 

process. Instead, the Warner-Lambert team began “one-to-one excipient compatibility

studies.” This basically involved mixing quinapril with various excipients and then 

studying the stability of quinapril over time. Using this method, the Warner-Lambert 

04-1506 6
team eventually determined that a formulation of magnesium carbonate and lactose 

created a stable quinapril drug.4

On February 24, 1987, five scientists from Warner-Lambert—Michael Harris, 

Gerard Hokanson, Kuchi Murthy, Robert Reisch, and Frank Waldman—filed a patent

application seeking protection for their stabilized ACE inhibitor formulation. The

application issued as the ’450 patent on May 10, 1988, and was assigned to WarnerLambert. 

Warner-Lambert also filed a New Drug Application (“NDA”) with the FDA seeking 

permission to market its quinapril formulation, which it named Accupril®. Pursuant to 

the Hatch-Waxman Amendments to the Federal Food, Drug, and Cosmetic Act,

Warner-Lambert notified the FDA that Accupril® was covered by the ’450 patent.5

 The

FDA subsequently listed the ’450 patent in the FDA’s “Approved Drug Products with 

Therapeutic Equivalence Evaluations” publication, commonly referred to as “the Orange 

Book.” Warner-Lambert obtained FDA approval of its quinapril formulation in November 

of 1991, and began marketing it as Accupril®. 

II. 

Teva entered the picture on January 15, 1999, when it filed an Abbreviated New 

Drug Application (“ANDA”) with the FDA, seeking approval to market a generic version 

 4 The Warner-Lambert scientists attributed the reduction in degradation by

cyclization and discoloration to the magnesium carbonate and the reduction in 

degradation by hydrolysis to the lactose. 

5 “The applicant shall file with the application the patent number and the 

expiration date of any patent which claims the drug for which the applicant submitted 

the application or which claims a method of using such drug and with respect to which a 

claim of patent infringement could reasonably be asserted if a person not licensed by

the owner engaged in the manufacture, use, or sale of the drug.” 21 U.S.C. § 355(b)(1) 

(2000). 

04-1506 7
of Warner-Lambert’s Accupril®. More specifically, Teva sought to manufacture and sell 

a generic hypertension drug formulation containing the active ingredient quinapril 

hydrochloride, as well as magnesium carbonate and lactose excipients. In connection 

with its ANDA, and pursuant to the requirements of the Hatch-Waxman Amendments, 

Teva filed what is termed a “paragraph IV certification.” This is a certification by the 

ANDA applicant that any patents pertinent to the generic formulation are either “invalid 

or will not be infringed by the manufacture, use, or sale of the new drug for which the 

application is submitted.” 21 U.S.C. § 355(j)(2)(A)(vii)(IV) (2000). Teva’s paragraph IV 

certification did not state that its generic formulation would not infringe the ’450 patent, 

but it did assert that the ’450 patent was invalid under 35 U.S.C. §§ 102 and 103. 

On March 2, 1999, Warner-Lambert responded to Teva’s paragraph IV 

certification by suing Teva in the District of New Jersey for infringement of the ’450 

patent. Warner-Lambert specifically alleged that, by filing its ANDA, Teva infringed the 

’450 patent under 35 U.S.C. § 271(e)(2)(A) (2000).6

 (Warner-Lambert appears to have 

later narrowed its suit to allege infringement of claims 1, 4-10, 12, 16, and 17.) Claims 1 

and 16 are the only independent claims. Claim 1 is a composition claim, and reads: 

A pharmaceutical composition which contains: 

(a) a drug component which comprises a suitable amount of 

an ACE inhibitor which is susceptible to cyclization, 

hydrolysis, and discoloration, 

(b) a suitable amount of an alkali or alkaline earth metal

carbonate to inhibit cyclization and discoloration, and 

(c) a suitable amount of a saccharide to inhibit hydrolysis. 

 6 Section 271(e)(2)(A) makes it an act of infringement to “submit . . . an 

application under section 505(j) of the Federal Food, Drug, and Cosmetic Act . . . for a 

drug claimed in a patent or the use of which is claimed in a patent . . . .” 

04-1506 8
’450 patent, col. 5, l. 52 to col. 6, l. 2. Claim 16 is directed at the method of stabilizing

the ACE inhibitor formulation. It reads: 

A process for stabilizing an ACE inhibitor drug against 

cyclization which comprises the step of contacting the drug 

with: 

(a) a suitable amount of an alkali or alkaline earth-metal

carbonate and, 

(b) one or more saccharides. 

Id. col. 6, ll. 54-63. 

In its answer Teva initially conceded that its ANDA filing constituted an act of 

infringement of the ’450 patent. (Answer ¶ 8.) However, Teva asserted two affirmative 

defenses, invalidity for “failure to meet one or more of the conditions for patentability 

specified in Part II of Title 35 of the United States Code” (Id. ¶ 14), and invalidity for 

anticipation and/or obviousness under 35 U.S.C. §§ 102 and 103 (Id. ¶ 16). Based on 

information Teva obtained during discovery, the district court later granted Teva leave to

amend its pleadings to deny infringement (Amended Answer ¶ 20) and to assert a third 

affirmative defense of unenforceability due to inequitable conduct (Id. ¶ 21). 

After discovery, various summary judgment motions were filed on the issues of 

infringement, invalidity, and unenforceability. Teva moved for summary judgment that 

its quinapril hydrochloride formulation did not infringe composition claims 1, 4-10, or 12 

of the ’450 patent. Teva also moved for summary judgment of unenforceability due to 

inequitable conduct.7

 Warner-Lambert, in turn, moved for summary judgment that 

claims 1, 4-10, 12, 16, and 17 were valid, enforceable, and infringed. In addition, 

although Teva did not move for summary judgment of invalidity, Teva asserted invalidity

 7

 Teva filed several other motions not relevant to this appeal. 

04-1506 9
by reason of obviousness, non-enablement, and lack of utility, in opposition to WarnerLambert’s motion for summary judgment of validity. 

On October 2, 2003, the district court granted Warner-Lambert summary 

judgment of infringement, concluding that no reasonable juror could find that Teva’s

formulation did not infringe claims 1, 4-10, 12, 16, and 17 of the ’450 patent. Summary 

Judgment, 289 F. Supp. 2d at 527. In doing so, the court rejected Teva’s contention 

that Warner-Lambert had failed to produce evidence showing that the lactose in Teva’s

formulation inhibited hydrolysis, id. at 524, or that the magnesium carbonate in Teva’s

formulation inhibited cyclization and discoloration, id. at 526-27. 

