Richard Williamson v. Citrix Online, LLC

United States Court of Appeals
for the Federal Circuit
______________________

RICHARD A. WILLIAMSON, Trustee for At Home
Bondholders Liquidating Trust,
Plaintiff-Appellant

v.

CITRIX ONLINE, LLC, CITRIX SYSTEMS, INC.,
MICROSOFT CORPORATION,
ADOBE SYSTEMS, INC.,
Defendants-Appellees

WEBEX COMMUNICATIONS, INC., CISCO WEBEX,
LLC, CISCO SYSTEMS, INC.,
Defendants-Appellees

INTERNATIONAL BUSINESS MACHINES
CORPORATION,
Defendant-Appellee
______________________

2013-1130
______________________

Appeal from the United States District Court for the
Central District of California in No. 11-CV-2409, Judge A.
Howard Matz.
______________________

Decided: June 16, 2015
______________________
2 WILLIAMSON v. CITRIX ONLINE, LLC

BRETT JOHNSTON WILLIAMSON, O’Melveny & Myers
LLP, Newport Beach, CA, argued for plaintiff-appellant.
Also represented by TIM D. BYRON; WILLIAM C. NORVELL,
JR., SCOTT DION MARRS, BRIAN T. BAGLEY, Beirne
Maynard & Parsons, LLP, Houston, TX.

KURT LOUIS GLITZENSTEIN, Fish & Richardson P.C.,
Boston, MA, argued for all defendants-appellees. Citrix
Online, LLC, Citrix Systems, Inc., Microsoft Corporation,
Adobe Systems, Inc., also represented by FRANK
SCHERKENBACH; INDRANIL MUKERJI, Washington, DC;
JONATHAN J. LAMBERSON, Redwood City, CA. Defendant-
appellee Microsoft Corporation also represented by
ISABELLA FU, Microsoft Corporation, Redmond, WA.

DOUGLAS M. KUBEHL, Baker Botts LLP, Dallas, TX,
for defendants-appellees Webex Communications, Inc.,
Cisco Webex, LLC, Cisco Systems, Inc. Also represented
by SAMARA KLINE, BRIAN DOUGLAS JOHNSTON.

MARK J. ABATE, Goodwin Procter LLP, New York, NY,
for defendant-appellee International Business Machines
Corporation. Also represented by CALVIN E. WINGFIELD,
JR.; WILLIAM F. SHEEHAN, Washington, DC.
______________________

Before MOORE, LINN, and REYNA, Circuit Judges. 1
Opinion for the court filed by Circuit Judge LINN.
Opinion concurring in part, dissenting in part, and with
additional views filed by Circuit Judge REYNA.

1 The earlier opinion in this case, reported at 770
F.3d 1371 (Fed. Cir. 2014), is withdrawn, and this opinion
substituted therefore. Part II.C.1. of this opinion has
been considered and decided by the court en banc. See
Order in this case issued this date.
WILLIAMSON v. CITRIX ONLINE, LLC 3

PROST, Chief Judge, LOURIE, LINN, DYK, MOORE,
O’MALLEY, REYNA, WALLACH, TARANTO, CHEN, and
HUGHES, Circuit Judges, have joined Part II.C.1. of this
opinion.
Opinion dissenting from Part II.C.1. filed by Circuit
Judge NEWMAN.
LINN, Circuit Judge.
Richard A. Williamson (“Williamson”), as trustee for
the At Home Corporation Bondholders’ Liquidating Trust,
owns U.S. Patent No. 6,155,840 (the “’840 patent”) and
appeals from the stipulated final judgment in favor of
defendants Citrix Online, LLC; Citrix Systems, Inc.;
Microsoft Corporation; Adobe Systems, Inc.; Webex Com-
munications, Inc.; Cisco Webex, LLC; Cisco Systems, Inc.;
and International Business Machines Corporation (collec-
tively, “Appellees”). Because the district court erroneous-
ly construed the limitations “graphical display
representative of a classroom” and “first graphical display
comprising . . . a classroom region,” we vacate the judg-
ment of non-infringement of claims 1–7 and 17–24 of
the ’840 patent. Because the district court correctly
construed the limitation “distributed learning control
module,” we affirm the judgment of invalidity of claims 8–
12 of the ’840 patent under 35 U.S.C. § 112 2, para. 2.
Accordingly, we remand.

2 35 U.S.C. § 112 was amended and subsections
were renamed by the America Invents Act, Pub. L. No.
112-29 (“AIA”), which took effect on September 16, 2012.
Because the application resulting in the ’840 patent was
filed before that date, this opinion refers to the pre-AIA
version of § 112.
4 WILLIAMSON v. CITRIX ONLINE, LLC

I. BACKGROUND
A. The ’840 Patent
The ’840 patent describes methods and systems for
“distributed learning” that utilize industry standard
computer hardware and software linked by a network to
provide a classroom or auditorium-like metaphor—i.e., a
“virtual classroom” environment. The objective is to
connect one or more presenters with geographically
remote audience members. ’840 patent col.2 ll.10–14.
The disclosed inventions purport to provide “the benefits
of classroom interaction without the detrimental effects of
complicated hardware or software, or the costs and incon-
venience of convening in a separate place.” Id. at col.2
ll.4–7.
There are three main components of the “distributed
learning” system set forth in the ’840 patent: (1) a pre-
senter computer, (2) audience member computers, and (3)
a distributed learning server. The distributed learning
server implements a “virtual classroom” over a computer
network, such as the Internet, to facilitate communication
and interaction among the presenter and audience mem-
bers. The presenter computer is used by the presenter to
communicate with the audience members and control
information that appears on the audience member’s
computer screen. Id. at col.4 l.66–col.5 l.2. An audience
member’s computer is used to display the presentation
and can be used to communicate with the presenter and
other audience members. Id. at col.5 ll.11–14.
The ’840 patent includes the following three inde-
pendent claims, with disputed terms highlighted:
1. A method of conducting distributed learning
among a plurality of computer systems coupled to
a network, the method comprising the steps of:
providing instructions to a first computer sys-
tem coupled to the network for:
WILLIAMSON v. CITRIX ONLINE, LLC 5

creating a graphical display representative
of a classroom;
creating a graphical display illustrating
controls for selecting first and second data
streams;
creating a first window for displaying the
first selected data stream; and
creating a second window for displaying
the second selected data stream, wherein
the first and second windows are dis-
played simultaneously; and
providing instructions to a second computer
system coupled to the network for:
creating a graphical display representative
of the classroom;
creating a third window for displaying the
first selected data stream; and
creating a fourth window for displaying
the second selected data stream, wherein
the third and fourth windows are dis-
played simultaneously.
8. A system for conducting distributed learning
among a plurality of computer systems coupled to
a network, the system comprising:
a presenter computer system of the plurality
of computer systems coupled to the network and
comprising:
a content selection control for defining at
least one remote streaming data source and
for selecting one of the remote streaming data
sources for viewing; and
6 WILLIAMSON v. CITRIX ONLINE, LLC

a presenter streaming data viewer for dis-
playing data produced by the selected remote
streaming data source;
an audience member computer system of the
plurality of computer systems and coupled to the
presenter computer system via the network, the
audience member computer system comprising:
an audience member streaming data
viewer for displaying the data produced by the
selected remote streaming data source; and
a distributed learning server remote from the
presenter and audience member computer sys-
tems of the plurality of computer systems and
coupled to the presenter computer system and the
audience member computer system via the net-
work and comprising:
a streaming data module for providing the
streaming data from the remote streaming da-
ta source selected with the content selection
control to the presenter and audience member
computer systems; and
a distributed learning control module for
receiving communications transmitted be-
tween the presenter and the audience member
computer systems and for relaying the com-
munications to an intended receiving comput-
er system and for coordinating the operation
of the streaming data module.
17. A distributed learning server for controlling a
presenter computer system and an audience
member computer system coupled to the distrib-
uted learning server via a network, the distribut-
ed learning server comprising:
WILLIAMSON v. CITRIX ONLINE, LLC 7

