United States Court of Appeals 

for the Federal Circuit ______________________ 

TAKEDA PHARMACEUTICAL COMPANY 

LIMITED, TAKEDA PHARMACEUTICALS NORTH 

AMERICA, INC., TAKEDA PHARMACEUTICALS,

LLC, TAKEDA PHARMACEUTICALS AMERICA, 

INC., AND ETHYPHARM, S.A.,

Plaintiffs-Appellees,

v.

ZYDUS PHARMACEUTICALS USA, INC. AND

CADILA HEALTHCARE LIMITED,

Defendants-Appellants.

______________________ 

2013-1406

______________________ 

Appeal from the United States District Court for the 

District of New Jersey in No. 10-CV-1723, Judge Joel A. 

Pisano.

______________________ 

Decided: February 20, 2014

______________________ 

ARLENE L. CHOW, Hogan Lovells US LLP, of New 

York, New York, argued for plaintiffs-appellees. With her 

on the brief were ERIC J. LOBENFELD of New York, New 

York; CATHERINE E. STETSON and FREDERICK LIU, of 

Washington, DC. Of counsel was PHILIPPE YOLAND 

RIESEN, of Tokyo, Japan. 
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STEVEN J. MOORE, Kelley Drye & Warren, LLP, of 

Stamford, Connecticut, argued for defendants-appellants. 

With him on the brief was JAMES E. NEALON. 

______________________ 

Before PROST, PLAGER, and CHEN, Circuit Judges.

PROST, Circuit Judge. 

Zydus Pharmaceuticals USA, Inc. and Cadila

Healthcare Limited (“appellants” or “Zydus”) appeal from 

a final judgment of the U.S. District Court for the District 

of New Jersey finding that appellants had infringed claim 

1 of U.S. Patent No. 6,328,994 (“’994 patent”) and had 

failed to establish that it was invalid. For the reasons 

stated below, we reverse the district court’s finding of 

infringement, but affirm its ruling on invalidity.

BACKGROUND

Takeda Pharmaceutical Company Limited, Takeda 

Pharmaceuticals North America, Inc., Takeda Pharmaceuticals, LLC, Takeda Pharmaceuticals America, Inc., 

and Ethypharm, S.A. (“appellees” or “Takeda”) own 

patents that claim the formulation for the brand-name 

drug Prevacid® SoluTabTM. Prevacid® SoluTabTM contains the active ingredient lansoprazole, which is a proton 

pump inhibitor used to treat gastroesophageal reflux 

disease, or acid reflux. It is the only proton pump inhibitor available as an orally disintegrable tablet. A patient 

taking Prevacid® SoluTabTM simply allows the tablet to 

disintegrate in his or her mouth, leaving behind thousands of granules which the patient then swallows. The 

stated objective of the ’994 patent is that the formulation 

contains granules small enough to avoid a feeling of 

roughness in the patient’s mouth upon disintegration. 

In 2010, Zydus filed an abbreviated new drug application (“ANDA”) with the Food and Drug Administration, 

seeking to manufacture a generic version of Prevacid® 
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SoluTabTM. Takeda then filed suit, alleging that Zydus’s 

ANDA product infringed multiple claims of several patents. Only claim 1 of the ’994 patent remains at issue. 

Zydus counterclaimed, alleging that claim 1 was invalid 

for failure to comply with the requirements of 35 U.S.C. 

§ 112. 

Claim 1 recites:

An orally disintegrable tablet which comprises (i) 

fine granules having an average particle diameter 

of 400 μm or less, which fine granules comprise a 

composition coated by an enteric coating layer 

comprising a first component which is an enteric 

coating agent and a second component which is a 

sustained-release agent, said composition having 

10 weight % or more of an acid-labile physiologically active substrate that is lansoprazole and (ii) 

an additive wherein said tablet having a hardness 

strength of about 1 to about 20 kg, is orally disintegrable. 

’994 patent col. 37 ll. 43-53. The district court held a 

claim construction hearing, at which it construed the 

claim term “fine granules having an average particle 

diameter of 400 μm or less.” Takeda argued that the term 

should be construed to include a deviation of ±10%, because it is “universally accepted” that there is a 10% 

standard of error for particle size measurements. J.A. 

