United States Court of Appeals 

for the Federal Circuit ______________________ 

BAYER CROPSCIENCE AG,

Plaintiff-Appellant,

v.

DOW AGROSCIENCES LLC,

Defendant-Appellee.

______________________ 

2013-1002

______________________ 

Appeal from the United States District Court for the 

District of Delaware in No. 10-CV-1045, Judge Renee 

Marie Bumb.

______________________ 

Decided: September 3, 2013

______________________ 

ROBERT J. KOCH, Milbank, Tweed, Hadley & McCloy,

LLP, of Washington, DC, argued for plaintiff-appellant. 

With him on the brief were FREDRICK M. ZULLOW and 

CHRISTOPHER J. GASPAR, of New York, New York. 

 

MARK S. DAVIS, Orrick, Herrington & Sutcliffe, LLP, 

of Washington, DC, argued for defendant-appellee. With 

him on the brief were RACHEL M. MCKENZIE; ELIZABETH 

A. HOWARD, of Menlo Park, California; PETER A. BICKS

and ALEX V. CHACHKES, of New York, New York. 

______________________ 

Before PROST, BRYSON, and TARANTO, Circuit Judges.
2 BAYER CROPSCIENCE AG v. DOW AGROSCIENCES LLC

TARANTO, Circuit Judge. 

When the inventors applied for the patent at issue, 

they had sequenced one gene coding for one enzyme, using 

a test purportedly capable of finding other, similar genes. 

In writing its claims, the owner—now Bayer CropScience 

AG—decided to claim a broad category based on the 

function of the particular enzyme, defining the category 

by using a term with an established scientific meaning. 

In doing so, Bayer got ahead of the science: experiments 

had not confirmed that the term even applied to the 

particular enzyme whose gene Bayer’s inventors had 

sequenced. Soon science showed that it did not, and 

Bayer knew as much years before its patent issued—but 

did not change its claim language. When it ultimately 

sued Dow AgroSciences for infringement, Bayer recognized that the term used, in its established scientific 

meaning, did not cover the accused product (itself different from the particular enzyme whose gene Bayer’s inventors had sequenced), so it argued for a broad functional 

claim construction. 

Applying our decisions about the potentially unwelcome consequences of a patentee’s chosen claim language, 

the district court rejected Bayer’s argument, explaining 

particularly the great breadth of the asserted functional 

construction, and entered summary judgment of noninfringement. We too are unpersuaded by Bayer’s proposed claim construction. Because Bayer has presented 

no argument for reversing the non-infringement judgment 

independent of our adopting that construction, we affirm. 

BACKGROUND

A 

The patent at issue concerns genetically modifying 

plants in order to confer resistance to a commonly used 

herbicide called 2,4-dichlorophenoxyacetic acid, or “2,4-D” 

for short. The process works by inserting a particular 

DNA segment—a segment containing the sequence of 

nucleotides identified as the gene coding for a particular 
BAYER CROPSCIENCE AG v. DOW AGROSCIENCES LLC 3

enzyme—into plant cells, which then reproduce to create 

new cells that contain that gene. The plant cells produce 

the enzyme that then catalyzes a biochemical reaction 

with the 2,4-D herbicide in which the herbicide is broken 

down into something harmless to the plant. A plant with 

the gene can thereby survive application of the herbicide 

while surrounding weeds do not.

Bayer owns U.S. Patent No. 6,153,401, entitled “Microorganisms and Plasmids for 2,4-Dichlorophenoxyacetic 

Acid (2,4-D) Monooxygenase Formation and Process for 

the Production of These Plasmids and Strains.” The 

application that eventually led to this patent was filed in 

the late 1980s. By that time, scientists had discovered 

that certain bacteria found in soil could grow on 2,4-D. To 

do so, those bacteria first convert 2,4-D into a substance 

called 2,4-dichlorophenol, or “2,4-DCP,” which the bacteria, far from finding toxic, use as a “source[] of carbon and 

energy.” ’401 patent, col. 3, lines 22-24; see id., col. 30, 

lines 34-36. Scientists hoped that, if they identified genes 

in such bacteria that coded for enzymes that catalyze 2,4-

D-to-2,4-DCP reactions, they could then transfer the 

“ability to inactivate 2,4-D” to plants. Id., col. 2, lines 27-

30. 

