Exmark Manufacturing Co. v. Briggs & Stratton Power Products Group, LLC

United States Court of Appeals

for the Federal Circuit

______________________

EXMARK MANUFACTURING COMPANY INC.,

Plaintiff-Appellee

v.

BRIGGS & STRATTON POWER PRODUCTS

GROUP, LLC,

Defendant-Appellant

______________________

2016-2197

______________________

Appeal from the United States District Court for the

District of Nebraska in No. 8:10-cv-00187-JFB-TDT, Chief

Judge Joseph F. Bataillon.

______________________

Decided: January 12, 2018

______________________

J. DEREK VANDENBURGH, Carlson, Caspers, Vanden-

burgh, Lindquist & Schuman, P.A., Minneapolis, MN,

argued for plaintiff-appellee. Also represented by JOSEPH

W. WINKELS, ALEXANDER RINN.

MATTHEW WOLF, Arnold & Porter Kaye Scholer LLP,

Washington, DC, argued for defendant-appellant. Also

represented by MARC A. COHN.

______________________

2 EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS.

GRP., LLC

Before WALLACH, CHEN, and STOLL, Circuit Judges.

STOLL, Circuit Judge.

Exmark Manufacturing Company filed suit against

Briggs & Stratton Power Products Group, LLC in the

United States District Court for the District of Nebraska,

alleging infringement of, inter alia, claim 1 of U.S. Patent

No. 5,987,863. The district court entered summary judg-

ment that claim 1 was not invalid because the claim

survived multiple reexaminations involving the same

prior art. The district court also denied summary judg-

ment of indefiniteness with respect to claim 1. 1 The case

proceeded to a jury trial, where the jury found that Briggs

willfully infringed Exmark’s patent. The jury awarded

$24,280,330 in compensatory damages, which the district

court doubled as enhanced damages for Briggs’ willful

infringement.

Briggs appeals several of the district court’s orders,

including the district court’s: (1) summary judgment that

claim 1 is not anticipated or obvious, (2) denial of sum-

mary judgment that claim 1 is indefinite, (3) denial of a

new trial on damages, (4) evidentiary rulings related to

damages, (5) denial of a new trial on willfulness, and

(6) denial of Briggs’ laches defense.

We conclude the district court erred by basing its

summary judgment of no invalidity solely on the fact that

claim 1 survived multiple reexaminations. Accordingly,

we vacate the district court’s summary judgment of no

invalidity. We remand to the district court for it to make

an independent determination of whether genuine issues

of material fact preclude summary judgment that claim 1

1 Although the district court’s anticipation, obvi-

ousness, and indefiniteness analyses addressed all dis-

puted claims of the ’863 patent, Briggs’ appeal focuses on

claim 1.

EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS. 3

GRP., LLC

is not anticipated or obvious in view of the prior art. We

also hold that the district court erred in denying a new

trial on damages because Exmark’s damages expert failed

to provide an adequate explanation as to how she arrived

at a 5% royalty rate for the patented feature relative to

other conventional features of the accused products. We

also conclude that the district court abused its discretion

by limiting the evidence relevant to damages to prior art

that had been commercialized. Likewise, we conclude

that the district court abused its discretion by excluding

from the willfulness trial evidence relating to patent

validity based on its determination that Briggs’ invalidity

defenses were objectively unreasonable. The district

court’s evidentiary ruling does not comport with the

Supreme Court’s recent decision in Halo Electronics, Inc.

v. Pulse Electronics, Inc., 136 S. Ct. 1923 (2016), mandat-

ing that willfulness is to be determined by the jury re-

gardless of whether Briggs’ defenses were objectively

reasonable. Accordingly, we vacate the jury’s finding of

willfulness, vacate the jury’s damages award, vacate the

district court’s enhanced damages award, and remand for

proceedings consistent with this precedent. We also

affirm the district court’s denial of summary judgment

that claim 1 is indefinite, and affirm its denial of Briggs’

laches defense.

BACKGROUND

Briggs and Exmark are competitors in the high-end

commercial lawn mower industry. Exmark filed suit

against Briggs and Schiller Grounds Care, Inc., 2 alleging,

inter alia, infringement of claim 1 of the ’863 patent. The

’863 patent is directed to a lawn mower having improved

flow control baffles. A baffle is a metal structure under

the mower deck that directs air flow and grass clippings

during operation.

2 Schiller is not a party in the present appeal.

4 EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS.

GRP., LLC

Claim 1 requires a side wall discharge opening and a

“first flow control baffle” having a certain shape. Specifi-

cally, the claim recites that the first baffle comprises “a

first arcuate baffle portion,” “a first elongated and sub-

stantially straight baffle portion,” and “a second arcuate

baffle portion,” with the elongated and substantially

straight baffle portion “angularly disposed . . . in a chord-

like fashion” with respect to the second cutting blade. Id.

at col. 6 ll. 21–39. The parties refer to this as a “curved-

straight-curved” baffle.

On appeal, Briggs provides an annotated version of

Figure 4 of the ’863 patent depicting the claimed curved-

straight-curved baffle.

Appellant Br. 13.

Claim 1 recites in relevant part:

1. A multiblade lawn mower, comprising:

....

said first side wall having a discharge opening

formed therein;

....

EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS. 5

GRP., LLC

a first flow control baffle positioned in said

mower deck which extends downwardly from the

interior surface of said top wall between said cut-

ting blades and said front wall;

said first flow control baffle extending sub-

stantially continuously from a first location adja-

cent the interior surface of said second side wall to

a second location adjacent the interior surface of

said first side wall and adjacent the forward end

of said discharge opening;

said first flow control baffle comprising a first

arcuate baffle portion, having first and second

ends, which extends from the interior surface of

said second side wall partially around said first

cutting blade, a first elongated and substantially

straight baffle portion, having first and second

ends, extending from said second end of said first

arcuate baffle portion, a second arcuate baffle por-

tion, having first and second ends, which extends

from said second end of said first elongated and

substantially straight baffle portion partially

around said second cutting blade;

said first elongated and substantially straight

baffle portion being angularly disposed with re-

spect to the said circle defined by the blade tip

path of said second cutting blade in a chord-like

fashion so that the cuttings from said first cutting

blade will be deflected inwardly within the said

circle defined by the blade tip path of said second

cutting blade; . . . .

’863 patent col. 5 l. 60–col. 6 l. 50.

Claim 1 of the ’863 patent was reexamined by the

United States Patent and Trademark Office on three

occasions. Exmark requested the first reexamination,

which was completed prior to the present suit, and the

6 EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS.

GRP., LLC

PTO confirmed the patentability of claim 1. The second

and third reexaminations were requested by Defendants

Schiller and Briggs during the pendency of this case

before the district court. The district court stayed pro-

ceedings pending completion of the reexaminations. The

patentability of claim 1 over the same prior art asserted

in the district court was confirmed in both reexamina-

tions.

