Uniloc 2017 LLC v. Facebook, Inc.

Case: 19-2162 Document: 81 Page: 1 Filed: 11/18/2021

NOTE: This disposition is nonprecedential.

United States Court of Appeals
for the Federal Circuit
______________________

UNILOC 2017 LLC,
Appellant

v.

FACEBOOK, INC., WHATSAPP, INC.,
Cross-Appellants

ANDREW HIRSHFELD, PERFORMING THE
FUNCTIONS AND DUTIES OF THE UNDER
SECRETARY OF COMMERCE FOR
INTELLECTUAL PROPERTY AND DIRECTOR OF
THE UNITED STATES PATENT AND TRADEMARK
OFFICE,
Intervenor
______________________

2019-2162, 2019-2159
______________________

Appeals from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in Nos. IPR2017-
01667, IPR2017-01668, IPR2017-02090, IPR2018-00579,
IPR2018-00580.
______________________

Decided: November 18, 2021
______________________
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2 UNILOC 2017 LLC v. FACEBOOK, INC.

BRIAN MATTHEW KOIDE, Etheridge Law Group, South-
lake, TX, argued for appellant. Also represented by JAMES
ETHERIDGE, RYAN S. LOVELESS, BRETT MANGRUM, JEFFREY
A. STEPHENS.

HEIDI LYN KEEFE, Cooley LLP, Palo Alto, CA, argued
for cross-appellants. Also represented by LOWELL D. MEAD,
MARK R. WEINSTEIN; PHILLIP EDWARD MORTON, Washing-
ton, DC.

ROBERT MCBRIDE, Office of the Solicitor, United States
Patent and Trademark Office, Alexandria, VA, for interve-
nor. Also represented by THOMAS W. KRAUSE, FARHEENA
YASMEEN RASHEED.
______________________

Before LOURIE, REYNA, and TARANTO, Circuit Judges.
TARANTO, Circuit Judge.
Uniloc 2017 LLC (Uniloc) owns U.S. Patent
No. 8,724,622, which addresses instant voice messaging by
use of voice-over-internet-protocol (VoIP) communications.
Facebook, Inc. and WhatsApp, Inc. (collectively, Facebook)
challenged various claims of the ’622 patent in two inter
partes reviews in the Patent and Trademark Office. The
Office’s Patent Trial and Appeal Board held all challenged
claims unpatentable for obviousness, except for dependent
claims 4 and 5. Facebook, Inc. v. Uniloc 2017 LLC,
IPR2017-01668, Paper No. 35, at 111–12 (P.T.A.B. Jan. 16,
2019) (Final Written Decision). Both Uniloc and Facebook
appeal. We reject Uniloc’s challenges to the Board’s deci-
sion. But on Facebook’s cross-appeal, we hold that the
Board misunderstood Facebook’s petition regarding claims
4 and 5, and we therefore vacate the Board’s decision as to
those claims and remand for any further proceedings as
may be necessary and appropriate regarding those claims.
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UNILOC 2017 LLC v. FACEBOOK, INC. 3

I
A
The ’622 patent, entitled “System and Method for In-
stant VoIP Messaging,” describes a “system and method for
enabling local and global instant VoIP messaging.” ’622
patent, title and col. 2, lines 57–59. A local, packet-
switched IP network connects an instant voice message cli-
ent, such as a telephone or a telephony-capable computer,
to a local instant voice message server. Id., Fig. 2; id.,
col. 6, line 50 through col. 7, line 36. In “record mode,” the
client “records the user’s speech into a digitized audio
file . . . (i.e., an instant voice message),” then transmits it
to the server. Id., col. 7, line 57 through col 8, line 26. The
server in turn delivers the message to selected recipient cli-
ents if those recipients are currently connected to the
server. Id., col. 8, lines 26–34. If a selected recipient is not
connected, the server “temporarily saves the instant voice
message” and delivers it later, once the recipient connects.
Id., col. 8, lines 34–39.
For present purposes, claims 3, 4, 5, and 24 are illus-
trative. They read:
3. A system comprising:
a network interface connected to a packet-switched
network;
a messaging system communicating with a plural-
ity of instant voice message client systems via the
network interface; and
a communication platform system maintaining
connection information for each of the plurality of
instant voice message client systems indicating
whether there is a current connection to each of the
plurality of instant voice message client systems,
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4 UNILOC 2017 LLC v. FACEBOOK, INC.

