Ironburg Inventions Ltd. v. Valve Corporation

Case: 21-2296 Document: 66 Page: 1 Filed: 04/03/2023
United States Court of Appeals
for the Federal Circuit
______________________
IRONBURG INVENTIONS LTD.,
Plaintiff-Cross-Appellant
v.
VALVE CORPORATION,
Defendant-Appellant
______________________
2021-2296, 2021-2297, 2022-1070
______________________
Appeals from the United States District Court for the
Western District of Washington in No. 2:17-cv-01182-TSZ,
Senior Judge Thomas S. Zilly.
______________________
Decided: April 3, 2023
______________________
GREGORY S. TAMKIN, Dorsey & Whitney LLP, Denver,
CO, argued for plaintiff-cross-appellant. Also represented
by ANDREA AHN WECHTER; FORREST KWAHADA TAH-
DOOAHNIPPAH, Minneapolis, MN; ROBERT DAVID BECKER,
Manatt, Phelps & Phillips, LLP, San Francisco, CA; BEN-
JAMIN G. SHATZ, Los Angeles, CA.
SHARON A. ISRAEL, Shook, Hardy & Bacon, LLP, Hou-
ston, TX, argued for defendant-appellant. Also represented
by KYLE E. FRIESEN; PATRICK A. LUJIN, MARK SCHAFER,
BASIL TRENT WEBB, Kansas City, MO; REYNALDO BARCELO,
Barcelo, Harrison & Walker, LLP, Newport Beach, CA.
Case: 21-2296 Document: 66 Page: 2 Filed: 04/03/2023
2 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
______________________
Before LOURIE, CLEVENGER, and STARK, Circuit Judges.
Opinion for the court filed by Circuit Judge STARK.
Dissenting opinion filed by Circuit Judge CLEVENGER.
STARK, Circuit Judge.
In 2015, Ironburg Inventions Ltd. (“Ironburg”) sued
Valve Corporation (“Valve”) for infringing U.S. Patent No.
8,641,525 (the “’525 patent”). In January 2021, after much
pretrial litigation and a change of venue, a jury trial was
held in the United States District Court for the Western
District of Washington. Due to the global pandemic caused
by the novel coronavirus, the trial proceeded virtually, with
each juror attending trial remotely through videoconfer-
encing technology. Before closing arguments, the parties
and the district court agreed that each juror should have
the accused product in hand, and that device – a hand held
controller for playing video games – was mailed to each ju-
ror.
The multitude of issues presented in these cross-ap-
peals does not, happily, include any challenge to the virtual
nature or mechanics of the trial. Nevertheless, the reality
of how the trial was conducted, and particularly the fact
that the jurors were free to assess, through their own in-
teractions with the accused device, whether a disputed
claim limitation is met, is pertinent to at least one of the
issues before us, so we mention the district court’s creative
approach here at the outset.
Prior to trial, the district court rejected invalidity chal-
lenges based on the purported indefiniteness of several
claim terms. It also held that Valve was estopped from
pressing its prior-art-based invalidity defenses as a conse-
quence of Valve’s partially instituted inter partes review
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IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 3
(“IPR”). Trial, therefore, proceeded only on infringement
and damages issues.
The jury returned a verdict of willful infringement and
assessed damages of over $4 million. On post-trial mo-
tions, the district court denied Valve’s motion for judgment
as a matter of law – which sought a judgment of non-in-
fringement and, failing that, a judgment that infringement
was not willful – and also for a new trial. The new trial
request was based on the admission of testimony from
Duncan Ironmonger, Ironburg’s inventor and corporate
representative, and on the exclusion of testimony from Karl
Quackenbush, Valve’s general counsel. The district court
also denied Ironburg’s motion to enhance damages. Both
parties appealed.
On appeal, we: (1) affirm the judgment that (a) “elon-
gate member” is not indefinite, (b) “extends substantially
the full distance between the top edge and the bottom edge”
is not indefinite, (c) the claims are infringed, (d) the in-
fringement was willful, (e) damages will not be enhanced,
and (f) Valve is estopped from litigating the prior-art
grounds on which IPR was requested but not instituted;
and (2) vacate the district court’s conclusion that Valve is
also estopped from litigating its later-discovered invalidity
grounds and remand for further proceedings solely with re-
spect to this issue.
I
A
Ironburg owns the ’525 patent, entitled “Controller for
Video Game Console,” which is directed to “a hand held
controller for a video game console” that “includes one or
more additional controls located on the back of the control-
ler in a position to be operated by the user’s [middle, ring,
or little] fingers.” ’525 patent 1:49-58. This back control is
described in the specification as “inherently resilient” and
is “elongate in shape and substantially extend[s] in a
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4 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
direction from the top edge to bottom edge of the control-
ler.” Id. 3:34, 3:51-53.
Claim 1 is representative and is reproduced below,
with the pertinent limitation highlighted:
A hand held controller for a game console comprising:
an outer case comprising a front, a back, a top edge,
and a bottom edge, wherein the back of the controller
is opposite the front of the controller and the top edge
is opposite the bottom edge; and
a front control located on the front of the controller;
wherein the controller is shaped to be held in the hand
of a user such that the user’s thumb is positioned to
operate the front control; and
a first back control and a second back control, each
back control being located on the back of the controller
and each back control including an elongate member
that extends substantially the full distance between the
top edge and the bottom edge and is inherently resilient
and flexible.
Id. cl. 1 (emphasis added).
B
Ironburg accused Valve’s Steam Controller, a video
game controller for PC gaming, of infringing claims 2, 4, 7,
9, 10, and 11 of the ’525 patent. The back of the Steam
Controller has two grip buttons. In development, the
Steam Controller went through a series of prototypes (pic-
tured below), including the Chell and Dog prototypes,
which were publicly disclosed.
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IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 5
Back of the Chell prototype (Appx13889).
Back of the Dog prototype (Appx13904).
After the ’525 patent issued, Ironburg sent a letter no-
tifying Valve of the patent and Valve’s potential infringe-
ment, pointing to the Chell prototype and also noting that
“current or future products that incorporate similar fea-
tures” might also infringe. Appx13517-19. Karl
Quackenbush, Valve’s general counsel, responded to the
letter by participating in several phone calls with Iron-
burg’s representatives. Valve then began selling the final
version of the Steam Controller, which is depicted below,
in November 2015.
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6 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
Back of the final Steam Controller (Appx13882).
Ironburg sued Valve in the Northern District of Geor-
gia on December 3, 2015. Valve then filed a petition with
the United States Patent and Trademark Office (“PTO”),
which partially instituted an IPR on September 27, 2016,
as was permitted prior to the Supreme Court’s decision in
SAS Institute Inc. v. Iancu, 138 S. Ct. 1348 (2018). The
Patent Trial and Appeal Board (“PTAB” or “Board”) insti-
tuted the IPR on three grounds, but declined to institute on
two other grounds (the “Non-Instituted Grounds”). The
Board then issued its Final Written Decision on September
22, 2017, cancelling claims 1, 6, 13, 14, 16, 17, 19, and 20
of the ’525 patent. Valve did not seek a remand pursuant
to SAS, which would have allowed the Board to consider
the Non-Instituted Grounds.
In August 2017, while the IPR was pending, the case
was transferred to the Western District of Washington, and
that court adopted many of the Board’s claim construc-
tions. Prior to trial, Ironburg moved for an order applying
IPR estoppel, pursuant to 35 U.S.C. § 315(e)(2), to: (1) the
Non-Instituted Grounds and (2) the invalidity grounds
Valve discovered based on a third party’s IPR petition that
was filed after Valve’s own IPR petition (the “Non-Peti-
tioned Grounds”). The district court granted the estoppel
motion in full. The case went to trial over Zoom for five
days, and on February 1, 2021, the jury returned a verdict
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IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 7
finding that Valve willfully infringed claims 2, 4, 7, 9, 10,
and 11 of the ’525 patent and awarded $4,019,533.93 in
damages. Following trial, the district court denied Valve’s
motions for judgment as a matter of law or alternatively a
new trial and also denied Ironburg’s motion for enhanced
damages. The parties timely appealed. We have jurisdic-
tion pursuant to 28 U.S.C. § 1295(a)(1).
II
Valve makes the following arguments on appeal: (a) the
asserted claims of the ’525 patent are invalid as indefinite;
(b) the trial record did not contain sufficient evidence to
support a finding of infringement or, alternatively, Valve
is entitled to a new trial on infringement because the dis-
trict court erroneously permitted a co-inventor of the ’525
patent to provide opinion testimony on infringement while
excluding proffered testimony from Valve’s general coun-
sel; (c) the district court erred by denying as moot Valve’s
motion for judgment as a matter of law that any infringe-
ment was not willful; and (d) Valve should not have been
estopped from asserting any of the prior art grounds it
sought to press against the validity of the ’525 patent. On
cross-appeal, Ironburg argues that the district court
abused its discretion in denying its motion for enhanced
damages. We address each of these issues in turn, affirm-
ing the district court on all points except with respect to
estoppel of the Non-Petitioned Grounds, as to which we va-
cate and remand for further proceedings.
A
Valve argues that the district court erred in concluding
that two claim terms in the ’525 patent were not indefinite.
In Valve’s view, Ironburg’s asserted claims are all invalid
based on the indefiniteness of “elongate member” and “sub-
stantially the full distance between the top edge and the
bottom edge.”
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8 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
“We review a determination of indefiniteness de novo.
Determinations about governing legal standards and about
intrinsic evidence are reviewed de novo, and any factual
findings about extrinsic evidence relevant to the question
. . . are reviewed for clear error.” BASF Corp. v. Johnson
Matthey Inc., 875 F.3d 1360, 1365 (Fed. Cir. 2017). A pa-
tent is indefinite “if its claims, read in light of the specifi-
cation delineating the patent, and the prosecution history,
fail to inform, with reasonable certainty, those skilled in
the art about the scope of the invention.” Nautilus, Inc. v.
