Implicit, LLC v. Sonos, Inc.

United States Court of Appeals
for the Federal Circuit
______________________
IMPLICIT, LLC,
Appellant
v.
SONOS, INC.,
Appellee
JOHN A. SQUIRES, UNDER SECRETARY OF
COMMERCE FOR INTELLECTUAL PROPERTY
AND DIRECTOR OF THE UNITED STATES
PATENT AND TRADEMARK OFFICE,
Intervenor
______________________
2020-1173, 2020-1174
______________________
Appeals from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in Nos. IPR2018-
00766, IPR2018-00767.
______________________
Decided: March 9, 2026
______________________
J ASON L EE R OMRELL , Finnegan, Henderson, Farabow,
Garrett & Dunner, LLP, Washington, DC, argued for ap-
pellant. Also represented by T IMOTHY P. MCANULTY ; J.
D EREK MC CORQUINDALE, Reston, VA.
COLE BRADLEY RICHTER , Lee Sullivan Shea & Smith
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IMPLICIT, LLC v. SONOS, INC. 2
LLP, Chicago, IL, argued for appellee. Also represented by
G EORGE I. L EE , RORY P ATRICK SHEA, SEAN MICHAEL
SULLIVAN.
ROBERT MCBRIDE, Office of the Solicitor, United States
Patent and Trademark Office, Alexandria, VA, argued for
intervenor. Also represented by P ETER J. AYERS , SARAH E.
CRAVEN.
______________________
Before T ARANTO, STOLL , and CUNNINGHAM , Circuit
Judges.
CUNNINGHAM , Circuit Judge.
Implicit, LLC (“Implicit”) appeals a final written deci-
sion on remand by the Patent Trial and Appeal Board
(“Board”) in an inter partes review (“IPR”) of U.S. Patent
No. 7,391,791 (the “’791 patent”) and U.S. Patent
No. 8,942,252 (the “’252 patent”), holding that certificates
of correction of inventorship issued after the final written
decisions had issued in the respective IPRs had no impact
on the final written decisions. Sonos, Inc. v. Implicit, LLC,
IPR2018-00766, IPR2018-00767, 2023 WL 6367720, at *1
(P.T.A.B. Sept. 19, 2023) (“Decision on Remand”). Implicit
also appeals the final written decisions in the IPRs of the
’791 patent and the ’252 patent. See also Sonos, Inc. v. Im-
plicit, LLC, IPR2018-00766, 2019 WL 4439131 (P.T.A.B.
Sept. 16, 2019) (“’791 Decision”); Sonos, Inc. v. Implicit,
LLC, IPR2018-00767, 2019 WL 4419356 (P.T.A.B.
Sept. 16, 2019) (“’252 Decision”). For the reasons discussed
below, we affirm.
I. BACKGROUND
Implicit owns the ’791 and ’252 patents. Decision on
Remand at *1; ’791 patent; ’252 patent. Both patents orig-
inally listed Edward Balassanian and Scott Bradley as the
only co-inventors. ’252 Decision at *4; ’791 patent; ’252 pa-
tent. Mr. Balassanian and Mr. Bradley were both
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IMPLICIT, LLC v. SONOS, INC. 3
employees of BeComm Corporation, the predecessor of Im-
plicit. ’252 Decision at *4; J.A. 2564.
Sonos, Inc. (“Sonos”) petitioned for inter partes review
of both patents, asserting unpatentability under 35 U.S.C.
§§ 102 and 103. ’791 Decision at *3; ’252 Decision at *2; see
Decision on Remand at *1. Sonos relied on alleged prior
art reference Janevski,1 which has a filing date of Decem-
ber 11, 2001. Decision on Remand at *3 (citing ’791 Deci-
sion at *5, *6–7); J.A. 335; J.A. 4031–33; J.A. 1789.
Implicit contended that Mr. Balassanian and Mr. Bradley
conceived of the inventions and worked with engineer Guy
Carpenter for implementation prior to December 11, 2001.
Decision on Remand at *3 (citing ’791 Decision at *6–7).
Thus, Implicit argued that Janevski did not constitute
prior art because the work of Mr. Carpenter inured to the
inventors’ benefit and the subject matter of the claims was
conceived and actually reduced to practice prior to Ja-
nevski’s filing date. Id.