154. Zydus, on the other hand, argued that the term 

should be construed as “precisely 400 μm.” J.A. 496. The 

district court agreed with Takeda, and construed the term 

to mean “fine granules up to and including the enteric 

coating layer having an average particle diameter of 400

μm (±10%) or less.” Takeda Pharm. Co. v. Zydus Pharms. 

USA Inc., No. 10-1723, 2011 WL 4736306, at *3-4 (D.N.J. 

Oct. 5, 2011). 

The issue of infringement turned on how particle size 

was measured. During the manufacturing process, indi-
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vidual cores of lansoprazole are enteric coated using a 

fluid-bed coating process. Inevitably, that process results 

in a certain portion of the coated cores becoming fused 

together. These fused multi-cored granules are known as 

“hard agglomerates.” 

Takeda argued that the average particle diameter 

should be determined by measuring each individual core, 

regardless of whether they had fused together into a hard 

agglomerate. Taking that measurement requires “virtual 

dissection” of hard agglomerates, meaning drawing an 

artificial line between the two fused cores such that the 

software will treat them separately for measurement 

purposes. Obviously, artificially dividing large hard 

agglomerates into several smaller granules for measurement purposes lowers the average particle size of a sample, making it more likely to infringe claim 1 of the ’994 

patent. Zydus argued that, to the contrary, because the 

specification describes measuring particle size after the 

coating process and says nothing about deagglomeration, 

it by definition includes hard agglomerates in the measurement of average particle diameter. In support of its 

position, Zydus pointed out that the actual size of the 

fused particles is what is relevant to how the granules feel 

in the patient’s mouth, regardless of the size of the smaller fused cores that make up a hard agglomerate. Under 

the district court’s claim construction, where the maximum average particle size is 440 μm, Zydus’s ANDA 

product would infringe claim 1 of the ’994 patent if hard 

agglomerates were virtually dissected prior to measurement, but would not infringe if hard agglomerates were 

included in the measurement. 

After a bench trial, the district court agreed with 

Takeda and found that the ’994 patent requires measuring the average diameter of each core, regardless of how 

many cores are in a given hard agglomerate. Takeda

Pharm. Co., Ltd. v. Zydus Pharms. USA Inc., No. 10-1723, 

slip op. at 12-13 (D.N.J. May 7, 2013) (“Opinion”). Based 
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on that finding, the district court determined that Zydus’s 

ANDA product infringed claim 1 of the ’994 patent. Id. at 

19-21. The district court further concluded that Zydus 

had failed to establish by clear and convincing evidence 

that claim 1 was invalid. Id. at 25-42. The court then 

entered an injunction preventing Zydus from manufacturing or selling its ANDA product until the expiration of 

the ’994 patent. Id. at 43-46. Zydus appealed all of the 

district court’s rulings.

We have jurisdiction under 28 U.S.C. § 1295(a)(1).

ANALYSIS

I. Claim Construction

Claim construction is a question of law that we review 

without deference. Cybor Corp. v. FAS Techs., Inc., 138 

F.3d 1448, 1455-56 (Fed. Cir. 1998) (en banc). Our starting point in construing a claim term must be the words of 

the claim itself. See Vitronics Corp. v. Conceptronic, Inc., 

90 F.3d 1576, 1582 (Fed. Cir. 1996); Phillips v. AWH 

Corp., 415 F.3d 1303, 1314 (Fed. Cir. 2005) (en banc)

(“[T]he claims themselves provide substantial guidance as 

to the meaning of particular claim terms.”). However, it 

is axiomatic that the claims “must be read in view of the 

specification, of which they are a part.” Phillips, 415 F.3d 

at 1315 (quoting Markman v. Westview Instruments, Inc., 

52 F.3d 967, 979 (Fed. Cir. 1995) (en banc), aff’d 517 U.S. 

370 (1996)). Additionally, a court “should also consider 

the patent’s prosecution history, if it is in evidence.” 