a module for providing a first graphical dis-
play on the presenter computer system, the first
graphical display comprising:
a first presenter content selection control
for selecting a first source of streaming con-
tent representative of graphical information;
a first presenter content display region for
displaying the graphical information repre-
sented by the streaming content from the first
selected source;
a second presenter content selection con-
trol for selecting a second source of streaming
content representative of graphical infor-
mation; and
a second presenter content display region
for displaying the graphical information rep-
resented by the streaming content from the
second selected source, wherein the first and
second presenter content display regions are
adapted to display simultaneously; and
a classroom region for representing the
audience member computer system coupled to
the distributed learning server; and
a module for providing a second graphical dis-
play on the audience member computer system,
the second graphical display comprising:
a first audience member content display
region for displaying the graphical infor-
mation represented by the streaming content
from the first source selected by the content
selection control; and
a second audience member content display
region for displaying the graphical infor-
mation represented by the streaming content
8 WILLIAMSON v. CITRIX ONLINE, LLC

from the second source selected by the content
selection control, wherein the first and second
audience member content display regions are
adapted to display simultaneously.
Id. at col.10 ll.28–52, col.11 ll.26–62, col.12 ll.29–65.
B. Procedural History
Williamson accused Appellees of infringing the ’840
patent based on their alleged manufacture, sale, offer for
sale, use, and importation of various systems and meth-
ods of online collaboration. On March 22, 2011, William-
son filed suit in the United States District Court for the
Central District of California specifically asserting in-
fringement of all 24 claims of the ’840 patent. On Sep-
tember 4, 2012, the district court issued a claim
construction order, construing, inter alia, the following
limitations of independent claims 1 and 17: “graphical
display representative of a classroom” and “first graphical
display comprising . . . a classroom region” (collectively,
the “graphical display” limitations). The district court
held that these terms require “a pictorial map illustrating
an at least partially virtual space in which participants
can interact, and that identifies the presenter(s) and the
audience member(s) by their locations on the map.”
In its claim construction order, the district court also
concluded that the limitation of claim 8, “distributed
learning control module,” was a means-plus-function term
under 35 U.S.C. § 112, para. 6. The district court then
evaluated the specification and concluded that it failed to
disclose the necessary algorithms for performing all of the
claimed functions. The district court thus held claim 8
and its dependent claims 9–16 invalid as indefinite under
§ 112, para. 2.
Williamson conceded that under the district court’s
claim constructions, none of Appellees’ accused products
infringed independent claims 1 and 17 and their respec-
WILLIAMSON v. CITRIX ONLINE, LLC 9

tive dependent claims 2–7 and 18–24, and that claims 8–
16 were invalid. The parties stipulated to final judgment.
Williamson appeals the stipulated entry of judgment,
challenging these claim construction rulings. We have
jurisdiction pursuant to 28 U.S.C. § 1295(a)(1).
II. DISCUSSION
A. Standard of Review
Regarding questions of claim construction, including
whether claim language invokes 35 U.S.C. § 112, para. 6,
the district court’s determinations based on evidence
intrinsic to the patent as well as its ultimate interpreta-
tions of the patent claims are legal questions that we
review de novo. Teva Pharm. USA, Inc. v. Sandoz, Inc.,
135 S. Ct. 831, 840-41 (2015). To the extent the district
court, in construing the claims, makes underlying find-
ings of fact based on extrinsic evidence, we review such
findings of fact for clear error. Id. Because the district
court’s claim constructions in this case were based solely
on the intrinsic record, the Supreme Court’s recent deci-
sion in Teva does not require us to review the district
court’s claim construction any differently than under the
de novo standard we have long applied. Fenner Invs., Ltd.
v. Cellco P’ship, 778 F.3d 1320, 1322 (Fed. Cir. 2015)
(“When the district court reviews only evidence intrinsic
to the patent . . . , the judge’s determination will amount
solely to a determination of law, and [we] review that
construction de novo.” (quoting Teva, 135 S. Ct. at 841))
(internal citations removed).
B. The “graphical display” Limitations
Williamson asserts that the district court erred in its
construction of the graphical display terms by improperly
importing an extraneous “pictorial map” limitation into
the claim. Williamson argues that requiring a “map”
unduly narrows the claims to the preferred embodiment
disclosed in the written description and that there is no
10 WILLIAMSON v. CITRIX ONLINE, LLC

support in the intrinsic record for confining the claims to
a “pictorial map” that identifies the location of the partic-
ipants. Williamson alleges that a proper definition must
require the audience members to be able to interact with
both the presenter and other audience members. He
therefore asserts that the proper construction of the
graphical display terms is “a viewable illustration of an at
least partially virtual space that allows audience mem-
bers to interact with both the presenter and other audi-
ence members.”
Appellees respond that the district court’s construc-
tion correctly limited the claims to a “pictorial map”
consistent with the teachings of the written description.
According to Appellees, this construction does not import
a limitation from the preferred embodiment, but simply
reflects the functional aspects of a “classroom” in a man-
ner that is consistent with what the patentee invented
and disclosed. Moreover, according to Appellees, it is
consistent with the only depiction of a classroom shown in
the ’840 patent, which shows a pictorial map as a seating
chart that identifies the presenters and audience mem-
bers by their locations on the map.
We agree with Williamson. The district court erred in
construing these terms as requiring a “pictorial map.”
First, the claim language itself contains no such “pictorial
map” limitation. “[I]t is the claims, not the written de-
scription, which define the scope of the patent right.”
Laitram Corp. v. NEC Corp., 163 F.3d 1342, 1347 (Fed.
Cir. 1998); see also id. (“[A] court may not import limita-
tions from the written description into the claims.”).
While the specification discloses examples and embodi-
ments where the virtual classroom is depicted as a “map”
or “seating chart,” nowhere does the specification limit the
graphical display to those examples and embodiments.
This court has repeatedly “cautioned against limiting the
claimed invention to preferred embodiments or specific
examples in the specification.” Teleflex, Inc. v. Ficosa N.
WILLIAMSON v. CITRIX ONLINE, LLC 11

Am. Corp., 299 F.3d 1313, 1328 (Fed. Cir. 2002) (quoting
cases) (citations omitted).
Here, there is no suggestion in the intrinsic record
that the applicant intended the claims to have the limited
scope determined by the district court. To the contrary,
the embodiments and examples in the specification of
classroom metaphors relating to “maps” are consistently
described in terms of preference. For example, the speci-
fication states that “[t]he classroom metaphor preferably
provides a map of the classroom showing the relative
relationships among the presenters and audience mem-
bers.” ’840 patent col.2 ll.37–39 (emphasis added). In
another example, the graphical display of Figure 6 is
described as an “exemplary display” on the presenter’s
computer. Id. at col.7 ll.35–36. That exemplary display
includes a window that “preferably provides a seating
chart showing the audience members and presenters in
the classroom or auditorium.” Id. at col.9 ll.5–7 (empha-
sis added).
The ’840 patent defines a classroom as “an at least
partially virtual space in which participants can interact.”
Id. at col.6 ll.5–6. Nothing further is required, and no
greater definition is mandated by the language of the
claims, the specification, or the prosecution history. As is
well settled, the claims must “not be read restrictively
unless the patentee has demonstrated a clear intention to
limit the claim scope using words or expressions of mani-
fest exclusion or restriction.” Innova/Pure Water, Inc., v.
Safari Water Filtration Sys., Inc., 381 F.3d 1111, 1117
(Fed. Cir. 2004) (internal quotations omitted).
For the foregoing reasons, we conclude that the dis-
trict court incorrectly construed the graphical display
terms to have a “pictorial map” limitation. We therefore
vacate the stipulated judgment of non-infringement of
claims 1–7 and 17–24. The “graphical display” limitations
in claims 1 and 17 are properly construed as “a graphical
12 WILLIAMSON v. CITRIX ONLINE, LLC

representation of an at least partially virtual space in
which participants can interact.”
C. The “distributed learning control module”
Limitation
1. Applicability of 35 U.S.C. § 112, para. 6 3
Means-plus-function claiming occurs when a claim
term is drafted in a manner that invokes 35 U.S.C. § 112,
para. 6, which states:
An element in a claim for a combination may be
expressed as a means or step for performing a
specified function without the recital of structure,
material, or acts in support thereof, and such
claim shall be construed to cover the correspond-
ing structure, material, or acts described in the
specification and equivalents thereof.
In enacting this provision, Congress struck a balance in
allowing patentees to express a claim limitation by recit-
ing a function to be performed rather than by reciting
structure for performing that function, while placing
specific constraints on how such a limitation is to be
construed, namely, by restricting the scope of coverage to
only the structure, materials, or acts described in the
specification as corresponding to the claimed function and
equivalents thereof. See Northrop Grumman Corp. v.
Intel Corp., 325 F.3d 1346, 1350 (Fed. Cir. 2003).