Following the reexaminations, the district court lifted

the stay, and Exmark moved for summary judgment that

claim 1 was not invalid as anticipated or obvious. Relying

solely on the fact that claim 1 survived multiple reexami-

nations, the district court concluded that “no reasonable

juror could find that the defendants have met their bur-

den of proving by clear and convincing evidence that the

claims of the patent are invalid.” Exmark Mfg. Co. v.

Briggs & Stratton Power Prods. Grp., LLC, No.

8:10CV187, 2015 WL 12697086, at *11 (D. Neb. July 28,

2015) (“Summary Judgment Order”).

Briggs also moved for summary judgment that the

claim limitation “elongated and substantially straight”

rendered claim 1 of the ’863 patent indefinite. The dis-

trict court denied Briggs summary judgment, concluding

that the specification informs one skilled in the art with

reasonable certainty as to the claim limitation’s meaning.

Id.

The district court granted summary judgment of in-

fringement by Briggs’ original mowers. At the same time,

however, the district court found that genuine issues of

material fact precluded summary judgment of infringe-

ment by Briggs’ redesigned mowers. Id. at *12.

The case proceeded to trial on whether Briggs’ rede-

signed mowers infringed claim 1, whether Briggs willfully

infringed, and damages. The jury found that Briggs

willfully infringed claim 1 of the ’863 patent with respect

to its originally designed mowers but found that its rede-

EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS. 7

GRP., LLC

signed mowers did not infringe claim 1. The jury awarded

$24,280,330 in damages.

Following the jury trial, the district court held a

bench trial on Briggs’ motion for a judgment of laches.

The district court denied the motion, concluding that

Briggs had not shown that it was entitled to the equitable

defense of laches. See Exmark Mfg. Co. v. Briggs &

Stratton Power Prods. Grp., LLC, 186 F. Supp. 3d 977,

988 (D. Neb. 2016). The district court also denied Briggs’

post-trial motion for a new trial on damages and willful-

ness. See Exmark Mfg. Co. v. Briggs & Stratton Power

Prods. Grp., LLC, No. 8:10CV187, 2016 WL 2772122, at

*7 (D. Neb. May 11, 2016). The district court granted

Exmark’s motion for enhanced damages based on Briggs’

willful infringement and doubled the jury’s damages

award. See Exmark Mfg. Co. v. Briggs & Stratton Power

Prods. Grp., LLC, No. 8:10CV187, 2016 WL 2772123, at

*6 (D. Neb. May 11, 2016).

Briggs appeals. We have jurisdiction pursuant to

28 U.S.C. § 1295(a)(1).

DISCUSSION

I.

SUMMARY JUDGMENT

We begin by addressing the district court’s summary

judgment that claim 1 of the ’863 patent is not invalid.

We review the district court’s grant of summary

judgment according to the law of the regional circuit.

Phil-Insul Corp. v. Airlite Plastics Co., 854 F.3d 1344,

1353 (Fed. Cir. 2017). The Eighth Circuit reviews a

district court’s grant of summary judgment de novo. Id.

(citing Wilson v. Spain, 209 F.3d 713, 716 (8th Cir. 2000)).

“Summary judgment is appropriate if ‘the movant shows

that there is no genuine dispute as to any material fact

and the movant is entitled to judgment as a matter of

8 EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS.

GRP., LLC

law.’” Id. (quoting Fed. R. Civ. P. 56(a)).

A.

Briggs argues that the district court erred by granting

summary judgment that claim 1 is not invalid as antici-

pated or obvious based solely on the fact that claim 1

survived multiple reexaminations involving the same

prior art. We agree.

The district court’s summary judgment decision was

limited to a single paragraph containing a single basis.

Specifically, the district court held:

The court first finds that no reasonable jury

could find on this record that the defendants have

met their burden of presenting clear and convinc-

ing evidence that the claims at issue are invalid

as anticipated or obvious. The ’863 patent has

now been examined four times by the PTO, and

each time the PTO held the claims of the ’863 pa-

tent to be patentable. The court has considered

the PTO reexaminations and affords them some,

though not determinative, weight. All of the de-

fendants’ prior art invalidity arguments have been

fully considered by the PTO and rejected. The

PTO has similarly rejected the argument that the

claims were anticipated by the plaintiffs’ own bro-

chures and that the patent is not entitled to a pri-

ority date of 1995. Under these circumstances, the

court finds that no reasonable juror could find

that the defendants have met their burden of

proving by clear and convincing evidence that the

claims of the patent are invalid.

Summary Judgment Order, 2015 WL 12697086, at *11

(emphases added). Though the district court stated that

it gave the reexaminations “some, though not determina-

tive, weight,” id. (emphasis added), it appears from its

cursory decision that, in fact, the court granted summary

EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS. 9

GRP., LLC

judgment based on the claim surviving multiple reexami-

nations. No other explanation for granting summary

judgment was provided. The question thus presented is

whether a reexamination confirming patentability of a

claim can form the sole basis for granting summary

judgment that a claim is not invalid based on the same

prior art.

We hold that a reexamination confirming patentabil-

ity of a patent claim alone is not determinative of whether

a genuine issue of fact precludes summary judgment of no

invalidity. Surviving a reexamination does not warrant

ipso facto summary judgment that a patent is not invalid.

Holding otherwise would improperly give complete defer-

ence and preclusive effect to the PTO’s patentability

determination, foreclosing challenges to patent validity in

district court based on the same prior art.

Our holding is supported by our prior decisions stat-

ing that a district court “is never bound by an examiner’s

finding in an ex parte patent application proceeding.”

Pfizer, Inc. v. Apotex, Inc., 480 F.3d 1348, 1359 (Fed. Cir.

2007) (citing Fromson v. Advance Offset Plate, Inc.,

755 F.2d 1549, 1555 (Fed. Cir. 1985)). We have said the

same regarding an examiner’s findings during reissue

proceedings. See Fromson, 755 F.2d at 1555 (“The Exam-

iner’s decision, on an original or reissue application, is

never binding on a court.”); Interconnect Planning Corp. v.

Feil, 774 F.2d 1132, 1139 (Fed. Cir. 1985) (“IPC’s view is

incorrect that the PTO’s [reissue] decision must be given

controlling weight . . . .”). While the PTO’s findings

during reexamination are “evidence the court must con-

sider in determining whether the party asserting invalidi-

ty has met its statutory burden by clear and convincing

evidence,” they are not dispositive. Fromson, 755 F.2d at

1555.