The inventors of the ’401 patent were the first “to isolate, to clone, and to characterize” a gene that had that 

property, a gene from the soil bacterium strain Alcaligenes eutrophus JMP134. Id., col. 1, lines 41-61. The 

patent sets forth the nucleotide sequence in Figure 10. It 

is the only gene identified in the ’401 patent. 

The specification explains the “growth test” used to 

isolate the identified gene. First, the inventors created a 

mutant strain of the bacterium that lacked the ability to 

grow on 2,4-D or convert it into 2,4-DCP. Id., col. 22, line 

56, through col. 25, line 42. Next, they fragmented the 

DNA of a non-mutant strain, which could still break down 

2,4-D. Id., col. 24, line 18, through col. 25, line 42. They 

then inserted the fragments into cells of the mutant 

strain, with (roughly speaking) no two fragments in the 
4 BAYER CROPSCIENCE AG v. DOW AGROSCIENCES LLC

same cell, and placed the cells on 2,4-D. When they 

identified cells that grew, they concluded that the DNA 

fragment that had restored the ability to grow on 2,4-D 

contained a gene producing an enzyme that caused the 

conversion of 2,4-D into 2,4-DCP. Id., col. 25, lines 38-42. 

They used known sequencing techniques to identify the 

nucleotide sequence of the successful fragment. Id., col. 

27, line 37, through col. 29, line 4.1

Although this work led the inventors to the Figure 10 

gene sequence, they did not fully understand the enzymatic reaction that they were studying. In particular, the 

reaction requires the presence of the oxygen molecule, O2, 

but the inventors did not know where one of the two 

oxygen atoms wound up. There was no doubt about the 

first: it combines with 2,4-D to create an unstable, hydroxylated 2,4-D, which then spontaneously splits apart 

into 2,4-DCP and a compound called glyoxylate. The 

patent describes this process as “bringing about the 

cleavage of the side chain of 2,4-D.” Id., col. 2, lines 25-27. 

As for the second oxygen atom, however, the inventors at 

1 Because the conversion of 2,4-D into 2,4-DCP was 

the first step (step A) of a known multi-step process for 

breaking down 2,4-D, an enzyme that catalyzes that firststep reaction has been called a TfdA enzyme—“Tfd” 

representing the initials of “two,” “four,” and “Dichlorophenoxyacetic Acid,” and “A” referring to step A. Similarly, a gene that encodes for such an enzyme has been 

called a “tfdA” gene (no initial capital, sometimes but not 

always in italics). Bayer has recognized that both terms 

cover categories of differing structures. See Opening Br. 

at 19 (“‘TfdAs’” (plural) are “enzymes” (plural) catalyzing 

the step A reaction); id. at 3 n.2 (“a ‘tfdA’ gene encodes a 

‘TfdA’ side-chain-cleaving enzyme”). Sometimes, however, 

the patent and other publications appear to have used the 

terms to refer to the particular Figure 10 gene and its 

particular enzyme product. 

 
BAYER CROPSCIENCE AG v. DOW AGROSCIENCES LLC 5

best simply shared the scientific community’s unverified 

belief that this atom was incorporated into water. As was 

established beyond dispute in the district court in this 

case, enzymes catalyzing a reaction in which one oxygen 

atom ends up in water and the second is incorporated into 

a product other than water are called monooxygenases, 

and the ’401 patent uses the term “monooxygenase” 

throughout the specification to characterize the enzyme 

whose gene it sequenced. And Bayer used the term 

“monooxygenase” in its claims—both alone and as part of 

“2,4-D-monooxygenase”—in the 1989 continuation-in-part 

application that eventually issued as the ’401 patent. 

U.S. Patent Application No. 07/322,604, pp. 66-70 (filed 

Mar. 10, 1989).

Bayer’s reliance on an unverified belief about its enzyme soon proved wrong. In 1993, when Bayer’s application was still pending, scientists determined that it was 

incorrect to refer to Bayer’s enzyme as a monooxygenase 

because the second oxygen atom does not actually end up 

in water. It was, instead, a dioxygenase, because both 

oxygen atoms are incorporated into products other than 

water. See Fumiyasu Fukumori & Robert P. Hausinger, 

Alcaligenes eutrophus JMP134 “2,4-

Dichlorophenoxyacetate Monooxygenase” Is an αKetoglutarate-Dependent Dioxygenase, 175 J. Bacteriology 

2083 (1993). Yet, despite the announcement of this 

discovery in the very title of the article, and Bayer’s 

knowledge of the article, Bayer did not alter the claims of 

its application—which did not mature into a patent until 

seven years after the 1993 discovery. Accordingly, the 

’401 patent issued in 2000 with independent claim 1 

reciting an artificially constructed gene as follows: 

A recombinant gene, comprising 

a DNA sequence encoding a polypeptide having 

the biological activity of 2,4-D monooxygenase 

which is capable of being expressed in a plant, 

operably linked to 
6 BAYER CROPSCIENCE AG v. DOW AGROSCIENCES LLC

a heterologous promoter capable of promoting the 

expression in a plant of a structural gene operably linked thereto.