3 Because the overruling of prior precedent can only
be done by the court en banc, see South Corp. v. United
States, 690 F.2d 1368, 1370 n. 2 (Fed. Cir. 1982) (en banc),
Part II.C.1. of this opinion has been considered by an en
banc court formed of PROST, Chief Judge, NEWMAN,
LOURIE, LINN, DYK, MOORE, O’MALLEY, REYNA, WALLACH,
TARANTO, CHEN, and HUGHES, Circuit Judges.
WILLIAMSON v. CITRIX ONLINE, LLC 13

To determine whether § 112, para. 6 applies to a claim
limitation, our precedent has long recognized the im-
portance of the presence or absence of the word “means.”
In Personalized Media Communications, LLC v. Interna-
tional Trade Commission, building upon a line of cases
interpreting § 112, para. 6, 4 we stated that the use of the
word “means” in a claim element creates a rebuttable
presumption that § 112, para. 6 applies. 161 F.3d 696,
703–04 (Fed. Cir. 1998) (citing cases). Applying the
converse, we stated that the failure to use the word
“means” also creates a rebuttable presumption—this time
that § 112, para. 6 does not apply. Id. We have not,
however, blindly elevated form over substance when
evaluating whether a claim limitation invokes § 112,
para. 6:
Merely because a named element of a patent
claim is followed by the word “means,” however,
does not automatically make that element a
“means-plus-function” element under 35 U.S.C.
§ 112, ¶ 6. . . . The converse is also true; merely
because an element does not include the word
“means” does not automatically prevent that ele-
ment from being construed as a means-plus-
function element.
Cole v. Kimberly-Clark Corp., 102 F.3d 524, 531 (Fed. Cir.
1996); see also Greenberg v. Ethicon Endo-Surgery, Inc.,
91 F.3d 1580, 1584 (Fed. Cir. 1996) (“We do not mean to

4 See, e.g., Laitram Corp. v. Rexnord, Inc., 939 F.2d
1533 (Fed. Cir. 1991); Greenberg v. Ethicon Endo-Surgery,
Inc., 91 F.3d 1580 (Fed. Cir. 1996); Cole v. Kimberly-Clark
Corp., 102 F.3d 524 (Fed. Cir. 1997); Mas-Hamilton
Group v. LaGard, Inc., 156 F.3d 1206 (Fed. Cir. 1998);
Unidynamics Corp. v. Automatic Prods. Int’l, Ltd., 157
F.3d 1311 (Fed. Cir. 1998).
14 WILLIAMSON v. CITRIX ONLINE, LLC

suggest that section 112(6) is triggered only if the claim
uses the word ‘means.’”).
In making the assessment of whether the limitation
in question is a means-plus-function term subject to the
strictures of § 112, para. 6, our cases have emphasized
that the essential inquiry is not merely the presence or
absence of the word “means” but whether the words of the
claim are understood by persons of ordinary skill in the
art to have a sufficiently definite meaning as the name for
structure. Greenberg, 91 F.3d at 1583 (“What is im-
portant is . . . that the term, as the name for structure,
has a reasonably well understood meaning in the art.”).
When the claim uses the word “means,” our cases have
been consistent in looking to the meaning of the language
of the limitation in assessing whether the presumption is
overcome. We have also traditionally held that when a
claim term lacks the word “means,” the presumption can
be overcome and § 112, para. 6 will apply if the challenger
demonstrates that the claim term fails to “recite[] suffi-
ciently definite structure” or else recites “function without
reciting sufficient structure for performing that function.”
Watts v. XL Sys., Inc., 232 F.3d 877, 880 (Fed. Cir. 2000).
In Lighting World, Inc. v. Birchwood Lighting, Inc.,
382 F.3d 1354, 1358 (Fed. Cir. 2004), we applied for the
first time a different standard to the presumption flowing
from the absence of the word “means” and held that “the
presumption flowing from the absence of the term ‘means’
is a strong one that is not readily overcome” (emphasis
added), citing as examples, Al–Site Corp. v. VSI Interna-
tional, Inc., 174 F.3d 1308, 1318–19 (Fed. Cir. 1999) and
Personalized Media Communications, 161 F.3d at 703–05.
A few years later, we reiterated Lighting World’s charac-
terization of the presumption as a “strong one that is not
readily overcome” in Inventio AG v. ThyssenKrupp Eleva-
tor Americas Corp., 649 F.3d 1350, 1358 (Fed. Cir. 2011).
In Flo Healthcare Solutions, LLC v. Kappos, 697 F.3d
1367, 1374 (Fed. Cir. 2012), decided just a year after
WILLIAMSON v. CITRIX ONLINE, LLC 15

Inventio, we raised the bar even further, declaring that
“[w]hen the claim drafter has not signaled his intent to
invoke § 112, ¶ 6 by using the term ‘means,’ we are un-
willing to apply that provision without a showing that the
limitation essentially is devoid of anything that can be
construed as structure” (emphasis added), citing Masco
Corp. v. United States, 303 F.3d 1316, 1327 (Fed. Cir.
2002), a case involving the different term “step for” and
the unusual circumstances in which § 112, para. 6 relates
to the functional language of a method claim. Recently, in
Apple Inc. v. Motorola, Inc., 757 F.3d 1286, 1297 (Fed. Cir.
2014), we yet again observed that this presumption is
“‘strong’ and ‘not readily overcome’” and noted that, as
such, we have “‘seldom’ held that a limitation without
recitation of ‘means’ is a means-plus-function limitation,”
citing Lighting World, 382 F.3d at 1358, 1362, Inventio,
649 F.3d at 1356, and Flo Healthcare, 697 F.3d at 1374.
Our opinions in Lighting World, Inventio, Flo Healthcare
and Apple have thus established a heightened bar to
overcoming the presumption that a limitation expressed
in functional language without using the word “means” is
not subject to § 112, para. 6.
Our consideration of this case has led us to conclude
that such a heightened burden is unjustified and that we
should abandon characterizing as “strong” the presump-
tion that a limitation lacking the word “means” is not
subject to § 112, para. 6. That characterization is unwar-
ranted, is uncertain in meaning and application, and has
the inappropriate practical effect of placing a thumb on
what should otherwise be a balanced analytical scale. It
has shifted the balance struck by Congress in passing
§ 112, para. 6 and has resulted in a proliferation of func-
tional claiming untethered to § 112, para. 6 and free of
the strictures set forth in the statute. Henceforth, we will
apply the presumption as we have done prior to Lighting
World, without requiring any heightened evidentiary
showing and expressly overrule the characterization of
16 WILLIAMSON v. CITRIX ONLINE, LLC

that presumption as “strong.” We also overrule the strict
requirement of “a showing that the limitation essentially
is devoid of anything that can be construed as structure.”
The standard is whether the words of the claim are
understood by persons of ordinary skill in the art to have
a sufficiently definite meaning as the name for structure.
Greenberg, 91 F.3d at 1583. When a claim term lacks the
word “means,” the presumption can be overcome and
§ 112, para. 6 will apply if the challenger demonstrates
that the claim term fails to “recite sufficiently definite
structure” or else recites “function without reciting suffi-
cient structure for performing that function.” Watts, 232
F.3d at 880. The converse presumption remains unaffect-
ed: “use of the word ‘means’ creates a presumption that
§ 112, ¶ 6 applies.” Personalized Media, 161 F.3d at 703.
2. Functional Nature of the Limitation
On appeal, Williamson argues that the district court
erred in construing the term “distributed learning control
module” as being governed by 35 U.S.C. § 112, para. 6.
Williamson contends that the district court failed to give
appropriate weight to the “strong” presumption against
means-plus-function claiming that attaches to claim
terms that do not recite the word “means.” Williamson
also argues that the district court wrongly focused its
analysis on the word “module” instead of the full term,
ignored the detailed support provided in the written
description, and misapplied our law by failing to view the
term from the perspective of one of ordinary skill in the
art.
Appellees respond that the district court properly con-
strued “distributed learning control module” as a means-
plus-function claim term despite the absence of the word
“means.” Appellees assert that the presumption against
means-plus-function claiming was rebutted because
“distributed learning control module” does not have a well
understood structural meaning in the computer technolo-
WILLIAMSON v. CITRIX ONLINE, LLC 17