wherein the messaging system receives an instant
voice message from one of the plurality of instant
voice message client systems, and
wherein the instant voice message includes an ob-
ject field including a digitized audio file.
Id., col. 24, lines 12–27 (emphasis added).
4. The system according to claim 3, wherein the in-
stant voice message includes an action field identi-
fying one of a predetermined set of permitted actions
requested by the user.
Id., col. 24, lines 28–30 (emphasis added).
5. The system according to claim 4, wherein the
predetermined set of permitted action includes at
least one of a connection request, a disconnection
request, a subscription request, an unsubscription
request, a message transmission request, and a set
status request.
Id., col. 24, lines 31–35.
24. A system comprising:
a network interface connected to a packet-switched
network;
a messaging system communicating with a plural-
ity of instant voice message client systems via the
network interface; and
a communication platform system maintaining
connection information for each of the plurality of
instant voice message client systems indicating
whether there is a current connection to each of the
plurality of instant voice message client systems,
wherein the messaging system receives connection
object messages from the plurality of instant voice
message client systems, wherein each of the
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UNILOC 2017 LLC v. FACEBOOK, INC. 5

connection object messages includes data repre-
senting a state of a logical connection with a given
one of the plurality of instant voice message client
systems.
Id., col. 25, line 59 through col. 26, line 8 (emphasis added).
B
On June 22, 2017, Facebook filed two petitions with the
Board for inter partes reviews of the ’622 patent. In one
petition, Facebook challenged claims 3, 6–8, 10–11, 13–23,
27–35, and 38–39. In the second petition, Facebook chal-
lenged claims 4–5, 12, and 24–26.
In its first petition, Facebook argued that claim 3 was
unpatentable for obviousness over a combination of prior-
art references including Zydney (PCT Pub. No. WO
01/11824 A2). Facebook relied on certain passages of Zy-
dney as disclosing the claim 3 limitation that “the instant
voice message includes an object field including a digitized
audio file.” J.A. 1554–56. Specifically, Zydney describes
voice exchange and voice distribution between users of
computer networks using “voice containers,” which are
“container object[s] that contain[] no methods, but con-
tain[] voice data or voice data and voice data properties.”
Zydney, p. 1, line 19 through p. 2, line 10; id., p. 12, lines
6–8. Zydney says that its voice container can be formatted
using the multipurpose internet mail extension (MIME)
format, which “allows non-textual messages and multipart
message bodies attachments [sic] to be specified in the mes-
sage headers.” Id., p. 19, line 7 through p. 20, line 9 (incor-
porating by reference RFC [Request for Comments] 1521,
which further describes the MIME protocol). Stating that
an “object field” is “a field containing content that will ac-
company the instant voice message, with the term ‘field’
simply referring to a block of data containing a particular
type of data,” Facebook contended that “Zydney discloses
the claimed ‘object field’ in at least two independent ways.”
J.A. 1554. First, “[i]t would . . . have been obvious that the
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6 UNILOC 2017 LLC v. FACEBOOK, INC.

Zydney voice container would contain an ‘object field’ be-
cause, without one, the recipient device could not separate
the voice data from the other fields of data in the voice con-
tainer and play back the voice data for the user—a capabil-
ity the recipient in Zydney has.” J.A. 1555. Second,
“[b]ecause Zydney itself discloses that voice containers can
be encoded using MIME and directly cites to RFC 1521, it
would have been plainly obvious to a person of ordinary
skill in the art to provide the receiving software agent with
the ability to format the voice container according to RFC
1521, thus encoding the voice data in the body (an ‘object
filed’) of the message.” J.A. 1555–56. To support those con-
tentions, Facebook relied on the expert declaration of Dr.
Tal Lavian. J.A. 251–57 (Lavian Decl., ¶¶ 136–45).
Regarding claim 4, which depends on claim 3, Facebook
relied in its second petition on a combination that, as rele-
vant here, included Zydney and Paul S. Hethmon, Illus-
trated Guide to HTTP (1997). Hethmon is a reference book
that discusses version 1.1 of Hypertext Transfer Protocol
(HTTP/1.1), which is a protocol for sending requests and
responses between client and server computers over the in-
ternet. Hethmon at 10–17; see also J.A. 225–26, 355–56
(Lavian Decl., ¶¶ 95, 305). Facebook argued that Zydney
and Hethmon disclosed the claim 4 limitation “wherein the
instant voice message includes an action field identifying
one of a predetermined set of permitted actions requested
by the user.” ’622 patent, col. 24, lines 28–30; J.A. 2672–
80.
Although claim 3 was not itself challenged in the sec-
ond petition, Facebook discussed the elements of claim 3
(incorporated into challenged claims 4 and 5) as “a founda-
tion for analyzing the obviousness of claims” 4 and 5.
J.A. 2655. In that discussion, Facebook stated that “Figure
1A of Zydney . . . expressly shows the central server (which
contains the messaging system) receiving a ‘voice con-
tainer’ (instant voice message) from a sending client sys-
tem,” thus treating Zydney’s voice container as teaching
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UNILOC 2017 LLC v. FACEBOOK, INC. 7