’401 patent, col. 32, lines 12-19. Dependent claim 4 

claims the recombinant gene of claim 1 “wherein the DNA 

sequence is the structural gene sequence of FIG. 10, 

except that the initiation codon is ATG,” or certain specified variants. Id., col. 32, lines 27-34. 

B 

Dow AgroSciences produces a line of genetically modified seeds that are resistant to 2,4-D as well as other 

herbicides. Dow’s products use two genes—called aad-1

and aad-12—that code for two AAD (AryloxyAlkanoate 

Dioxygenase) enzymes. Like the enzyme of Bayer’s 

patent specification, those AAD enzymes are dioxygenases 

that catalyze a reaction in which 2,4-D converts to 2,4-

DCP. 

In December 2010, Bayer brought suit accusing Dow’s 

seeds of infringing the ’401 patent. Although Dow’s 

products do not use the Figure 10 gene, Bayer argued that 

they fall within the broader claim 1, which encompasses 

enzymes that “hav[e] the biological activity of 2,4-D 

monooxygenase.” Bayer’s position from the outset has 

been that the quoted phrase covers any enzyme that 

triggers cleaving of the side chain of 2,4-D to produce 2,4-

DCP, even if it is a dioxygenase and even if it does not 

share other biological activities of the particular enzyme 

whose gene Bayer sequenced. Because Dow’s seeds 

contain genes coding for enzymes that allegedly cause the 

cleaving of 2,4-D’s side chain, Bayer contended that they 

infringe. 

After holding a Markman hearing with witness testimony and receiving cross-motions for summary judgment, 

the district court entered judgment in Dow’s favor. See

Bayer CropScience AG v. Dow AgroSciences LLC, Civ. No. 

10-1045 RMB/JS, 2012 WL 4498527 (D. Del. Sept. 27, 

2012). Limiting its analysis to the “biological activity of 
BAYER CROPSCIENCE AG v. DOW AGROSCIENCES LLC 7

2,4-D monooxygenase” phrase, the court rejected Bayer’s 

view of its claims. Instead, the court concluded that the 

“plain and ordinary meaning” requires that “2,4-D 

monooxygenase” be read to embody the established scientific meaning of “monooxygenase,” which involves one 

oxygen atom going to water, and that the whole phrase 

therefore means “the enzymatic activity of an enzyme, in 

a biological system, that causes a reaction with 2,4-D, and 

two molecules of oxygen, where one molecule of oxygen is 

added to 2,4-D and the other ultimately forms water.” Id.

at *4; see id. at *3-8. Under that construction, there was 

no dispute that Dow’s products do not infringe because 

they are dioxygenases, even though they “create 2,4-D 

resistant plants” through an enzymatic activity that 

produces cleaving of the side chain of 2,4-D to yield 2,4-

DCP. Id. at *2. 

Having rejected Bayer’s “broad functional-based” construction, id. at *8, the court went on to explain that, if it

had concluded otherwise, it still would have granted 

summary judgment for Dow, just for a different reason. 

Id. at *8-10. Specifically, the court ruled that the claim so 

construed would “fail[] to satisfy the written description 

requirement of 35 U.S.C. § 112” because disclosing one 

gene and the test used to find it was not enough to capture the large genus that Bayer purported to have 

claimed. Id. Bayer appeals. We have jurisdiction under 

28 U.S.C. § 1295(a)(1).

DISCUSSION

This case turns on claim construction, a matter that 

we review de novo. Specifically, it turns on whether 

Bayer’s proposed construction of the term “the biological 

activity of 2,4-D monooxygenase” in the only independent 

claim (claim 1) is correct. Bayer rests its appeal entirely 

on the contention that the district court erred in failing to 

construe the term broadly to mean “bringing about the 

cleavage of the side chain of 2,4-D,” without further 

qualification. Like the district court, we see two problems 

with this position: (A) familiar aspects of textual analysis 
8 BAYER CROPSCIENCE AG v. DOW AGROSCIENCES LLC

point strongly the other way; and (B) it would read independent claim 1 so broadly as to raise serious doubts 

about validity. Together, those problems lead us to conclude that Bayer’s proposed claim construction is wrong, 

which leaves us with no basis for disturbing the district 

court’s judgment of non-infringement of claim 1 (and 

hence all dependent claims).