gy field. Appellees note that the “distributed learning
control module” limitation is drafted in the same format
as a traditional means-plus-function limitation, and
merely replaces the term “means” with “nonce” word
“module,” thereby connoting a generic “black box” for
performing the recited computer-implemented functions.
In Appellees’ view, since the term should be treated as a
means-plus-function claim term and there is no algorith-
mic structure for implementing the claimed functions in
the written description, the finding of indefiniteness
should be affirmed.
We begin with the observation that the claim limita-
tion in question is not merely the introductory phrase
“distributed learning control module,” but the entire
passage “distributed learning control module for receiving
communications transmitted between the presenter and
the audience member computer systems and for relaying
the communications to an intended receiving computer
system and for coordinating the operation of the stream-
ing data module.” This passage, as lengthy as it is, is
nonetheless in a format consistent with traditional
means-plus-function claim limitations. It replaces the
term “means” with the term “module” and recites three
functions performed by the “distributed learning control
module.”
“Module” is a well-known nonce word that can operate
as a substitute for “means” in the context of § 112, para. 6.
As the district court found, “‘module’ is simply a generic
description for software or hardware that performs a
specified function.” J.A. 31. Generic terms such as
“mechanism,” “element,” “device,” and other nonce words
that reflect nothing more than verbal constructs may be
used in a claim in a manner that is tantamount to using
the word “means” because they “typically do not connote
sufficiently definite structure” and therefore may invoke
§ 112, para. 6. Mass. Inst. of Tech. & Elecs. for Imaging,
18 WILLIAMSON v. CITRIX ONLINE, LLC

Inc. v. Abacus Software, 462 F.3d 1344, 1354 (Fed. Cir.
2006); see generally M.P.E.P. § 2181.
Here, the word “module” does not provide any indica-
tion of structure because it sets forth the same black box
recitation of structure for providing the same specified
function as if the term “means” had been used. 5 Indeed,
Williamson himself acknowledges that “the term ‘module,’
standing alone is capable of operating as a ‘nonce word’
substitute for ‘means.’” Op. Br. at 43.
The prefix “distributed learning control” does not im-
part structure into the term “module.” These words do
not describe a sufficiently definite structure. Although
the “distributed learning control module” is described in a
certain level of detail in the written description, the
written description fails to impart any structural signifi-
cance to the term. At bottom, we find nothing in the
specification or prosecution history that might lead us to

5 We have addressed the use of the word “module”
in a means-plus-function dispute in the unpublished
decision Ranpak Corp. v. Storopack, Inc., 168 F.3d 1316,
No. 98-1009, 1998 WL 513598 (Fed. Cir. July 15, 1998)
(unpublished). In Ranpak, we were presented with two
closely related claim terms, a “settable control means,”
which indisputably invoked means-plus-function claim-
ing, and a “settable control module.” Id. at *2. In the
context of the patent at issue, we found that the word
“module” in the term “settable control module” did not
connote structure. Id. We came to this conclusion be-
cause “module” merely sets forth “the same black box
without recitation of structure for providing the same
specified function” as did “means.” Id. Since there was no
difference in the structural implications of the terms, we
held that the presumption against means-plus-function
claiming was rebutted and the “settable control module”
was properly construed as a means-plus-function term.
WILLIAMSON v. CITRIX ONLINE, LLC 19

construe that expression as the name of a sufficiently
definite structure as to take the overall claim limitation
out of the ambit of § 112, para. 6. While Williamson is
correct that the presence of modifiers can change the
meaning of “module,” the presence of these particular
terms does not provide any structural significance to the
term “module” in this case.
While portions of the claim do describe certain inputs
and outputs at a very high level (e.g., communications
between the presenter and audience member computer
systems), the claim does not describe how the “distributed
learning control module” interacts with other components
in the distributed learning control server in a way that
might inform the structural character of the limitation-in-
question or otherwise impart structure to the “distributed
learning control module” as recited in the claim.
Williamson also points to the declaration of Dr. Shuk-
ri Souri to show that one of ordinary skill in the art would
understand the term “distributed learning control mod-
ule” to connote structure. The district court did not
discuss Dr. Souri’s testimony in its claim construction
ruling. We have considered it but do not find it persua-
sive. Dr. Souri’s declaration, like the claim language and
portions of the written description Williamson identifies,
fails to describe how the distributed learning control
module, by its interaction with the other components in
the distributed learning control server, is understood as
the name for structure. Dr. Souri also testified that, “as
one of ordinary skill in the art, reading the specification, I
would know exactly how to program” a computer to per-
form the recited functions and further testified that
structure “could be in software or it could be in hard-
ware.” J.A. 1391 (256:12–258:16). But the fact that one
of skill in the art could program a computer to perform
the recited functions cannot create structure where none
otherwise is disclosed. See Function Media, L.L.C. v.
Google, Inc., 708 F.3d 1310, 1319 (Fed. Cir. 2013).
20 WILLIAMSON v. CITRIX ONLINE, LLC

For the foregoing reasons, we conclude that the “dis-
tributed learning control module” limitation fails to recite
sufficiently definite structure and that the presumption
against means-plus-function claiming is rebutted. We
therefore agree with the district court that this limitation
is subject to the provisions of 35 U.S.C. § 112, para. 6.
3. Disclosure of Corresponding Structure
Having found that the “distributed learning control
module” is subject to application of § 112, para. 6, we next
determine whether the specification discloses sufficient
structure that corresponds to the claimed function. We
conclude that it does not.
Construing a means-plus-function claim term is a
two-step process. The court must first identify the
claimed function. Noah Sys., Inc. v. Intuit Inc., 675 F.3d
1302, 1311 (Fed. Cir. 2012). Then, the court must deter-
mine what structure, if any, disclosed in the specification
corresponds to the claimed function. Where there are
multiple claimed functions, as we have here, the patentee
must disclose adequate corresponding structure to per-
form all of the claimed functions. Id. at 1318–19. If the
patentee fails to disclose adequate corresponding struc-
ture, the claim is indefinite. Id. at 1311–12.
The district court identified three claimed functions
associated with the “distributed learning control module”
term: (1) receiving communications transmitted between
the presenter and the audience member computer sys-
tems; (2) relaying the communications to an intended
receiving computer system; and (3) coordinating the
operation of the streaming data module. The district
court then found that the specification fails to disclose
structure corresponding to the “coordinating” function.
On appeal, it is undisputed that the claimed “coordinat-
ing” function is associated with the “distributed learning
control module.” Thus, we must ascertain whether ade-
WILLIAMSON v. CITRIX ONLINE, LLC 21

quate structure corresponding to this function is disclosed
in the specification. Id. at 1311.
Structure disclosed in the specification qualifies as
“corresponding structure” if the intrinsic evidence clearly
links or associates that structure to the function recited in
the claim. Id. (citing B. Braun Med., Inc. v. Abbott Labs.,
124 F.3d 1419, 1424 (Fed. Cir. 1997)). Even if the specifi-
cation discloses corresponding structure, the disclosure
must be of “adequate” corresponding structure to achieve
the claimed function. Id. at 1311–12 (citing In re Don-
aldson Co., 16 F.3d 1189, 1195 (Fed. Cir. 1994) (en banc)).
Under 35 U.S.C. § 112, paras. 2 and 6, therefore, if a
person of ordinary skill in the art would be unable to
recognize the structure in the specification and associate
it with the corresponding function in the claim, a means-
plus-function clause is indefinite. Id. at 1312 (citing
AllVoice Computing PLC v. Nuance Commc’ns, Inc., 504
F.3d 1236, 1241 (Fed. Cir. 2007)).
The district court was correct that the specification of
the ’840 patent fails to disclose corresponding structure.
The written description of the ’840 patent makes clear
that the distributed learning control module cannot be
implemented in a general purpose computer, but instead
must be implemented in a special purpose computer—a
general purpose computer programmed to perform partic-
ular functions pursuant to instructions from program
software. A special purpose computer is required because
the distributed learning control module has specialized
functions as outlined in the written description. See,
e.g., ’840 patent col.5 ll.48–64. In cases such as this,
involving a claim limitation that is subject to § 112,
para. 6 that must be implemented in a special purpose
computer, this court has consistently required that the
structure disclosed in the specification be more than
simply a general purpose computer or microprocessor.
E.g., Aristocrat Techs. Austl. Pty Ltd. v. Int’l Game Tech.,
521 F.3d 1328, 1333 (Fed. Cir. 2008) (citing WMS Gam-
22 WILLIAMSON v. CITRIX ONLINE, LLC