Instead, the “deference [owed] to the decisions of the

USPTO takes the form of the presumption of validity

10 EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS.

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under 35 U.S.C. § 282. That is, by statute a patent is

valid upon issuance and included within the presumption

of validity is a presumption of non-obviousness.” Pfizer,

480 F.3d at 1359 (emphases added) (citations omitted).

This presumption also follows a patent claim surviving

reexamination. See Superior Fireplace Co. v. Majestic

Prods. Co., 270 F.3d 1358, 1367 (Fed. Cir. 2001) (“Chal-

lenges to the validity of claims, whether regularly issued,

issued after a reexamination . . . or issued after a reis-

sue . . . must meet the clear and convincing standard of

persuasion. This requirement is based on the presump-

tion of validity.” (emphasis added) (citations omitted)).

The presumption of validity, however, is just that—a

presumption—which can be overcome by the patent

challenger who meets its high burden of proving the

factual elements of invalidity by clear and convincing

evidence. Id. We recognize the district court must con-

sider reexaminations as evidence “in determining whether

the party asserting invalidity has met its statutory bur-

den by clear and convincing evidence.” Pfizer, 480 F.3d at

1360 (quoting Fromson, 755 F.2d at 1555). But just as an

original examination resulting in patent issuance does not

foreclose an invalidity attack in district court, so too does

a reexamination confirming a claim not preclude a patent

challenger from meeting its burden of proving invalidity.

We thus “affirm the obligation of the district court to

reach an independent conclusion.” Interconnect, 774 F.2d

at 1139.

Exmark concedes that the PTO’s findings on reexami-

nation are not dispositive, see Appellee Br. 30, but it

nonetheless argues that the district court properly gave

those findings substantial weight and considered other

factors in its summary judgment decision. We disagree

with Exmark’s characterization of the district court’s

decision. The district court’s summary judgment was

based solely on the fact that the patentability of claim 1

was confirmed following multiple reexaminations. The

EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS. 11

GRP., LLC

district court made no other findings regarding the ele-

ments of anticipation or obviousness to determine wheth-

er a genuine issue of material fact precluded summary

judgment.

Exmark cites two cases in which this court previously

affirmed summary judgment in view of reexamination

proceedings. But neither case supports the district court’s

analysis in this case. In Transmatic, Inc. v. Gulton Indus-

tries, Inc., we affirmed the district court’s summary

judgment that patent claims were not invalid following

reexamination. 53 F.3d 1270 (Fed. Cir. 1995). But there,

we concluded that “[i]t [was] apparent from the district

court’s opinion that the court considered all the relevant

prior art . . . in reaching its nonobviousness determina-

tion.” Id. at 1275. Only after reaching this conclusion did

we note that “[t]he claims twice passed scrutiny in the

PTO, including a reexamination procedure in which [the

patent challenger] participated as the requester.” Id.

Thus, we do not read Transmatic as condoning a grant of

summary judgment based on the reexamination outcome

alone.

Similarly, in SRI International, Inc. v. Advanced

Technology Laboratories, Inc., a non-precedential deci-

sion, we affirmed summary judgment of nonobviousness

in view of prior art that had been considered by the PTO

during reexamination. 45 F.3d 443, 1994 WL 712487

(Fed. Cir. 1994) (non-precedential). We stated that “[b]y

issuing the reexamination certificate, the Patent Office

concluded that the asserted claims would not have been

obvious in view of [the prior art reference]” and, accord-

ingly, “‘[d]eference [was] due the Patent Office decision to

issue the patent with respect to evidence bearing on

validity which it considered.’” Id. at *3 (second alteration

in original) (citations omitted). We explained that, “when

a party attacking validity relies only on prior art that was

before the PTO examiner during prosecution, that party

has [the] added burden of overcoming the deference due a

12 EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS.

GRP., LLC

qualified governmental agency.” Id. (citing Polaroid Corp.

v. Eastman Kodak Co., 789 F.2d 1556, 1560 (Fed. Cir.

1986)). But the district court in SRI did not grant sum-

mary judgment based on the reexamination outcome

alone. Instead, it considered all the record evidence,

including the prior art and expert testimony, to conclude

that the parties’ arguments regarding the prior art did

not create an issue of fact and summary judgment of

invalidity was appropriate. See id. at *3–4.

Finally, Exmark asserts that Briggs’ strategic deci-

sion to challenge validity through reexamination at the

PTO gave Briggs advantages that it would not get in

district court, including a lack of a presumption of validity

and the ability to rely on the broadest reasonable inter-

pretation. Therefore, Exmark argues, Briggs cannot

ignore the result of reexamination having chosen its

forum and lost. Exmark seems to suggest that because

Briggs was unable to invalidate the claims under a lower

standard of patentability and a broader claim construc-

tion standard, Briggs cannot establish invalidity by clear

and convincing evidence. While this argument seems

facially logical, it fails nonetheless.

It is important to consider the substantive and proce-

dural differences between challenging patentability in an

ex parte reexamination and challenging patent validity in

federal court. Notably, unlike challenging validity in

district court, in an ex parte reexamination, the claims

are construed under the broadest reasonable interpreta-

tion, the patent challenger does not participate beyond its

initial request for reexamination, the admission of evi-

dence is not governed by the Federal Rules, and the

burden of proving unpatentability is merely a preponder-

ance of evidence. Such differences, however, are material

in district court litigation. For example, the scope of the

construed claims, particularly to the extent there are

differences between the PTO’s and district court’s con-

struction, must be considered in determining whether a

EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS. 13

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genuine issue of material fact exists as to whether a prior

art reference anticipates or renders a claim obvious.

In this case, the district court adopted the parties’

agreed-to construction of “first flow control baffle” as “a

front structure within the walls of the mower deck that

controls the flow of air and grass clippings.” Exmark Mfg.

Co. v. Briggs & Stratton Power Prods. Grp., LLC, No.

8:10CV187, 2011 WL 5976264, at *4 (D. Neb. Nov. 29,

2011); see also J.A. 1558 at 105:14–18. On appeal of the

reexamination before the Board, in which Briggs did not

participate, Exmark and the examiner disagreed about

the proper interpretation of “baffle” and “flow control

baffle.” Exmark argued that “the entire first flow control

baffle must be a baffle, and thus, the individual baffle

portions must also be baffles,” and that “a ‘baffle’ needs to

control the flow of air and grass clippings.” J.A. 3708.

The Board agreed with Exmark and construed “baffle”

and “flow control baffle” as “an element that ‘controls’ the

flow of air and grass clippings within the mower deck in a

‘meaningful way.’” J.A. 3707.