A 

To get to its construction of “the biological activity of 

2,4-D monooxygenase” as “bringing about the cleavage of 

the side chain of 2,4-D,” Bayer takes two steps. First, it 

treats the phrase “2,4-D monooxygenase” as not carrying 

the ordinary meaning of sending one of the two oxygen 

atoms to water—treating it instead either as if it said 

merely “oxygenase” or as if it were a proper name of a 

particular enzyme (or class) without any descriptive 

meaning. Second, Bayer broadens the claim coverage by 

defining the term “the biological activity of” as referring 

to any enzyme that alters 2,4-D by cleaving its side

chain—neither encompassing other biological activities 

nor limited to those cleaving reactions that make the 

enzyme a monooxygenase. Both steps encounter serious 

textual difficulties.

To begin with, these efforts fight a facially straightforward textual analysis. As the district court recognized, 

all agree that the word “monooxygenase” has long had a 

clear meaning—i.e., an enzyme catalyzing a reaction in 

which one oxygen atom is incorporated into water and the 

second is incorporated into something other than water. 

See Bayer, 2012 WL 4498527, at *3-4. Putting “2,4-D” in 

front of “monooxygenase,” then, appears to be simply the 

standard way of conveying what the monooxygenase acts 

on, namely, 2,4-D. And “the biological activity of,” in 

turn, is naturally understood to refer to the activity that 

makes the identified enzyme a monooxygenase that acts 

on 2,4-D: the attachment of one oxygen atom to the 2,4-D 

molecule to trigger cleaving with the other atom of O2

going to water. Under this reading, the full phrase works 
BAYER CROPSCIENCE AG v. DOW AGROSCIENCES LLC 9

as an integrated unit in a way that fits its structure and 

the ordinary meaning of its words.

Arguing against this textual analysis, Bayer proposes 

a construction that first requires stripping the phrase 

“2,4-D monooxygenase” of the scientifically accepted 

descriptive content of the term “monooxygenase.” Adopting Bayer’s position, we think, would require that the ’401 

patent, or its history, make reasonably clear that Bayer 

was not using the term in its established descriptive 

sense. See, e.g., Abbott Labs. v. Syntron Bioresearch, Inc., 

334 F.3d 1343, 1355 (Fed. Cir. 2003). Familiar claimconstruction policies regarding public notice and patentee 

drafting duties make it appropriate to demand such 

clarity here: Bayer chose the language based on an unverified belief that it accurately described its enzyme, 

learned that the belief was false while its application was 

pending, had seven years before its patent issued to alter 

the language, but never did. 

The patent and its history, however, do not clearly indicate that the patent uses the language at issue without 

its accepted scientific descriptive meaning. On the contrary, Bayer’s usage in the intrinsic record is at the very 

best inconsistent. Much of it actually reinforces the 

straightforward descriptive meaning of the claim terms. 

Nothing in the intrinsic record affirmatively indicates 

that, if the phrase “2,4-D monooxygenase” is descriptive, 

the “mono” part is to be ignored. Perhaps Bayer should 

have recognized that its background assumption that 

“mono” was accurate was unverified, and initially used a 

different phrase. But given its reliance on that assumption, one would hardly expect the 1989 written description 

to contain a redefinition to override the “mono” meaning.