ing, Inc. v. Int’l Game Tech., 184 F.3d 1339 (Fed. Cir.
1999)). We require that the specification disclose an
algorithm for performing the claimed function. Net Mon-
eyIN, Inc. v. VeriSign, Inc., 545 F.3d 1359, 1367 (Fed. Cir.
2008). The algorithm may be expressed as a mathemati-
cal formula, in prose, or as a flow chart, or in any other
manner that provides sufficient structure. Noah, 675
F.3d at 1312 (citing Finisar Corp. v. DirecTV Grp., Inc.,
523 F.3d 1323, 1340 (Fed. Cir. 2008)).
Williamson points to certain disclosures in the specifi-
cation that, it claims, meet the § 112, para. 6 require-
ments. Williamson argues that the “distributed learning
control module” controls communications among the
various computer systems and that the “coordinating”
function provides a presenter with streaming media
selection functionality. These disclosures, however, are
merely functions of the “distributed learning control
module.” The specification does not set forth an algorithm
for performing the claimed functions.
Williamson argues that figures 4 and 5 disclose the
required algorithm. This is not the case. Figure 4 is a
representative display from the presenter computer
system under the direction of the “distributed learning
control module.” ’840 patent col.7 ll.1–3.
WILLIAMSON v. CITRIX ONLINE, LLC 23

Id. figure 4. This display includes an address or uniform
resource locator or URL field, a channel field, an “add this
node” button, and a “back” link. Id. col.7 ll.5–7, 13–15,
18–19. This is not a disclosure of an algorithm corre-
sponding to the claimed “coordinating” function; it is a
description of a presenter display interface.
Figure 5 similarly fails to disclose an algorithm, as it
is another representative display on the presenter com-
puter system. Id. col.7 ll.20–24. This display allows the
presenter to preview data before presenting it to the
audience. Id. col.7 ll.32–34.
24 WILLIAMSON v. CITRIX ONLINE, LLC

Id. figure 5. This figure contains a box listing the sources
of data and a media window that displays the current feed
received from the source of data selected in the list box.
Id. col.7 ll.24–28. Again, this figure is a description of a
presenter display interface; it is not a disclosure of an
algorithm corresponding to the claimed functions. Wil-
liamson has failed to point to an adequate disclosure of
corresponding structure in the specification.
Williamson points to the declaration of Dr. Souri to
show that the ’840 patent discloses structure. The testi-
mony of one of ordinary skill in the art cannot supplant
the total absence of structure from the specification.
Noah, 675 F.3d at 1312 (quoting Default Proof Credit
Card Sys., Inc. v. Home Depot U.S.A., Inc., 412 F.3d 1291,
1302 (Fed. Cir. 2005)). The prohibition against using
expert testimony to create structure where none other-
wise exists is a direct consequence of the requirement that
the specification adequately disclose corresponding struc-
ture. Id. (quoting AllVoice Computing, 504 F.3d at 1240).
WILLIAMSON v. CITRIX ONLINE, LLC 25

Thus, the testimony of Dr. Souri cannot create structure
where none otherwise exists.
Because the ’840 patent fails to disclose any structure
corresponding to the “coordinating” function of the “dis-
tributed learning control module,” we affirm the judgment
that claims 8–16 are invalid for indefiniteness under 35
U.S.C. § 112, para. 2.
CONCLUSION
The district court erred in construing the “graphical
display representative of a classroom” terms in claims 1–7
and 17–24. The district court did not err in construing
the term “distributed learning control module” in claims
8–16 of the ’840 patent as a means-plus-function claim
term lacking corresponding structure. We therefore
vacate the final judgment of non-infringement with re-
spect to claims 1–7 and 17–24 and affirm the final judg-
ment of invalidity of claims 8–16. We remand for further
proceedings consistent with this opinion.
AFFIRMED-IN-PART, VACATED-IN-PART, AND
REMANDED
COSTS
Each party shall bear its own costs for this appeal.
 United States Court of Appeals
for the Federal Circuit
______________________

RICHARD A. WILLIAMSON, Trustee for At Home
Bondholders Liquidating Trust,
Plaintiff-Appellant

v.

CITRIX ONLINE, LLC, CITRIX SYSTEMS, INC.,
MICROSOFT CORPORATION,
ADOBE SYSTEMS, INC.,
Defendants-Appellees

WEBEX COMMUNICATIONS, INC., CISCO WEBEX,
LLC, CISCO SYSTEMS, INC.,
Defendants-Appellees

INTERNATIONAL BUSINESS MACHINES
CORPORATION,
Defendant-Appellee
______________________

2013-1130
______________________

Appeal from the United States District Court for the
Central District of California in No. 11-CV-2409, Judge A.
Howard Matz.
______________________
2 WILLIAMSON v. CITRIX ONLINE, LLC

REYNA, Circuit Judge, concurring-in-part, dissenting-in-
part, and additional views.
This is the second time around for this case. In the
first, Williamson I, I dissented from the majority conclu-
sion that the “distributed learning control module” term
of claim 8 of the ’840 patent recites sufficient structure to
keep the claim limitation “distributed learning control
module” outside of the purview of 35 U.S.C. § 112, para-
graph 6. 1
In this second time around, Williamson II, the majori-
ty reverses itself to conclude that the “distributed learn-
ing control module” term does not recite sufficient
structure, is governed by 35 U.S.C. § 112, paragraph 6,
and is indefinite under paragraph 2. Because this con-
clusion is the correct result, I concur. To explain my
concurrence, I rely on the reasons I laid out in my dissent
in Williamson I.
The majority, however, continues to ignore critical ev-
idence showing that an image of a visually depicted
virtual classroom is required by claim 8 of the ‘840 patent.
I dissent from that portion of this opinion.
In addition, the majority embraces this case as an op-
portune vehicle to overrule as improper certain adjectives
used in prior opinions in describing the § 112, paragraph
6 presumption. See e.g., Inventio AG v. ThyssenKrupp
Elevator Americas Corp., 649 F.3d 1350, 1360 (Fed. Cir.
2011) (describing a “strong” presumption in favor of § 112,
paragraph 6 application where a claim recites “means”).
I cannot say that I disagree with those statements, but I
question whether those statements sidestep underlying
fundamental issues involving the development of func-

1 Williamson v. Citrix Online, LLC, 770 F.3d 1371,
1380 (Fed. Cir. 2014)
WILLIAMSON v. CITRIX ONLINE, LLC 3

tional claiming law since 1952 when 35 U.S.C. § 112,
paragraph 6 was passed.
For these and the reasons set forth below,
I respectfully concur-in-part, dissent in part, and provide
certain comments concerning means-plus-function claim-
ing.
I. The “Graphical Display” Limitations.
The majority reverses the district court’s conclusion
that the “graphical display representative of a classroom”
terms require a pictorial map and construes the terms as
“a graphical representation of an at least partially virtual
space in which participants can interact.” While the
majority is correct that the claims of the ’840 patent do
not require a pictorial map, the majority’s construction
ignores a critical limitation. As reviewed below, the
specification and prosecution history make clear that the
“graphical display representative of a classroom” terms
are properly construed as requiring a visually depicted
virtual classroom.
During prosecution, the applicant explained that the
invention is distinct from the prior art because the patent
requires a “visual virtual classroom” displayed on both a
first and second computer system:
Additionally, [the prior art] does not disclose the
claimed feature of “creating a graphical display
representative of the classroom” on a second com-
puter system coupled to the network. The present
invention allows both a first computer system (for
example, the presenter computer system) and a
second computer system (for example, an audience
member) to view a graphical display of the class-
room. This claimed feature of the present inven-
tion allows the audience members to interact in a
visual virtual classroom environment with both
the presenter and other audience members.
4 WILLIAMSON v. CITRIX ONLINE, LLC