Biosig Instruments, Inc., 572 U.S. 898, 901 (2014). This
standard “mandates clarity, while recognizing that abso-
lute precision is unattainable.” Id. at 910. Words of degree
are not “inherently indefinite,” but “the court must deter-
mine whether the patent provides some standard for meas-
uring that degree.” Biosig Instruments, Inc. v. Nautilus,
Inc., 783 F.3d 1374, 1378 (Fed. Cir. 2015) (internal quota-
tion marks omitted). “Moreover, any fact critical to a hold-
ing on indefiniteness . . . must be proven by the challenger
by clear and convincing evidence.” Grace Instrument In-
dus., LLC v. Chandler Instruments Co., 57 F.4th 1001,
1008 (Fed. Cir. 2023) (internal quotation marks omitted).
Applying de novo review, we agree with the district
court that neither of the challenged terms is indefinite.
1
The parties and the district court agreed that an elon-
gate shape must be longer than it is wide. Appellant Br. at
29-30; Appellee Br. at 26; Appx11 (elongate member is “no-
tably long in comparison to its width”). Valve contends,
nonetheless, that “elongate member” is indefinite due to
the patent’s lack of objective guidance as to how much
longer than wider the member must be in order to be “elon-
gate.” Appellant Br. at 29-31. Such numerical precision is
not always required, even when using a term of degree. See
Exmark Mfg. Co. v. Briggs & Stratton Power Prods. Grp.,
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IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 9
879 F.3d 1332, 1346 (Fed. Cir. 2018); see also Sonix Tech.
Co. v. Publ’ns Int’l, Ltd., 844 F.3d 1370, 1377 (Fed. Cir.
2017) (“[A] patentee need not define his invention with
mathematical precision.”) (internal quotation marks omit-
ted). Here, notwithstanding the lack of such precision in
the patent, the record does not contain clear and convincing
evidence that a person of ordinary skill in the art would fail
to be reasonably certain whether a member is elongate or
not. To the contrary, the patent provides sufficient guid-
ance to give one of ordinary skill reasonable certainty as to
the scope of the claims.
In particular, the specification states that “[t]he pad-
dles 11 are elongate in shape and substantially extend in a
direction from the top edge to the bottom edge of the con-
troller 10.” ’525 patent 3:51-53. The specification contin-
ues:
This elongate shape allows a user to engage
the paddles with any of the middle, ring, or
little finger; it also provides that different us-
ers having different size hands can engage
with the paddles in a comfortable position
thereby reducing the effects of prolonged or
repeated use such as repetitive strain injury.
Id. 3:56-61.
In this way, the specification instructs a person of ordi-
nary skill in the art that the “elongate member” on the back
of the controller must substantially extend from the top to
bottom edge of the controller such that users of varying
hand sizes may engage the paddle with their third, fourth,
and fifth fingers. The patent expressly discloses an embod-
iment, Figure 2 (shown below), which depicts how paddles
(item 11 in the figure) may constitute elongate members.
From all this intrinsic evidence, as well as the undisputed
requirement that the length be greater than the width, one
of ordinary skill would understand that for members to be
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10 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
elongate, as the claims require, they must be sufficiently
long to permit a wide range of people, having very different
sized hands, to operate the member.
’525 patent fig. 2.
As the district court did, we find further support for our
conclusion, that a person of ordinary skill would be able to
reasonably ascertain the scope of the “elongate member” in
the context of the ’525 patent’s claims, in prior cases in
which we have rejected indefiniteness challenges to similar
claim terms. See, e.g., Exmark, 879 F.3d at 1345-47 (up-
holding “elongated and substantially straight” baffle as
definite); Biosig, 783 F.3d at 1382-84 (finding “spaced rela-
tionship,” in claim which also required “elongate member,”
correlated with width of user’s hand and not proven indef-
inite); see also generally Hologic, Inc. v. SenoRx, Inc., 639
F.3d 1329 (Fed. Cir. 2011) (involving claim requiring “elon-
gate member” in patent for balloon-expandable coronary
stent); Thomas & Betts Corp. v. Litton Sys. Inc., 720 F.2d
1572 (Fed. Cir. 1983) (involving claim requiring “elongate
member” in patent for electrical connecting device).
Valve’s arguments do not persuade us to reach a differ-
ent conclusion. Valve asserts that Ironburg’s expert’s trial
testimony that an elongate member is “notably longer than
[it is] wide,” Appx11784, was contradicted by a portion of
Ironburg’s closing statement, in which counsel told the jury
that “elongate member” imposes “no width requirement,”
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IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 11
Appx12112. Valve did not make this argument to the dis-
trict court, and it is forfeited. See In re Google Tech. Hold-
ings LLC, 980 F.3d 858, 862 (Fed. Cir. 2020) (“[F]orfeiture
is the failure to make the timely assertion of a right.”) (in-
ternal quotation marks omitted).
Valve also insists that if “elongate member” is not in-
definite, then the district court needed to construe it. The
district court, after identifying examples of cases involving
patent claims containing “elongate member” limitations
that were not held to be indefinite, and explaining that “the
patent[] use[s] the word ‘elongate’ in its usual sense, as a
modifier indicating that an element is ‘notably long in com-
parison to its width,’” stated “[t]he term ‘elongate member’
means what it says” and gave the term its plain and ordi-
nary meaning. Appx9-11, 15; see also Appx49. It also re-
jected Valve’s proposed construction – “distinct slender
object having a length much greater than a maximum
width” – because it “improperly import[ed] limitations (dis-
tinct, slender, much greater than a maximum) into the
claims.” Appx15. On de novo review, we agree with the
district court’s determinations on these points. See Sum-
mit 6, LLC v. Samsung Elecs. Co., 802 F.3d 1283, 1291
(Fed. Cir. 2015) (“Because the plain and ordinary meaning
of the disputed claim language is clear, the district court
did not err by declining to construe the claim term.”); Ac-
tiveVideo Networks, Inc. v. Verizon Commc’ns, Inc., 694
F.3d 1312, 1326 (Fed. Cir. 2012) (“ActiveVideo’s proposed
construction erroneously reads limitations into the claims
and the district court properly rejected that construction
and resolved the dispute between the parties.”).
Finally, the parties argue over whether additional ob-
jective guidance as to the meaning of “elongate member” is
provided in the prosecution history, especially the patent
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12 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
applicant’s discussion of the Ogata reference. 1 We agree
with Ironburg that Ogata provides some additional data to
a person of ordinary skill, at minimum confirming that an
“elongate member” in the context of the ’525 patent cannot
be circular. In any event, even if Valve were correct that a
skilled artisan would find nothing meaningful in the pros-
ecution history, our conclusion would remain that Valve
has nevertheless failed to prove the claim is indefinite.
2
Valve’s second indefiniteness challenge is to the claim
term “substantially the full distance between the top and
bottom edge.” This term is closely related to the “elongate
member” term; it is the “elongate member” that must ex-
tend “substantially the full distance between the top edge
and the bottom edge.” ’525 patent cl. 1. On this term, we
again agree with the district court and conclude that Valve
has failed to prove indefiniteness. 2
1 The Ogata reference is U.S. Patent No. 6,394,609.
2 While the district court labeled the section in which
it resolved this indefiniteness dispute “Substantially,”
Appx11, it is clear that it understood the dispute to be about
the alleged indefiniteness of the full claim term: “substan-
tially the full distance between the top edge and the bottom
edge.” In the first sentence of its discussion, the court re-
peated the entire challenged claim term and expressly held
that it “is likewise not indefinite.” Appx11; see also Appx4-
5 (stating that Valve contends “the . . . fourth . . . disputed
claim term[] [is] indefinite” and identifying such fourth
term as “substantially the full distance between the top
edge and the bottom edge”). Later in its analysis, the court
explained that “the elongate members, which extend ‘sub-
stantially the full distance’ between the top and bottom
edges of the controller case, can be calibrated by a skilled
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IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 13
The intrinsic evidence permits a person of ordinary
skill in the art to understand the scope of the term with
reasonable certainty. In particular, the specification de-
picts an embodiment, in Figure 1, in which “[t]here is a left
trigger 6, a right trigger 7, a left bumper 8, and a right
bumper 9 located on the top edge of the controller 1.” ’525
patent 1:27-29.
Id. Fig. 1. The patent then states that “the top edge is op-
posite the bottom edge.” Id. cl. 1; see also id. Fig. 2 (show-
ing exemplary embodiment). All this guidance reasonably
informs a person of ordinary skill in the art that the “full
artisan to suit the average span of a human hand,” connect-
ing its reasoning for finding no indefiniteness with the full
term that Valve was challenging. Appx12. In the absence
of any clear indication that the district court misappre-
hended or overlooked the full scope of Valve’s indefiniteness
contention, we must presume that the court considered, and
here rejected, all of it. See Novartis AG v. Torrent Pharms.
Ltd., 853 F.3d 1316, 1328 (Fed. Cir. 2017) (“[T]his court has
said on multiple occasions that failure to explicitly discuss
every issue or every piece of evidence does not alone estab-
lish that the tribunal did not consider it.”).
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14 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
distance” is the entirety of the length between the top edge
and the bottom edge directly opposite it.
As the district court further explained, “[w]ith respect
to the rear controls, the word ‘substantially’ is reasonably
precise, given that the purpose of the elongate shape is to
allow ‘a user to engage the paddles with any of the middle,
ring, or little finger.’” Appx11 (quoting ’525 patent 3:56-
58). We agree with the district court that, just as in Biosig,
where we concluded that an ordinarily skilled artisan
would understand that “the term ‘spaced relationship’ cor-
related with the width of a user’s hand,” Appx11 (citing 783
F.3d at 1383), here such an artisan “can . . . calibrate[]” the
elongate member “to suit the average span of a human
hand.” Appx11-12. The need to meet the purpose of the
claimed invention, which here is to allow users of various
hand sizes to operate the back controls on a hand held
game controller, helps inform one of ordinary skill’s under-
standing of the scope of the claims with reasonable cer-
tainty. Those embodiments that allow the claim’s purpose
to be effectuated are within the scope of the claims, while
those that do not are not.