claim 3’s “instant voice message.” J.A. 2668. Then, when
discussing claim 4 and its added “action field” limitation,
Facebook turned to Hethmon as teaching that limitation in
combination with Zydney. J.A. 2672–80. What Facebook
said there about how the Zydney-Hethmon combination
teaches an “instant voice message [that] includes an action
field identifying one of a predetermined set of permitted
actions requested by the user,” ’622 patent, col. 24, lines
28–30 (emphasis added), is the source of the dispute now
before us over the Board’s rejection of Facebook’s challenge
to claim 4 (and its dependent claim 5).
Recognizing that the instant voice message must “in-
clude” the required action field, Facebook asserted that
while “Zydney does not appear to explicitly describe that
the instant voice message contains a ‘field’ that identifies
one of a predetermined set of permitted actions requested
by the user,” “this feature would have been obvious over
Zydney in view of Hethmon, which confirms that the
claimed ‘action field’ is a well-known and built-in feature
of [HTTP/1.1].” J.A. 2672. Facebook explained that
HTTP/1.1 clients communicate with the server through re-
quest messages, which contain a “Request-Line” element
that specifies a “Method” to indicate the type of action re-
quested of the server, as well as an “Entity-Body” field in
which “[t]he data to be transmitted is contained.” J.A.
2672–74 (citing Hethmon at 10–11, 54–61, 78; J.A. 355–58
(Lavian Decl., ¶¶ 304–09)). Facebook said: “The ‘Method’
field in the ‘Request-Line’ is the critical field for purposes
of claim 4.” J.A. 2673 (citing Hethmon at 55). One such
method, called POST, is used to transmit data of various
types. J.A. 2674 (citing Hethmon at 78; J.A. 357–58 (La-
vian Decl., ¶ 309)). Facebook elaborated:
An HTTP message with a POST method provides
an example of an action field identifying one of
a predetermined set of permitted actions re-
quest by the user, as claimed. In fact, the ’622
patent expressly refers to a “post message” as one
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8 UNILOC 2017 LLC v. FACEBOOK, INC.

of the permitted actions that can be in the “action
field.” (’622, 14:6–10.)
Rationale and Motivation to Combine. As
noted previously, Zydney explains that an instant
voice message can be sent by the sender to central
server. (Zydney, 16:7–12, 15:19–21, 27:15–16; Fig.
1A (showing voice container transmission path
through the central server), Fig. 8 (Step 1.2.3.).) It
would have been obvious to a person of ordinary
skill in the art to combine Zydney with Hethmon,
with no change in their respective functions, pre-
dictably resulting in the voice container of Zydney
being transmitted by the sending client to the cen-
tral server using HTTP/1.1 message. This, in turn,
would have resulted in the voice container being
carried in an HTTP/1.1 message that includes an
“action field,” e.g. the “POST” method described
above. And because the “POST” message in this
combination was the result of the Zydney user’s de-
cision to send an instant voice message, the action
field includes a “permitted action[] requested
by the user,” as claimed. A person of ordinary
skill in the art would have had ample motivation to
combine Zydney and Hethmon in this manner.
(Lavian, ¶¶312–319.)
J.A. 2675. Facebook repeated the point when discussing
claim 5. J.A. 2680 (“The POST method specified in the
HTTP request message . . . discloses a message transmis-
sion request, as claimed, because it is used (in the combi-
nation of Zydney and Hethmon) to transmit the voice
container to the central server in Zydney.”) (quoting J.A.
365–66 (Lavian Decl., ¶ 320)).
As to claim 24, Facebook argued that the claim was un-
patentable for obviousness over a combination of prior-art
references including Zydney and Hethmon, which, Face-
book said, together met claim 24’s requirement that “the
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UNILOC 2017 LLC v. FACEBOOK, INC. 9