In its summary judgment decision, however, the dis-

trict court apparently did not agree with all aspects of the

Board’s construction. The district court stated that

“Exmark’s purported contention that the baffle must have

a ‘meaningful effect’ is not in the claim, but was argued to

the PTO.” Summary Judgment Order, 2015 WL

12697086, at *10 n.8. The district court then stated:

The court’s decision does not hinge on the

“meaningful effect” construction. The “meaningful

effect” language was adopted by the [Board] mere-

ly to explain why the mounting plates of the prior

art . . . patent were not “flow control baffles.” The

parties previously agreed to the interpretation of

the claim term “flow control baffle” to mean the

“structure within the walls of the mower deck that

controls the flow of air and grass clippings.” That

14 EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS.

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term is easily understood. The court will not

adopt the construction that every portion of the

baffle have a meaningful effect on the flow of air

and grass clippings.

Id. (citation omitted). 3

To the extent the district court adopted a broader con-

struction than the PTO’s construction, it precluded Briggs

from arguing that the prior art anticipated the claims or

rendered them obvious under the district court’s broader

construction of the claims. The fact that the Board held

that the asserted anticipating prior art reference did not

disclose the claim requirements (entire baffle and mean-

ingful effect) as construed by the Board, does not foreclose

the possibility that a jury may find otherwise under a

broader construction not requiring those aspects. Thus,

contrary to Exmark’s argument, the mere fact that the

asserted claims survived Briggs’ requested reexamination

does not necessarily establish that it cannot meet its

burden to overcome the presumption of validity under a

broader claim construction.

B.

In the alternative, Exmark argues that we should

affirm the district court because no reasonable juror could

conclude that the prior art anticipates or renders obvious

claim 1 of the ’863 patent. On appeal, the parties ada-

mantly dispute whether the prior art discloses the

claimed “first flow control baffle” and “discharge opening.”

Moreover, the parties appear to present a claim construc-

3 This statement by the district court appears in a

footnote discussing indefiniteness. On remand, the dis-

trict court should consider how its claim construction, to

the extent it is the same or different from the Board’s

construction, impacts its anticipation and obviousness

analysis.

EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS. 15

GRP., LLC

tion dispute on appeal: whether the claims of the ’863

patent require that the first flow control baffle be spaced

apart from the front wall.

It is unclear, however, from the limited record before

us, the extent to which these arguments were raised

before the district court on summary judgment. Indeed,

the district court did not address these arguments. We

are mindful that we review the district court’s judgment,

not its opinion, and review the grant of summary judg-

ment de novo. But we decline the invitation to scour the

record to determine in the first instance whether genuine

issues of fact preclude summary judgment with respect to

the teachings of the prior art, particularly where claim

construction issues were not clearly presented or ad-

dressed by the district court. Cf. OSRAM Sylvania, Inc. v.

Am. Induction Techs., Inc., 701 F.3d 698, 707–08 (Fed.

Cir. 2012) (“It is not our role to scour the record and

search for something to justify a lower court’s conclusions,

particularly at the summary judgment stage. Whether

dealing with an issue of law like claim construction or an

issue of fact such as infringement, this court must be

furnished ‘sufficient findings and reasoning to permit

meaningful appellate scrutiny.’” (citations omitted)).

Accordingly, we vacate the district court’s summary

judgment of no invalidity and remand with instruction for

the district court to consider the entire record and reach

its own independent conclusion on whether a genuine

issue of fact exists regarding invalidity consistent with

this opinion. The district court should resolve any re-

maining claim construction disputes relevant to the

invalidity analysis. The district court should weigh all

the evidence, including, but not limited to, the evidence

considered by the PTO during reexamination, mindful

that the evidence must be viewed in the light most favor-

able to Briggs, with all justifiable inferences drawn in its

favor. While the reexamination evidence is to be consid-

16 EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS.

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ered, it is not dispositive of the issue on summary judg-

ment.

II.

INDEFINITENESS

Briggs also argues that the district court erred in

denying summary judgment that claim 1 of the ’863

patent is indefinite. Briggs contends that the ’863 patent

does not explain how to objectively determine whether a

baffle portion is straight enough or long enough to be

“elongated and substantially straight” for purposes of

determining infringement. We disagree.

Pursuant to 35 U.S.C. § 112, ¶ 2, a patent specifica-

tion must “conclude with one or more claims particularly

pointing out and distinctly claiming the subject matter

which the applicant regards as his invention.” 4 A claim is

indefinite if, when read in light of the specification and

prosecution history, it fails to inform those skilled in the

art about the scope of the invention with reasonable

certainty. Nautilus, Inc. v. Biosig Instruments,

Inc., 134 S. Ct. 2120, 2129 (2014). The district court’s

ultimate determination that a patent claim is not indefi-

nite under § 112 is a question of law, which we review de

novo. UltimatePointer, L.L.C. v. Nintendo Co., 816 F.3d

816, 826 (Fed. Cir. 2016).

We agree with the district court that the claim lan-

guage and specification of the ’863 patent provide reason-

able certainty as to the meaning of “elongated and

4 Because the ’863 patent was filed before the adop-

tion of the Leahy–Smith America Invents Act, Pub. L. No.

112–29, § 4(e), 125 Stat. 284, 296-97 (2011), the pre-AIA

version of § 112 governs. See AbbVie Deutschland GmbH

& Co., KG v. Janssen Biotech, Inc., 759 F.3d 1285, 1290

n.3 (Fed. Cir. 2014).

EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS. 17

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substantially straight.” Claim 1 recites that the elongat-

ed and substantially straight baffle portion “extend[s]

from [the] second end of [the] first arcuate baffle portion”

and that a second arcuate baffle portion “extends from

[the] second end of [the] first elongated and substantially

straight baffle portion.” ’863 patent col. 6 ll. 26–30.

The specification similarly explains that this elongat-

ed and substantially straight baffle portion is located

between two “arcuate” (curved) baffle portions, both of

which extend partially around a mower blade. Id. at

col. 4 ll. 8–17. Figures 3 and 4 also show that the elon-

gated and relatively straight portion of the baffle extends

such that the elongated portion connects two arcuate

portions of the baffle. Id. Figs. 3 and 4.

Therefore, the claims and specification provide that

the elongated and straight portion of the baffle must be

long enough and straight enough to at least connect these

two arcuate portions of the baffle. This is illustrated

clearly in Exmark’s annotated depiction of Figure 4 of the

’863 patent below:

Appellee Br. 41.

The specification also refers to a “relatively straight

baffle portion.” ’863 patent col. 4 ll. 11–12 (emphasis

added). It is clear from the disclosure that the “substan-

18 EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS.

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tially straight” portions are straight relative to the curved

baffle portions. This is consistent with Exmark’s experts’

testimony that the “elongated and substantially straight”

terms should be construed as “relative to the proportions

of the other components” and that one of ordinary skill in

the art would understand the limitation to mean “some-

thing which is longer than it is wide, for something which

is relatively straight, for something which transitions

between arcuate portions, something which meets the

chord-like limitation.” J.A. 11679 at 210:13–17;

J.A. 11127 at 67:14–23.