In September 2019, the Board determined that all chal-
lenged claims were unpatentable.2 Id. at *1; ’791 Decision
at *1; ’252 Decision at *1. The Board concluded that Im-
plicit’s “evidence was insufficient to establish the concep-
tion of the invention and the communication of the
invention to Mr. Carpenter such that any reduction to
practice could inure to the inventors’ benefit.” Decision on
Remand at *3 (citing ’791 Decision at *7–9). As a result,
the Board determined that Janevski constituted prior art
to the challenged claims of the ’791 patent and the ’252 pa-
tent and determined that “the challenged claims [were]
1 U.S. Patent No. 7,269,338.
2 The Board concluded that claims 1–3, 6–9, 12, 16,
19, and 23–25 of the ’791 patent and claims 1–3, 8, 11, and
17 of the ’252 patent are unpatentable. ’791 Decision at *1;
’252 Decision at *1.
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IMPLICIT, LLC v. SONOS, INC. 4
unpatentable as anticipated by Janevski or obvious over
Janevski, alone or in combination with other prior art.” Id.
After this court issued Arthrex, Inc. v. Smith &
Nephew, Inc., 941 F.3d 1320, 1325 (Fed. Cir. 2019), Im-
plicit filed notices of appeal in November 2019, identifying
various issues to appeal including Appointments Clause vi-
olations. J.A. 1083–88; J.A. 4766–71. This court vacated
the Board’s decisions and remanded to the Board for pro-
ceedings consistent with this court’s decision in Arthrex.
ECF No. 61. On June 21, 2021, the Supreme Court in
United States v. Arthrex, Inc., 594 U.S. 1 (2021), agreed
that there was an Appointments Clause violation, held that
the appropriate remedy was to ensure IPR parties an op-
portunity for Director review of a Board’s final written de-
cision, and remanded to provide the opportunity for such
Director review. 594 U.S. at 23, 25–26.
In November 2021, this court remanded the present
case for the limited purpose of allowing Implicit to request
rehearing and review by the Director of the final written
decisions in light of the Supreme Court’s Arthrex decision.
ECF No. 70 at 2; see Decision on Remand at *2. On Febru-
ary 7, 2022, the requests for Director review were denied
without opinion. J.A. 1123–24. Implicit was granted a new
deadline to file its amended notice of appeal to challenge
the denial of Director review. ECF No. 72; Decision on Re-
mand at *2.
On December 17, 2021, Implicit requested that the
United States Patent and Trademark Office correct the in-
ventorship of the ’791 and ’252 patents to add Mr. Carpen-
ter as an inventor. Decision on Remand at *2; ECF No. 78,
Exs. E–F. The corresponding certificates of correction for
both patents issued in August 2022. J.A. 174, 192. After
the certificates of correction issued, this court remanded to
the Board “for the sole purpose of having the [Board] issue
an order addressing what, if any, impact the certificates of
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IMPLICIT, LLC v. SONOS, INC. 5
correction would have on the final written decisions in
these cases.” ECF No. 85 at 2; Decision on Remand at *2.
On September 19, 2023, the Board determined that
while 35 U.S.C. § 256 is generally retroactive, “judicial es-
toppel and waiver appl[ied] under the specific circum-
stances of these cases.” Decision on Remand at *1; see id.
at *10 n.11 (acknowledging that waiver and forfeiture ap-
plied). Subsequently, the Board concluded that Implicit
was precluded from relying on the certificates of correction
of inventorship in the IPR proceedings as a basis to revisit
the final written decisions. Id. at *10–11.
Implicit timely appealed. We have jurisdiction under
28 U.S.C. § 1295(a)(4)(A).
II. STANDARD OF REVIEW
“We review the Board’s legal conclusions de novo and
its fact findings for substantial evidence.” Game & Tech.
Co. v. Wargaming Grp. Ltd., 942 F.3d 1343, 1348 (Fed. Cir.
2019) (citation omitted). “We set aside the Board’s action
if it is ‘arbitrary, capricious, an abuse of discretion, or oth-
erwise not in accordance with law.’” Veritas Techs. LLC
v. Veeam Software Corp., 835 F.3d 1406, 1413 (Fed. Cir.
2016) (quoting 5 U.S.C. § 706(2)(A)). “Whether a party for-
feited an argument by failing to timely raise it is . . . re-
viewed for abuse of discretion.” Centripetal Networks, LLC
v. Palo Alto Networks, Inc., 156 F.4th 1368, 1374 (Fed. Cir.