As for any understanding of the claim phrase as a 

proper name whose “monooxygenase” portion lacks any 

descriptive significance, the intrinsic record provides 

Bayer nothing like clear support. The patent uses the 

phrase or its variants in different ways, sometimes with 
10 BAYER CROPSCIENCE AG v. DOW AGROSCIENCES LLC

an indefinite article implying a descriptive class-defining 

use, sometimes with other indicators that it is describing 

a genus (naturally defined by the ordinary meaning), and 

only sometimes as what might seem to be just a proper 

name (but even then without excluding an implication 

that the name conveys the underlying mechanism of 

action). E.g., ’401 patent, col. 1, lines 21-23 (“2,4-DMonooxygenase is an enzyme catalyzing in many 2,4-Ddegrading organisms the first step in the metabolizing of 

[2,4-D].”); id., col. 2, lines 66-67 (referring to the enzyme’s 

“2,4-D-monooxygenase activity”); id., col. 1, line 63 (referring to “the tfdA-encoded 2,4-D-monooxygenase,” the 

adjective suggesting a narrowing of the broader class 

identified by the noun).2 The prosecution history is 

similar. Notably, claims filed in the 1989 application 

claimed “a 2,4-D monooxygenase gene . . . encoding a 

polypeptide having the biological activity of such a 

monooxygenase,” U.S. Patent Application No. 07/322,604, 

pp. 66-67 (filed Mar. 10, 1989) (emphasis added)—

language that reinforces rather than undermines the 

ordinary descriptive meaning.

The conclusion we draw is that there is no clear message that the patent gives Bayer’s broad meaning to “2,4-

D monooxygenase” in place of the term’s accepted scientific meaning, which describes a particular mechanism of 

action. Bayer’s usage in this court reinforces the conclusion. Much of Bayer’s language continues to suggest a 

2 See also, e.g., ’401 patent, col. 25, lines 13-14 (“a 

functional 2,4-D-monooxygenase”); id., col. 2, line 25 

(“[t]he tfdA gene codes for 2,4-D [monooxygenase]”); id., 

col. 3, lines 5-6 (“the 2,4-D monooxygenase gene”); id., col. 

7, lines 15-16 (“the tfdA-coded 2,4-D-monooxygenase”); 

id., col. 8, lines 7-8 (“the 2,4-D-monooxygenase activity”); 

id., col. 25, lines 53-56 (“[p]lasmids . . . containing an 

intact tfda gene . . . can produce 2,4-D-monooxygenase in 

large amounts”).

 
BAYER CROPSCIENCE AG v. DOW AGROSCIENCES LLC 11

class-defining descriptive meaning. See note 1, supra; 

Opening Br. at 14 (claim 4 “recites the DNA sequence of 

one exemplary 2,4-D monooxygenase”); Reply Br. at 4 

(“specification also unambiguously refers to a genus of 

genes encoding a genus of ‘2,4-D monooxygenases’”); 

Opening Br. at 15 (“One claim phrase is at issue here: 

‘biological activity of a 2,4-D monooxygenase.’”). 

Bayer’s argument regarding the “biological activity” 

language of claim 1 is likewise unpersuasive. As the 

district court recognized, the ordinary meaning of that 

phrase alone places no particular limit on what kinds of 

activities in living cells are covered. See Bayer, 2012 WL 

4498527, at *3-4. As indicated above, a natural narrowing is provided by giving “monooxygenase” its “mono” 

meaning: the “biological activity” would be that activity 

which makes the enzyme a monooxygenase. But Bayer 

rejects both the all-biological-activities meaning and the 

premise of the narrowing integrated interpretation. 

Instead, it argues that the specification “defines” the 

“biological activity” claimed to be “bringing about the 

cleavage of the side chain of 2,4-D,” no more and no less. 

We disagree. 

The specification uses the phrase “biological activity” 

just twice. Bayer focuses heavily on the first appearance, 

which says: “The tfdA gene codes for 2,4-D monooxygenase, a polypeptide having the biological activity of bringing about the cleavage of the side chain of 2,4-D.” ’401 

patent, col. 2, lines 25-27 (as corrected by certificate of 

correction). That language does not have the form of, or 

otherwise convey that it is, a definition of “the biological 

activity.” It describes something that a “2,4-D monooxygenase” does, but it does not say that every enzyme with 

that function is a “2,4-D monooxygenase.” See Bayer, 

2012 WL 4498527, at *5. More is needed for a term with 

an established scientific meaning to be redefined in the 

specification.

The specification’s second reference to “biological activity” actually works against Bayer’s argument. In the 
12 BAYER CROPSCIENCE AG v. DOW AGROSCIENCES LLC

same column, the patent refers to “coding for a protein 

which has the biological activity of the protein encoded by 

tfda, e.g., its 2,4-D-monooxygenase activity.” ’401 patent, 

col. 2, lines 65-67. The use of “e.g.,” rather than “i.e.,” 

strongly suggests that there is more than one “biological 

activity.” And “its 2,4-D monooxygenase activity” suggests the activity that makes it a monooxygenase. 