The district court also granted Warner-Lambert’s motion for summary judgment 

of validity with respect to claims 1, 4-10, and 12. Id. at 528. Specifically, the court 

concluded that claims 1, 4-10, and 12 were not obvious in view of Vasotec®. Id. The 

court reasoned that, although Vasotec® contained lactose, there was “no evidence that

the lactose contained in Merck’s Vasotec composition serves [Warner-Lambert’s

claimed] function of inhibiting hydrolysis or that Warner-Lambert’s inventors thought that 

it did.” Id. Claims 16 and 17, however, do not have the limitation requiring that the 

lactose inhibit hydrolysis. Rather, they merely require “one or more saccharides.” This 

difference, the court concluded, created a genuine issue of material fact as to whether 

claims 16 and 17 were obvious in view of Vasotec®. The court therefore denied 

Warner-Lambert’s motion for summary judgment of validity with respect to claims 16 

and 17. Id. at 531-32. The court did not say anything about the enablement issue.8

 8 Although it is not clear whether the district court actually ruled on the 

issue, the court did make passing reference to Teva’s utility defense. Summary 

Judgment, 289 F. Supp. 2d at 528. In any event, Teva does not argue utility on appeal. 

04-1506 10
Finally, the district court denied both parties’ motions for summary judgment on 

the issue of inequitable conduct. Teva’s allegation was that Warner-Lambert committed 

inequitable conduct by failing to disclose the existence of Merck’s Vasotec® to the

Patent and Trademark Office (“PTO”). Id. at 532. The court concluded that, although 

the existence of Vasotec® was of high materiality, it could not be determined on the 

record before the court whether Warner-Lambert intentionally had withheld this

information in an effort to deceive the PTO. Id. at 536-43. 

After the district court disposed of the summary judgment motions, Schwarz

Pharma, Inc. and Schwarz Pharma AG. (“Schwarz”), exclusive licensees of the ’450 

patent, filed a motion to intervene. The court granted Schwarz’s motion on April 12,

2004. Warner-Lambert Co. v. Teva Pharm. USA, Inc., No. 99-0922 (D.N.J. Apr. 12,

2004) (“Order Granting Schwarz Pharma, Inc.’s and Schwarz Pharma AG’s Motion to 

Intervene”). 

A bench trial was subsequently held on the issues of inequitable conduct and 

invalidity of claims 16 and 17. The court concluded that claims 16 and 17 were not 

invalid by reason of anticipation or obviousness.9

 Bench Trial Opinion, 2004 WL 

1498162, at *21. The court also concluded that Warner-Lambert did not commit 

inequitable conduct and that the ’450 patent was therefore enforceable. Id. at *10-14. 

With respect to inequitable conduct, after hearing testimony from inventors of the ’450 

patent, the court found that, although the existence of Vasotec® was material,10 the 

 9

 Teva does not appeal either of these two rulings. 

10 After trial, it appeared the court found Vasotec® a bit less material than it 

did at the summary judgment stage of the proceedings. See Bench Trial Opinion, 2004

WL 1498162, at *10 (“Whether Vasotec was as ‘highly material’ as stated in [the 

04-1506 11
evidence did not show clearly and convincingly that Warner-Lambert intentionally

withheld the existence of Vasotec® in order to deceive the PTO. Id. at *14. In 

particular, the court credited the testimony of Dr. Murthy and Dr. Harris, who stated that

the Warner-Lambert formulation team simply lost interest in Vasotec® and, specifically,

its sodium bicarbonate excipient, after their initial pH investigations failed to yield a 

stable quinapril formulation. Id. at *12-14. In addition, the court found that the WarnerLambert inventors did not intend the claims to include bicarbonates, only carbonates. 

Id. at *13. Having found no inequitable conduct with respect to claims 16 and 17, the 

district court entered judgment that, through the filing of its ANDA, Teva infringed claims

1, 4-10, 12, 16, and 17 of the ’450 patent. 

Teva now appeals from the final judgment of the district court. We have 

jurisdiction pursuant to 28 U.S.C. § 1295(a)(1). 

DISCUSSION 

On appeal, Teva challenges the district court’s grant of summary judgment in 

favor of Warner-Lambert on the issues of enablement and infringement. Teva also

challenges the district court’s holding, following trial, that the ’450 patent is not

unenforceable by reason of inequitable conduct. We address each of these contentions 

in turn, beginning with the summary judgment issues. 

I. 

We review a district court’s decision on summary judgment de novo. Bus.

Objects, S.A. v. Microstrategy, Inc., 393 F.3d 1366, 1371 (Fed. Cir. 2005); Conoshenti 

(Cont.’d. . . .) 

summary judgment] opinion is subject to question in view of the facts developed at the 

trial.”). 

04-1506 12
v. Pub. Serv. Elec. & Gas Co., 364 F.3d 135, 140 (3d Cir. 2004). Summary judgment 

must be granted “if the pleadings, depositions, answers to interrogatories, and 

admissions on file, together with the affidavits, if any, show that there is no genuine

issue as to any material fact and that the moving party is entitled to a judgment as a 

matter of law.” Fed. R. Civ. P. 56(c). In applying this standard, “[t]he evidence of the 

non-movant is to be believed, and all justifiable inferences are to be drawn in [the nonmovant’s] favor.” Anderson v. Liberty Lobby, Inc., 477 U.S. 242, 255 (1986). 

A. 

Teva first challenges the district court’s grant of Warner-Lambert’s motion for 

summary judgment of validity. Before the district court, Teva opposed WarnerLambert’s motion on the ground that genuine issues of material fact remained as to,

among other things, whether the ’450 patent was enabled. (Teva’s Opp’n to WarnerLambert’s Mot. for Summ. J. of Validity at 7-14.) Teva’s primary contention was that “a

person of ordinary skill in the art of pharmaceutical formulation would need to resort to 

undue experimentation in order to practice the claimed inventions.” (Id. at 12.) Teva 

supported this contention with a statement by its expert witness, Dr. Joseph B. 

Schwartz, that one of skill in the art would need to perform numerous experiments in 

order to practice the claimed invention. The district court thereafter granted WarnerLambert’s motion for summary judgment of validity with respect to claims 1, 4-10, and 

12. However, the court’s decision, while thoroughly addressing Teva’s obviousness

defense, does not appear to address Teva’s enablement defense. See Summary 

Judgment, 289 F. Supp. 2d at 528 (“In light of Teva’s experts’ affidavits affirming the 

04-1506 13
lack of obviousness of the saacharide [sic] claim limitation Warner-Lambert is entitled to 

summary judgment of validity of claims 1, 4-10 and 12 of the ’450 patent.”). 

On appeal, Teva contends that sufficient issues of fact remain regarding 

enablement so as to preclude summary judgment of validity for Warner-Lambert. In

particular, Teva maintains that the ’450 patent is not enabled because the patent’s 

written description does not teach a person of skill in the art how to make and use the 

full scope of the invention without undue experimentation. That, according to Teva, is

because, while the patent claims numerous combinations of ACE inhibitors, alkali or 

alkaline earth metal carbonates, and saccharides, the specification only discloses two 

working examples, both of which are based on the same general combination of

enalapril hydrochloride, magnesium carbonate, and lactose. Moreover, Teva continues, 

the specification is so lacking in guidance that, outside of the one combination disclosed 

in the patent’s examples, a person of skill in the art could not practice the invention

without undue experimentation. Accordingly, Teva asks us to vacate the district court’s 

decision and remand for resolution of whether one skilled in the art would be required to

exercise undue experimentation before practicing the claimed invention. 