Markman, 52 F.3d at 980. Although courts are permitted 

to consider extrinsic evidence, such as expert testimony, 

dictionaries, and treatises, we have cautioned that such 

evidence is generally of less significance than the intrinsic 

record. Phillips, 415 F.3d at 1317 (citing C.R. Bard, Inc. 

v. U.S. Surgical Corp., 388 F.3d 858, 862 (Fed. Cir. 2004)). 

Ultimately, “[t]he construction that stays true to the 

claim language and most naturally aligns with the patent’s description of the invention will be, in the end, the 
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correct construction.” Renishaw PLC v. Marposs Societa’ 

per Azioni, 158 F.3d 1243, 1250 (Fed. Cir. 1998). 

With these principles in mind, we turn to the disputed 

claim language. Zydus challenges the district court’s 

construction of the claim term “fine granules having an 

average particle diameter of 400 μm or less.” The district 

court construed that term to include a ±10% deviation. 

Zydus argues that it should be construed to require an 

average particle diameter of “precisely 400 μm or less.” 

We agree with Zydus that the district court erred in 

reading a margin of error into the disputed claim term. 

Beginning with the claim language itself—as we 

must—there is no indication in the claim that 400 μm was 

intended to mean anything other than exactly 400 μm. To 

the contrary, the phrase “400 μm or less” is not qualified 

by the word “about” or any other indicator of imprecision. 

Moreover, the specification confirms that the inventors did not intend to deviate from that clear and unambiguous plain meaning. First, the specification contrasts 

the “fine granules” of the claimed invention with larger 

“conventional” granules, which it defines as “400 μm or 

more of average particle diameter.” ’994 patent col. 2 ll. 

17-18. The specification explains that conventional 

granules of that size “produce a feeling of roughness in 

the mouth”—one of the very problems the claimed invention purports to solve. Id. col. 2 ll. 16-17. That clear 

dividing line between the “fine” granules of 400 μm or less 

(which avoid a feeling of roughness in the mouth) and 

“conventional” granules of 400 μm or more (which do not) 

disappears if the “fine granules” are construed as incorporating a 10% deviation. Thus, there can be little doubt 

that the narrower construction “most naturally aligns 

with the patent’s description of the invention.” Renishaw, 

158 F.3d at 1250. 

Second, the specification goes on to explain that the 

maximum particle size is “practically 425 μm or less,” 
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where “practically” means that “the particles may include 

a small quantity (about 5 weight % or less) of particles 

whose particle diameter is out of above described 

range.” ’994 patent col. 5 l. 65–col. 6 l. 8. Elsewhere, the 

patent defines “average particle diameter” to mean the 

median particle diameter. See id. col. 5 ll. 43-46. It would 

be impossible for a tablet to comply with the specification’s maximum particle diameter of practically 425 μm 

(meaning that only 5% of particles have diameters larger 

than 425 μm) if it had a median particle diameter of 440 

μm (meaning that 50% of the particles are larger than 440

μm), as the district court’s claim construction would 

permit. This tension suggests that the inventors did not 

intend to incorporate a ±10% deviation into the average 

particle diameter of claim 1. 

Takeda argues that the inventors effectively acted as 

their own lexicographers and modified the plain meaning 

of the term “fine granules” in the specification. The 

specification states:

In the present invention, “fine granules having an 

average particle diameter of 400 μm or less, which 

fine granules comprise a composition coated by an 

enteric coating layer, said composition having 10 

weight % or more of an acid-labile physiologically 

active substance” have an average particle diameter of about 400 μm or less, in order that roughness is not felt in the mouth. Preferably, the 

average particle diameter of the fine granules is 

300 to 400 μm. 

’994 patent col. 5 ll. 57-64 (emphasis added). Takeda 

maintains that the inventors therefore expressly defined 

400 μm as an approximate figure, and that a skilled 

artisan would know that a standard deviation for particlesize measurements is ±10%. We disagree.

The word “about” is used to modify the phrase “400 

μm or less” only three times in the specification. In 
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addition to the passage quoted above, the specification 

states: 

[T]he average particle a [sic] diameter of the included granules must be about 400 μm or less, 

preferably about 350 μm.

Id. col. 2 ll. 20-22. And later, it reiterates:

The “fine granules” have an average particle diameter of about 400 μm or less, preferably 350 μm 

or less. Preferably; the average particle diameter 

of the fine granules is 300 to 400 μm. 