Though Briggs seeks to impose a strict requirement of

how straight the baffle portions must be, no such numeri-

cal precision is required when using such terms of degree.

See Sonix Tech. Co. v. Publ’ns Int’l, Ltd., 844 F.3d 1370,

1377 (Fed. Cir. 2017) (“[W]e have rejected the proposition

that claims involving terms of degree are inherently

indefinite. Thus, ‘a patentee need not define his invention

with mathematical precision in order to comply with the

definiteness requirement.’” (quoting Invitrogen Corp. v.

Biocrest Mfg., L.P., 424 F.3d 1374, 1384 (Fed. Cir. 2005)));

see also Apple Inc. v. Samsung Elecs. Co., 786 F.3d 983,

1002 (Fed. Cir. 2015) (upholding a claim term “substan-

tially centered” as definite because the patent challenger

failed to produce evidence that an ordinarily skilled

artisan would lack reasonable certainty of the claim’s

scope), rev’d and remanded on other grounds, 137 S. Ct.

429 (2016); Enzo Biochem, Inc. v. Applera Corp., 599 F.3d

1325, 1335 (Fed. Cir. 2010) (“Because the intrinsic evi-

dence here provides a general guideline and examples

sufficient to enable a person of ordinary skill in the art to

determine [the scope of the claims], the claims are not

indefinite even though the construction of the term ‘not

interfering substantially’ defines the term without refer-

ence to a precise numerical measurement.” (alteration in

original) (citations and internal quotation marks omit-

ted)). All that is required is some standard for measuring

EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS. 19

GRP., LLC

the term of degree. Biosig, 783 F.3d at 1378. In this case,

one skilled in the art would understand that the “substan-

tially straight” portions of the baffle must be sufficiently

straight to connect two arcuate portions of the baffle.

The function of the elongated and substantially

straight baffle portions provides further guidance regard-

ing the scope of the claim language. Functional language

can “promote[] definiteness because it helps bound the

scope of the claims by specifying the operations that the

[claimed invention] must undertake.” Cox Commc’ns, Inc.

v. Sprint Commc’n Co. LP, 838 F.3d 1224, 1232 (Fed. Cir.

2016). The claims of the ’863 patent recite that the “elon-

gated and substantially straight baffle portion[s]” are

oriented in such a way “that the cuttings from said first

cutting blade will be deflected inwardly within the said

circle defined by the blade tip path of said second cutting

blade.” ’863 patent col. 6 ll. 36–39. Thus, one skilled in

the art would understand that the elongated and straight

portions of the baffle must be extended, straightened, and

positioned in such a way that the grass cuttings from each

blade deflect the clippings into the direction of the next

blade.

Briggs cites our recent decision in GE Lighting Solu-

tions, LLC v. Lights of America, Inc., in which we found

the claim term “elongated” indefinite. 663 F. App’x 938

(Fed. Cir. 2016). We note that GE Lighting is a non-

precedential decision, which is not binding, and should be

read as limited to the particular claim and specification at

issue in that case. Further, our indefiniteness determina-

tion in GE Lighting was based on our conclusion that

nothing in the patent at issue provided any objective

boundaries for the term “elongated.” Id. at 940–41. In

contrast, as we explained above, we find that the ’863

patent does provide information to objectively define the

scope of the “elongated” claim term.

20 EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS.

GRP., LLC

Briggs also argues that Exmark’s own experts were

unable to explain how a competitor would be able to

determine if their baffles infringe. We are not persuaded

by this argument. Exmark’s expert and co-inventor of the

’863 patent, Garry Busboom, testified that if the length of

the “elongated and substantially straight” baffle portion

were too short, such that it would act as an arcuate baffle

portion, it would not be an elongated and substantially

straight portion. And although Mr. Busboom was unable

to provide any order of magnitude to quantify exactly how

long the elongated baffle portion must be, he testified that

its length was relative to the proportions of other compo-

nents of the baffle and of other mower components. This

testimony is consistent with the claim language and

specification and supports the district court’s conclusion

that one skilled in the art would understand the objective

boundaries of the claim.

We agree with the district court’s conclusion that

claim 1, when read in light of the specification, informs

those skilled in the art of the scope of the “elongated and

substantially straight” limitation with reasonable certain-

ty. Accordingly, we affirm the district court’s denial of

summary judgment that claim 1 is indefinite.

III.

DAMAGES

Briggs also appeals the district court’s denial of a new

trial on damages. For the reasons explained below, we

vacate the jury’s damages award and remand for a new

trial on damages.

Briggs presents three specific arguments on appeal.

First, Briggs asserts that the district court erred by

permitting Exmark to use the sales price of the accused

mowers as the royalty base instead of the sales price of

the flow control baffles. Briggs next argues that Exmark’s

damages expert’s opinion should have been excluded

EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS. 21

GRP., LLC

because she failed to adequately explain how she arrived

at her proposed 5% royalty rate. Finally, Briggs asserts

that the district court improperly excluded evidence

relevant to damages. We address each argument in turn.

“When reviewing damages in patent cases, we apply

regional circuit law to procedural issues and Federal

Circuit law to substantive and procedural issues pertain-

ing to patent law.” Whitserve, LLC v. Comput. Packages,

Inc., 694 F.3d 10, 26 (Fed. Cir. 2012) (quoting Wordtech

Sys., Inc. v. Integrated Networks Sols., Inc., 609 F.3d

1308, 1318 (Fed. Cir. 2010) (internal citations and quota-

tion marks omitted). In the Eighth Circuit, a district

court’s denial of a motion for a new trial on damages is

reviewed for an abuse of discretion. See Harrison v.

Purdy Bros. Trucking Co., 312 F.3d 346, 351 (8th Cir.

2002). Likewise, the district court’s evidentiary rulings,

including those related to the admissibility of damages

expert evidence, are reviewed for an abuse of discretion.

See Barrett v. Rhodia, Inc., 606 F.3d 975, 980 (8th Cir.

2010). “A district court abuses its discretion when its

decision is based on clearly erroneous findings of fact, is

based on erroneous interpretations of the law, or is clearly

unreasonable, arbitrary or fanciful.” Whitserve, 694 F.3d

at 26 (quoting Cybor Corp. v. FAS Techs., Inc., 138 F.3d

1448, 1460 (Fed. Cir. 1998) (en banc)).

A.