In response, Warner-Lambert contends that the district court properly granted its

motion for summary judgment of validity. First, Warner-Lambert argues that Teva has 

not presented competent evidence showing a genuine issue of fact as to whether the 

’450 patent’s specification failed to provide sufficient guidance. Warner-Lambert asserts 

that the only evidence offered by Teva consists of two legally and technically

incompetent expert reports by Dr. Schwartz. Warner-Lambert asserts that the reports 

are legally incompetent because they are unsworn. Second, Warner-Lambert contends 

04-1506 14
that the written description, particularly the two working examples for 5 and 40 mg 

quinapril formulations, see ’450 patent, col. 4, l. 57 to col. 5, l. 12, provide sufficient 

guidance so as to enable the full scope of the claims. Warner-Lambert also asserts that

we should not consider some of Teva’s arguments, such as the alleged unpredictability

of the art, because they were not properly raised before the district court.

The enablement provision of the Patent Act requires that the patentee provide a 

written description of the invention “in such full, clear, concise, and exact terms as to 

enable any person skilled in the art to which it pertains, or with which it is most nearly

connected, to make and use the same.” 35 U.S.C. § 112, ¶ 1 (2000). The purpose of

this requirement is to ensure that “the public knowledge is enriched by the patent 

specification to a degree at least commensurate with the scope of the claims.” Nat’l 

Recovery Techs., Inc. v. Magnetic Separation Sys., Inc., 166 F.3d 1190, 1195-96 (Fed. 

Cir. 1999); see also Donald S. Chisum, 3 Chisum on Patents § 7.01 (2002).

Accordingly, we have held that the specification must provide sufficient teaching such

that one skilled in the art could make and use the full scope of the invention without 

undue experimentation. CFMT, Inc. v. Yieldup Int’l Corp., 349 F.3d 1333, 1338 (Fed.

Cir. 2003); Genentech, Inc. v. Novo Nordisk A/S, 108 F.3d 1361, 1365 (Fed. Cir. 1997);

In re Wands, 858 F.2d 731, 736-37 (Fed. Cir. 1988). “The key word is ‘undue,’ not

experimentation.’” Wands, 858 F.2d at 737 (citation omitted). That is, the specification 

need only teach those aspects of the invention that one skilled in the art could not figure 

out without undue experimentation. See, e.g., Nat’l Recovery Techs., 166 F.3d at 1196 

(“The scope of enablement . . . is that which is disclosed in the specification plus the 

scope of what would be known to one of ordinary skill in the art without undue

04-1506 15
experimentation.”); Wands, 858 F.2d at 736-37 (“Enablement is not precluded by the

necessity for some experimentation such as routine screening.”). 

Although the ultimate determination of whether one skilled in the art could make 

and use the claimed invention without undue experimentation is a legal one, it is based 

on underlying findings of fact. CFMT, 349 F.3d at 1337. Furthermore, “[w]hether undue 

experimentation is needed is not a single, simple factual determination, but rather is a 

conclusion reached by weighing many factual considerations.” Wands, 858 F.2d at 737. 

Some of these considerations, commonly referred to as “the Wands factors,” include 

“(1) the quantity of experimentation necessary, (2) the amount of direction or guidance 

presented, (3) the presence or absence of working examples, (4) the nature of the 

invention, (5) the state of the prior art, (6) the relative skill of those in the art, (7) the 

predictability or unpredictability of the art, and (8) the breadth of the claims.” Id.; see

also Amgen, Inc. v. Chugai Pharm. Co., 927 F.2d 1200, 1213 (Fed. Cir. 1991) (stating 

that the Wands factors “are illustrative, not mandatory” and that what is relevant to an

enablement determination depends upon the facts of the particular case). 

At the outset, we find the issue of enablement difficult to review because the 

district court did not address it in its decision granting Warner-Lambert’s summary 

judgment motion. We have no way of knowing what the district court thought of Teva’s 

enablement defense or why the court did not address the issue in its decision. In short, 

we are being asked to review an incomplete record. Not knowing the reasoning of the 

district court, we have nevertheless considered the arguments of the parties, reviewed 

the limited record before us, and now conclude that Teva has presented fact-based 

arguments in support of its enablement defense that are deserving of consideration by 

04-1506 16
the district court. Specifically, Teva has argued that, at the time of filing for the ’450 

patent, one of skill in the art would have had to resort to undue experimentation in order

to make the claimed formulations not disclosed in the patent’s two working examples.

In opposition to Warner-Lambert’s motion for summary judgment, Teva supported this 

contention with declarations from its expert witnesses, Dr. Schwartz, who stated that 

one of skill in the art would need to undertake a range of experimentation in order to 

practice the claimed invention. (Teva Opp’n to Warner-Lambert Mot. for Summ. J. of 

Validity at 9, 13.)11 Accordingly, we reverse the grant of summary judgment on WarnerLambert’s motion for validity and remand to the district court for further proceedings on

the issue of enablement. See Nazomi Communications, Inc. v. ARM Holdings, PLC, 

403 F.3d 1364, 1371-73 (Fed. Cir. 2005) (remanding issues of claim construction and 

infringement based in part on the district court’s failure to provide sufficient reasoning 

for its decision). 

B. 

Teva next challenges the district court’s grant of summary judgment of 

infringement in favor of Warner-Lambert. Before the district court, Teva asserted three 

main non-infringement defenses. The first defense related to the function of lactose in 

 11 We do not address Warner-Lambert’s argument regarding the legal and 

technical competency of Dr. Schwartz’s expert reports. These types of evidentiary

issues are most appropriately addressed in the first instance by the trial court. On the 

other hand, we reject Warner-Lambert’s assertion that Teva waived some of its 

enablement arguments, such as the unpredictability of the art, by not raising them 

before the trial court. In this case, it was sufficient that Teva raised the general issue of 

enablement. See Interactive Gift Express, Inc. v. CompuServe Inc., 256 F.3d 1323, 

1346 (Fed. Cir. 2001) (stating that, in general, it is the claim or issue that must be 

pressed before the trial court, not the underlying arguments in support of that claim or 

issue); see also Stratoflex, Inc. v. Aeroquip Corp., 713 F.2d 1530, 1540 (Fed. Cir. 1983)

(“We sit to review judgments, not opinions.”). 

04-1506 17
Teva’s formulation and whether it inhibited degradation by hydrolysis. The second and 

third defenses related to magnesium carbonate and, specifically, whether it served to

inhibit degradation by cyclization and discoloration in Teva’s formulation. The district

court rejected all three of these arguments. 