Id. col. 12 ll. 58-61. In every one of these instances, the 

word “about” is immediately followed by a preference for 

an average particle size lower than 400 μm. Nowhere 

does the specification suggest that an average particle 

size greater than 400 μm (even within 10% of that figure) 

could achieve the inventive result of avoiding a feeling of 

roughness in the mouth. Thus, we are not persuaded that 

the mere presence of the word “about” at three points in 

the specification can justify a 10% expansion of claim 

scope. 

Indeed, the remainder of claim 1 demonstrates that 

the inventors knew how to express ambiguity in claim 

language when they so desired; it provides that the tablet 

must have a hardness strength of “about 1 to about 20 

kg.” ’994 patent col. 37 l. 52 (emphasis added). Plainly, 

then, had the inventors desired the average particle 

diameter to include a margin of error, they could easily 

have included the word “about” in the claim language. In 

the absence of their decision to do so, however, we will not 

take it upon ourselves to rewrite the claim in that way.

This reading of the specification is confirmed by the 

prosecution history. There, the inventors distinguished 

the claimed invention over a potentially invalidating prior 

art reference because the reference failed to disclose an 

average particle diameter of 400 μm or less. J.A. 7228. 
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The inventors explained that “[b]y having the average 

particle diameter of the granules within 400 μm, the 

feeling of roughness in a mouth can be prevented.” J.A. 

7228 (emphasis added). In other words, the inventors 

have consistently relied on 400 μm as the dividing line 

between granules that would avoid roughness in the 

mouth and those that would not—meaning those that 

were within the scope of the invention, and those that 

were not. We long ago established that “[w]here there is 

an equal choice between a broader and a narrower meaning of a claim, and there is an enabling disclosure that 

indicates that the applicant is at least entitled to a claim 

having the narrower meaning, we consider the notice 

function of the claim to be best served by adopting the 

narrower meaning.” Athletic Alternatives, Inc. v. Prince 

Mfg., Inc., 73 F.3d 1573, 1581 (Fed. Cir. 1996). Thus, 

even if the two proposed constructions before us presented 

an “equal choice”—and they do not—the narrower construction would be more appropriate. 

We therefore reverse the district court’s claim construction and conclude that the proper construction of the 

disputed claim term is “fine granules having an average 

particle diameter of precisely 400 μm or less.”

II. Infringement

As explained above, the dispute as to literal infringement turned on whether the patent required virtual 

dissection of hard agglomerates prior to particle size 

measurement. Even using virtual dissection, however, 

Takeda measured Zydus’s ANDA product as having an 

average particle diameter of 412.28 μm—well outside the 

claimed range as we have now construed it. Appellants’ 

Br. 31; J.A. 8338. Thus, there can be no dispute that 
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Zydus’s ANDA product does not literally infringe claim 1 

of the ’994 patent.1 

We therefore reverse the district court’s finding of literal infringement.

III. Invalidity

Zydus raises several challenges to the validity of 

the ’994 patent based on a failure to satisfy the requirements of 35 U.S.C. § 112. A number of those arguments 

related to the claim construction adopted by the district 

court, which we have now reversed, and are therefore 

moot. We will address the remaining arguments in turn.

A. Indefiniteness 

We review a district court’s ruling on indefiniteness 

de novo, as it is a question of law. ePlus, Inc. v. Lawson 

Software, Inc., 700 F.3d 509, 516 (Fed. Cir. 2012). 

“Whether a claim is invalid for indefiniteness requires a 

determination whether those skilled in the art would 

understand what is claimed when the claim is read in 

light of the specification.” Morton Int’l, Inc. v. Cardinal 

Chem. Co., 5 F.3d 1464, 1470 (Fed. Cir. 1993). As always,

the party challenging the patent bears the burden of 

proving invalidity by clear and convincing evidence. 

Microsoft Corp. v. i4i Ltd. P’ship, 131 S. Ct. 2238, 2242 

(2011).

Zydus argues that the ’994 patent is indefinite because it does not specify the method of measurement that 

1 Although it was not necessary for us to consider 

whether the ’994 patent requires deagglomeration in our 

infringement analysis, we do consider that question below 

in the context of Zydus’s invalidity arguments. See infra 

Section III.C. 