Similar reasoning recently led us to vacate a district
court holding that claims directed to an “enlarged cham-
ber” in a patent for a liquid pressurized viscometer in con-
nection with oil drilling were indefinite. See Grace
Instrument, 57 F.4th at 1012. We concluded in Grace that
“the intrinsic record provides an objective boundary for a
skilled artisan – i.e., the ‘enlarged chamber’ must be large
enough to prevent, during elevated pressurization, com-
mingling of sample and pressurization fluids in the lower
measurement zone.” Id. at 1010. “Thus, in the context of
this patent, ‘enlarged chamber’ does not require that cham-
ber to be larger than some baseline object; rather it must
be large enough to accomplish a particular function.” Id. at
1009. The indefiniteness challenge in Grace was unsuc-
cessful because a person of ordinary skill in the art would
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IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 15
know when a chamber is large enough to accomplish the
function identified in the patent. Likewise, here, a person
of ordinary skill in the art would know that an elongate
member extends substantially the full distance between
the top and bottom edge of a controller when the elongate
member is long enough for different-sized hands to engage
with the member using a middle, ring, or little finger.
At trial, Ironburg’s expert, Mr. Garry Kitchen, ex-
plained just that, testifying:
[T]his positioning and shape of the back con-
trols is specifically so someone with different
length fingers, whether it be a child or an
adult, and different size hands can wrap their
hand around the controller and always have
the end of their fingers laying on the control.
Obviously if it was just a button and it was
not substantially the distance between the top
edge and the bottom edge, the fingers, de-
pending on the length of them, may not land
on the button.
Appx11767. Mr. Kitchen added that “[t]his is specifically
designed to be easy for the user to use because it covers
that range behind the fingers.” Appx11768; see also gener-
ally Guangdong Alison Hi-Tech Co. v. Int’l Trade Comm’n,
936 F.3d 1353, 1362 (“[T]he degree of precision necessary
[for a term of degree] is a function of the nature of the sub-
ject matter.”) (internal quotation marks omitted). 3
3 Further support for our conclusion is found in the
fact that the PTAB was able to construe the claim term
without any indication the parties (or their experts) had
any difficulty discerning the meaning of the term. Specifi-
cally, the Board construed “substantially the full distance
between the top edge and the bottom edge” as “largely but
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16 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
Valve compares the ’525 patent claims to claims we
held indefinite in Dow Chemical Co. v. Nova Chemicals
Corp., 803 F.3d 620 (Fed. Cir. 2015), and Teva Pharmaceu-
ticals USA, Inc. v. Sandoz, Inc., 789 F.3d 1335 (Fed. Cir.
2015). In Dow, 803 F.3d at 634-35, we found indefiniteness
because the patent failed to teach how the “slope of strain
hardening” should be measured. The evidence revealed at
least three different methods to measure the slope (the 10%
secant method, final slope method, and most linear
method) and the patentee’s expert created a fourth method
for his analysis. See id. at 633-34. We held that “the exist-
ence of multiple methods leading to different results with-
out guidance in the patent or the prosecution history as to
which method should be used renders the claims indefi-
nite.” Id. at 634. Similarly, in Teva, 789 F.3d at 1344-45,
we concluded that “molecular weight” was indefinite be-
cause the intrinsic evidence did not teach which one of
three measurements, Mp, Mn, and, Mw, was most appropri-
ate yet the different techniques produced different results.
See 789 F.3d at 1341 (“The parties agree that ‘molecular
weight’ could refer to Mp, Mw, or Mn. And they agree that
each of these measures is calculated in a different way and
would typically yield a different result for a given polymer
sample.”).
We are not persuaded by this comparison. 4 As we ex-
plained in Presidio Components, Inc. v. American Technical
not necessarily the entire distance between the top and the
bottom edges,” a construction the district court later
adopted as well. Appx11.
4 Valve did not cite Dow or Teva to the district court,
so, understandably, that court did not consider the impact
of these cases. Less understandable is why Ironburg did
not address them in its brief to us, as Valve featured Dow
and Teva in its opening brief. Neither party’s briefing
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IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 17
Ceramics Corp., 875 F.3d 1369, 1377 (Fed. Cir. 2017), what
rendered the claims in Dow and Teva indefinite was that
“the challenger ha[d] shown that there were competing ex-
isting methodologies that reached different results, and the
patent failed to describe which of the multiple methods to
use.” Here, by contrast, both parties’ experts agreed on and
used the same measurement methodology – which was
simply to find the distance between two points. That is,
unlike the parties in Dow and Teva, the disagreement be-
tween Ironburg and Valve is about the application of an
agreed-upon, straightforward methodology.
While Dow found indefinite claims of a patent that
failed to teach with reasonable certainty “how the ‘slope of
strain hardening’ should be measured,” 803 F.3d at 633(emphasis added), our case presents no dispute as to how
the “full distance” (or “substantially the full distance”) is to
be measured. Valve’s argument, instead, is that one of skill
in the art would not know where to measure. In Valve’s
view, while the “top edge” may be reasonably ascertaina-
ble, skilled artisans would not know where to locate the
“bottom edge.” This is a dispute about application of an
agreed-upon measurement technique. In the context of the
case before us, this dispute gives rise to a question of in-
fringement, because the parties disagree as to where to ap-
ply their agreed-upon measurement technique to Valve’s
accused product. The parties’ dispute in this case does not,
however, constitute clear and convincing evidence of lack
of reasonable certainty as to claim scope, given what we
have identified in the specification and given the skilled ar-
tisan’s understanding of the need to meet the purpose of
failures absolve us of our obligation to apply our binding
precedent. Ironburg does not argue that Valve forfeited its
opportunity to rely on Dow and Teva, and Ironburg’s own
decision not to brief these cases cannot be read as a conces-
sion that they are indistinguishable.
Case: 21-2296 Document: 66 Page: 18 Filed: 04/03/2023
18 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
the invention (i.e., to allow users of various hand sizes to
operate the back controls on a hand held game controller).
See generally Presidio, 875 F.3d at 1377 (“[E]ven where the
claims require a particular test result, there may be (and
often are) disputes between the parties as to the proper ap-
plication of the test methodology in the circumstances of an
individual case. But those disputes are disputes about
whether there is infringement, not disputes about whether
the patent claims are indefinite.”).
Valve devotes a sizeable portion of its briefing to de-
scribing how the parties’ infringement experts espoused
different views on the location of the top and bottom edge,
and how far an elongate member must stretch to extend
“substantially the full distance.” Ironburg correctly re-
sponds that reasonable disputes over infringement do not
make a patent claim indefinite. See Appellee Br. at 36-37
(“In every case where the parties contest infringement,
they will have some dispute as to how to apply the claim
language to the accused device. This does not mean that
every patent is indefinite [except where] infringement is
indisputable. . . . [T]o accept Valve’s argument would allow
an infringer to manufacture indefiniteness by simply hir-
ing an expert willing to disagree with the patentee’s in-
fringement analysis.”). That the jury could have credited
Valve’s expert and found that the Steam Controller does
not have elongate members stretching “substantially the
full distance from the top edge to the bottom edge,” but al-
ternatively was free to (and did) credit Ironburg’s contrary
position, does not render the claim indefinite. See
SmithKline Beecham Corp. v. Apotex Corp., 403 F.3d 1331,
1340-41 (Fed. Cir. 2005) (“The test for indefiniteness does
not depend on a potential infringer’s ability to ascertain the
nature of its own accused product to determine infringe-
ment, but instead on whether the claim delineates to a
skilled artisan the bounds of the invention.”). Instead, it
simply means the parties here had a genuine dispute on
the material question of infringement.
Case: 21-2296 Document: 66 Page: 19 Filed: 04/03/2023
IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 19
The dissent contends we are disrupting settled law by
“artificially bifurcating the ‘how’ and ‘where’” of measure-
ment and are doing so “in order to remove the ‘where’ ques-
tion from the assessment of indefiniteness.” Dissent at 6.
This is a misreading of our analysis, which is consistent
with precedent for the reasons we have explained. As the
dissent elsewhere acknowledges, the distinction between
“how” and “where” is not our creation and has been recog-
nized in our cases at least since Dow. Id. at 5 (“Dow makes
clear that the indefiniteness of measurement claims can in-
volve both ‘how’ to measure (i.e., the means for making the
measurement) and ‘where’ along an item to be measured to
apply the ‘how’ means.”). And our decision today does not
establish per se rules that teaching “how” to measure nec-
essarily renders a claim definite or that questions of
“where” are always issues of infringement.
Instead, our holding today is, necessarily, bound to the
record before us, which is one on which Valve has failed to
prove, by the requisite clear and convincing evidence, that
one of skill in the art would lack reasonable certainty as to
claim scope. One weakness in Valve’s showing – and a
principal distinction from Dow and Teva – is that here the
parties agree on how to measure distance between two
points and disagree as to where to find those two points.
This is essentially the opposite of Dow, where we assumed
the patentee was correct as to where to take the pertinent
measurement (at the maximum value of the slope of the
hardening curve) but invalidated the claims due to the un-
certainty as to how to measure. Moreover, as we have ex-
plained, the ’525 patent provides a person of skill in the art
some guidance as to where to measure, including in figures
identifying exemplary top and bottom edges and in the re-
quirements that embodying paddles extend sufficiently far
to allow “a user to engage the paddles with any of the mid-
dle, ring, or little finger” and enable “different users having
different size hands [to] engage with the paddles in a com-
fortable position.” ’525 patent 3:56-60.
Case: 21-2296 Document: 66 Page: 20 Filed: 04/03/2023
20 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
Accordingly, we affirm the district court’s conclusion
that the claims are not indefinite.
B
The district court correctly denied Valve’s motions for
judgment as a matter of law and for a new trial. The jury
had substantial evidence to conclude that the Steam Con-
troller’s elongate members are “inherently resilient and
flexible” – which is the only claim limitation Valve chal-
lenges on appeal – and the district court did not abuse its
discretion in its evidentiary rulings with respect to Mr.
Ironmonger or Mr. Quackenbush.
We review decisions on motions for judgment as a mat-
ter of law, motions for a new trial, and evidentiary rulings
under the law of the regional circuit. See InTouch Techs.,
Inc. v. VGO Commc’ns, Inc., 751 F.3d 1327, 1338 (Fed. Cir.