messaging system receives connection object messages
from the plurality of instant voice message client systems.”
’622 patent, col. 26, lines 3–5; J.A. 2681–88. Specifically,
Facebook contended that “[t]he combination of Zydney and
Hethmon here would have predictably resulted in Zydney’s
instant voice messaging system in which the clients report
their statuses using HTTP messages with POST methods,
thus disclosing the claimed connection object messages.”
J.A. 2685; see also J.A. 2682–83 (citing Zydney, p. 7, line 21
through p. 8, line 6, p. 26, lines 16–19; Hethmon at 78; J.A.
370–71 (Lavian Decl., ¶¶ 328–30)).
C
The Board instituted the requested reviews, determin-
ing that Facebook had established a reasonable likelihood
of prevailing on all challenged claims, J.A. 1666–704; J.A.
2747–77, and Uniloc thereafter filed its patent owner’s re-
sponses, J.A. 1758–807; J.A. 2811–38. Concerning claim
3’s “object field” limitation, Uniloc argued in part that Zy-
dney does not disclose an object field or digitized audio file
specifically. J.A. 1781–88; Final Written Decision at 47–51
(summarizing Uniloc’s seven responses on this limitation).
As to claim 4’s requirement that “the instant voice message
include[] an action field identifying one of a predetermined
set of permitted actions requested by the user,” Uniloc re-
sponded only that Zydney taught away from modifying the
“voice container” to include elements such as Hethmon’s
POST method (i.e., an action field) since Zydney’s voice
“container—by intended design—contains no methods.”
J.A. 2831–33; see also Zydney, p. 12, lines 6–8 (“The term
‘voice containers’ as used throughout this application refers
to a container object that contains no methods . . . .”).
Uniloc made no additional arguments concerning Zydney
and Hethmon’s disclosure of the additional limitation of
claim 5. J.A. 2831–33. Finally, for claim 24’s requirement
concerning “connection object messages,” Uniloc argued
that Zydney taught away from the combination for multi-
ple, independent reasons, J.A. 2833–36, including that
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10 UNILOC 2017 LLC v. FACEBOOK, INC.

Zydney “purports to utilize transport mechanisms that rely
on data compression of then-existing hardware and soft-
ware” but that HTTP in August 2000 did not have compres-
sion capabilities, J.A. 2836 (citing Zydney, p. 11, lines 14–
16; J.A. 3462, 3467 (Easttom Decl., ¶¶ 51, 64)).
Facebook then filed replies. J.A. 1835–65; J.A. 2861–
86. Regarding the “object field” limitation of claim 3, Face-
book responded (in part) that Uniloc’s position “appears to
assume an unstated narrow claim interpretation of the
term ‘object field’ (e.g., that it is a ‘specific type of field’),”
but that “[u]nder either the plain and ordinary meaning
informed by the specification or under the construction
[Uniloc] proposed in [earlier] litigation, Zydney discloses
and renders obvious that the instant voice message (voice
container) contains an object field (block of data) including
an audio file, for the reasons explained in the Petition.”
J.A. 1848–53. Regarding claim 4’s “action field” limitation,
Facebook answered that Uniloc had “misstate[d] the pro-
posed obviousness combination.” J.A. 2874–76. Specifi-
cally, Facebook stated:
The combination would not result in the voice con-
tainer itself containing any methods. Rather, the
Petition explains that it would have been obvious
to transport the voice containers in Zydney as the
“payload” contained in [HTTP/1.1] messages as
taught by Hethmon. (Petition at 40–42.) Using
[HTTP/1.1], the voice container would be contained
as the “entity body” in an HTTP POST message, for
example. (Petition at 39–40; Hethmon, pp. 54 (“En-
tity-Body” field), 78 (“[u]sing the POST method, the
client sends an entity body to the server for pro-
cessing”).) The Request-Line in the HTTP message
is distinct from the Entity-Body “payload” of the
message. (See id.) Therefore, the Zydney voice con-
tainer, transported as the payload of an HTTP mes-
sage disclosing the claimed “instant voice
message,” would not contain any methods.
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UNILOC 2017 LLC v. FACEBOOK, INC. 11