 
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should be used to determine average particle diameter.2 

Zydus insists that there are several methods that could 

potentially be used to take that measurement, and the 

same sample could be either infringing or non-infringing 

depending on the measurement technique used. Thus, 

the skilled artisan has no way to determine whether his 

or her product infringes the ’994 patent based on the 

information provided in the specification. 

We disagree. It is true that there was evidence from 

both parties’ experts that there are several possible ways 

to measure average particle diameter. Indeed, the patent 

specification itself identifies laser diffraction as just one 

“example” of such a measurement technique, ’994 patent 

col. 5 ll. 46-50, and the experts agreed that optical microscopy is another equally viable method. Additionally, the 

experts agreed that different measurement techniques 

could indeed produce different results. The variation 

arises from the difficulty in measuring the average diameter of particles that are not perfect spheres. By necessity, both techniques involve indirect measurements; laser 

diffraction involves analyzing the diffraction patterns of a 

laser beam passed through a field of particles, while 

optical microscopy involves equating a pixelated image 

with an equivalent spherical diameter. See J.A. 3733-34, 

3736-37. Because the two methods use different means of 

approximating average particle diameter, they can produce different results even for the same sample. 

However, we do not believe that the mere possibility 

of different results from different measurement tech2 Zydus actually argued that this fact rendered the 

claim invalid for lack of enablement. However, in support 

of its argument Zydus cited the legal standard for indefiniteness and relied on cases applying that same standard. 

We have therefore construed Zydus’s argument to be one 

of indefiniteness, rather than enablement. 

 
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niques renders claim 1 indefinite. Rather, the evidence 

established that both methods of measurement accurately 

report average particle diameter; the experts agreed that 

“the correct but differing particle size results obtained 

using various instruments are all equally correct, but 

each simply may be expressing its correct results in 

different terms.” J.A. 3983 (testimony of Zydus’s expert 

Dr. Harry Brittain); see also J.A. 4148-49 (testimony of 

Takeda’s expert Dr. Stephen Byrn). 

Moreover, there is no evidence that the differences between these techniques are in fact significant; there was

evidence before the trial court that although the results 

may be different, there is a “high degree of correlation for 

the results” between the two techniques, which should 

“give equivalent numbers with respect to any variants 

associated with either technique.” See J.A. 3738, 3792. 

And indeed, there was no evidence in this case that different measurement techniques in fact produced significantly different results for the same sample. To the contrary, 

the measurements of Zydus’s ANDA product using laser 

diffraction and optical microscopy, though not exactly the 

same, were substantially similar. Compare J.A. 8338 

with J.A. 2115. Any theoretical minor differences between the two techniques are therefore insufficient to 

render the patent invalid. See PPG Indus., Inc. v. Guardian Indus. Corp., 75 F.3d 1558, 1563 (Fed. Cir. 1996) 

(finding no indefiniteness despite failure to specify which 

method should be used to measure ultraviolet transmittance because all conventional methods produced “essentially identical results”).3

3 Indeed, the evidence showed that four samples of 

Zydus’s ANDA product, each measured using optical 

microscopy, produced average particle diameters of 457.1

μm, 446.5 μm, 443.4 μm, and 444.0 μm. Appellants’ Br. 

31; J.A. 8338. Plainly, then, there is the potential for 

 
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Amgen Inc. v. Hoechst Marion Roussel, Inc., 314 F.3d 

1313 (Fed. Cir. 2003), on which Zydus relies, does not 

compel a contrary result. Amgen involved patents relating to the production of erythropoietin, a naturally occurring hormone that controls the formation of red blood cells 

in bone marrow. One of the disputed claims related to an 

erythropoietin glycoprotein product “having glycosylation 

which differs from that of human urinary erythropoietin,” 

or uEPO. Id. at 1340. However, the district court had 

found that “two uEPO preparations produced from the 

same batch of starting materials could nevertheless have 

different glycosylation patterns.” Id. at 1341. Thus, the 

claim itself was a moving target; as we explained, “one 

must know what the glycosylation of uEPO is with certainty before one can determine whether the claimed 

glycoprotein has a glycosylation different from that of 

uEPO.” Id. (emphasis added). We therefore affirmed the 

district court’s finding that the claims requiring “glycosylation which differs” were invalid for indefiniteness. Id. at 