2025). “An abuse of discretion is found if the deci-
sion: (1) is clearly unreasonable, arbitrary, or fanciful;
(2) is based on an erroneous conclusion of law; (3) rests on
clearly erroneous fact finding; or (4) involves a record that
contains no evidence on which the Board could rationally
base its decision.” Intelligent Bio-Sys., Inc. v. Illumina
Cambridge Ltd., 821 F.3d 1359, 1367 (Fed. Cir. 2016)
(quoting Bilstad v. Wakalopulos, 386 F.3d 1116, 1121
(Fed. Cir. 2004)).
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IMPLICIT, LLC v. SONOS, INC. 6
III. D ISCUSSION
Implicit contends that 35 U.S.C. § 256 corrections have
a retroactive effect, and as a result, equitable doctrines
such as judicial estoppel, waiver, and forfeiture should not
apply “to nullify the effect of that correction.” Appellant’s
Br. 45–47. Additionally, Implicit argues that its case has
not met the substantive requirements of judicial estoppel,
waiver, or forfeiture and that the Board erred in applying
such doctrines in its decision. Id. at 27–44. We hold that
forfeiture can apply notwithstanding the retroactive effect
of 35 U.S.C. § 256 and that the Board did not abuse its dis-
cretion in applying forfeiture to the circumstances of this
case. Accordingly, we need not and do not reach the issues
of judicial estoppel or waiver.
A.
We begin by addressing whether forfeiture applies in
cases where a section 256 correction has been issued. Im-
plicit argues that section 256 does not limit the time during
which inventorship can be corrected, and thus, forfeiture is
inapplicable to section 256 corrections of inventorship. Ap-
pellant’s Br. 38–39. Sonos and the United States Patent
and Trademark Office (“PTO”) argue that forfeiture can ap-
ply even after section 256 corrections have been issued.
Appellee’s Br. 27–28; Intervenor’s Br. 30–33. We agree
with Sonos and the PTO.
We hold that forfeiture can apply to Implicit’s antedat-
ing argument despite the 35 U.S.C. § 256 correction of in-
ventorship. As an initial matter, the PTO granted
Implicit’s petitions to correct inventorship. Decision on Re-
mand at *2; ECF No. 78, Exs. E–F; J.A. 174, J.A. 192. The
Board merely decided that Implicit could not make new an-
tedating arguments based on this correction of inventor-
ship. Decision on Remand at *10 & n.11. Even so, we have
indicated that whether there is a requirement of diligence
in seeking correction of inventorship is “determined on the
facts of that case.” Stark v. Advanced Magnetics, Inc.,
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IMPLICIT, LLC v. SONOS, INC. 7
29 F.3d 1570, 1575 (Fed. Cir. 1994). For example, we have
“agree[d] that diligent action is required during a pending
interference proceeding, where a change of inventorship
can directly affect the trial and outcome of the proceeding.”
Id. These principles apply in this case where Implicit had
the opportunity to seek correction of inventorship and as-
sert its change of inventorship theory earlier in this pro-
ceeding, and such a change could “directly affect the trial
and outcome of the proceeding.” Id. Thus, we hold that it
can be appropriate to apply forfeiture principles in a case
when a 35 U.S.C. § 256 correction has issued.
B.
We next consider whether the Board abused its discre-
tion in determining that Implicit forfeited its ability to ar-
gue a new antedating argument based on the correction of
inventorship. Implicit argues that its assertion of correc-
tion of inventorship was timely because it sought correction
of inventorship for its patents while proceedings were on-
going, before Director Review finalized the proceedings.
Appellant’s Br. 39–41. Sonos and the PTO argue that Im-
plicit’s failure to raise its new antedating argument until
years after the final written decisions and without suffi-
cient justification for the delay constituted forfeiture and
that the Board did not abuse its discretion in determining
that Implicit forfeited this new antedating argument. Ap-
pellee’s Br. 24–27; Intervenor’s Br. 27–30. We agree with
Sonos and the PTO.
“[F]orfeiture is the failure to make the timely assertion
of a right.” United States v. Olano, 507 U.S. 725, 733
(1993). A party forfeits an argument that it failed to pre-
sent to the Board.3 See, e.g., Schwendimann v. Neenah,
3 This Court has often used “waiver” and “forfeiture”
interchangeably, although waiver is different than
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IMPLICIT, LLC v. SONOS, INC. 8
Inc., 82 F.4th 1371, 1383–84 (Fed. Cir. 2023).