2014). “Under Ninth Circuit law, when reviewing the de-
nial of a renewed motion for JMOL [i.e., judgment as a mat-
ter of law], ‘[t]he test is whether the evidence, construed in
the light most favorable to the nonmoving party, permits
only one reasonable conclusion, and that conclusion is con-
trary to that of the jury.’” Id. (quoting White v. Ford Motor
Co., 312 F.3d 998, 1010 (9th Cir. 2002)). The Ninth Circuit
reviews the denial of a new trial motion and evidentiary
rulings for abuse of discretion. See id. at 1339 (citing Mol-
ski v. M.J. Cable, Inc., 481 F.3d 724, 728 (9th Cir. 2007);
United States v. Wiggan, 700 F.3d 1204, 1210 (9th Cir.
2012)). Infringement is a question of fact that we review
for substantial evidence when tried to a jury. See ACCO
Brands, Inc. v. ABA Locks Mfr. Co., 501 F.3d 1307, 1311
(Fed. Cir. 2007). Applying these standards, we affirm the
district court on each of the infringement-related issues.
1
To infringe the asserted claims, the Steam Controller
must have an “elongate member” that is “inherently
Case: 21-2296 Document: 66 Page: 21 Filed: 04/03/2023
IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 21
resilient and flexible.” The district court, following the
PTAB, construed “inherently resilient and flexible” as “the
member may be bent or flexed by a load, for example, the
force exerted by a user’s finger, and will then return to the
unloaded position.” Appx128-29. While Valve insists the
jury lacked substantial evidence that its accused device
satisfies this claim limitation, we disagree.
The evidence the jury was free to credit, and on which
it could base its finding of infringement, begins with the
patent and the Steam Controller itself. “Each juror re-
ceived a Steam Controller via overnight delivery and had
access to the accused device during closing arguments and
deliberations.” Appx44. Neither party objected to the pro-
vision of an accused device to each juror as part of the re-
mote trial and neither party proposed that jurors be
instructed they could not base their infringement decision
on their own perception of the device. To the contrary, both
parties emphasized to the jury the simplicity of the tech-
nology and Valve, especially, encouraged jurors to decide
the case based solely on their review of the patent and the
device they held in their hands. See, e.g., Appx11396
(Valve informing jury during opening statement it could
make every necessary decision “with just two pieces of evi-
dence:” the ’525 patent and Steam Controller); Appx12017
(Ironburg beginning closing argument by noting jurors had
received accused device, adding “[y]ou’re probably going to
want to have the controller out and in your hand. The is-
sues in this case are simple, . . . but now that you have the
controller, you’re probably going to be asking yourself: Why
was this so difficult? Because it’s really pretty easy.”). In
his closing argument, Valve’s counsel told jurors “there are
two pieces of essential evidence. The patent and the con-
troller. Everything that you need to do at the end of this
trial you can do with these two things.” Appx12149. He
urged the jury to “ignore the distractions in this case” and
focus on “the ball. The Steam Controller is the ball. This
Case: 21-2296 Document: 66 Page: 22 Filed: 04/03/2023
22 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
should be your singular focus through your deliberations.”
Id. During closing, Valve invited the jurors to “pull out
your Steam Controller, again.” Appx12157.
Valve identifies no reason why jurors would have been
unable to determine for themselves whether the alleged
“elongate members” in the Steam Controller “may be bent
or flexed by” the jurors pressing on the device itself, and
then evaluating whether it “returns” to its original “un-
loaded position.” Given our record, this undertaking would
have provided substantial evidence to support a verdict
finding infringement. Thus, we agree with the district
court that “expert testimony was not necessary; the tech-
nology at issue was easily understandable. . . . [T]he jury
could therefore have reached its decision on infringement
by ignoring all of the expert testimony and focusing solely
on the patent and the accused device.” Appx50 (internal
quotation marks and citations omitted).
Of course, the record contains additional evidence of in-
fringement, including expert testimony. The jury heard
testimony from Ironburg’s expert, Mr. Kitchen, who ex-
plained his opinion as to why the Steam Controller in-
fringed. See Appx11761-72. For instance, Mr. Kitchen
testified that the elongate members he identified on the
Steam Controller have ribbing on the back panel that
strengthens the plastic and makes the button feel “firm,”
and also that the ribbing tapers down so that “when you
press the button, . . . your pressing can flex the button, . . .
leaving the thin plastic to be able to be flexible.”
Appx11762. While the jury also heard from Valve’s non-
infringement expert, Mr. Dezmelyk, see Appx11982-88, it
is presumed to have found Mr. Kitchen more credible and
persuasive, as it was permitted to do. See, e.g., Ericsson,
Inc. v. D-Link Sys., Inc., 773 F.3d 1201, 1224-25 (Fed. Cir.
2014) (“Both parties presented expert testimony . . . and we
see no reason why the jury was not entitled to credit [plain-
tiff’s] evidence over [defendant’s] evidence.”). In this
Case: 21-2296 Document: 66 Page: 23 Filed: 04/03/2023
IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 23
regard, it is worth noting that Valve chose to barely cross-
examine Mr. Kitchen, asking him only four questions, none
of which related to the substance of his infringement opin-
ion. Appx11808-10.
Duncan Ironmonger, a co-inventor of the ’525 patent,
also testified. We address his testimony in more detail just
below. For purposes of Valve’s motion for judgment as a
matter of law concerning infringement, all that we need to
say about Mr. Ironmonger’s testimony is that it could have
provided additional support for the jury’s finding of in-
fringement, although there is also sufficient evidence to
support the verdict even without considering it.
Hence, we affirm the district court’s denial of Valve’s
motion with respect to infringement.
2
Valve moves for a new trial on infringement based on:
(1) the district court’s admission of what Valve character-
izes as unqualified expert opinion testimony from Iron-
burg’s corporate representative, Mr. Ironmonger, who is
also a co-inventor on the ’525 patent-in-suit, and (2) the ex-
clusion of testimony Valve sought to admit through its own
corporate representative, Karl Quackenbush, who serves
as its general counsel. We find no abuse of discretion in
either of these evidentiary rulings.
On direct examination, Ironburg’s counsel asked Mr.
Ironmonger why Ironburg sent its pre-suit letter, dated De-
cember 3, 2015, to Valve. Mr. Ironmonger responded by
explaining how he and his colleagues had, after the ’525
patent was issued, waited to receive a Steam Controller,
which his team then evaluated and determined infringed
the Ironburg patent. Appx11529-30. There was no objec-
tion from Valve to this testimony. In response to a subse-
quent question, Mr. Ironburg answered that the Steam
Controller has “two paddles that obviously are flexible” and
Case: 21-2296 Document: 66 Page: 24 Filed: 04/03/2023
24 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
a button underneath the paddles – and at that point Valve
objected, stating that “[t]he witness is providing expert tes-
timony, opinion testimony.” Id. at 11530. The district
court overruled the objection and Mr. Ironmonger pro-
ceeded to offer additional testimony, including that he
thought the claim elements were met and that the final
version of the Steam Controller “infringed still on our pa-
tent.” Id. at 11532. 5
The testimony about which Valve complains all came
in the context of Mr. Ironmonger describing Ironburg’s De-
cember 3, 2015 letter to Mr. Quackenbush, accusing the
Steam Controller of infringing the ’525 patent. The district
court overruled Valve’s objection because, as it later ex-
plained, “Ironmonger did not provide lay opinions about in-
fringement, but rather explained why plaintiff’s attorney,
at Mr. Ironmonger’s behest, sent a cease-and-desist letter
to defendant.” Appx61. This was fact, not expert, testi-
mony, and the district court was free to exercise its discre-
tion to treat it as relevant to Ironburg’s willfulness claim
and, therefore, admissible.
We recognize that after Valve’s objection was over-
ruled, Mr. Ironmonger proceeded to provide more testi-
mony, which ultimately stretched to two pages of the trial
transcript, stating his opinion that certain elements of the
’525 patent’s claims are met by the Steam Controller.
Appx11530-32. Even assuming this strayed into the realm
of undisclosed expert opinion, Valve has failed to show that
any error in admitting it was prejudicial, given all the other
5 On cross-examination, defense counsel attempted to
undermine whatever weight the jury might accord to Mr.
Ironmonger’s testimony, getting him to agree that he is not
a patent lawyer, has no specialized training in patents, and
must consult a patent lawyer when he has a question re-
garding infringement. See Appx11549.
Case: 21-2296 Document: 66 Page: 25 Filed: 04/03/2023
IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 25
evidence of infringement the jury had before it, and given
that the jury had already heard, without objection, Mr.
Ironmonger’s general opinion that the Steam Controller in-
fringed.
In seeking a new trial, Valve relies heavily on
HVLPO2, LLC v. Oxygen Frog, LLC, 949 F.3d 685 (Fed.
Cir. 2020), in which we found a district court abused its
discretion by permitting a non-expert to testify on issues of
validity. HVLPO2 is not analogous, however, as there the
witness was directly asked for his opinion on a disputed
patent issue (obviousness). See id. at 689. Here, Mr. Iron-
monger was not asked for an opinion on infringement, nor
was there any objection from Valve when he opined gener-
ally that he believed the Steam Controller infringed; his
testimony, instead, was directed to proving Valve’s
knowledge of the patent, the course of the parties’ interac-
tions, and his own decision-making process, all of which
were probative of Ironburg’s willful infringement claim.
Moreover, and importantly, “any error was harmless be-
cause it was ‘more probable than not that the . . . admission
of the [Ironmonger] evidence did not affect the jury’s ver-
dict.’” Hardeman v. Monsanto Co., 997 F.3d 941, 968 (9th
Cir. 2021).
For all of these reasons, there was no abuse of discre-
tion in admitting Mr. Ironmonger’s testimony and, even if
there was, any error was harmless, as the jury had sub-
stantial evidence to support a verdict of infringement even
without considering this testimony.