By contrast, [the prior art] merely discloses “[as]
the students log in, their seating locations in the
classroom are shown by a highlighted icon in the
classroom map on the teacher’s screen.” . . . [The
prior art] does not teach or suggest displaying a
graphical display representative of a classroom on
a student’s screen.
J.A. 1267-68 (original emphasis removed and emphases
added). These statements in conjunction with the pa-
tent’s claim terms confirm the significance of displaying
visually depicted virtual classroom.
The “classroom metaphor” is used extensively in
characterizing the operation, and touting the benefits, of
the inventions embodied in the ’840 patent. The Abstract
teaches that “[t]he classroom environment module pro-
vides a classroom metaphor having a podium and rows of
seats to the presenter and audience computer systems.”
’840 patent Abstract. The Summary of the Invention
states that the drawbacks of the prior art are overcome
“by a distributed learning system that uses industry-
standard computer hardware and software linked by a
network like the Internet to provide a classroom- or
auditorium-like metaphor to at least one presenter and at
least one audience member.” Id. col. 2 ll. 10-14. The
patent further teaches that a “feedback region” on the
presenter’s computer “preferably displays a graphical
representation of the classroom” and the “classroom
environment module” is used to provide “a classroom- or
auditorium-like metaphor to the presenter and audience
members.” Id. col. 3 ll. 11-13, col. 5 l. 67-col. 6 l. 1.
The repeated mention of the classroom metaphor
within the context of the invention and the importance of
a visually depicted virtual classroom in the prosecution
history indicate that the “graphical display representative
of a classroom” terms require a visually depicted virtual
classroom. The construction derived by the majority
WILLIAMSON v. CITRIX ONLINE, LLC 5

reads out this important limitation that distinguishes the
invention from the prior art. See Callicrate v. Wadsworth
Mfg., Inc., 427 F.3d 1361, 1369 (Fed. Cir. 2005) (holding
that it was error for the district court to read out a limita-
tion clearly required by the claim language and specifica-
tion). It is error to read a claim too broadly, as it is to
read a claim too narrowly. See, e.g., Phillips v. AWH
Corp., 415 F.3d 1303, 1321 (Fed. Cir. 2005). In reading
out this important limitation on the “graphical display
representative of a classroom” terms, the majority side-
steps our well established rules of claim construction,
causing them to reach an erroneous result.
II. Functional Claiming
The majority switches course from its prior decision,
Williamson I, and now affirms the district court’s conclu-
sion that the term “distributed learning control module” is
governed by § 112 para. 6 and is indefinite under § 112
para. 2 because the specification of the ’840 patent fails to
disclose corresponding structure. The majority goes on to
explicitly “overrule the characterization of th[e] presump-
tion [that § 112 para. 6 does not apply when the term
“means” is not used] as ‘strong.’” Maj. Op. at 15–16.
While I agree with that conclusion, we stop short of
addressing other equally fundamental concerns about
functional claiming.
Our use of § 112, para. 6 presumptions relies on a rig-
id framework, where a flexible one is arguably more apt.
A “presumption” is a procedural tool that shifts the bur-
den of proof on a substantive issue: if a basic fact is estab-
lished, a court accepts a conclusion on the issue unless the
presumption is rebutted with evidence that meets the
presumption’s associated standard of proof. 1-301 Wein-
6 WILLIAMSON v. CITRIX ONLINE, LLC

stein’s Federal Evidence § 301.02 (2015). 2 Our § 112
para. 6 presumptions come from the notion that, all else
being equal, it is more likely that a party is covered by a
statute when it uses the words of the statute. The use of
formal presumptions, the argument goes, takes this
concept to the extreme, supplying one substantive test for
a claim that recites “means” and another for a claim that
recites other non-structural terms like “module.” The
statute admits no such variation, supplying only one test:
is the element “expressed as a means or step for perform-
ing a specified function without the recital of structure,
material, or acts in support thereof.” What arguably
changes is the weight we attach to different recitations in
meeting this test: “means” weighs heavily, non-structural
terms like “module” weigh a little less, and, at the other
end of the spectrum, purely structural terms weigh heavi-
ly in the opposite direction.
A related concern is, assuming that a presumption is
the right tool to analyze the statute, should a presump-
tion arise based on the word “means.” Almost twenty
years ago, this court adopted a presumption that a claim
term that recites “means” invokes § 112, para. 6. York

2 One familiar presumption is the presumption of
patent validity. Under this presumption, a court accepts
the conclusion that an issued patent is valid absent clear
and convincing evidence negating that presumption, i.e.,
evidence showing that the patent is invalid. Microsoft
Corp. v. i4i Ltd. P'ship, 131 S. Ct. 2238, 2242 (2011);
Commil USA, LLC v. Cisco Systems, Inc., No. 13-896, slip
op. at 10–11 (U.S. May 26, 2015). I note that the majority
opinion does not provide an associated standard of proof
for the § 112 para. 6 presumptions. Indeed, I remain
unconvinced that this court has applied a different stand-
ard of proof dependent on how the presumption is labeled
or characterized.
WILLIAMSON v. CITRIX ONLINE, LLC 7

Products, Inc. v. Central Tractor Farm & Family Center,
99 F.3d 1568 (Fed. Cir. 1996); Greenberg v. Ethicon Endo-
Surgery, Inc., 91 F.3d 1580 (Fed. Cir. 1996). Appellees’
petition for rehearing en banc argues that § 112 para. 6
provides no basis for adopting a presumption that a claim
term is governed by this statute when the term “means” is
used. Appellees argue that “[w]hat started out as a
straightforward issue of substance. . . has morphed into
an issue of form.” Appellee’s Petition for Rehearing En
Banc at 6. Appellees argue that “the text of [§ 112 para.
6], the Supreme Court authority leading to it, and its
legislative history universally confirm that [the statute]
applies to all claims that do not recite sufficient structure
for performing the recited function—regardless of wheth-
er the word ‘means’ is used.” Id. at 11. Moreover, the fact
that the statute uses both terms—“means” and “step”—
would suggest that any presumption should apply to the
use of either word. Yet, it is arguably not clear to what
extent this court attaches a presumption to the word
“step.”
Finally, it is generally accepted that § 112, para. 6
was passed in response to the Supreme Court’s decision in
Halliburton Oil Well Cementing Co. v. Walker, 329 U.S. 1
(1946). See Warner-Jenkinson Co., Inc. v. Hilton Davis
Chem. Co., 520 U.S. 17, 27 (1997) (collecting cases);
Technitrol, Inc. v. Control Data Corp., 550 F.2d 992, 998
n. 5 (4th Cir. 1977). In Halliburton, the Supreme Court
made the following observations in holding certain claims
that recite “means” language invalid:
The language of the claim . . . describes this . . .
element in the ‘new’ combination in terms of what
it will do rather than in terms of its own physical
characteristics or its arrangement in the new
combination apparatus. We have held that a claim
with such a description of a product is invalid . . . .
Id. at 8.
8 WILLIAMSON v. CITRIX ONLINE, LLC

Arguably, this rationale applies to functional claiming
generally, not just to claims that recite “means.” Indeed,
the Halliburton Court relied on precedent invalidating
functional claims that did not recite the term “means.”
Id. at 9 (citing Holland Furniture Co. v. Perkins Glue Co.,
277 U.S. 245, 256–57 (1928).) The continued viability of
this rationale, and its impact on how this Court applies
§ 112, para. 6 merits attention.
In sum, my view is that perhaps we need to revisit our
judicially-created § 112, para. 6 presumptions.
 United States Court of Appeals
for the Federal Circuit
______________________

RICHARD A. WILLIAMSON, Trustee for At Home
Bondholders Liquidating Trust,
Plaintiff-Appellant

v.