J.A. 2875. Finally, regarding claim 24’s “connection object
messages” limitation, Facebook replied to each of Uniloc’s
various teaching-away arguments. J.A. 2876–84. Specifi-
cally, Facebook stated that Zydney does not require data
compression when transmitting voice containers and that,
even if it did, HTTP/1.1 in fact supported data compression
as of August 2000, whether done separately by other soft-
ware on the client device or through the HTTP protocol it-
self. J.A. 2882–84 (citing Hethmon at 42, 47).
D
After hearing oral argument from the parties, the
Board issued its final written decision on January 16, 2019,
consolidating the proceedings and holding unpatentable all
the challenged claims except claims 4 and 5. Final Written
Decision at 1, 4–5, 112. On the “object field” limitation of
claim 3, the Board specifically concluded it was “persuaded
by [Facebook’s] evidence, including Dr. Lavian’s testimony,
that it would have been obvious to a person of ordinary skill
in the art . . . to include an object field in Zydney’s voice
container” because, without a field to hold the voice data in
the container, Zydney could not operate as specified. Id. at
53–54 (citing J.A. 253–54 (Lavian Decl., ¶ 138 & n.13)).
The Board also “credit[ed] Dr. Lavian’s unrebutted testi-
mony, supported by RFC 1521, that when in MIME format,
Zydney’s voice container would contain the digitized audio
file—i.e., the voice data—in an object field.” Id. at 54 (cit-
ing J.A. 255–57 (Lavian Decl., ¶¶ 141–44)). Similarly, the
Board determined that the subject matter of claim 24
would have been obvious to the relevant artisan, specifi-
cally crediting the evidence that a relevant artisan would
have made the Zydney-Hethmon combination using HTTP
POST messages. Id. at 107–08.
Regarding claim 4’s “action field” limitation, the Board
concluded that Facebook had not established that the prior
art taught this element. The Board reasoned:
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12 UNILOC 2017 LLC v. FACEBOOK, INC.

[Facebook] . . . consistently relies on Zydney’s voice
container as being the recited “instant voice mes-
sage” of claim 3, from which claim 4 depends. See,
e.g., 1668 Pet. 33 (reciting “a ‘voice container’ (in-
stant voice message)”). Thus, even if we were to
agree with [Facebook] that the HTTP/1.1 Request-
Line, as described by Hethmon, “discloses an action
field identifying one of a predetermined set of per-
mitted actions requested by the user” (id. at 39),
the combination of Hethmon with Zydney . . .
would result in “instant voice message” being “dis-
tinct from” such “action field” (see 1668 Reply 11)
rather than “includ[ing]” the action field as claim 4
explicitly recites. [Facebook] does not explain how
an instant voice message distinct from an action
field would have rendered obvious an instant voice
message including an action field.
Id. at 102–03. The Board did not consider whether the
HTTP message, which undisputedly included an action
field, could be considered the claimed “instant voice mes-
sage,” as the Board evidently did not see Facebook as hav-
ing made such a contention for claim 4. For that reason,
the Board found that Facebook had failed to meet its bur-
den on claim 4 and, hence, claim 5. Id. at 103.
Facebook and Uniloc each timely appealed the Board’s
final written decision. We have jurisdiction under 28
U.S.C. § 1295(a)(4)(A) and 35 U.S.C. §§ 141(c), 319.
II
On appeal, Uniloc ultimately makes two contentions,
having withdrawn certain additional challenges it substan-
tially briefed, including a challenge to the Board’s determi-
nation of unpatentability of claim 27. It argues that the
Board committed reversible error in key factual determi-
nations concerning (1) Zydney and the claim 3 requirement
that an instant voice message include “an object field in-
cluding a digitized audio file” and (2) the combination of
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UNILOC 2017 LLC v. FACEBOOK, INC. 13