Briggs first argues that the district court erred by al-

lowing Exmark to compute a royalty rate without proper-

ly identifying a royalty base to apportion the value of the

patentee’s invention in comparison to the value of the

whole lawn mower. The parties do not dispute that

apportionment is required in this case. Although claim 1

of the ’863 patent is broadly directed to “a multiblade

lawn mower,” our law recognizes that a reasonable royal-

ty award “must be based on the incremental value that

the patented invention adds to the end product.” Erics-

22 EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS.

GRP., LLC

son, Inc. v. D-Link Sys., Inc., 773 F.3d 1201, 1226 (Fed.

Cir. 2014). Here, the patent makes clear that the patent-

ed improvement relates to the mower’s flow control baffle,

which through its structure and orientation within the

mower deck purportedly efficiently directs grass clippings

toward a side discharge and thereby improves the quality

of grass cut in a manner that distinguishes it from prior

art. See, e.g., ’863 patent col. 1 l. 30–col. 2 l. 9. The

remaining limitations of claim 1 recite conventional

features of a lawn mower, including a mower deck, a side

discharge opening, and a power means for operating the

mower. In these circumstances, the patent owner must

apportion or separate the damages between the patented

improvement and the conventional components of the

multicomponent product. Cf. Commonwealth Sci. &

Indus. Research Organisation v. Cisco Sys., Inc., 809 F.3d

1295, 1301 (Fed. Cir. 2015) (requiring apportionment

between patented and unpatented features of a multi-

component product); VirnetX, Inc. v. Cisco Sys., Inc.,

767 F.3d 1308, 1329 (Fed. Cir. 2014) (same). This ensures

that Exmark is compensated for the patented improve-

ment (i.e., the improved flow control baffle) rather than

the entire mower. See Garretson v. Clark, 111 U.S. 120,

121 (1884).

On appeal, Briggs argues that Exmark’s expert should

have apportioned or separated the value of the baffle from

the other features of the mower through the royalty base

rather than the royalty rate. We disagree. We have held

that apportionment can be addressed in a variety of ways,

including “by careful selection of the royalty base to

reflect the value added by the patented feature [or] . . . by

adjustment of the royalty rate so as to discount the value

of a product’s non-patented features; or by a combination

thereof.” Ericsson, 773 F.3d at 1226. So long as Exmark

adequately and reliably apportions between the improved

and conventional features of the accused mower, using the

accused mower as a royalty base and apportioning

EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS. 23

GRP., LLC

through the royalty rate is an acceptable methodology.

Id. (citing Garretson, 111 U.S. at 121). “The essential

requirement is that the ultimate reasonable royalty

award must be based on the incremental value that the

patented invention adds to the end product.” Id.

Using the accused lawn mower sales as the royalty

base is particularly appropriate in this case because the

asserted claim is, in fact, directed to the lawn mower as a

whole. The preamble of claim 1 recites a “multiblade

lawn mower.” ’863 patent col. 5 l. 60. It is not the baffle

that infringes the claim, but rather the entire accused

mower. Thus, claim 1 covers the infringing product as

whole, not a single component of a multi-component

product. There is no unpatented or non-infringing feature

of the product. Nonetheless, “[w]hen a patent covers the

infringing product as a whole, and the claims recite both

conventional elements and unconventional elements, the

court must determine how to account for the relative

value of the patentee’s invention in comparison to the

value of the conventional elements recited in the claim,

standing alone.” AstraZeneca AB v. Apotex Corp., 782

F.3d 1324, 1338 (Fed. Cir. 2015) (citing Ericsson, 773 F.3d

at 1233). We hold that such apportionment can be done

in this case through a thorough and reliable analysis to

apportion the royalty rate. We have recognized that one

possible way to do this is through a proper analysis of the

Georgia-Pacific factors. See id; see also Georgia-Pacific

Corp. v. U.S. Plywood Corp., 318 F. Supp. 1116 (S.D.N.Y.

1970). As we have explained, “the standard Georgia-

Pacific reasonable royalty analysis takes account of the

importance of the inventive contribution in determining

the royalty rate that would have emerged from the hypo-

thetical negotiation.” AstraZeneca, 782 F.3d at 1338.

Finally, we note that Exmark’s use of the accused

lawn mower sales as the royalty base is consistent with

the realities of a hypothetical negotiation and accurately

reflects the real-world bargaining that occurs, particularly

24 EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS.

GRP., LLC

in licensing. As we stated in Lucent Technologies, Inc. v.

Gateway, Inc., “[t]he hypothetical negotiation tries, as

best as possible, to recreate the ex ante licensing negotia-

tion scenario and to describe the resulting agreement.”

580 F.3d 1301, 1325 (Fed. Cir. 2009). “[S]ophisticated

parties routinely enter into license agreements that base

the value of the patented inventions as a percentage of

the commercial products’ sales price,” and thus “[t]here is

nothing inherently wrong with using the market value of

the entire product, especially when there is no established

market value for the infringing component or feature, so

long as the multiplier accounts for the proportion of the

base represented by the infringing component or feature.”

Id. at 1339. This is consistent with the settlement

agreement relied on by Exmark’s damages expert, which

the parties agree provided an effective royalty of 3.64% of

the sales of the accused mowers.

B.

While we reject Briggs’ argument directed to the roy-

alty base, we ultimately agree with Briggs that Exmark’s

damages expert’s opinion was inadmissible as it failed to

adequately tie the expert’s proposed reasonable royalty

rate to the facts of this case. We conclude that the district

court abused its discretion in denying Briggs’ motion for a

new trial on damages.

After a discussion of each of the Georgia-Pacific fac-

tors, including the benefits of the patented technology,

sales and profitability, and the competitive relationship of

the parties, Exmark’s expert concluded with little expla-

nation that Exmark and Briggs would have agreed to a

5% reasonable royalty rate on the sales of the accused

lawn mowers as the value for the improved baffle. No-

where in her report, however, did she tie the relevant

Georgia-Pacific factors to the 5% royalty rate or explain

how she calculated a 5% royalty rate using these factors.

To be admissible, expert testimony opining on a reasona-

EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS. 25

GRP., LLC

ble royalty must “sufficiently [tie the expert testimony on

damages] to the facts of the case. If the patentee fails to

tie the theory to the facts of the case, the testimony must

be excluded.” Uniloc USA, Inc. v. Microsoft Corp.,

632 F.3d 1292, 1315 (Fed. Cir. 2011) (quoting Daubert v.

Merrell Dow Pharm., Inc., 509 U.S. 579, 591 (1993))

(alteration in original).