We reach the same conclusions with respect to the dis-
trict court’s exclusion of certain testimony Valve sought to
offer through Mr. Quackenbush. The district court did not
abuse its discretion and its decision does not warrant a new
trial.
Valve initially proffered that it intended to have Mr.
Quackenbush testify as to his own opinion on infringement.
Case: 21-2296 Document: 66 Page: 26 Filed: 04/03/2023
26 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
Because, however, Valve had not permitted him to testify
about this topic during his deposition, instead asserting at-
torney-client privilege, the district court granted Iron-
burg’s motion in limine to exclude this testimony. Valve
then revised its proffer of what it would seek to elicit from
Mr. Quackenbush at trial and he was permitted to testify
consistent with that revision.
The district court did not abuse its discretion in pre-
cluding Valve from presenting evidence at trial on a topic
for which it did not provide discovery. See Energy Heating,
LLC v. Heat On-The-Fly, LLC, 889 F.3d 1291, 1303 (Fed.
Cir. 2018) (“The attorney-client privilege cannot be used as
both a sword and a shield.”); see also Chevron Corp. v.
Pennzoil Co., 974 F.2d 1156, 1162 (9th Cir. 1992) (same).
In Energy Heating, 889 F.3d at 1303, we held that the dis-
trict court did not abuse its discretion by excluding witness
testimony at trial after the proponent of the testimony had
prohibited the same witness from providing such testimony
at his deposition, instead asserting privilege. Id. (stating
party “cannot have it both ways”). It follows, and we hold,
it was not an abuse of discretion to deny the new trial Valve
sought on the basis of the excluded evidence.
Moreover, if any error had occurred in connection with
Mr. Quackenbush’s testimony, it did not prejudice Valve.
Mr. Quackenbush was permitted to present part of Valve’s
non-infringement defense, which was that Ironburg’s letter
attacked the Chell prototype and by the time Valve re-
ceived the letter, Valve was “past that design, and that was
not the design anymore. And so the claims about the Chell
controller weren’t really relevant anymore.” Appx11643-
44. Valve makes no persuasive showing that admission of
the excluded portion of Mr. Quackenbush’s testimony
would have affected the jury’s verdict. See Unicolors, Inc.
v. H&M Hennes & Mauritz, L.P., 52 F.4th 1054, 1063 (9th
Cir. 2022) (“Such [evidentiary] rulings will be reversed only
if the error more likely than not affected the verdict.”).
Case: 21-2296 Document: 66 Page: 27 Filed: 04/03/2023
IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 27
Valve also argues it should get a new trial because
Ironburg’s counsel observed in closing argument that the
jury had never heard Mr. Quackenbush “say to anyone, ‘We
don’t infringe.’” Appx12193. We disagree. As the district
court pointed out, Valve “did not contemporaneously ob-
ject” to this statement “and it never requested a limiting
instruction.” Appx63; see also Appx12193. Valve has not
identified a meritorious basis for relief.
Thus, we affirm the district court’s denial of Valve’s
motion for a new trial.
3
Valve also moved for judgment as a matter of law that
any infringement was not willful or, in the alternative, for
a new trial on willfulness. The district court erroneously
struck this motion as moot, reasoning that because it was
not going to exercise its discretion to enhance infringement
damages, it did not matter whether the willfulness judg-
ment remained or not. Willfulness and enhancement are
separate issues, see Halo Elecs., Inc. v. Pulse Elecs., Inc.,
579 U.S. 93, 106 (2016) (explaining enhanced damages
“should generally be reserved for egregious cases typified
by willful misconduct” and need not follow automatically
from “a finding of egregious misconduct”); SRI Int’l, Inc. v.
Cisco Sys., Inc., 14 F.4th 1323, 1330 (Fed. Cir. 2021) (dis-
tinguishing standards for enhancement and willfulness),
and a finding of willful infringement may have collateral
consequences even for a party not ordered to pay enhanced
damages, such as reputational injuries and possible non-
dischargeability of debts in bankruptcy, see In re Tran-
tham, 304 B.R. 298, 305-06 (B.A.P. 6th Cir. 2004). Valve
should have been provided a ruling on the merits of its mo-
tion.
Nevertheless, the district court’s error is harmless. See
generally 28 U.S.C. § 2111 (“On the hearing of any appeal
or writ of certiorari in any case, the court shall give
Case: 21-2296 Document: 66 Page: 28 Filed: 04/03/2023
28 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
judgment after an examination of the record without re-
gard to errors or defects which do not affect the substantial
rights of the parties.”); Tex. Advanced Optoelectronic Sols.
v. Renesas Elecs. Am., Inc., 895 F.3d 1304, 1316 (Fed. Cir.
2018) (“Harmless-error review is a flexible one in which we
determine whether the error is harmless through the case
specific application of judgment, based on examination of
the record.”) (internal quotation marks and alterations
omitted). Valve does not seek remand for the district court
to conduct any further review on the issue of willfulness; it
seeks only reversal. Accordingly, both parties’ arguments
are devoted entirely to the merits of the evidence for or
against willfulness. In these circumstances, it is proper for
us to follow the parties’ lead and assess whether there is
substantial evidence of record to support the finding of will-
ful infringement. See Orion Tech., Inc. v. United States,
704 F.3d 1344, 1350 (Fed. Cir. 2013) (“An appellate court
can affirm a decision of the trial court upon any ground
supported by the record.”); Singleton v. Wulff, 428 U.S. 106,
121 (1976) (“[T]here are circumstances in which a federal
appellate court is justified in resolving an issue not passed
on below, as where the proper resolution is beyond any
doubt.”). There is.
To prevail on its claim for willful infringement, Iron-
burg was required to prove, by a preponderance of the evi-
dence, that Valve knew of the ’525 patent and then engaged
in “deliberate or intentional infringement.” SRI Int’l, 14
F.4th at 1330. Cognizant of these required elements, the
parties stipulated that Valve had notice of the patent –
since Ironburg, “through its counsel, sent [Valve] a letter
dated March 7, 2014, and provided [Valve] with notice of
the ’525 patent,” Appx11168 – and agreed to the court in-
structing the jury that it needed to determine whether
Valve acted with “deliberate or reckless disregard of plain-
tiff’s patent rights,” Appx12094. The jury heard Mr.
Quackenbush’s admission that he never provided the ’525
Case: 21-2296 Document: 66 Page: 29 Filed: 04/03/2023
IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 29
patent to Valve’s designers, a point which the designers
confirmed in their testimony, and learned that Valve did
not attempt to design around the patent. Appx11602-03,
11632-33, 11702. All of this provided the jury with sub-
stantial evidence to support a finding that Valve “reck-
lessly” disregarded Ironburg’s patent rights and, therefore,
willfully infringed. 6
Thus, we affirm the district court’s denial of Valve’s
motion and its entry of judgment of willful infringement.
C
Valve identified four grounds for invalidity, all of which
the district court ruled Valve was estopped from litigating.
Appx24-30. On appeal, Valve argues that it could not rea-
sonably have raised either the Non-Instituted Grounds
(the Enright-Tosaki-Ono and the Tosaki-Jimakos grounds)
or the Non-Petitioned Grounds (the Kotkin and the Will-
ner-Koji-Raymond grounds) in the IPR. 7 Interpretation of
6 “A jury is presumed to follow jury instructions.”
Omega Pats., LLC v. CalAmp Corp., 13 F.4th 1361, 1372
(Fed. Cir. 2021) (internal quotation marks omitted).
7 The prior art references making up these combina-
tions are: U.S. Pub. 2010/0073283 (“Enright”); U.S. Patent
No. 5,989,123 (“Tosaki”); U.S. Pub. 2001/0025778 (“Ono”);
Jimakos Sn, Rapid Fire Mod for Wireless Xbox 360 Control-
ler, Step by Step Tutorial with Pictures, (July 9, 2008),
http://forums.xbox-scene.com/index.php?/topic/643928rapi-
d-fire-mod-forwireless-xbox-360-controller/page-23 (posts
341 to 346) (“Jimakos”); U.S. Pub. 2010/0298053 (“Kotkin”);
U.S. Patent No. 6,760,013 (“Willner”); Japanese Patent
Appl. No. JP-A H10-020951 (“Koji”); and U.S. Patent No.
5,773,769 (“Raymond.”). Contrary to Ironburg’s contention,
the estoppel issue is not moot with respect to claims 12 and
15 of the ’525 patent, as Valve filed counterclaims for a
Case: 21-2296 Document: 66 Page: 30 Filed: 04/03/2023
30 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
the IPR estoppel statute, an issue unique to patent law, is
a question of law we review de novo applying Federal Cir-
cuit law. See Click-to-Call Techs. LP v. Ingenio, Inc., 45
F.4th 1363, 1367 (Fed. Cir. 2022); Pharmacia & Upjohn Co.
v. Mylan Pharms., Inc., 170 F.3d 1373, 1381 n.4 (Fed. Cir.
1999). Undertaking this review, we affirm the district
court with respect to estoppel of the Non-Instituted
Grounds but vacate and remand with respect to estoppel of
the Non-Petitioned Grounds.
The estoppel statute provides:
(2) Civil actions and other proceedings. The
petitioner in an inter partes review of a claim
in a patent under this chapter that results in
a final written decision under section 318(a),
or the real party in interest or privy of the pe-
titioner, may not assert either in a civil action
arising in whole or in part under section 1338
of title 28 or in a proceeding before the Inter-
national Trade Commission under section 337
of the Tariff Act of 1930 that the claim is in-
valid on any ground that the petitioner raised
or reasonably could have raised during that
inter partes review.
35 U.S.C. § 315(e)(2) (emphasis added). We now consider
the application of this statutory language to the Non-Insti-
tuted Grounds and the Non-Petitioned Grounds.
1
judgment that these claims are invalid. See Appx1250-51;
see also Fort James Corp. v. Solo Cup Co., 412 F.3d 1340,
1341 (Fed. Cir. 2005) (“A counterclaim questioning the va-
lidity or enforceability of a patent raises issues beyond the
initial claim for infringement that are not disposed of by a
decision for non-infringement.”).