Zydney and Hethmon and the claim 24 “connection object
message” limitation. We reject both challenges.
We review the Board’s legal conclusions de novo and its
factual findings for substantial-evidence support. Arendi
S.A.R.L. v. Apple Inc., 832 F.3d 1355, 1360 (Fed. Cir. 2016).
The ruling on obviousness is a legal conclusion based on
underlying determinations of fact. PersonalWeb Techs.,
LLC v. Apple, Inc., 917 F.3d 1376, 1381 (Fed. Cir. 2019).
Such factual determinations include what a prior-art refer-
ence teaches and whether a prior-art reference teaches
away. Gen. Elec. Co. v. Raytheon Techs. Corp., 983 F.3d
1334, 1345 (Fed. Cir. 2020); Ariosa Diagnostics v. Verinata
Health, Inc., 805 F.3d 1359, 1364 (Fed. Cir. 2015). “Sub-
stantial evidence review asks ‘whether a reasonable fact
finder could have arrived at the agency’s decision’ and re-
quires examination of the ‘record as a whole, taking into
account evidence that both justifies and detracts from an
agency’s decision.’” Intelligent Bio-Systems, Inc. v. Illu-
mina Cambridge Ltd., 821 F.3d 1359, 1366 (Fed. Cir. 2016)
(quoting In re Gartside, 203 F.3d 1305, 1312 (Fed. Cir.
2000)). 1
A
Substantial evidence supports the Board’s finding
about Zydney’s teaching related to claim 3—the crucial
finding that supports the determination that “Zydney ren-
ders obvious an instant voice message including ‘an object
field including a digitized audio file,’ as recited in claim 3,”
and hence by the challenged claims that depend on claim
3. Final Written Decision at 53. Uniloc argues that there
was not substantial evidence that a digitized audio file

1 To the extent that Uniloc suggests that the Board
failed to provide an explanation allowing us to discern the
path of its reasoning, or failed to ask the legally required
questions in its analysis, we reject the suggestion.
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14 UNILOC 2017 LLC v. FACEBOOK, INC.

(rather than just voice data) would be in an object field (ra-
ther than just a field) in Zydney. Uniloc Opening Br. 36–
38; Uniloc Reply Br. 9–10. We disagree.
First, the Board permissibly credited Dr. Lavian’s tes-
timony that the voice container in Zydney must have a sep-
arate field in which the voice data was stored. Final
Written Decision at 53–54 (quoting J.A. 253–54 (Lavian
Decl., ¶ 138 n.13)). Second, the Board reasonably found,
again based on Dr. Lavian’s testimony, that Zydney dis-
closed the limitation when the voice container was in
MIME format. Id. at 54 (citing J.A. 255–57 (Lavian Decl.,
¶¶ 141–44)). Dr. Lavian’s explanation sufficed to connect
the concepts of a digitized audio file and voice data and the
concepts of an object field and a field, using either of two
claim constructions of “object field,” with no contrary con-
struction meaningfully advanced or argued by Uniloc. See
J.A. 254–56 (Lavian Decl., ¶¶ 139, 141) (concerning digit-
ized audio files); J.A. 251–52 (Lavian Decl., ¶¶ 136–37) (ex-
plaining two potential claim constructions for “object field”:
one based on Uniloc’s position in pending litigation and one
based on the broadest reasonable construction as informed
by the specification); J.A. 1782–83 (Uniloc arguing in its
response that an object field is “a specific type of field,”
without additional elaboration).
B
Substantial evidence likewise supports the Board’s
finding that the “connection object messages” limitation of
claim 24 is taught by the sufficiently motivated combina-
tion of Zydney and Hethmon. Final Written Decision at
103–08. Uniloc’s only focused contention in this court con-
cerns its argument to the Board that Zydney taught away
from using the HTTP POST method taught by Hethmon,
since (according to Uniloc) Zydney used transport mecha-
nisms that relied on data compression of then-existing
hardware and software and HTTP in August 2000 did not
offer compression. Uniloc Opening Br. 39–40; Uniloc Reply
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UNILOC 2017 LLC v. FACEBOOK, INC. 15

Br. 10–11. We reject this contention, concluding that the
Board said enough to make clear that it was rejecting the
contention and why.
The Board stated that it generally “disagree[d] with
[Uniloc’s] argument that Zydney teaches away from a com-
bination in which the HTTP POST method described in
Hethmon would be used as a vehicle to provide client status
information to Zydney’s central server,” and, in support of
that statement, the Board explained that it credited Dr.
Lavian’s testimony undermining Uniloc’s numerous other,
related teaching-away arguments. Final Written Decision
at 107–08. Further, the Board stated that it was “per-
suaded, for the reasons stated by [Facebook] and discussed
above,” id. at 106, and the “above” discussion included rec-
itations of Facebook’s specific counterarguments to
Uniloc’s compression argument—counterarguments that
are amply grounded in the disclosures of Zydney and Heth-
mon, id.; see Zydney, p. 11, lines 14–16 (stating only that
“the present invention is designed to adapt to the voice and
data compression capabilities of the user’s existing hard-
ware and software platform,” not that compression was re-
quired or had to be carried out by the HTTP protocol itself);
Hethmon at 42 (discussing content codings that “allow[] an
application to serve resources in a compressed format”), 47
(referring to “zip” and “gif” media types). Accordingly, we
reject Uniloc’s challenge to the Board’s determination of
unpatentability of claim 24 (and dependent challenged
claims).
III
Facebook cross-appeals the Board’s determination that
it did not carry its burden of proving claims 4 and 5 un-
patentable for obviousness. Final Written Decision at 98–
103. More specifically, Facebook contends that the Board
overlooked its argument about claim 4, starting in its per-
tinent petition, that the required “instant voice message in-
clud[ing] an action field” was taught by an HTTP message
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16 UNILOC 2017 LLC v. FACEBOOK, INC.