CITRIX ONLINE, LLC, CITRIX SYSTEMS, INC.,
MICROSOFT CORPORATION,
ADOBE SYSTEMS, INC.,
Defendants-Appellee

WEBEX COMMUNICATIONS, INC., CISCO WEBEX,
LLC, CISCO SYSTEMS, INC.,
Defendants-Appellees

INTERNATIONAL BUSINESS MACHINES
CORPORATION,
Defendant-Appellee
______________________

2013-1130
______________________

Appeal from the United States District Court for the
Central District of California in No. 11-CV-2409, Judge A.
Howard Matz.
______________________
2 WILLIAMSON v. CITRIX ONLINE, LLC

NEWMAN, Circuit Judge, dissenting.
I respectfully dissent from the en banc ruling that is
inserted into this panel opinion at Section II.C.1. The
court en banc changes the law and practice of 35 U.S.C.
§ 112 paragraph 6, by eliminating the statutory signal of
the word “means.” The purpose of this change, the bene-
fit, is obscure. The result, however, is clear: additional
uncertainty of the patent grant, confusion in its interpre-
tation, invitation to litigation, and disincentive to patent-
based innovation.
Curiously, the court acknowledges that it “has long
recognized the importance of the presence or absence of
the word ‘means.’” Maj. Op. at 13. Nonetheless, the court
rejects the meaning and usage of “means” to signal
means-plus-function claim construction. The court now
overrules dozens of cases referring to a “strong presump-
tion” of means-plus-function usage, and goes to the oppo-
site extreme, holding that this court will create such
usage from “[g]eneric terms such as ‘mechanism,’ ‘ele-
ment,’ ‘device,’ and other nonce words.” Maj. Op. at 17.
In the case before us, the so-called “nonce” word is “mod-
ule.” Thus the court erases the statutory text, and holds
that no one will know whether a patentee intended
means-plus-function claiming until this court tells us.
I dissent from the majority’s reasoning and the major-
ity’s holding that “distributed learning control module”
falls under paragraph 6. I express no opinion on the
ultimate validity of the claim; the claim must stand or fall
on its merit, but does not fall under paragraph 6.
I urge the court to recognize that it is the applicant’s
choice during prosecution whether or not to invoke para-
graph 6, and the court’s job is to hold the patentee to his
or her choice. This approach is clear, easy to administer
by the USPTO in examination and the courts in litigation,
and does no harm, for patent applicants know how to
invoke paragraph 6 if they choose.
WILLIAMSON v. CITRIX ONLINE, LLC 3

The statute is clear
When the statute is clear, judicial interpretation is
unnecessary. See Sebelius v. Cloer, 133 S. Ct. 1886, 1896
(2013) (“[R]ules of thumb give way when the words of a
statute are unambiguous . . .”) (internal quotations omit-
ted); Arlington Cent. Sch. Dist. Bd. of Educ. v. Murphy,
548 U.S. 291, 296 (2006) (“When the statutory ‘language
is plain, the sole function of the courts—at least where the
disposition required by the text is not absurd—is to
enforce it according to its terms.’”) (quoting Hartford
Underwriters Ins. Co. v. Union Planters Bank, N.A., 530
U.S. 1, 6 (2000)); Hughes Aircraft Co. v. Jacobson, 525
U.S. 432, 438 (1999) (“As in any case of statutory con-
struction, our analysis begins with the language of the
statute. And where the statutory language provides a
clear answer, it ends there as well.”) (internal citations
and quotations omitted); Estate of Cowart v. Nicklos
Drilling Co., 505 U.S. 469, 475 (1992) (“[W]hen a statute
speaks with clarity to an issue judicial inquiry into the
statute's meaning, in all but the most extraordinary
circumstance, is finished.”).
35 U.S.C. § 112 paragraph 6 authorizes and limits the
claiming of a function:
¶ 6 An element in a claim for a combination may
be expressed as a means or step for performing
a specified function without the recital of struc-
ture, material, or acts in support thereof, and such
claim shall be construed to cover the corre-
sponding structure, material, or acts described in
the specification and equivalents thereof.
(Boldface added. Paragraph 6 was redesignated para-
graph “f” in 2012 – I retain the earlier designation here,
for concordance with precedent.).
The statute is clear. To claim an element by the func-
tion performed, the element is “expressed as” a “means
4 WILLIAMSON v. CITRIX ONLINE, LLC

for,” as the statute provides. The court’s holding that
“distributed learning control module” is “a means-plus-
function claim term despite the absence of the word
‘means’,” maj. op. at 16, is not only unclear – it also vio-
lates the statute.
The signal “means for” is clear – and is clearly
understood
When the statutory signal “means for” is given, the
entire patent-concerned community: the patent attorney,
the patent examiner, the competitor, the infringer, the
inventor, and the judge, know “the subject matter which
the applicant regards as his invention,” 35 U.S.C. § 112
¶ 2, and know how the means-plus-function term is
required to be construed. When an applicant claims a
“means for” performing a function, the statute limits the
scope of the claim to the structure in the specification and
its equivalents. With today’s en banc change of law, as
the case sub judice illustrates, everyone must guess
whether the claimed “module” is claimed as a function or
an apparatus or something else, and whether it is to be
limited by the “structure, material, or acts described in
the specification and equivalents thereof.” 35 U.S.C.
§ 112, ¶ 6.
Until today, the signal “means for” instructed the
claim interpretation. There was no ambiguity about how
the claim was to be interpreted. I discern no groundswell
for this change in the law of claiming – indeed, the public
voice has been silent. I know of no legal or public interest
served by introducing this uncertainty into claim con-
struction. I urge the court to restore this claim construc-
tion to its clear and effective role.
Legislation by footnote
An unheralded footnote, announcing en banc change
of law, without notice to and participation of the interest-
ed public, is not the optimum judicial path. There is
WILLIAMSON v. CITRIX ONLINE, LLC 5

indeed a need for judicial consistency concerning the
construction of means-plus-function claims. The answer
is not to strain the statute and reject consistency, but to
enforce the statute as it is written.
We should act en banc to correct this departure from
statute. If the statute is to be changed, that is not the
judicial prerogative. Indeed, it is noteworthy that in eight
years of congressional study of proposals for legislative
change, culminating in the America Invents Act of 2012,
the legislative record shows no proposal to depart from
the “strong presumption” embodied in section 112 para-
graph 6 and the statutory signal “means for.”
The burden is on the applicant, not the judge
The burden of determining whether paragraph 6 ap-
plies to a particular element is on the applicant, not the
court. As the Faber/Landis treatise states: “To be sure you
are under section 112, paragraph 6, use the pure ‘means
for . . .’ Other words lead to ambiguity and the need for
the court to decide. Use of clear structure words avoids
ambiguity.” ROBERT C. FABER, LANDIS ON MECHANICS OF
PATENT CLAIM DRAFTING at 3-201 (5th ed. 2008).
The Donner treatise teaches by example:
For example, suppose an invention relates to a
new television set. The television set includes a
new transistor-based picture tube, as well as other
new features. The picture tube can be recited two
ways in the claim for the television:
Standard claim element format:
A television, comprising:
A picture tube; . . .
Means-plus-function format:
A television comprising:
Picture tube means for displaying a televi-
sion picture; . . .
6 WILLIAMSON v. CITRIX ONLINE, LLC

IRAH H. DONNER, PATENT PROSECUTION: PRACTICE AND
PROCEDURE BEFORE THE U.S. PATENT AND TRADEMARK
OFFICE at 46-47 (2d ed. 1999).
My colleagues protest that the statutory presumption
of “means” “has resulted in a proliferation of functional
claiming untethered to § 112, para. 6 and free of the
strictures set forth in the statute.” Maj. Op. at 15. This is
an indictment of the court’s fidelity to the statute, not a
flaw in the statute itself. The court’s reasoning today that
there is no “algorithm” for “module” in the specification,
and the word “module” is a “nonce word” for “means,” and
thus the claim is written in accordance with paragraph 6,
is not easy to fathom.
The enactment in 1952
This paragraph was enacted to overturn several Su-
preme Court rulings rejecting “functional” claiming. The
statute authorizes claiming a function or step in a combi-
nation, while safeguarding against the Court’s stated
concerns. P.J. Federico’s Commentary explains:
The last paragraph of section 112 relating to so-
called functional claims is new. It provides that
an element of a claim for a combination (and a
combination may be not only a combination of me-
chanical elements, but also a combination of sub-
stances in a composition claim, or steps in a
process claim) may be expressed as a means or
step for performing a specified function, without
the recital of structure, material or acts in support
thereof.
WILLIAMSON v. CITRIX ONLINE, LLC 7

P.J. Federico, Commentary on the New Patent Act, in 35
U.S.C.A. 1, 25 (West 1954), reprinted in 75 J. PAT. &
TRADEMARK OFF. SOC’Y 161 (1993). 1
The Commentary made clear that the statute was
intended to overrule some Court decisions:
It is unquestionable that some measure of greater
liberality in the use of functional expressions in
combination claims is authorized than had been
permitted by some court decisions and that deci-
sions such as that in Halliburton Oil Well Cement-
ing Co. v. Walker, 67 S.Ct. 6, 329 U.S. 1, 91 L. Ed.
3 (1946), are modified or rendered obsolete, but
the exact limits of the enlargement remain to be
determined.
Id. Federico explained that paragraph 6 enlarges the
opportunity to claim a function, but limits how that
function is supported and construed:
The paragraph ends by stating that such a claim
shall be construed to cover the corresponding
structure, material, or acts described in the speci-
fication and equivalents thereof. This relates
primarily to the construction of such claims for
the purpose of determining when the claim is in-
fringed (note the use of the word “cover”), and