Case: 21-2296 Document: 66 Page: 31 Filed: 04/03/2023
IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 31
We have previously held that “[t]o give effect to the lan-
guage ‘reasonably could have raised,’” as used in
§ 315(e)(2), “estoppel applies not just to claims and grounds
asserted in the petition and instituted for consideration by
the Board, but to all grounds not stated in the petition but
which reasonably could have been asserted against the
claims included in the petition.’” Click-to-Call, 45 F.4th at
1370 (quoting Cal. Inst. of Tech. v. Broadcom Ltd., 25 F.4th
976, 991 (Fed. Cir. 2022)). “[T]he petition, not the institu-
tion decision” “defines the scope of the IPR” litigation. Id.
at 1369. The Non-Instituted Grounds were explicitly con-
tained in the petition. They were “raised . . . during the
inter partes review.” 35 U.S.C. § 315(e)(2). Contrary to
Valve’s argument that an IPR does not begin until institu-
tion, we have concluded that “[g]iven the statutory inter-
pretation in SAS [Institute, Inc. v. Iancu, 138 S. Ct. 1348
(2018)], any ground that could have been raised in a peti-
tion is a ground that could have been reasonably raised
‘during inter parties review.’” Cal. Inst. of Tech., 25 F.4th
at 990. Thus, Valve is estopped from litigating the Non-
Instituted Grounds.
As Valve acknowledges, it had the opportunity, follow-
ing the Supreme Court’s issuance of its decision in SAS,
which held that the PTO may institute on all or none of the
claims challenged in a petition but could not grant a partial
institution, to seek remand of its IPR to the Board. Valve
chose not to pursue this course. Valve’s “choice to leave
unremedied the Board’s mistake does not shield it from es-
toppel . . . [with respect to the grounds] it included in its
IPR petition.” Click-to-Call, 45 F.4th at 1370.
Case: 21-2296 Document: 66 Page: 32 Filed: 04/03/2023
32 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
Thus, we affirm the district court’s estoppel determina-
tion with respect to the Non-Instituted Grounds. 8
2
We turn now to the district court’s decision to estop
Valve from asserting the Non-Petitioned Grounds. Be-
cause the district court improperly placed the burden of
proof on Valve, to show that it could not “reasonably . . .
have raised” the Non-Petitioned Grounds in its petition,
when instead the burden of proof rests with Ironburg to
prove that these were grounds Valve “reasonably could
have raised” during the IPR, we vacate and remand for fur-
ther proceedings.
We have not fully addressed the standards by which a
determination is to be made as to what invalidity grounds
not presented in a petition are estopped pursuant to
§ 315(e)(2). In this challenging context, the district court
looked to other district courts that have confronted the is-
sue. The district court agreed with those courts that have
concluded that an IPR petition “reasonably could have
raised” any grounds that “a skilled searcher conducting a
diligent search reasonably could have been expected to dis-
cover.” Appx27 (citing SiOnyx, LLC v. Hamamatsu Pho-
tonics K.K., 330 F. Supp. 3d 574, 602 (D. Mass. 2018)); see
also Clearlamp, LLC v. LKQ Corp., 2016 WL 4734389, at
*8 (N.D. Ill. 2016) (stating and rejecting proposition that
8 Valve’s heavy reliance on Shaw Industries Group,
Inc. v. Automated Creel Systems, Inc., 817 F.3d 1293 (Fed.
Cir. 2016), is unavailing, as we recently overruled Shaw.
See Cal. Inst. of Tech., 25 F.4th at 991 (explaining Shaw
“rests on the [flawed] assumption that the Board need not
institute on all grounds” stated in petition).
Case: 21-2296 Document: 66 Page: 33 Filed: 04/03/2023
IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 33
“[c]urrent law . . . is amenable to the interpretation that
litigants are estopped from raising any issue . . ., even if
only a scorched-earth search around the world would have
uncovered the prior art in question”). As these cases
demonstrate, the “skilled searcher” standard is consistent
with the statutory requirement that a petitioner be es-
topped from asserting “any ground that the petitioner . . .
reasonably could have raised during . . . inter partes re-
view.” § 315(e)(2) (emphasis added). Both parties before
us agree we should apply this standard here, see Appellant
Br. at 60; Appellee Br. at 50-51, and we do so. See generally
Cal. Inst. of Tech., 25 F.4th at 990 (“[A]ny ground that
could have been raised in a petition is a ground that could
have been reasonably raised ‘during inter partes review.’”)
(emphasis added). Accordingly, we hold that, provided the
other conditions of the statute are satisfied, § 315(e)(2) es-
tops a petitioner as to invalidity grounds a skilled searcher
conducting a diligent search reasonably could have been
expected to discover, as these are grounds that the peti-
tioner “reasonably could have raised” in its petition.
The district court did not explicitly address which
party has the burden to prove what a skilled searcher con-
ducting a diligent search reasonably could, or could not,
have been expected to discover. Implicit in the district
court’s reasoning, however, is the view that the burden of
proof rests on Valve, as the party challenging the patent’s
validity.
Ironburg’s evidence consisted of pointing to the face of
the ’525 patent, which listed Willner as a prior art refer-
ence, and to a January 3, 2018 IPR directed to Ironburg’s
’525 patent, filed by a third-party entity, Collective Minds.
The Collective Minds petition listed Willner-Koji-Raymond
and, separately, Kotkin, as its grounds for invalidity. In
response to Ironburg’s contentions, Valve produced evi-
dence of its own search, which did not uncover Kotkin, Koji,
and Raymond, and tried to show the court that its search
Case: 21-2296 Document: 66 Page: 34 Filed: 04/03/2023
34 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
was, nevertheless, reasonably diligent. Valve further ob-
served that the record is silent as to the level of diligence
Collective Minds undertook in finding its references. As
Valve explained, Collective Minds may have used “many
other possible ways . . . that have nothing to do with what
a skilled searcher would have found” and Ironburg had not
proven otherwise. Appx8447.
After reviewing this record, the district court concluded
that “Valve has offered no evidence concerning the degree
of difficulty involved in locating the prior art references at
issue.” Appx28-30; see also id. at 29 (faulting Valve’s “lack
of information concerning how Collective Minds” discov-
ered references). It then held this hole in the record
against Valve, relying on it as the basis to find Valve es-
topped from pressing the Non-Petitioned Grounds. In this
way, it is plain that the district court was imposing the bur-
den of proof on Valve.
The district court’s estoppel conclusion rests, however,
on an assumption, not yet proven on the record, that the
prior art search undertaken by Collective Minds was only
“reasonably” diligent and did not involve extraordinary
measures. If Collective Minds employed “scorched earth”
tactics to find the references making up the Non-Petitioned
Grounds, then its experience may be irrelevant to a deter-
mination of what would have been discovered by an ordi-
narily skilled searcher acting with merely reasonable
diligence.
Valve challenges the district court’s reasoning, point-
ing us to other district courts that have placed the estoppel
burden of proof solely on the patent owner, as the party
seeking to benefit from an assertion of estoppel. See Clear-
lamp, 2016 WL 4734389, at *9 (“It is the proponent of an
estoppel argument that bears the burden.”); Pavo Sols.
LLC v. Kingston Tech. Co., 2020 WL 1049911, at *4 (C.D.
Cal. 2020) (same); Innovative Memory Sys., Inc. v. Micron
Case: 21-2296 Document: 66 Page: 35 Filed: 04/03/2023
IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 35
Tech., Inc., 2022 WL 4548644, at *3 (D. Del. 2022) (parties
agreeing that burden is on patentee asserting estoppel).
We agree with Valve and now hold that the burden of prov-
ing, by a preponderance of the evidence, that a skilled
searcher exercising reasonable diligence would have iden-
tified an invalidity ground rests on the patent holder, as
the party asserting and seeking to benefit from the affirm-
ative defense of IPR estoppel. Our holding is consistent
with the general practice that a party asserting an affirm-
ative defense bears the burden to prove it. See, e.g., K-Mart
Corp. v. Oriental Plaza, Inc., 875 F.2d 907, 912 (1st Cir.
1989) (“The party asserting the estoppel has the burden of
proving it.”); United States v. Asmar, 827 F.2d 907, 912 (3d
Cir. 1987) (same); Kennedy v. United States, 965 F.2d 413,
417 (7th Cir. 1992) (same); Van Antwerp v. United States,
92 F.2d 871, 875 (9th Cir. 1937) (same); see also Fuji Photo
Film Co. v. Int’l Trade Comm’n, 474 F.3d 1281, 1293 (Fed.
Cir. 2007) (placing burden on party asserting affirmative
defense of repair); Titan Tire Corp. v. Case New Holland,
Inc., 566 F.3d 1372, 1376 (Fed. Cir. 2009) (placing burden
on alleged infringer who raises affirmative defense of inva-
lidity).
Ironburg cites no persuasive basis for us to depart from
this approach here. Ironburg relies on one district court’s
view that while the “initial burden to assert estoppel
should be on the party seeking to invoke it,” thereafter “the
burden shifts to the responding party.” See Palomar
Techs., Inc. v. MRSI Sys., LLC, 2020 WL 2115625, at *4 (D.
Mass. 2020). Ironburg’s principal contention is that the
burden of proof should not rest on the patent owner be-
cause often the patent challenger will aim to protect details
of its search efforts by asserting attorney-client privilege
relating to its undertaking. While district courts may en-
counter privilege issues, this would not be out of the ordi-
nary for patent litigation and, in all events, the district
court can resolve such issues and can factor such resolution
Case: 21-2296 Document: 66 Page: 36 Filed: 04/03/2023
36 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
into any findings that must be made with respect to estop-
pel. The inquiry into what a skilled and diligent searcher
would reasonably have discovered is ultimately concerned
with what the searcher of ordinary skill would find through
reasonable diligence and not what an actual researcher in
fact did find through whatever level of diligence she exer-
cised.
Accordingly, the burden is on Ironburg to prove, by a
preponderance of the evidence, that a skilled searcher con-
ducting a diligent search reasonably would have been ex-
pected to discover the Willner-Koji-Raymond and Kotkin
grounds for invalidating claims of the ’525 patent. Because
the district court did not place this burden on Ironburg, but
instead on Valve, we will vacate and remand for the district
court to determine whether Ironburg can meet its burden.