1342. That is a far cry from this case. Here, the claim 

term itself could not be more straightforward; as we ruled

above, the claim plainly requires an average particle 

diameter of 400 μm or less. That there is more than one 

way of determining the average particle diameter of a 

particular sample does not render that clear claim language indefinite.4 

inconsistent results even within the same method of 

measurement, but that surely does not render a claim 

indefinite.

4 Honeywell International, Inc. v. International

Trade Commission, 341 F.3d 1332 (Fed. Cir. 2003), is no 

more persuasive. There, the patent-in-suit related to the 

production of a polyester yarn product. Because the 

specification did not discuss which sample preparation 

method should be used, and the particular method chosen 

 
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Therefore, we conclude that Zydus has not met its 

burden of establishing by clear and convincing evidence 

that claim 1 of the ’994 patent is invalid for indefiniteness.

B. Written Description

The test for written description is “whether the disclosure of the application . . . reasonably conveys to those 

skilled in the art that the inventor had possession of the 

claimed subject matter as of the filing date.” Ariad 

Pharms., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1351 (Fed. 

Cir. 2010) (en banc). The question of whether a patent 

specification contains sufficient written description is a 

question of fact that we review for clear error. Pozen Inc. 

v. Par Pharm., Inc., 696 F.3d 1151, 1166 (Fed. Cir. 2012).

Zydus argues that claim 1 addresses average particle 

size in the finished tablet, while the specification only 

teaches how to measure particle size pre-tableting with no 

discussion of how to ensure particle size is not altered by 

that process. Thus, Zydus argues that the specification 

does not demonstrate that the inventors were in possession of the claimed invention—tablets with particles of 

400 μm or less post-tableting. 

However, Zydus’s argument depends on there actually 

being an impact on particle size from the tableting process, and the evidence showed the opposite. Indeed, 

actual testing conducted by Takeda’s expert showed no 

was “critical to discerning whether [an infringing yarn] 

has been produced by the claimed process,” we affirmed 

the Commission’s conclusion that the claims were indefinite. Id. at 1340. Here, by contrast, no extensive manipulation of the samples is required prior to measurement, 

and, as discussed above, Zydus did not present clear and 

convincing evidence that the method of measurement is in 

fact outcome-determinative in the infringement analysis. 

 
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effect from compression forces on the granules in Zydus’s 

ANDA product. J.A. 3756-57, 3872-73. This case is 

therefore distinguishable from Eli Lilly & Co. v. Teva 

Pharmaceuticals USA, Inc., 619 F.3d 1329 (Fed. Cir. 

2010), on which Zydus relies. There, we upheld a finding 

of invalidity where the invention related to particle size of 

a formulated drug but the specification only disclosed how 

to measure particle size pre-formulation. Id. at 1345. 

However, the evidence in that case demonstrated that the 

particle size of Teva’s product fell outside the claimed 

range before formulation and within it after formulation. 

Id. at 1344. Thus, without disclosing how to measure 

particle size post-formulation, the inventors had not 

demonstrated that they had in fact invented a formulated 

drug with sufficiently small particles. By contrast, here, 

the evidence established only a hypothetical possibility 

that tableting could affect particle size in a relevant way.5 

We simply cannot say that the district court committed 

clear error by finding that such evidence was not clear 

and convincing proof of invalidity.6

5 Additionally, in Eli Lilly we were affirming the 

district court’s finding of invalidity, whereas here a ruling 

in Zydus’s favor would require us to conclude that the 

district court had committed clear error, a much higher 

standard. 6 Takeda also points out that the district court 

found that a skilled artisan would have known how to 

extract granules from a finished tablet to measure their 

size. However, that fact is only relevant to the enablement inquiry, which Zydus has not challenged on this 

basis. 

 
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C. Enablement

Under the enablement requirement of 35 U.S.C. 