In short, as the district court explained, the claim 

language has a strong accepted scientific meaning. 

Bayer’s alternative construction strips the monooxygenase half of the claim phrase of its accepted descriptive 

meaning and then asserts a specification “definition” of 

the biological-activity half. We do not find enough in the 

specification or prosecution history to justify those steps.

B 

Bayer’s construction has not only textual problems. It 

goes far beyond the Figure 10 enzyme, beyond monooxygenases, beyond enzymes produced by bacteria found 

mainly in soil, to capture the broad functionally defined 

genus of enzymes that cause cleaving of the 2,4-D side 

chain. This broad reading would call into serious doubt 

the claim’s validity under 35 U.S.C. § 112(a). See Bayer, 

2012 WL 4498527, at *8-10. 

In this case, which is not one in which a patentee invokes invalidity considerations to support a narrowing 

construction, Bayer seeks a broad construction of its own 

patent, and the alleged infringer Dow has raised invalidity problems with that construction. A record regarding 

those problems was extensively developed at the same 

time as the record for claim construction. In these circumstances, it is both possible and sensible to find that 

such grave doubts reinforce the textual objections to 

Bayer’s proposed construction. This court’s decision in 

Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005), 

while observing that “validity analysis is [not] a regular 

component of claim construction,” leaves room for reliance 

on this bolstering consideration where, as here, the record 
BAYER CROPSCIENCE AG v. DOW AGROSCIENCES LLC 13

on invalidity is sufficiently developed to establish grave 

validity doubts under the court’s standards. Id. at 1327-

28.3 

Bayer’s proposed construction broadly covers a class 

of enzymes defined by their function of causing cleaving of 

the side chain of 2,4-D, while its written description 

structurally identifies just one gene sequence and the 

enzyme it encodes. We have not articulated a comprehensive and precise formulation for identifying when such a 

combination runs afoul of Section 112(a)’s writtendescription requirement; indeed, we have counseled 

against “bright-line rules” in this area. Ariad Pharms., 

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

2010). But we have indicated the primacy of structural 

identification for inventions in certain areas like the one 

at issue here, and when we have adverted to the possibility of other means of identification, we have focused on 

whether such alternative means sufficiently correlate 

with structure. See, e.g., Novozymes A/S v. DuPont 

Nutrition Biosciences APS, No. 2012-1433, 2013 WL 

3779376, at *14 (Fed. Cir. July 22, 2013); Ariad, 598 F.3d 

at 1350; Carnegie Mellon Univ. v. Hoffman-La Roche Inc., 

541 F.3d 1115, 1121, 1124 (Fed. Cir. 2008); Univ. of 

Rochester v. G.D. Searle & Co., Inc., 358 F.3d 916, 925 

(Fed. Cir. 2004) (“functional descriptions of genetic material can, in some cases, meet the written description 

requirement if those functional characteristics are ‘coupled with a known or disclosed correlation between function and structure, or some combination of such 

characteristics’”) (quoting Enzo Biochem, Inc. v. GenProbe Inc., 323 F.3d 956, 964 (Fed. Cir. 2002)); Regents of 

3 We identify the circumstances here simply to define what we are deciding, which leaves open to argument 

in a different case whether the same conclusion, or a 

different conclusion, would be warranted in circumstances 

different from those presented here.

 
14 BAYER CROPSCIENCE AG v. DOW AGROSCIENCES LLC

Univ. of Cal. v. Eli Lilly & Co., 119 F.3d 1559, 1566, 1569

(Fed. Cir. 1997) (discussing situation where patent describes a “representative number” of species). 

The coverage of claim 1 that Bayer proposes would 

leave the ’401 patent far from providing even an indirect 

structural identification of all that would be within the 

claim’s scope. The enzymatic function—under Bayer’s 

construction, causing the cleaving of the side chain of 2,4-

D—would be broad, yet the patent provides the DNA 

sequence (and hence amino-acid sequence) of just one 

embodiment. As the district court explained, Bayer, 2012 

WL 4498527, at *9-10, neither the patent nor the 

knowledge in the art showed that what Bayer offered in 

place of a description of the shared structure—the growth 

test—correlated closely with an enzyme’s structure. The 

patent provided what was “[a]t best . . . a roadmap [that 

would] ‘leav[e] it to the . . . industry to complete [the] 

unfinished invention.’” Novozymes, 2013 WL 3779376, at 

*14. Moreover, the “roadmap” told a person of ordinary 

skill how to find some, perhaps even many, but not all 

members of the genus claimed under Bayer’s broad construction, because enzymes not found in soil bacteria may 

catalyze 2,4-D-degrading reactions but could not be discovered (reliably or perhaps at all) using the growth test. 