The relief we are granting is consistent with that which
Valve seeks in its briefing to us: that we vacate and remand
for further proceedings on whether Valve should be es-
topped with respect to the Non-Petitioned Grounds. While
Valve specifically asks for a “trial,” it will be for the district
court to determine if a trial is needed or whether the dis-
pute is amenable to resolution via case-dispositive motions
or some other mechanism. 9 We also leave it to the district
court, in the first instance, to address related issues that
may arise, such as whether to reopen the record and permit
9 Ironburg argues that Valve waived the right to ask
for a trial on issues relating to estoppel. See Appellee Br. at
49 n. 3. This is incorrect. Valve expressly asked for a trial,
in the event the district court did not agree that Valve’s own
evidence showed a reasonable search would not have
yielded the non-petitioned grounds. See Appx1301, 8448;
see also Appellant Resp. & Reply Br. at 43.
Case: 21-2296 Document: 66 Page: 37 Filed: 04/03/2023
IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 37
discovery, the relevance of Valve’s own search efforts, and
how to handle any attorney-client privilege disputes.
D
III
Finally, we address Ironburg’s cross-appeal, which
asks us to award Ironburg enhanced damages for Valve’s
willful infringement. We review a district court’s decision
regarding enhanced damages for an abuse of discretion.
See Halo, 579 U.S. at 107.
“Enhanced damages are generally only appropriate in
egregious cases of misconduct, such as willful, wanton, or
malicious behavior,” “[b]ut an award of enhanced damages
does not necessarily flow from a willfulness finding.” Pre-
sidio Components, 875 F.3d at 1382. “In determining
whether enhanced damages are appropriate, courts should
consider the overall circumstances of the case.” Id.The district court did not abuse its discretion in declin-
ing to grant enhanced damages. There is nothing unrea-
sonable in the district court’s finding that this a “garden
variety” case of infringement and that there was no evi-
dence of copying, notwithstanding the jury’s finding of will-
fulness, which could have been based on evidence other
than copying. Appx48. For example, consistent with the
court’s instructions, the jury could have predicated its find-
ing of willful infringement on “deliberate or reckless disre-
gard of plaintiff’s patent rights,” Appx12094 (jury
instructions), without necessarily finding that Valve copied
Ironburg’s patent claims. The jury might, for instance,
have concluded that Mr. Quackenbush’s decision to not no-
tify Valve’s designers and engineers of Ironburg’s patent
was reckless, and therefore that Valve’s infringement was
willful. The jury could have found Valve did not copy, but
was reckless in not trying to avoid copying, and, based on
the court’s instructions, nevertheless still found Valve’s
Case: 21-2296 Document: 66 Page: 38 Filed: 04/03/2023
38 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
infringement was willful. See generally Presidio Compo-
nents, 875 F.3d at 1382 (concluding that district court did
not abuse discretion in declining to enhance damages after
jury’s willfulness finding).
Nor did the district court abuse its discretion in find-
ing, as further reason not to enhance, that the only patent
claim Ironburg alleged Valve infringed prior to suit was
later cancelled by the PTAB in the IPR. Appx47 (“[T]he
Court takes into account that Claim 1 of the ’525 Patent
has been declared invalid by the PTAB, and thus, the fea-
tures that plaintiff accuses defendant of intentionally cop-
ying and/or making ‘no attempt to design around,’ namely
the two back controls comprised of elongate members, are
not themselves protected by the ’525 Patent.”) (internal ci-
tation omitted). It was not clear error to accept the testi-
mony of Valve’s designer that he only learned of Ironburg’s
patent at his deposition, nor was it an abuse of discretion
to conclude therefrom that “[t]he record does not support a
conclusion that defendant pirated plaintiff’s invention.”
Appx47. Further, the record establishes that, for whatever
reason, Valve’s development process following receipt of
Ironburg’s pre-suit letter evolved away from the Chell pro-
totype on which Ironburg had based its allegations. See id.In sum, there was no abuse of discretion in the district
court’s consideration of the totality of the circumstances
and denial of enhanced damages. We affirm this part of
the district court’s judgment.
IV
We have considered the parties’ remaining arguments
and find them unpersuasive. Thus, for the foregoing rea-
sons, we affirm the judgment that (1) the asserted claims
are not invalid as indefinite, (2) Valve willfully infringed,
(3) no enhanced damages are warranted, and (4) Valve is
estopped from asserting the Non-Instituted Grounds. We
vacate and remand for proceedings consistent with this
Case: 21-2296 Document: 66 Page: 39 Filed: 04/03/2023
IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 39
opinion with respect to whether Valve is estopped from lit-
igating any of the Non-Petitioned Grounds.
AFFIRMED-IN-PART, VACATED-IN-PART, AND
REMANDED
COSTS
Costs awarded to Ironburg.
Case: 21-2296 Document: 66 Page: 40 Filed: 04/03/2023
United States Court of Appeals
for the Federal Circuit
______________________
IRONBURG INVENTIONS LTD.,
Plaintiff-Cross-Appellant
v.
VALVE CORPORATION,
Defendant-Appellant
______________________
2021-2296, 2021-2297, 2022-1070
______________________
Appeals from the United States District Court for the
Western District of Washington in No. 2:17-cv-01182-TSZ,
Senior Judge Thomas S. Zilly.
______________________
CLEVENGER, Circuit Judge, dissenting.
The Supreme Court held in Nautilus, Inc. v. Biosig In-
struments, Inc. that to satisfy the definiteness requirement
of 35 U.S.C. §112, “a patent’s claims, viewed in light of the
specification and prosecution history, [must] inform those
skilled in the art about the scope of the invention with rea-
sonable certainty.” 572 U.S. 898, 910 (2014). The definite-
ness analysis “entails a delicate balance” that “must take
into account the inherent limitations of language” and al-
low for “[s]ome modicum of uncertainty,” but must also “be
precise enough to afford clear notice of what is claimed,
thereby apprising the public of what is still open to them.”
Id. at 909.
Case: 21-2296 Document: 66 Page: 41 Filed: 04/03/2023
2 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
The claims in this case require two back controls, each
with “an elongate member that extends substantially the
full distance between the top edge and the bottom edge” of
the handheld controller. An ordinary artisan desiring to
produce a non-infringing handheld controller with back
controls including elongate members (as in Ironburg’s pa-
tent) needs to design a device with an elongate member
that does not run substantially the full distance from the
top edge to the bottom edge of the controller. To make the
“full distance” measurement, the artisan needs to know
from the patent where along the top edge to start the meas-
urement, and where along the bottom edge to complete the
measurement. The ’525 patent specification teaches the
artisan where to find the claimed top edge—it is where cer-
tain controls are mounted. But, the artisan still needs to
know where along the top edge the key measurement will
start, and the specification provides no such guidance. And
unlike for the top edge, neither the claims nor the specifi-
cation give any specific indication of where the claimed bot-
tom edge of the controller is. One could argue that the
drawings teach an artisan how to identify the bottom edge
of the claimed device (i.e., the edge opposite the top edge),
but the artisan is then faced with the same basic dilemma:
where along the bottom edge does the key measurement
end? A picture is worth a thousand words, as Figure 2 of
the patent demonstrates:
Case: 21-2296 Document: 66 Page: 42 Filed: 04/03/2023
IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 3
The figure begs the question where an ordinary artisan
or would-be competitor of Ironburg should identify the rel-
evant points of measurement on the top and bottom edges
of his handheld controller to know if his device infringes
the ’525 patent. Whether an accused device meets the
claimed distance surely depends on which points along the
top and bottom edges are chosen for the required measure-
ment. The policy purpose of the definiteness requirement
is to give a competitor at least a fair chance of avoiding in-
fringement. Sometimes, an invention cannot be described
with perfect clarity, and Section 112 cuts some slack for
such inventions (e.g., inherent limitations of language).
But in this case Ironburg should get no slack: nothing
about the English language or the relevant art prevented
the patentee from clearly stating where along his top and
bottom edges he required his “full distance” measurement
to be made.
Before the district court, Valve argued that “an elon-
gate member that extends substantially the full distance
between the top edge and the bottom edge” is indefinite be-
cause, inter alia, a person of ordinary skill in the art “would
not be able to determine or measure that distance with rea-
sonable certainty.” J.A. 3892 (D.I. 161 at 17); see also J.A.
4232 (D.I. 167 at 9). 1 Specifically, Valve explained to the
district court that a person of ordinary skill “would not
know with reasonable certainty where or how to measure
the ‘distance’ between the ‘top edge’ and ‘bottom edge’ of
the controller” because “the specification provides no guid-
ance regarding where along those edges the ‘distance’
measurement should be made.” J.A. 3887 (D.I. 161 at 12).
Valve characterized this lapse as a “significant source of
1 “J.A.” citations herein refer to the parties’ joint ap-
pendix. “D.I.” parentheticals have been included to show
the district court docket number where helpful for refer-
ence.
Case: 21-2296 Document: 66 Page: 43 Filed: 04/03/2023
4 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
uncertainty” given that “the distance varies considerably
depending on where the measurement is taken.” Id. Valve
noted, for example, that “[t]he distance from the trigger on
the ‘top edge’ to the tip of the handle on the ‘bottom edge’
is much greater than if the measurement is taken near the
paddles, which in turn is greater than a measurement
taken near the center of the controller.” Id. at 3887-88 (D.I.
161 at 12-13). Not surprisingly, Ironburg offered no expla-
nation to the district court of how a person of ordinary skill
would know, from the claims or specification of the ’525 pa-
tent, how to measure the distance between the top and bot-
tom edge of an accused controller.
The district court held ipse dixit that Valve did not
carry its burden to show that the claim term “substantially
the full distance between the top edge and the bottom edge”
is indefinite. J.A. 8. But the district court did not mention
Valve’s specific indefiniteness argument or offer any ra-
tionale for its holding. Noticeably absent from the district
court opinion is any explanation about how an ordinary ar-
tisan would know with reasonable certainty from the pa-
tent how to satisfy the required measurement. See, e.g.,
J.A. 11-12.