With respect to Teva’s first defense, the court concluded that Warner-Lambert 

submitted evidence sufficient to show that the lactose in Teva’s formulation inhibited 

hydrolysis. The court cited Teva’s “Final Development Report,” which stated that the 

lactose monohydrate “excipient serves as a filler and will also inhibit hydrolysis of the 

active raw material.” Summary Judgment, 289 F. Supp. 2d at 522-23 (emphasis in

original). This report, the court noted, was subsequently approved by Teva’s Senior

Vice-President of Research and Development. Id. at 523. In addition, as part of its 

ANDA, the court noted that Teva submitted an “Excipient Function Report,” which

similarly stated that the lactose serves to “inhibit hydrolysis of the raw material.” Id. 

Finally, the court found that Teva could not reasonably deny that it designed its generic

formulation with the ’450 patent fully in mind. That, according to the court, was because 

the ’450 patent was listed in one of Teva’s internal data bases as a patent covering 

Warner-Lambert’s Accupril® product. Furthermore, the court noted, Teva’s formulation 

team met in January of 1998 to discuss whether, in addition to a formulation containing 

magnesium carbonate and lactose, the team should also “develop a totally different 

formulation in parallel to our current formulation to avoid any potential patent issues with 

our current strategy.” Id. at 524. 

With respect to Teva’s second two defenses, relating to the functions served by

magnesium carbonate in connection with cyclization and discoloration, the district court 

04-1506 18
first addressed Warner-Lambert’s argument that the defenses were untimely. WarnerLambert argued that Teva should be precluded from asserting the defenses because it 

did not disclose them in response to Warner-Lambert’s contention interrogatories. In 

addition, considering discovery had since closed, Warner-Lambert believed it would be 

prejudiced by allowing the defenses. The court found that Warner-Lambert’s argument 

had “considerable merit” and that “[a]t the very least the circumstances require[d] that 

Teva’s motion for summary judgment be denied to give Warner-Lambert the opportunity 

to take discovery on the issue . . . .” Id. at 526. However, the court decided to 

nevertheless address the defenses because it found them to lack merit. Id.

The court reasoned that Teva chose to “use[] magnesium carbonate because . . . 

it ensured chemical and physical stability.” Id. Indeed, the court noted, Teva 

specifically represented to the FDA that magnesium carbonate “stabilize[d]” its quinapril 

formulation. Further, the court continued, “[b]ecause lactose is claimed to inhibit

hydrolysis, magnesium carbonate must be the inhibitor of the only two other kinds of 

degradation, cyclization and discoloration.” Id. The court found support for this 

conclusion in the deposition testimony of Teva’s Director of Analytical Research & 

Development, who stated that the magnesium carbonate in the generic formulation 

served to “inhibit[] D.P. formation” (which is the quinapril impurity formed by cyclization). 

Id. at 527. 

The court therefore concluded that “no reasonable fact-finder could find that 

lactose in Teva’s quinapril formulations does not inhibit hydrolysis, and no such fact

finder could find that the magnesium carbonate in Teva’s quinapril formulations does

not inhibit cyclization and discoloration.” Id. Accordingly, the court denied Teva’s

04-1506 19
motion for summary judgment of non-infringement of claims 1, 4-10, and 12, and 

granted Warner-Lambert’s motion for summary judgment of infringement of claims 1, 4-

10, 12, 16, and 17. 

On appeal, Teva contends the district court erred because Warner-Lambert failed 

to make out a prima facie case of infringement with respect to claims 1, 4-10, and 12.12 

Teva specifically maintains that Warner-Lambert did not present evidence showing (1) 

that the quinapril in Teva’s formulation is susceptible to oxidative discoloration, or (2) 

that any oxidative discoloration that does occur is inhibited by the magnesium

carbonate. Teva asserts that, as evidenced by the deposition statement of Mr. Reisch, 

an inventor on the ’450 patent, discoloration of quinapril can be caused by a variety of 

factors besides oxidation. Teva similarly asserts that any discoloration could be 

inhibited by excipients other than magnesium carbonate. Given Warner-Lambert’s lack

of evidence on these issues, and considering that the case was before the district court 

on Warner-Lambert’s motion for summary judgment of infringement, Teva contends, the 

district court should have given Teva the reasonable inferences that any discoloration of

the quinapril was caused by some process other than oxidation, and that some 

excipient other than magnesium carbonate could be responsible for inhibiting any

oxidative discoloration that did occur.

In response, Warner-Lambert argues that the district court’s decision should be 

affirmed because Teva did not timely disclose its discoloration defense. In the 

alternative, Warner-Lambert contends the evidence shows that, in the absence of 

magnesium carbonate, the quinapril in Teva’s product exhibits degradation by oxidative 

 12 Teva does not challenge the district court’s summary judgment of 

infringement with respect to claims 16 and 17. 

04-1506 20
discoloration. Schwarz, the intervening plaintiff and exclusive licensee of the ’450 

patent, also argues that the district court improperly construed the term “discoloration” 

to mean “oxidative discoloration” instead of just “change in color.”13

A determination as to patent infringement is a two-step process. PC Connector 

Solutions LLC v. SmartDisk Corp., 406 F.3d 1359, 1362 (Fed. Cir. 2005). First, the 

court must construe the claims. Id. Second, the court must compare the accused 

product or process to the properly construed claims. Id. The first step is a question of

law and the second step is a question of fact. SmithKline Beecham Corp. v. Apotex 

Corp., 403 F.3d 1331, 1337 (Fed. Cir. 2005). Infringement may be found only where 

the accused product or process contains each limitation of the claim, either literally or

under the doctrine of equivalents. Deering Precision Instruments, L.L.C. v. Vector 

Distrib. Sys., Inc., 347 F.3d 1314, 1324 (Fed. Cir. 2003). 

In this case, the first issue is whether the district court erred in construing 

“discoloration” to mean “oxidative discoloration” instead of just “change in color.” We do 

not think that it did. As the court noted in its summary judgment ruling, the only type of 

discoloration referred to in the ’450 patent is oxidative discoloration. Summary

Judgment, 289 F. Supp. 2d at 524. The Background section of the patent, for example,

lists cyclization, hydrolysis, and “oxidation to form products having often unwanted 

coloration,” as the three types of degradation exhibited by ACE inhibitors. ’450 patent, 

col. 1, ll. 9-12. The specification then goes on to disclose one embodiment that 

withstands “oxidative, hydrolytic, and cyclization degradation.” Id. col. 1, ll. 20-22; see 

 13 In its reply brief, Teva argues that we should not allow Schwarz to

challenge the district court’s claim construction because it did not intervene until after 

the summary judgment ruling on infringement. We do not need to address Teva’s

argument because, either way, we think the district court construed the claims correctly. 

04-1506 21
also id. col. 1, ll. 29-35 (touting one advantage of the invention as being “no detectable 

oxidative discoloration”). Additionally, the parties previously stipulated that 

“discoloration” referred to oxidative discoloration. Warner-Lambert Co. v. Teva Pharm. 