At oral argument in this court, Bayer has sought to 

mitigate this concern by expressly arguing that any genes 

not derived from soil bacteria would fall outside of the 

claimed genus. But Bayer did not present a claim construction based on that trimming effort to the district 

court, or even in its opening brief in this court. Rather 

than undertake to show how a “soil” limitation could be 

justified, Bayer argued for its broad construction, which 

contains no such limitation. Bayer, 2012 WL 4498527, at 

*3; Opening Br. at 6. Only Bayer’s proposed construction, 

not a belated narrowing construction, is at issue. And the 

significant invalidity troubles that accompany Bayer’s 

construction substantiate our rejection of it.
BAYER CROPSCIENCE AG v. DOW AGROSCIENCES LLC 15

C 

Neither party has presented us with a reason to go 

beyond rejecting Bayer’s proposed claim construction. 

Our rejection of Bayer’s construction settles the question 

of non-infringement and thus provides us with sufficient 

grounds for affirming summary judgment in Dow’s favor. 

In other cases, this court has limited its claimconstruction analysis to go no further than was required 

to affirm or otherwise rule on the judgment appealed. 

See, e.g., Verizon Servs. Corp. v. Vonage Holdings Corp., 

503 F.3d 1295, 1305 (Fed. Cir. 2007); Rheox, Inc. v. Entact, Inc., 276 F.3d 1319, 1324-25 (Fed. Cir. 2002); see also 

Leo Pharm. Prods., Ltd. v. Rea, No. 2012-1520, 2013 WL 

4054937, at *5 (Fed. Cir. Aug. 12, 2013). We take the 

same approach here. Bayer has not timely argued that it 

can prevail without the adoption of its broad construction, 

and we need not affirmatively construe the claims in 

order to affirm the district court’s judgment. 

Dow has offered two alternative constructions. Dow 

primarily defends the district court’s construction, which 

reads claim 1 on its own terms and limits it to genes 

coding for “monooxygenases.” See Bayer, 2012 WL 

4498527, at *3-8. Dow also suggests a second, much 

narrower construction that would limit the claims by 

reference to the specific Figure 10 gene sequence. 

The first of those alternatives is strongly supported by 

the most natural reading of the claim language, as we 

have explained. On the other hand, it excludes the specific gene based on Figure 10 that was Bayer’s core invention. While that result is generally disfavored, there is no 

absolute rule against it, Lucent Technologies, Inc. v. 

Gateway, Inc., 525 F.3d 1200, 1215-16 (Fed. Cir. 2008), 

and skilled artisans would readily understand the explanation here, namely, Bayer’s initial mistaken belief about 

its enzyme’s properties and then its insistence on retaining claim language reflecting that belief even after it was 

known to be false. The second of Dow’s interpretations 

offers the advantage of protecting Bayer’s specific se-
16 BAYER CROPSCIENCE AG v. DOW AGROSCIENCES LLC

quencing invention. But the claim most tailored to that

important advance, claim 4, is not a free-standing one; it 

is written as a dependent claim, thus requiring satisfaction of claim 1, whose language therefore must be properly construed. Moreover, it is hardly unknown for a 

patentee with an invention that could be protected to fail 

in securing such protection by bad choices in claim drafting. See, e.g., Chef Am., Inc. v. Lamb-Weston, Inc., 358 

F.3d 1371, 1374 (Fed. Cir. 2004); Elekta Instrument S.A. 

v. O.U.R. Scientific Int’l, Inc., 214 F.3d 1302, 1308-09 

(Fed. Cir. 2000). 

We do not have to address the issues raised by the alternatives proffered by Dow. Nor do we have before us 

any other construction that Bayer might propose in 

another case. We need not say whether some narrower 

construction, if timely offered and defended by Bayer,

would have enough to recommend it to overcome the 

difficulties we have found decisive against its broad 

construction. All we need and do say is that, because we 

do not accept the only claim construction under which 

Bayer has alleged infringement, we affirm the summary 

judgment of non-infringement.

AFFIRMED