as a whole, in which the Request-Line portion contains the
action field (specifically a POST method) and the Entity-
Body carries the Zydney voice container. Facebook Open-
ing Br. 32–38; Facebook Reply Br. 2–8. We agree with Fa-
cebook.
We review the Board’s judgments concerning what ar-
guments are fairly presented in a petition and other plead-
ings for abuse of discretion. See Ericsson Inc. v. Intellectual
Ventures I LLC, 901 F.3d 1374, 1379 (Fed. Cir. 2018); Al-
taire Pharms., Inc. v. Paragon Bioteck, Inc., 889 F.3d 1274,
1284 (Fed. Cir. 2018), remand order modified by stipula-
tion, 738 F. App’x 1017 (Fed. Cir. 2018); Intelligent Bio-Sys-
tems, 821 F.3d at 1367; see also AMC Multi-Cinema, Inc. v.
Fall Line Patents, LLC, No. 2021-1051, 2021 WL 4470062,
at *6 (Fed. Cir. Sep. 30, 2021); MModal LLC v. Nuance
Commc’ns, Inc., 846 F. App’x 900, 906 (Fed. Cir. 2021). “An
abuse of discretion is found if the decision: (1) is clearly un-
reasonable, arbitrary, or fanciful; (2) is based on an errone-
ous 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.” In-
telligent Bio-Systems, 821 F.3d at 1367 (citation omitted).
Under those standards, we hold that the Board committed
an abuse of discretion in overlooking, and therefore not
considering, Facebook’s argument about the teaching of the
HTTP message as a whole.
Facebook’s petition provided “an understandable ex-
planation of the element-by-element specifics of its un-
patentability contentions.” AMC, 2021 WL 4470062, at *5
(citing 35 U.S.C. § 312(a)(3); 37 C.F.R. §§ 42.22(a)(2),
42.104(b)(4)–(5); Harmonic Inc. v. Avid Tech., Inc., 815
F.3d 1356, 1363–64 (Fed. Cir. 2016); Ariosa, 805 F.3d at
1367). Facebook made clear that it was addressing why the
HTTP message, based on the combination of Zydney and
Hethmon, meets the claim 4 requirement that “the instant
voice message contains a ‘field’ that identifies one of a pre-
determined set of permitted actions requested by the user.”
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UNILOC 2017 LLC v. FACEBOOK, INC. 17

J.A. 2672 (emphasis added). It made its argument for that
conclusion by detailing the components of an HTTP mes-
sage and stating that the Request-Line component would
contain the required action field (a POST method), while
the body of the message would carry the voice container of
Zydney. J.A. 2672–75. And it stressed that “[t]he ‘Method’
field in the ‘Request-Line’ is the critical field for purposes
of claim 4.” J.A. 2673 (citing Hethmon at 55). The whole
point of this discussion was to convey that the claim re-
quirement of an instant voice message that “includes an
action field” of the specified sort was met by the HTTP mes-
sage, and that meaning was strongly implied by the state-
ment that the just-described arrangement “would have
resulted in the voice container being carried in an
HTTP/1.1 message that includes an ‘action field,’ e.g. the
‘POST’ method.” J.A. 2675. All of this, fairly read, conveys
that the HTTP message as a whole is an “instant voice mes-
sage” meeting the claim 4 requirement. When Facebook,
in its reply, was more explicit in so stating, see J.A. 2875
(“[T]he Zydney voice container, transported as the payload
of an HTTP message disclosing the claimed ‘instant voice
message,’ would not contain any methods.” (emphasis
added)), it was permissibly clarifying what it had said in
the petition, not making a previously unmade point, see
AMC, 2021 WL 4470062, at *6.
The Board did not state, and Uniloc has not advanced,
any contrary fair reading of the petition or reply passages.
For example, Uniloc suggested at oral argument that the
petition’s reference to “the voice container being carried in
an HTTP/1.1 message that includes an ‘action field,’ e.g.
the ‘POST’ method described above,” J.A. 2675, may be in-
dicating that it is the voice container, not the HTTP mes-
sage, that “includes an ‘action field’” (and hence is the
claimed instant voice message). Oral Arg. at 24:00–25:34;
see also Uniloc Response Br. 3. Similarly, in its briefing,
Uniloc stated that the reply’s reference to “the Zydney voice
container, transported as the payload of an HTTP message
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18 UNILOC 2017 LLC v. FACEBOOK, INC.