1 See Giles S. Rich, Congressional Intent—or, Who
wrote the Patent Act of 1952?, in PATENT PROCUREMENT
AND EXPLOITATION 61, 66 (BNA Inc., 1963) (“Mr. Federico
received a letter . . . saying the [House] committee re-
quested him to undertake the preparation of ‘an overall
patent revision bill’ at his earliest convenience. . . .”); see
also Louis S. Zarfas, Notes from the Editor, J. PAT. &
TRADEMARK OFF. SOC’Y 160 (1993) (“Examiner-in-Chief
Federico was the primary author of the Patent Act of
1952.”).
8 WILLIAMSON v. CITRIX ONLINE, LLC

would not appear to have much, if any, applicabil-
ity in determining the patentability of such claims
over the prior art, that is, the Patent Office is not
authorized to allow a claim which “reads on” the
prior art.
Id. at 26.
Thus this paragraph of the 1952 Act overruled the
Halliburton case, which had been supported by earlier
precedent, as the Court discussed. Halliburton, 329 U.S.
at 10 (citing General Elec. Co. v. Wabash Appliance Corp.,
304 U.S. 364, 371 (1938) for the proposition that claims
are indefinite for using “conveniently functional language
at the exact point of novelty.”).
This paragraph established that an inventor could
claim a function, and the “means for” signal entered the
patent lexicon, where it has reposed ever since, as a
universally understood signal of a functional claim.
The Examination Guidelines
The PTO Examination Guidelines instruct examiners
and practitioners in accordance with law. The 2000
Guidelines dealt with means-plus-function claiming as
follows:
The PTO must apply 35 U.S.C. 112 ¶6 in appro-
priate cases, and give claims their broadest rea-
sonable interpretation, in light of and consistent
with the written description of the invention in
the application. [2] Thus, a claim limitation will
be interpreted to invoke 35 U.S.C. 112 ¶ 6 if it
meets the following 3-prong analysis:
(1) The claim limitations must use the
phrase “means for” or “step for;”
(2) the “means for” or “step for” must be
modified by functional language; and
WILLIAMSON v. CITRIX ONLINE, LLC 9

(3) the phrase “means for” or “step for”
must not be modified by structure, material or
acts for achieving the specified function.
Supplemental Examination Guidelines for Determining
the Applicability of 35 U.S.C. 112 ¶ 6, 65 Fed. Reg. 38510,
38514 (June 21, 2000). Endnote 2 cites In re Donaldson
for “stating that 35 U.S.C. 112 ¶ 6 sets a limit on how
broadly the PTO may construe means-plus-function
language under the rubric of ‘reasonable interpretation’.”
Id. at 38515. The Guidelines further explained:
With respect to the first prong of this analysis, a
claim element that does not include the phrase
“means for” or “step for” will not be considered to
invoke 35 U.S.C. 112 ¶ 6. If an applicant wishes
to have the claim limitation treated under 35
U.S.C. 112 ¶ 6, applicant must either: (1) Amend
the claim to include the phrase “means for” or
“step for” in accordance with these interim guide-
lines; or (2) show that even though the phrase
“means for” or “step for” is not used, the claim lim-
itation is written as a function to be performed
and does not provide any structure, material, or
acts which would preclude application of 35 U.S.C.
112 ¶ 6.
Id. at 38514.
The 2000 Guidelines place the burden for invoking
paragraph 6 on the applicant by way of the “means”
signal. Id. at 38514 (citing Notice, Means or Step Plus
Function Limitation under 35 U.S.C. 112, ¶6, 1162
OFFICIAL GAZETTE U.S. PAT. OFF. 59 (May 17, 1994)). The
Revised Examination Guidelines in 2011 attempted to
incorporate this court’s intervening decisions, for the
Federal Circuit had begun its retreat from clarity. See
Supplementary Examination Guidelines for Determining
Compliance With 35 U.S.C. 112 and for Treatment of
10 WILLIAMSON v. CITRIX ONLINE, LLC

Related Issues in Patent Applications, 76 Fed. Reg. 7162
(Feb. 9, 2011).
Examiners are now instructed to scrutinize claims for
“a nonce word or verbal construct that is not recognized as
the name of a structure.” Id. at 7167 (citing Lighting
World, 382 F.3d at 1360). The examiner is instructed to
“determine whether the claim limitation uses a non-
structural term (a term that is simply a substitute for the
term “means for”).” Id. (citing Welker Bearing Co. v. PHD,
Inc., 550 F.3d 1090, 1096 (Fed. Cir. 2008). The examiner
must guess whether the term is intended as a means-
plus-function term, now that the court holds that the
signal “means for” need not be used. Paragraph 6 has
morphed from a clear legal instruction into a litigator’s
delight.
Federal Circuit precedent, on and off
This court has recognized that the absence of “means
for” signals the patentee’s intent not to invoke section
112, para. 6, and that this intent should not be rejected
lightly. E.g., Apple Inc. v. Motorola, Inc., 757 F.3d 1286,
1297 (Fed. Cir. 2014) (“We have repeatedly characterized
this presumption as ‘strong’ and ‘not readily overcome’
and, as such, have ‘seldom’ held that a limitation without
recitation of “means” is a means-plus-function limita-
tion.”); Flo Healthcare Solutions, LLC v. Kappos, 697 F.3d
1367, 1374 (Fed. Cir. 2012) (“Our cases make clear ... that
the presumption flowing from the absence of the term
‘means' is a strong one that is not readily overcome.”)
(quoting Lighting World, Inc. v. Birchwood Lighting, Inc.,
382 F.3d 1354, 1358 (Fed. Cir. 2004)); Inventio AG v.
ThyssenKrupp Elevator Americas Corp., 649 F.3d 1350,
1356 (Fed. Cir. 2011) (“Thus, the presumption flowing
from the absence of the term “means” is a strong one that
is not readily overcome”); Al–Site Corp. v. VSI Interna-
tional, Inc., 174 F.3d 1308, 1318 (Fed. Cir. 1999) (“[W]hen
an element of a claim does not use the term “means,”
WILLIAMSON v. CITRIX ONLINE, LLC 11

treatment as a means-plus-function claim element is
generally not appropriate.”); Personalized Media Commu-
nications, LLC v. International Trade Commission, 161
F.3d 696, 704 (Fed. Cir. 1998) (“failure to use the word
“means” creates a presumption that § 112, ¶ 6 does not
apply.”). On this weighty precedent, the court’s en banc
rejection of this simple signal is not readily understood.
The en banc court still permits use of the “means” sig-
nal, although without a “strong presumption” of signifi-
cance. The result is fresh uncertainty, for the judge can
invoke paragraph 6 although the patentee chose other-
wise and wrote the specification and claims on a different
legal standard.
All claims must meet the requirements of patenta-
bility
The court states its concern with overly broad inter-
pretation of software claims. The court is not powerless to
require software claims to comply with the statutory
requirements of description, enablement, definiteness,
unobviousness, etc. If there have been abuses, as the
majority states, the remedy is not to eliminate the stat-
ute, but to apply the statute.
Today’s ruling is an example. The court holds that
the clause “distributed learning control module” is subject
to paragraph 6 because “module” is a “nonce word.” The
court then finds no “algorithm” for “module” in the specifi-
cation, and invalidates the claim for failing to comply with
paragraph 6. However, contrary to the apparent belief of
the majority, the presence or absence of the paragraph 6
signal does not affect the requirements of patentability.
All claims must meet the requirements of patentabil-
ity. Paragraph 6 is a statute of authorization and limita-
tion; it does not annul the other provisions of the statute.
The problem with today’s ruling is that the court has
rejected the rigor and simplicity of paragraph 6 and the
12 WILLIAMSON v. CITRIX ONLINE, LLC

patentee’s intent, replacing it with arbitrary judicial
subjectivity.
CONCLUSION
Paragraph 6 was designed to authorize and provide
the rules for claiming a functional element or step. No
purpose is served by discarding the statutory signal. The
result is further inroad into stability of claim construc-
tion. I respectfully dissent.