§ 112, “the specification must enable one of ordinary skill 

in the art to practice the claimed invention without undue 

experimentation.” Transocean Offshore Deepwater Drilling, Inc. v. Maersk Drilling USA, Inc., 699 F.3d 1340, 

1355 (Fed. Cir. 2012) (quoting Nat’l Recovery Techs., Inc. 

v. Magnetic Separation Sys., Inc., 166 F.3d 1190, 1196 

(Fed. Cir. 1999)). Enablement is a question of law that we 

review de novo based on underlying factual findings. 

CFMT, Inc. v. Yieldup Int’l Corp., 349 F.3d 1333, 1337 

(Fed. Cir. 2003).

Zydus argues that the patent is invalid for lack of enablement because a skilled artisan would not be able to 

determine the average particle diameter using the coulter 

counter method of measurement without undue experimentation. The district court concluded that Zydus had 

not met its burden of establishing lack of enablement by 

clear and convincing evidence because it had submitted 

only “conclusory statements” regarding the amount of 

experimentation necessary, and because there was no 

dispute that a skilled artisan would know how to measure 

particle size using laser diffraction and/or optical microscopy. See Opinion at 29-30. 

We agree with the district court. It is well established 

that the “enablement requirement is met if the description enables any mode of making and using the invention.” Johns Hopkins Univ. v. CellPro, Inc., 152 F.3d 

1342, 1361 (Fed. Cir. 1998) (emphasis added) (internal 

quotation marks omitted). Thus, because the patent 

identifies laser diffraction as a viable measurement 

technique, and there is no dispute that a skilled artisan 

would know how to use laser diffraction to measure 

particle diameter, Zydus has not established that the 

patent is invalid for lack of enablement on this basis. 
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However, we note for the record that if the district 

court had been correct that the patent requires deagglomeration prior to particle size measurement, we would be 

forced to reach a different conclusion regarding enablement. Specifically, nothing in the written description 

directs a skilled artisan to evaluate whether a sample

contains “more than nominal” hard agglomerates prior to 

measurement, such that optical microscopy should be 

used, nor does it explain how one would make that determination. Similarly, it does not explain how to conduct 

virtual dissection of deagglomerates using optical microscopy. Thus, if the patent required deagglomeration prior 

to measurement in certain circumstances, as the district 

court found that it did, it could not be said that the written description informed a skilled artisan how to make 

and use the claimed invention. However, for the reasons 

that follow, we believe that the district court clearly erred 

in making that finding and will not invalidate the patent 

on that basis. 

Takeda argues that the skilled artisan would simply 

have known to use optical microscopy (and deagglomeration) when a sample contains more than “nominal” hard 

agglomerates. But the virtual dissection of agglomerates 

runs counter to the lone methodology disclosed in the 

specification. The only method of measurement discussed 

in the specification is laser diffraction, which cannot

account for hard agglomerates. Indeed, there is no indication in the specification that the inventors themselves 

undertook deagglomeration of their own samples prior to 

measurement, or even evaluated whether deagglomeration was necessary. We cannot conclude that the patent 

affirmatively requires a step that was entirely absent 

from (and even precluded by) the procedure described in 

the specification. 

And indeed, this conclusion is entirely consistent with 

the underlying objective of the patent; it is the actual size 

of the granule itself—regardless of how many cores it is 
 TAKEDA PHARMACEUTICAL CO. v. ZYDUS PHARMACEUTICALS 

USA

18

comprised of—that determines whether or not the granules have a rough feeling in the mouth. If large hard 

agglomerates are “virtually” dissected (a telling phrase) 

for measurement purposes, a sample could be measured 

as having an average particle diameter of 400 μm or less 

despite the fact that the actual size of the granules would 

create significant roughness in the mouth. 

In light of our conclusion that the ’994 patent does not 

require deagglomeration prior to particle size measurement, we conclude that it is not invalid for lack of enablement based on a failure to explain when and how to do 

so. 

CONCLUSION

For the foregoing reasons, we reverse the district 

court’s claim construction ruling and resulting finding of 

literal infringement, affirm the court’s judgment of no

invalidity, and remand for further proceedings consistent 

with this opinion. 

REVERSED-IN-PART, AFFIRMED-IN-PART, AND 

REMANDED