USA, Inc., No. 99-922 (D.N.J. May 7, 2002) (“Stipulation and Order”) (“The phrase ‘a 

suitable amount of an ACE inhibitor which is susceptible to cyclization, hydrolysis, and 

discoloration’ in Claim 1 of the ’450 patent means ‘an amount of an ACE inhibitor having 

antihypertensive properties having the structural capacity to cyclize via internal 

nucleophilic attack, hydrolyze a side chain ester, and undergo oxidative discoloration, 

wherein the amount of such ACE inhibitor is sufficient to treat hypertension or

congestive heart failure.’” (emphasis added)). Therefore, we conclude that 

embodiments of claims 1, 4-10, and 12, must include an ACE inhibitor that is 

susceptible to oxidative discoloration, and must also include an alkali or alkaline earth 

metal carbonate (or bicarbonate)14 that inhibits oxidative discoloration. 

Having confirmed the proper construction of claims 1, 4-10, and 12, we next must 

determine whether the district court erred in concluding that no reasonable juror could 

find non-infringement. We turn first to Teva’s contention that the district court erred 

because Warner-Lambert failed to show that the quinapril in Teva’s formulation is 

susceptible to oxidative discoloration. The court stated that “[o]xidation is almost all the 

time the source of discoloration,” and that when discoloration does occur, it is “obvious

and is detected by the unaided eye” through a pink or purple color change. Summary 

Judgment, 289 F. Supp. 2d at 526. This finding is supported by the record. For 

 14 Our prior decision in Schwarz Pharma, Inc. v. Warner-Lambert Co., No. 

03-1384, 95 Fed. Appx. 994, 997-99 (Fed. Cir. Jan. 29, 2004), construed “alkali or

alkaline earth metal carbonates,” as used in the claims of the ’450 patent, to include 

both carbonate and bicarbonate ions. 

04-1506 22
example, Teva’s Analytical Research and Development Report showed that a quinapril 

hydrochloride sample “changed color [over time] from white to a light purple color.” 

(J.A. 12671.) Similar observations were documented in Teva’s lab notebooks. (J.A.

12821.) 

Teva argues that this was still insufficient evidence because it submitted 

evidence establishing that “it is impossible to determine whether discoloration is

oxidative from an observable color change.” (Reply Br. of Teva at 26.) However,

Warner-Lambert only needed to show that the color change made it more likely than not

that oxidation had occurred. See Liberty Lobby, 477 U.S. at 252 (“[T]he inquiry involved 

in a ruling on a motion for summary judgment . . . implicates the substantive evidentiary 

standard of proof that would apply at the trial on the merits.”).15 We believe WarnerLambert satisfied this burden. Warner-Lambert cites to a “Comprehensive Summary of 

Quinapril,” in which it appeared generally understood that quinapril, in the absence of a 

suitable stabilizing agent, suffered from oxidative discoloration. (J.A. 1174.) Teva has

given us no reason to believe its quinapril should behave any differently than the 

quinapril studied and used by Warner-Lambert. Teva points to deposition testimony of 

one of the co-inventors on the ’450 patent, Mr. Reisch. When asked if a change in color 

indicated that oxidation had occurred, he responded, “not definitively.” However, Mr. 

Reisch went on to state that oxidation was the “most likely” cause of a pink coloration. 

Q: What is the purpose for determining the color of these 

samples? 

A: The color is considered undesirable. 

 15 A claim for patent infringement must be proven by a preponderance of the 

evidence, Advanced Cardiovascular Sys., Inc. v. Scimed Life Sys., Inc., 261 F.3d 1329, 

1336 (Fed. Cir. 2001), which simply requires proving that infringement was more likely

than not to have occurred. 

04-1506 23
Q: Is a change in color related to the level of oxidation for

the quinapril? 

A: Most likely. 

Q: And what is the most likely relationship of color to

oxidation in quinapril? 

A: I don’t understand. 

Q: Well, you start with white, correct? 

A: Right. 

Q: If you do this test and you see pink, does that make it 

more likely or less likely that the quinapril has

undergone oxidation? 

A: It makes it more likely. 

(July 20, 2000 Dep. of Robert G. Reisch at 50.) 

In sum, Teva’s bald assertion that something else could be responsible for the 

color change is not sufficient to rebut Warner-Lambert’s prima facie showing that the 

color change is more than likely due to oxidation. Liberty Lobby, 477 U.S. at 252 

(stating that, after the moving party makes out a prima facie showing, the party 

opposing summary judgment must come forward with more than a scintilla of evidence 

to create a genuine issue of material fact). Therefore, because Warner-Lambert made 

a prima facie showing that the quinapril in Teva’s formulation was susceptible to

oxidative discoloration, and because Teva failed to respond with specific evidence to 

the contrary, we hold that no reasonable juror could conclude that the quinapril in 

Teva’s formulation was not susceptible to oxidative discoloration. 

However, Teva also contends the district court erred because, even if the 

quinapril in its formulation is susceptible to oxidative discoloration, Warner-Lambert 

failed to produce evidence showing that the magnesium carbonate in the formulation 

inhibited the discoloration. We agree with Teva that Warner-Lambert failed to make out 

a prima facie case as to this claim limitation. In that regard, we note the following 

portion of the court’s decision: 

04-1506 24
Warner-Lambert’s inventors found that magnesium 

carbonate inhibited [oxidative] discoloration. Likewise, Teva 

never observed discoloration in its magnesium carbonatebased formulation. It used magnesium carbonate because it 

concluded that it ensured chemical and physical stability. It 

represented to the FDA that magnesium carbonate 

“stabilizes” its quinapril formulation. Because lactose is 

claimed to inhibit hydrolysis, magnesium carbonate must be 

the inhibitor of the only two other kinds of degradation,

cyclization and discoloration. 

Summary Judgment, 289 F. Supp. 2d at 526 (emphasis added). We do not think this 

reasoning supports the grant of summary judgment in favor of Warner-Lambert. It may 

very well be that the magnesium carbonate inhibits oxidative discoloration. However, it

may also be that some other excipient in the formulation is responsible. Cf. Fisher, 427

F.2d at 838-39 (stating that many chemical reactions are unpredictable). The point is 

that Warner-Lambert, the party who bears the burden of proving infringement by a 

preponderance of the evidence, has not presented evidence to show that it is in fact the 

magnesium carbonate that serves this particular stabilizing function. It is true that 

Warner-Lambert presented evidence showing that the lactose inhibits hydrolysis and 

that the magnesium carbonate inhibits cyclization. That does not necessarily mean,

though, that the magnesium carbonate also inhibits oxidative discoloration.

Accordingly, at this stage of the proceedings, drawing all reasonable inferences in favor 

of Teva, we must conclude that genuine issues of fact remain as to whether the 

magnesium carbonate in Teva’s formulation inhibits oxidative discoloration of the 

quinapril. 

In reaching our conclusion, we offer no views as to Warner-Lambert’s argument 

that Teva should be procedurally barred from asserting its discoloration defense. The 

district court seemed to agree with Warner-Lambert that the defense was untimely and 

04-1506 25
prejudicial to Warner-Lambert. Nevertheless, the district court chose to dispose of the 

defense on its merits. Having reversed the district court’s judgment on the merits, we 

leave to the sound discretion of the district court the matter of how to most appropriately

proceed on remand. 