Exmark’s expert began her analysis by explaining her

understanding of the benefits of the mowers covered by

the ’863 patent. Relying on the testimony of experts and

fact witnesses, she identified a number of advantages

arising from the use of the claimed baffle, including

improved air and grass flow for reduced blowout, in-

creased grass cut quality, minimized grass clumping, and

more uniform discharge, all of which improve the mower’s

function and allows a mower to go faster in heavy grass

areas. She concluded that negotiators would have recog-

nized the importance of these advantages to customers

and operators and the key role they play in Briggs’ sale of

its mowers. She repeated these advantages as relevant to

Georgia-Pacific factors nine (utility and advantage of the

patented technology) and ten (the nature of the patented

invention). But she did not explain how these ad-

vantages, or her analysis of the Georgia-Pacific factors,

led to her proposed 5% royalty rate.

Under similar circumstances, we have held that a

“superficial recitation of the Georgia-Pacific factors,

followed by conclusory remarks, [cannot] support the

jury’s verdict.” Whitserve, 694 F.3d at 31. When an

expert employs the Georgia-Pacific factors, “reciting each

factor and making a conclusory remark about its impact

on the damages calculation before moving on does no

more than tell the jury what factors a damages analysis

could take into consideration.” Id. When performing a

Georgia-Pacific analysis, damages experts must not only

analyze the applicable factors, but also carefully tie those

factors to the proposed royalty rate. “[W]hile mathemati-

26 EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS.

GRP., LLC

cal precision is not required, some explanation of both

why and generally to what extent the particular factor[s]

impact[] the royalty calculation is needed.” Id.

Thus, it was not enough for Exmark’s expert to ex-

plain the advantages of the baffle claimed in the ’863

patent and state that they would have been important in

a hypothetical negotiation. This told the jury nothing

more than that the patented technology was important

and commercially successful. A reasonable royalty analy-

sis requires that “the trial court . . . carefully tie proof of

damages to the claimed invention’s footprint in the mar-

ket place.” ResQNet.com, Inc. v. Lansa, Inc., 594 F.3d

860, 869 (Fed. Cir. 2010). To sufficiently tie the ad-

vantages of the patented baffles to the royalty rate in this

case, Exmark’s expert was required to explain the extent

to which they factored into the value of the lawn mower

and her 5% royalty rate.

The expert’s analysis under Georgia-Pacific factor

thirteen—the portion of realized profits attributable to

non-patented elements—was also troublesome. Exmark’s

expert acknowledged that other elements of the mowers

affect sales and profits of the mowers, including durabil-

ity, reliability, brand position, dealer support, and war-

ranty. But she failed to conduct any analysis indicating

the degree to which these considerations impact the

market value or profitability of the mower and therefore

impacted her suggested 5% royalty rate.

Equally problematic, the expert acknowledged that

Briggs and its co-defendant, Schiller, have patents cover-

ing other components of the accused mowers. But she

ignored those components, opining without support that

they do not relate to the quality of cut, which she consid-

ered “paramount” to selling mowers. J.A. 14453. We are

skeptical that other patented components of the mower

bear no relation to the overall value of the accused mow-

ers, which would influence the relative value of the pa-

EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS. 27

GRP., LLC

tented baffle and thus the royalty rate. Even assuming,

however, that they do not, the expert was required to

support her opinion to that effect with sound economic

reasoning. Merely concluding that other components do

not affect the value of the accused mower amounts to

nothing more than speculation. To cure this deficiency,

the jury could have received evidence itemizing the rela-

tive value of these other components to better guide the

jury’s understanding of the value of the baffle in relation

to the other components of the accused multi-component

mower. Without a more detailed analysis, the jury is

simply left to speculate or adopt the expert’s unsupported

conclusory opinion.

The remainder of Exmark’s expert’s opinion similarly

recited the remaining Georgia-Pacific factors and either

stated that they did not apply or provided a cursory

explanation of the evidence considered for each factor.

The opinion is devoid of any analysis tying either the

evidence or the specific Georgia-Pacific factors to the

proposed 5% royalty rate.

Exmark defends its expert’s opinion, arguing that her

royalty rate is reasonable because (1) it is only a small

fraction of Exmark’s profits on its mowers; and (2) she

relied on quantitative market valuation evidence in

forming her opinion. Exmark further states that she

considered evidence such as Briggs’ selling value docu-

ments, detailing the value that Briggs placed on each of

its mower’s components, a litigation settlement agree-

ment involving the ’863 patent resulting in a comparable

effective royalty rate, and the parties’ profit margins

during the damages period. We address Exmark’s argu-

ments in turn.

First, we cannot agree that using an allegedly low

royalty rate alone supports the admissibility of the ex-

pert’s reasonable royalty opinion. Regardless of how low

28 EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS.

GRP., LLC

the royalty rate, the expert must still apportion damages

and sufficiently tie the royalty rate to the facts of the case.

Moreover, we recognize that Exmark’s expert dis-

cussed quantitative market evidence in her opinion. As

explained above, however, we are troubled by the expert’s

analysis because, even assuming she properly considered

this record evidence, she failed to explain how the evi-

dence factored into the proposed royalty rate. She merely

addressed the Georgia-Pacific factors in light of the facts

and then plucked the 5% royalty rate out of nowhere. It is

not enough for an expert to simply assert that a particular

royalty rate is reasonable in light of the evidence without

tying the proposed rate to that evidence.

Because her proposed royalty rate lacked sufficient

ties to the facts of the case, we hold that the district court

erred by not excluding Exmark’s damages expert’s opinion

and abused its discretion by denying Briggs a new trial on

damages based on inadmissible evidence. Accordingly, we

vacate the damages award and remand for a new trial on

damages.

C.

Briggs next challenges three of the district court’s

evidentiary rulings related to damages.

Briggs first argues that the district court improperly

excluded evidence of certain prior art, which it argues was

related to the damages analysis. Specifically, Briggs

sought to present evidence of conventional modes of

mowing to rebut Exmark’s argument that the mower

claimed in the ’863 patent was a big advancement over

the prior art. Briggs argues that by showing the jury the

small differences between the invention and prior art

mowers, it would have demonstrated that many of the

benefits Exmark attributed to the baffle were already

present in the prior art. The district court allowed the

introduction of some prior art but excluded any prior art

EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS. 29

GRP., LLC

that had not been commercialized, holding that “prior art

is relevant to damages only to the extent that the patent

was used in a product.” Exmark Mfg. Co. v. Briggs &

Stratton Power Prods. Grp., LLC, No. 8:10:CV187, 2015

WL 5177759, at *4 (D. Neb. Sept. 4, 2015). The district

court appears to have based its ruling on the language of

Georgia-Pacific factor nine, which considers “old modes or

devices, if any, that had been used for working out similar

results.” Georgia-Pacific, 318 F. Supp. at 1120 (emphasis

added).

We conclude that the district court abused its discre-

tion by holding that prior art is relevant to damages only

to the extent that the prior art was commercialized.

Neither the district court nor Exmark cited any case to

support the view that Georgia-Pacific factor nine limits

evidence of prior art to commercialized modes or devices.