disclosing the claimed ‘instant voice message,’” J.A. 2875,
is “at best ambiguous,” Uniloc Response Br. 6, seemingly
implying that “claimed ‘instant voice message’” could mod-
ify “Zydney voice container” rather than “HTTP message.”
But these are unnatural readings, given the “rule of the
last antecedent,” which “provides that, absent ‘other,’ con-
trary ‘indicia of meaning,’ ‘a limiting clause or phrase . . .
should ordinarily be read as modifying only the noun or
phrase that it immediately follows.’” Apple Inc. v. United
States, 964 F.3d 1087, 1096 (Fed. Cir. 2020) (quoting Lock-
hart v. United States, 136 S. Ct. 958, 962–63 (2016)); see
also Barnhart v. Thomas, 540 U.S. 20, 26 (2003).
More substantially, Uniloc stresses that, in the imme-
diately preceding discussion of claim 3 in the petition, the
Zydney voice container is itself the claimed “instant voice
message,” whereas the claim 4 petition passage, in Face-
book’s reading, asserts that something else, namely, the
HTTP message as a whole, is (also) the “instant voice mes-
sage.” Uniloc Response Br. 4–5. That shift may have been
surprising, but Uniloc makes too much of it. Uniloc has
acknowledged that there is no inconsistency between the
two theories, see Oral Arg. at 26:13–27:08, and there is
nothing improper about arguing that the prior art discloses
particular claim language in several different ways. The
shift, of course, could have been more clearly signaled or
announced, but the relevant question is whether the sub-
stance of the claim 4 assertion was clear enough. Here, we
think that the substance of the petition passage was suffi-
ciently clear that the Board was obliged to recognize that
substance—especially after the reply made it still clearer.
In short, Facebook’s petition together with the reinforc-
ing reply statement put the Board on notice that Facebook
was alleging that the HTTP message, not the Zydney voice
container, was the “instant voice message” of claims 4 and
5. By overlooking those statements and instead basing its
findings on the mistaken assumption that Facebook was
treating only Zydney’s voice container as teaching the
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UNILOC 2017 LLC v. FACEBOOK, INC. 19

instant voice message, Final Written Decision at 102–03,
the Board abused its discretion. Because the Board’s mis-
understanding of Facebook’s submissions infected its as-
sessment of claims 4 and 5, we must set aside the Board’s
determination regarding those claims. See, e.g., Singh v.
Brake, 222 F.3d 1362, 1370 (Fed. Cir. 2000).
Failing to appreciate what Facebook had contended,
the Board did not determine the correctness of the conten-
tion that the HTTP message meets claim 4’s requirements.
At least for that reason, it is not clear to us whether, once
Facebook’s contention is properly appreciated, Facebook is
entitled to a determination of unpatentability of claims 4
or 5 or whether Uniloc may have properly preserved argu-
ments that remain open after our decisions here (concern-
ing, e.g., claim 24) and in Uniloc 2017 LLC v. Facebook Inc.,
989 F.3d 1018, 1031–33 (Fed. Cir. 2021), and that could af-
fect the bottom-line determination concerning claims 4 or
5. In these circumstances, we think it advisable to vacate
the Board decision regarding claims 4 and 5 and to remand
for any further proceedings that may be warranted.
IV
For the foregoing reasons, we affirm the Board’s deter-
minations concerning all challenged claims except for
claims 4 and 5; we vacate the Board’s decision concerning
claims 4 and 5; and we remand the matter to the Board.
The parties shall bear their own costs.
AFFIRMED IN PART, VACATED IN PART, AND
REMANDED