II. 

Teva also challenges the district court’s finding, following a bench trial, that the 

’450 patent is not unenforceable by reason of inequitable conduct. Inequitable conduct

occurs when a patentee breaches his or her duty to the PTO of “candor, good faith, and 

honesty.” Molins PLC v. Textron, Inc., 48 F.3d 1172, 1178 (Fed. Cir. 1995). This can 

occur through “affirmative misrepresentations of a material fact, failure to disclose 

material information, or submission of false information, coupled with an intent to 

deceive.” Id. “One who alleges inequitable conduct arising from a failure to disclose 

prior art must offer clear and convincing proof of the materiality of the prior art, 

knowledge chargeable to the applicant of that prior art and of its materiality, and the 

applicant’s failure to disclose the prior art, coupled with an intent to mislead the PTO.” 

Id.; see also Duro-Last, Inc. v. Custom Seal, Inc., 321 F.3d 1098, 1109-10 (Fed. Cir. 

2003). 

We review the district court’s findings of fact for clear error and the ultimate 

determination of whether inequitable conduct occurred for abuse of discretion. DuroLast, 321 F.3d at 1110. “A finding [of fact] is ‘clearly erroneous’ when although there is 

evidence to support it, the reviewing court on the entire evidence is left with the definite 

and firm conviction that a mistake has been committed.” Am. Pelagic Fishing Co., L.P. 

v. United States, 379 F.3d 1363, 1371 (Fed. Cir. 2004) (citation omitted). “An abuse of 

04-1506 26
discretion may be established under Federal Circuit law by showing that the court made 

a clear error of judgment in weighing the relevant factors or exercised its discretion 

based on an error of law or clearly erroneous fact finding.” Int’l Rectifier Corp. v. 

Samsung Elecs. Co., 361 F.3d 1355, 1359 (Fed. Cir. 2004) (citation omitted). 

Teva’s argument before the district court was that the inventors of the ’450 patent 

committed inequitable conduct by failing to disclose the existence of Merck’s Vasotec®

to the PTO during prosecution of the ’450 patent. In its decision denying the parties’ 

cross motions for summary judgment on the issue, the court concluded that while 

Vasotec® was highly material,16 genuine issues of fact remained as to whether the 

Warner-Lambert inventors withheld information relating to Vasotec® with the intent to 

deceive the PTO. Summary Judgment, 289 F. Supp. 2d at 536-43. The court therefore 

held a bench trial to determine whether such a deceptive intent accompanied the 

inventors’ failure to disclose Vasotec®. At the end of the trial, the court concluded that 

there was no such deceptive intent and consequently granted Warner-Lambert 

judgment of no inequitable conduct. Bench Trial Opinion, 2004 WL 1498162, at *13-14. 

In reaching its decision, the district court stated that it had not fully appreciated 

the significance of Warner-Lambert’s two-stage quinapril investigation until hearing 

Warner-Lambert’s witnesses testify at trial. Id. at *12. In particular, the testimony of Dr. 

Murthy and Dr. Harris, two of the inventors listed on the ’450 patent, indicated to the 

court that Warner-Lambert’s formulation team was only interested in Vasotec® during 

the first investigatory stage, involving the pH studies, and that, even at this stage, their 

interest was limited to “ascertaining the pH of the Vasotec tablet in solution.” Id. The 

 16 As noted above, see note 10, supra, after trial, the district court backed 

away from this conclusion somewhat. 

04-1506 27
court noted that Warner-Lambert’s formulation team knew Vasotec® contained sodium

bicarbonate. However, the court found, the team did not know how sodium bicarbonate 

was used to stabilize enalapril. Id. at *12-13. Warner-Lambert abandoned the pH 

studies sometime in May 1986, and soon thereafter commenced the second stage of its

investigation, involving one-to-one excipient compatability studies. By June or July of 

1986, the court stated, “Vasotec and its use of sodium bicarbonate were no longer of

interest to Warner-Lambert’s scientists[.]” Id. at *12. Therefore, considering that it was 

the compatibility studies that ultimately resulted in the discovery of the stable quinapril,

magnesium carbonate, and lactose formulation, the court found that the inventors 

simply did not consider Vasotec® relevant to their invention when they filed for patent 

protection. Id. at *13-14. 

The district court acknowledged that Dr. Murthy, a co-inventor of the ’450 patent,

made some rather inculpatory statements in his deposition. Id. at *11. In particular, he 

stated that at the time he and his co-inventors were preparing to file the ’450 patent’s

application, they discussed Vasotec® and decided not to disclose it to their patent

attorney. Id. However, at trial, Dr. Murthy stated that he had made a mistake in his 

deposition testimony: 

Here’s what I recall today, your Honor. At the time when I 

testified to this was back in 2001. . . . I was trying to recall 

events that took place about 14 years. And it was true that 

we discussed about sodium bicarbonate, and we discussed 

it with Enalapril and Merck’s [Vasotec®] at the beginning of

our program. But after we ran experiments, sodium

bicarbonate at different levels and different methods or

incorporation, we were not successful in stabilizing this 

product. Sodium bicarbonate did not help us in any way. So 

the whole sodium bicarbonate, and Enalapril, and Vasotec®

fell off the table as--after we stabilized our product with

magnesium carbonate and lactose. And so we did not--it's 

04-1506 28
true that I--I did testify to this effect, but after reflecting on it,

it just--I was mixed up with the dates at the time. It was true,

we did discuss about this, but that was the beginning of the 

program and not at the time of the filing. The discussions 

took place much earlier, at the beginning of the program. 

Id. Dr. Harris, another co-inventor of the ’450 patent, also testified that he did not recall 

any discussions of Vasotec® after the team abandoned the pH studies. Id. at *12. The

court found both of these inventors to be “completely credible witnesses,” noting that 

neither of them were still employees at Warner-Lambert. Id.

Teva argued that the Warner-Lambert scientists must have known Vasotec® was

material, considering that claims 16 and 17, as originally filed, referred only to “alkali or

alkaline earth metal salts,” and therefore read on formulations comprising enalapril and 

sodium bicarbonate (two of the key ingredients of Vasotec®). However, the district

court rejected this argument, finding that mere knowledge of sodium bicarbonate as one 

of the ingredients of Vasotec® in no way informed the Warner-Lambert scientists as to 

how sodium bicarbonate was used to stabilize enalapril. Id. at * 12-13. This, the court

stated, was confirmed by the fact that the Warner-Lambert team only used sodium

bicarbonate to adjust pH during the first phase of the investigation. Merck, on the other

hand, utilized sodium bicarbonate for a much different purpose, to convert enalapril 

maleate into its sodium salt form. Id. at *13. 