Nor do we see any principled reason for such a narrow

reading. The fact that some prior art mowers were not

commercialized does not make them immaterial to deter-

mining the extent to which the mower claimed in the ’863

patent provides utility and advantages over the prior art.

Moreover, the district court is not constrained by the

Georgia-Pacific factors, as there are ways of determining

a reasonable royalty other than through the Georgia-

Pacific factors. Thus, the language of Georgia-Pacific

factor nine does not bind the district court and should not

be construed as limiting.

The district court also limited the damages evidence

to prior art directed to side discharge mowers. The record

demonstrates that commercial lawn mowers come in two

varieties, mulching mowers and side discharge mowers.

Briggs argues that the district court abused its discretion

by excluding prior art directed to mulching mowers. We

disagree. The only asserted claim of the ’863 patent

requires a side-discharge mower. Therefore, it was rea-

sonable and within the district court’s discretion to ex-

clude prior art mowers that were not side-discharge

30 EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS.

GRP., LLC

mowers, commensurate with the scope of the asserted

claim. Thus, we hold that the district court did not abuse

its discretion in excluding evidence of mulching mowers.

Briggs also argues the district court abused its discre-

tion by excluding evidence of Exmark’s purportedly de-

layed decision to sue for infringement. Briggs argues that

such delay undermines Exmark’s evidence that it would

never have condoned infringement without a high royalty.

We agree with the district court that Briggs’ attempt

to introduce evidence of Exmark’s delay in filing suit for

infringement is not relevant to damages, even when

considering Georgia-Pacific factors four (licensing policy)

and fifteen (hypothetical negotiation). As the district

court recognized, “[t]he argument that the delay in bring-

ing suit somehow establishes Exmark’s perception of the

value of its invention is specious. There are many reasons

to forego filing a lawsuit, to imply that Exmark did so

because it did not think the invention had value is specu-

lative.” Exmark, 2015 WL 5177759, at *2. The record

supports that there were other reasons for Exmark’s delay

in filing suit, including scarcity of financial resources to

do so. Thus, we conclude that the district court did not

abuse its discretion in excluding this evidence.

IV.

WILLFULNESS

Briggs next argues that the Supreme Court’s recent

decision in Halo warrants a new trial on willfulness and

vacatur of the district court’s enhanced damages award.

The willfulness trial in this case proceeded under the

former standard set forth in In re Seagate Technology,

LLC., 497 F.3d 1360 (Fed. Cir. 2007) (en banc). Before

trial, the district court found that Briggs’ litigation de-

fenses were unreasonable. Based on that finding, the

district court precluded Briggs from presenting any

evidence regarding the validity of claim 1 or how closely

EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS. 31

GRP., LLC

the prior art tracks claim 1. Briggs argues that it should

have been allowed to present such evidence to mitigate

any finding that it acted with an objectively high risk of

infringement. Briggs further argues that the district

court’s exclusion of this evidence is inconsistent with

Halo, which mandates that the inquiry into the degree of

risk of infringement is for the jury, not the district court,

to decide. We agree with Briggs that the district court

erred to the extent it excluded this evidence without also

determining whether it was relevant to Briggs’ state of

mind at the time of accused infringement. Halo, 136 S. Ct.

at 1933 (“[C]ulpability is generally measured against the

knowledge of the actor at the time of the challenged

conduct.”).

In Halo, the Supreme Court held that “[t]he subjective

willfulness of a patent infringer, intentional or knowing,

may warrant enhanced damages, without regard to

whether his infringement was objectively reckless.” Id.

Thus, under Halo, the district court no longer determines

as a threshold matter whether the accused infringer’s

defenses are objectively reasonable. Rather, the entire

willfulness determination is to be decided by the jury. In

this case, the sole basis for excluding the prior art from

the willfulness trial was the district court’s determination

that Briggs’ litigation defenses were unreasonable. See

id. (criticizing and abrogating our Seagate test because it

improperly “ma[de] dispositive the ability of the infringer

to muster a reasonable (even though unsuccessful) de-

fense at the infringement trial”).

To the extent that decision excluded evidence relevant

to Briggs’ state of mind at the time of the accused in-

fringement, however, it does not comport with the stand-

ard articulated in Halo, which mandates that willfulness

is an issue for the jury, not the district court. WBIP, LLC

v. Kohler Co., 829 F.3d 1317, 1341 n.13 (Fed. Cir. 2016)

32 EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS.

GRP., LLC

(“[T]here is a right to a jury trial on the willfulness ques-

tion.”). The district court must reconsider its decision to

exclude evidence of the prior art during the jury trial on

willfulness to determine whether Briggs had developed

any views about the prior art at the time of accused

infringement or whether the evidence only relates to

Briggs’ litigation-inspired defenses. Whether there is a

genuine issue of material fact about when Briggs knew of

its prior art defenses, and thus whether a new jury trial is

required, we leave to the district court to determine in the

first instance. See id. at 1340 (“[A]s the Supreme Court

explained in Halo, timing . . . matter[s]. [A party] cannot

insulate itself from liability for enhanced damages by

creating an (ultimately unsuccessful) invalidity defense

for trial . . . .”). Accordingly, we vacate the jury’s finding

of willful infringement, vacate the district court’s en-

hanced damages award, and remand for the district court

to determine whether a new trial on willfulness is neces-

sary.

V.

LACHES

Finally, Briggs argues the district court erred by dis-

missing its laches defense. We disagree. The Supreme

Court recently held in SCA Hygiene Products Aktiebolag

v. First Quality Baby Products, LLC, that laches is no

longer a defense against damages for patent infringement

that occurred within 35 U.S.C. § 286’s six-year statute of

limitations period. 137 S. Ct. 954 (2017). Because

Exmark only seeks damages for the six-year period prior

to filing its complaint against Briggs, we agree with the

district court that Briggs cannot assert laches as a de-

fense.

EXMARK MFG. CO. v. BRIGGS & STRATTON POWER PRODS. 33

GRP., LLC

CONCLUSION

We have considered the parties’ remaining arguments

and find them unpersuasive. In sum, we hold that the

district court improperly relied on the PTO’s reexamina-

tions of claim 1 of the ’863 patent as the sole basis to

grant summary judgment that claim 1 is not invalid. We

remand with instruction for the district court to reach its

own independent conclusion as to whether a factual

dispute regarding invalidity precludes summary judg-

ment. We also vacate the jury’s damages award and the

district court’s award of enhanced damages, and remand

to the district court for, if necessary, a new trial on will-

fulness and damages consistent with this opinion. We

affirm the district court in all other respects.

AFFIRMED-IN-PART, VACATED-IN-PART, AND

REMANDED

COSTS

No costs.