The majority claims to find a rationale in the district
court opinion; see its footnote 2. Majority Opinion, p. 12
n.2. The first 11 lines of the footnote merely recite the dis-
trict court’s holding that the claim is not indefinite, which
is not a rationale. The majority then notes that the district
court concluded that the patent is definite about the length
of the elongate members, which can be measured relative
to the average span of a human hand, and also stated that
the elongate members extend substantially the full dis-
tance between the top and bottom edges of the controller.
But the district court could not know that the elongate
members extend that full distance unless it knows what
the full distance is, which in turn requires knowing the
points for measurement. The district court overlooked
Valve’s argument that the patent fails to provide
Case: 21-2296 Document: 66 Page: 44 Filed: 04/03/2023
IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 5
reasonable certainty about how to measure the top to bot-
tom distance. The majority’s attempt to find a convincing
rationale for the district court’s holding is unavailing.
This court has a stable body of law that tests the indef-
initeness of claims that require measurements: if a claim
demands a measurement but the patent lacks reasonable
certainty in sufficiently teaching how to make the meas-
urement, the claim is indefinite. See Dow Chemical Co. v.
Nova Chemicals Corp., 803 F.3d 620 (Fed. Cir. 2015); Teva
Pharmaceuticals USA, Inc. v. Sandoz, Inc., 789 F.3d 1335(Fed. Cir. 2015).
Dow makes clear that the indefiniteness of measure-
ment claims can involve both “how” to measure (i.e., the
means for making the measurement) and “where” along an
item to be measured to apply the “how” means. 803 F.3d
at 633. This is so, because the patent in Dow was chal-
lenged as indefinite for failure to provide reasonable cer-
tainty on both a “how” question (i.e., which means for
testing “slope of strain hardening” to employ) and a
“where” question (i.e., where along a stress/strain curve to
make the measurement). Id. 2 As the majority notes, the
patent was held indefinite on the “how” question because it
2 Dow included a third indefiniteness challenge,
which was the lack of clear teaching about which units—
whether a type of metric, English, or some other unit—
should be used to measure if the “slope of strain hardening
coefficient [was] greater than or equal to 1.3” as required
by the claims, assuming one of the various possible testing
means were used at one of the various possible testing lo-
cations. See 803 F.3d at 624 nn.2-3, 633 n.8. The Dow de-
cision did not treat the third indefiniteness question as just
one of infringement; instead, it declined to reach the indef-
initeness challenge as unnecessary because it had already
held the patent indefinite on “how” to make the required
measurement alone. See id. at 633 n.8.
Case: 21-2296 Document: 66 Page: 45 Filed: 04/03/2023
6 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
did not specify which of many possible measurement
means should be used. Id. at 634-35. But the patent was
not held indefinite on the “where” question, because each
of the measurement means were ultimately applied at the
same place, “at the end of the curve where the maximum
slope is located.” Id. at 633. The bottom line in Dow was
that a person of ordinary skill knew where to take the
claimed measurement but did not know which measuring
means to use. Most notably, the court in Dow did not hold
that the “where” question is just a question of infringement
and not a part of the indefiniteness analysis. In short, Dow
recognizes that a measurement claim can be indefinite ei-
ther for failure to specify a test, or for failure to sufficiently
specify how to use a specified test (e.g., “where” to use it),
or for both. Today, the majority unsettles this stable law
by artificially bifurcating the “how” and “where” of Iron-
burg’s measurement claims in order to remove the “where”
question from the assessment of indefiniteness. 3
3 The majority’s attempt to find definiteness about
“where” to measure in the ’525 patent’s teaching about the
size of the elongate members (see Majority Opinion, p. 15
ll. 2-7, p. 19 ll. 29-37) essentially repeats the district court’s
equally flawed reasoning, explained above. And the major-
ity’s reliance on dicta in Presidio Components, Inc. v. Amer-
ican Technical Ceramics Corp., to make the “where”
indefiniteness question just a mere question of infringe-
ment is unavailing. Majority Opinion, p. 18. (citing Pre-
sidio Components, Inc. v. Am. Tech. Ceramics Corp., 875
F.3d 1369, 1377 (Fed. Cir. 2017)). Nothing in the Presidio
opinion explains why the indefiniteness question in that
case produced a “where” question or suggests why the
“where” question in this case must be treated solely as a
matter of infringement. A quotation of dicta from the Pre-
sidio opinion is being asked to do a mountain of incorrect
work here.
Case: 21-2296 Document: 66 Page: 46 Filed: 04/03/2023
IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 7
One need look no further than the experts’ own testi-
mony in this case to understand that, here, the majority’s
distinction between the “where” and the “how” of a meas-
urement method is a false one. Because the ’525 patent’s
drafters chose not to include any guidance on how (i.e., in-
cluding where) to measure the claimed “full distance,” both
experts had no choice but to invent their own arbitrary
methods of identifying points on the top edge and bottom
edge of a handheld controller and measure the distance be-
tween them. The majority is simply wrong that “both par-
ties’ experts agreed on and used the same measurement
methodology – which was simply to find the distance be-
tween two points.” See Majority Opinion, p. 17. Rather,
the parties’ experts arrived at two different methods that
could yield different answers on infringement for the same
device—and in fact did for the accused product.
Specifically, Valve’s expert testified that “he measured
the claimed ‘distance’ ‘in a place that is related to where
the [elongate member] is on the back’” of the device and
arrived at 2.6 inches. Appellant’s Corrected Principal Br.
at 36 (quoting J.A. 11980). He used the “center line” of the
elongate member as an “axis” and measured the distance
between the point where this axis intersected the top edge
and the point where it intersected the bottom edge. 4 See
id. at 36-37 (citing J.A. 11976-77). His method required
disassembling a physical controller to account for—at least
to some extent—any three-dimensional curvature in its
back surface (like that in the back surface of the accused
4 Valve’s expert’s noninfringement report includes a
detailed explanation of his three-step method for measur-
ing the claimed “full distance,” exceeding that in his trial
testimony or Valve’s principal appeal brief. It specifically
notes multiple instances where, to arrive at any measure-
ment at all, he needed to make assumptions to compensate
for the ’525 patent’s lack of guidance. See J.A. 6211-14.
Case: 21-2296 Document: 66 Page: 47 Filed: 04/03/2023
8 IRONBURG INVENTIONS LTD. v. VALVE CORPORATION
product). See J.A. 6213-14, 11976-78 (“[S]ometimes when
we have a complicated three-dimensional shape, it’s hard
to measure. It’s not like a flat bookcase, or something,
where we can lay a ruler along it and know how big it is.”).
Ironburg’s expert had, by contrast, measured the claimed
“full distance” between two other points on the top edge
and bottom edge “that have no relationship to the location
or orientation of the elongate members.” Appellant’s Cor-
rected Principal Br. at 37. Specifically, he appears to have
used an image of a controller to measure the distance be-
tween “the bottom of the top edge and the top of the bottom
edge” in only two dimensions. See id. at 38 (citing J.A.
11764-65, 9071). 5
The two methods led to patently different results when
applied to the accused “elongate member” of the accused
product. Valve’s method, which accounted for the shape
and location of the accused elongate member, resulted in
the accused elongate member extending only 53% of the
“full distance” of 2.60 inches. J.A. 6220-21, 11978-81. But,
with Ironburg’s method, the identical elongate member
was seen to extend more than (i.e., over 100% of) the “full
distance.” J.A. 11764-66. Thus, even though Ironburg’s
expert did not provide a numerical value for his identified
“full distance,” given the relationship of the competing “full
distances” to the same elongate member, Ironburg’s “full
distance” is necessarily less than Valve’s 2.60 inches. This
5 This is Valve’s description of Ironburg’s expert’s
measurement, but it does not appear to be in dispute. Iron-
burg’s expert testified at trial that the “full distance”
stretched from “the bottom of the top edge of the controller”
to the “bottom edge of the controller.” J.A. 11764. And in
its rebuttal appeal brief, Ironburg suggested its expert
measured “from the top of the ‘bottom edge’” rather than
from a lower point on the bottom edge, unlike Valve’s ex-
pert. See Cross-Appellant’s Principal Br. at 34.
Case: 21-2296 Document: 66 Page: 48 Filed: 04/03/2023
IRONBURG INVENTIONS LTD. v. VALVE CORPORATION 9
is because Ironburg’s expert identified the “full distance”
as the distance between the bottom of the top edge and the
top of the bottom edge in two dimensions, i.e., the shortest
possible distance between the two edges, without regard to
the shape or location of the elongate member or the three-
dimensional curvature of the back surface of the accused
product. See J.A. 11764-65, 9071; Cross-Appellant’s Prin-
cipal Br. at 34. In other words, the ambiguity of the ’525
patent allowed Ironburg’s expert to identify the shortest
possible “full distance,” which was less than even its ac-
cused elongate member, while simultaneously allowing
Valve’s expert to measure a different “full distance” that
was longer than Ironburg’s identified elongate member.
The definiteness requirement is meant to guard
against precisely this sort of uncertainty in the scope of a
patent’s claims. Importantly, Dow recognized that claims
may be “even more clearly indefinite” where a patent’s lack
of guidance allows a party’s expert to develop a new method
of measurement for the particular case rather than use an
established one. 803 F.3d at 635; see also id. at 633-34.
Such clearly happened in this case. As Dow recognizes and
this case proves, both the “how” and “where” matter in a
measurement-claim indefiniteness analysis. But for the
majority’s artificial distinction between the two considera-
tions, and the improper relegation of the “where” question
to an infringement inquiry, there is no defense to Valve’s
indefiniteness challenge.
The majority concedes that a proper indefiniteness in-
quiry for measurement claims can include questions of
“where” measurements are taken, and, correspondingly,
that not all “where” questions are just infringement ques-
tions. But the majority fails to explain why the “where”
issue in this case falls out of the indefiniteness inquiry and
into an infringement concern. With respect, I dissent from
the majority’s conclusion that the ’525 patent is not indefi-
nite.