The district court’s conclusion was also not affected by our intervening decision 

of January 29, 2004, in Schwarz Pharma, in which we construed “carbonate” in the ’450 

patent to include “bicarbonate.” 95 Fed. Appx. at 997-99. The court reiterated that the 

subjective intent of the patentees was not to claim sodium bicarbonate or the Vasotec®

formulation. Rather, “[b]ased on their success with magnesium carbonate and failure 

04-1506 29
with sodium bicarbonate, they were thinking only in terms of an excipient possessed of

the carbonate ion.” Bench Trial Opinion, 2004 WL 1498162, at *13. The court therefore 

concluded that “[t]he evidence does not support Teva’s argument that failure to disclose 

Vasotec®, which contained sodium bicarbonate, was intended to deceive the PTO.” Id.

at *14. 

On appeal, Teva contends the district court abused its discretion in not finding 

inequitable conduct. Teva’s primary argument is that the court failed to appreciate the 

difference between what the ’450 patent discloses and what it claims. In particular,

while the working examples of the patent only disclose the quinapril, magnesium

carbonate, and lactose formulation, Teva asserts that the claims cover much more, 

including enalapril stabilized by sodium bicarbonate and lactose (i.e. the Vasotec® 

formulation). Teva further asserts that the patentees, knowing claims 16 and 17 

actually read on Vasotec®, intentionally withheld its existence from the PTO in order to 

gain allowance of the broadly drafted claims. Therefore, Teva contends that an 

inference of intent to deceive the PTO is warranted under our decision in Critikon, Inc. v. 

Becton Dickinson Vascular Access, Inc., 120 F.3d 1253, 1257 (Fed. Cir. 1987), where 

we held that “a patentee facing a high level of materiality and clear proof that it knew or 

should have known of that materiality, can expect to find it difficult to establish 

‘subjective good faith’ sufficient to prevent the drawing of an inference of intent to 

mislead.” In addition, Teva contends that the submission of an oath by the ’450 

patentees, stating that they were the first to invent a method of stabilizing enalapril,

constitutes an independent basis for finding inequitable conduct. 

04-1506 30
Teva urges us to reject Warner-Lambert’s explanation for not disclosing 

Vasotec®, i.e., Warner-Lambert’s argument that, while their formulation team knew of 

Vasotec®, they did not know how sodium bicarbonate was used to stabilize enalapril

against cyclization. Teva argues that the story is not believable, because the claims

read on Vasotec® irrespective of whether the ’450 patentees actually knew how Merck

used sodium bicarbonate to stabilize enalapril. That, according to Teva, is because 

claim 16 places no limitation on how the excipients stabilize the ACE inhibitor; it simply

recites a method of “contacting” an ACE inhibitor with an “alkali or alkaline earth metal

carbonate” and “one or more saccharides.” Therefore, while Warner-Lambert may not 

have known how Merck stabilized enalapril, Teva argues that the ingredients of the 

Vasotec® formulation (i.e. enalapril and sodium bicarbonate) remained relevant

throughout prosecution of claims 16 and 17. 

In response, Warner-Lambert first argues that Teva is not entitled to a finding of

inequitable conduct because it has not been “frank and fair” with the court in its 

representations, and, a party may not seek equitable relief if it has unclean hands.17 In

any event, Warner-Lambert maintains that Vasotec® is not material to claims 16 and 17 

because the claims require more than just “contacting an ACE inhibitor a carbonate and 

a saccharide.” They also require that the alkali or alkaline earth metal carbonate 

stabilize the ACE inhibitor against cyclization. And, because its inventors did not know 

that sodium bicarbonate had a stabilizing effect on the enalapril in Vasotec®, Warner-

 17 In particular, Warner-Lambert argues that Teva has made various factual 

misrepresentations to this court. For example, Warner-Lambert states that Teva

repeatedly characterizes the district court as having found Vasotec® “highly material,” 

even though that statement was made in the court’s summary judgment decision and 

was subsequently called into doubt in the court’s bench trial opinion.

04-1506 31
Lambert asserts that the district court properly found that Vasotec® was not material.18 

Warner-Lambert similarly maintains that, even if Vasotec® was material, the district 

court found that its inventors did not withhold Vasotec® with the intent to deceive the 

PTO. In addition, Warner-Lambert argues that this finding involved numerous credibility 

determinations, made after hearing live testimony at trial. Warner-Lambert asserts that 

Merck’s decision to maintain its method of stabilizing Vasotec® as a trade secret further 

demonstrates that the ’450 inventors did not know the role sodium bicarbonate played in 

Vasotec® and, consequently, had no intent to deceive the PTO in not disclosing

Vasotec®. Finally, Warner-Lambert contends that Teva’s “false oath” argument should 

not be considered because it was not raised below.

We cannot say the district court erred on the inequitable conduct issue. In 

particular, we cannot say that the court clearly erred in finding that the Warner-Lambert 

inventors did not intend to deceive the PTO in not disclosing the existence of Vasotec®. 

It is true that “[d]irect evidence of intent or proof of deliberate scheming is rarely 

available in instances of inequitable conduct,” and that “intent may [therefore] be 

inferred from the surrounding circumstances.” Critikon, 120 F.3d at 1256. It is also true 

that “[t]he more material the omission or the misrepresentation, the lower the level of 

intent required to establish inequitable conduct . . . .” Id. However, determining whether

there was intent to deceive is still a contextual exercise, and “materiality does not

presume intent, which is a separate and essential component of inequitable conduct.” 

 18 Warner-Lambert notes that, while the district court initially considered 

Vasotec® a “highly material” reference, Summary Judgment, 289 F. Supp. 2d at 536, 

the court backed off this statement after hearing from Dr. Murthy and Dr. Harris during 

the bench trial, Bench Trial Opinion, 2004 WL 1498162, at *10 (“Whether Vasotec was

as ‘highly material’ as stated in [the summary judgment] opinion is subject to question in 

view of the facts developed at the trial.”). 

04-1506 32
GFI, Inc. v. Franklin Corp., 265 F.3d 1268, 1274 (Fed. Cir. 2001). To be sure, “a 

patentee facing a high level of materiality and clear proof that it knew or should have 

known of that materiality, can expect to find it difficult to establish ‘subjective good faith’

sufficient to prevent the drawing of an inference of intent to mislead,” Critikon, 120 F.3d 

at 1257, but our case law does not foreclose the possibility, id. (“No single factor or 

combination of factors can be said always to require an inference of intent to

mislead[.]”). Therefore, while “smoking gun” evidence is not required in order to find

intent to deceive, “the involved conduct, viewed in light of all the evidence, including 

evidence indicative of good faith, must indicate sufficient culpability to require a finding

of intent to deceive.” Kingsdown Med. Consultants Ltd. v. Hollister, Inc., 863 F.2d 867, 

876 (Fed. Cir. 1988) (en banc) (emphasis added); see also Paragon Podiatry Lab., Inc. 