The Board did not abuse its discretion when it deter-
mined that Implicit forfeited its right to argue that
Mr. Carpenter was an inventor to support its antedating
argument. The Board explained that Implicit failed to ar-
gue before the Board in the first instance any other theo-
ries of inventorship and waited until after the final written
decisions had already been issued to seek certificates of cor-
rection. Decision on Remand at *10; see In re Google,
980 F.3d at 863. Implicit argues that the final written de-
cisions “illuminated Mr. [Carpenter]’s necessary presence
as an inventor,” Appellant’s Br. 39–41, relying on Egenera,
Inc. v. Cisco Sys., Inc., 972 F.3d 1367, 1376, 1378 (Fed. Cir.
2020). But the key circumstance allowing a mid-litigation
effort to seek correction of inventorship in Egenera is not
present here. In Egenera, a judicial adoption of a particu-
lar claim construction changed the scope of the claims and,
hence, justified a new assessment by the patentee of who
the co-inventors were. See Egenera, 972 F.3d at 1377–78
(relying on the district court’s “legal determination” of
forfeiture. In re Google Tech. Holdings LLC, 980 F.3d 858,
862 (Fed. Cir. 2020). But “[w]hereas forfeiture is the fail-
ure to make the timely assertion of a right, waiver is the
‘intentional relinquishment or abandonment of a known
right.’” Id.; Olano, 507 U.S. at 733 (quoting Johnson
v. Zerbst, 304 U.S. 458, 464 (1938)). While Implicit briefly
argues that the Board’s discussion of both terms lacks rea-
sonable clarity required for review under 5 U.S.C. § 706,
Appellant’s Br. 37–38, the Board’s explanation of the dif-
ference between the terms and its usage provides “suffi-
cient clarity to permit ‘effective judicial review.’” Timken
U.S. Corp. v. United States, 421 F.3d 1350, 1355 (Fed. Cir.
2005) (quoting Camp v. Pitts, 411 U.S. 138, 142–43 (1973));
Decision on Remand at *10 n.11 (citing In re Google,
980 F.3d at 862).
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IMPLICIT, LLC v. SONOS, INC. 9
claim construction as creating a new issue as to an individ-
ual’s “necessary presence as an inventor”); id. at 1376 (de-
scribing inventorship as a “legal conclusion” that “may
vary depending on what . . . a court determines the claim
scope to be”).
No change in the claim scope occurred in the present
case. From the beginning, Implicit “had in its sole posses-
sion the evidence of inventorship and intentionally pre-
sented evidence asserting a certain inventorship”—
Mr. Balassanian and Mr. Bradley, without Mr. Carpenter.
Decision on Remand at *10. Implicit has not adequately
explained why it could not have made any arguments re-
lated to Mr. Carpenter in the first instance or more dili-
gently sought correction of inventorship. When asked at
oral argument about difficulties in asserting correction of
inventorship earlier, Implicit explained that: (1) it be-
lieved its initial position was correct; and (2) Mr. Carpen-
ter resided in Australia. Oral Arg. 9:55–10:50,
https://www.cafc.uscourts.gov/oral-arguments/20-1173_10
092025.mp3. Implicit’s first response raises concerns of
sandbagging, where Implicit could “suggest[] or permit[],
for strategic reasons, that the [Board] pursue a certain
course, and later—if the outcome is unfavorable—claim[]
that the course followed was reversible error.” In re Google,
980 F.3d at 864 (quoting Freytag v. C.I.R., 501 U.S. 868,
895 (1991) (Scalia, J., concurring in part and concurring in
the judgment)). And Implicit forfeited its second argument
by not arguing it before the Board or in its briefs before us.
J.A. 1210–27; J.A. 1257–66; Appellant’s Br. 38–41;
Schwendimann, 82 F.4th at 1383–84; ABS Global, Inc.
v. Cytonome/ST, LLC, 984 F.3d 1017, 1027 (Fed. Cir.
2021). Given these circumstances, we conclude that the
Board did not abuse its discretion in finding that Implicit
forfeited its argument. Because forfeiture is an independ-
ent ground for affirmance, we need not and do not reach
Implicit’s arguments regarding judicial estoppel and
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IMPLICIT, LLC v. SONOS, INC. 10
waiver. See, e.g., LSI Corp. v. Regents of Univ. of Minn.,
43 F.4th 1349, 1355 (Fed. Cir. 2022).
IV. CONCLUSION
We have considered the remaining arguments raised in
Implicit’s briefing in this appeal and find them unpersua-
sive. For the foregoing reasons, we affirm.
AFFIRMED
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