V. KLM Labs., Inc., 984 F.2d 1182, 1189-90 (Fed. Cir. 1993). 

In this case, Vasotec® is of relatively high materiality.19 Claim 16, for example, 

recites a method of contacting an ACE inhibitor with an alkali or alkaline earth metal 

carbonate and a saccharide, and the Vasotec® formulation includes enalapril, sodium

bicarbonate, and a saccharide. Claim 16 therefore, at least on its face, appears to read 

on much of the Vasotec® formulation.20 However, after hearing all the evidence and, 

specifically, the testimony of Dr. Murthy and Dr. Harris, the trial court concluded that the 

 19 It is not clear exactly how material the district court considered Vasotec®. 

The court characterized it as “highly material” at the summary judgment stage,

Summary Judgment, 289 F. Supp. 2d at 536, but then seemed to back off this 

statement after hearing the evidence presented at trial, Bench Trial Opinion, 2004 WL 

1498162, at *10 (“Whether Vasotec was as ‘highly material’ as stated in [the summary

judgment] opinion is subject to question in view of the facts developed at the trial.”). 

20 That is because claim 16 appears to simply claim the ingredients used to 

make the ACE inhibitor formulation. It does not, for example, place limitations on how 

the ingredients are specifically combined or what it is that the ingredients do to stabilize

the ACE inhibitor. 

04-1506 33
inventors acted with subjective good faith in not disclosing Vasotec®. The court found 

that they did not disclose Vasotec® because, at the time of filing for the ’450 patent, 

they simply did not think it had any relevance to their application. In other words, they 

did not appreciate its materiality. See Molins, 48 F.3d at 1178 (holding that the 

patentee must be aware of both the reference and its materiality). They knew Vasotec®

contained sodium bicarbonate, but they did not know how sodium bicarbonate 

functioned in Vasotec® or that “alkali or alkaline earth metal carbonate” included

bicarbonate. Bench Trial Opinion, 2004 WL 1498162, at *11-12 (finding Dr. Murthy and 

Dr. Harris “completely credible” witnesses). We cannot say that the district court 

committed clear error in assessing the credibility of these witnesses and finding an 

absence of deceitful intent. 

Teva argues that, even assuming the Warner-Lambert scientists did not know 

how to stabilize Vasotec®, the patentees still committed inequitable conduct because 

claims 16 and 17 nevertheless read on Vasotec®. This, according to Teva, is because 

the claims simply require “contacting” an ACE inhibitor with a metal carbonate and a 

saccharide. Teva also points out that the originally filed claims were not limited to

carbonates, but merely referred to “alkali and alkaline earth metal salts,” and that this 

court’s decision in Schwarz Pharma construed “carbonate” to include “bicarbonate.” 

The problem with this argument is that the district court, after hearing testimony

and making credibility determinations, found that the Warner-Lambert scientists did not 

use sodium bicarbonate for anything other than adjusting the pH of quinapril during the 

stage one investigations, and that their subsequent failure to disclose Vasotec® was the 

result of their good-faith belief that Vasotec® did not relate to their claimed invention.

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Id. at *12. Dr. Murthy specifically testified to the fact that he did not think claims 16 or

17 included sodium bicarbonate: 

Because I took [“[a] suitable amount of an alkali or alkaline 

earth metal salt”] to mean mostly carbonates because those 

are the ones that worked. There was no bicarbonate that 

has worked for us in our efforts to stabilize the product, so 

we did not have any bicarbonate in mind. 

. . . . 

We do not--we did not have in mind sodium bicarbonate, 

otherwise we would have been very specific about it. 

Because our experiments with sodium bicarbonate did not

help us in the stabilizing of quinapril. So we didn’t --at least I 

did not have in mind sodium bicarbonate and to prevent 

cyclization of quinapril. 

Id. at *13-14. In short, based on the testimony presented at trial, the court concluded 

that the Warner-Lambert inventors were concerned only with carbonate ions, had no 

intention of claiming bicarbonates, and consequently had no intent to deceive the PTO 

in not disclosing Vasotec®. Id. In keeping within our role as an appellate court of 

review, we cannot say that the district court committed clear error in making these 

findings. See Anderson v. Bessemer City, 470 U.S. 564, 575 (1985) (“[W]hen a trial 

judge’s finding is based on his decision to credit the testimony of one of two or more 

witnesses, each of whom has told a coherent and facially plausible story that is not 

contradicted by extrinsic evidence, that finding, if not internally inconsistent, can virtually

never be clear error.”); LNP Eng’g Plastics, Inc. v. Miller Waste, Inc., 275 F.3d 1347,

1361 (Fed. Cir. 2001) (“[T]he district court’s determination on intent in this case depends

heavily on the assessment of witness testimony at trial. This court may not reassess, 

and indeed is incapable of reassessing, witness credibility and motive issues on

review.”). 

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Teva also argues that this case is analogous to Critikon, where we reversed a 

district court’s finding of no inequitable conduct, and that we must consequently reverse 

the court’s finding in this case as well. We disagree. We first reiterate that there is no 

bright line test for determining whether inequitable conduct occurred; each case must

be assessed independently. In any event, however, the facts of this case are 

distinguishable from those in Critikon. In that case, the evidence showed that the 

patentee was not only “intimately familiar” with the withheld prior art, but was repeatedly

confronted with it and knew of its particular relevance to the PTO examiner. Critikon, 

120 F.3d at 1256-57. In addition, the patentee “made no effort to offer a good faith

explanation of why [the prior art] was never cited, but merely offered conclusory

statements that the reference was cumulative.” Id. at 1257. Here, by contrast, the 

district court’s findings do not suggest that the patentees were “intimately familiar” with

Vasotec® or knew of its potential relevance to the PTO. On the contrary, the evidence,

particularly with respect to Warner-Lambert’s abandonment of Vasotec® after the failed 

pH studies, suggests that the patentees had only limited familiarity with the Vasotec®

formulation. This is not surprising considering that Merck maintained its sodium

bicarbonate stabilization process as a trade secret. Perhaps most importantly though,

unlike the situation in Critikon, Warner-Lambert, through Dr. Murthy and Dr. Harris, 

offered a plausible, good faith explanation for why Vasotec® was not cited to the PTO. 

Accordingly, given the district court’s view of the evidence, we do not think the facts of 

this case necessarily require a finding of intent to deceive. 

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CONCLUSION 

We hold that there are genuine issues of material fact as to enablement and 

infringement of the ’450 patent. We therefore reverse the district court’s grant of 

summary judgment on the issue of enablement with respect to claims 1, 4-10, 12, 16, 

and 17, and on the issue of infringement of claims 1, 4-10, and 12, the claims with 

respect to which Teva challenges the judgment of infringement. The case is remanded 

to the district court for further proceedings on those issues. However, we see no error 

in the district court’s determination that the ’450 patent is not unenforceable by reason 

of inequitable conduct. We therefore affirm the court’s judgment on that issue. 

COSTS 

Each party shall bear its own costs. 

AFFIRMED-IN-PART, REVERSED-IN-PART, and REMANDED

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