 United States Court of Appeals
     for the Federal Circuit
             ______________________

                TECSEC, INC.,
               Plaintiff-Appellant,

                        v.

    INTERNATIONAL BUSINESS MACHINES
        CORPORATION AND EBAY INC.,
               Defendants,

                      AND

CISCO SYSTEMS, INC., SAS INSTITUTE, INC., SUN
  MICROSYSTEMS, INC. (now known as Oracle
  America, Inc.), ORACLE CORPORATION, AND
                  PAYPAL, INC.,
               Defendants-Appellees,

                      AND

SAP AMERICA, INC., SAP AG, AND SYBASE, INC.,
           Defendants-Appellees

                      AND

    SOFTWARE AG AND SOFTWARE AG, INC.,
            Defendants-Appellees,

                      AND

           ADOBE SYSTEMS, INC.,
             Defendant-Appellee.
2                   TECSEC, INC.   v. INTL BUSINESS MACHINES



                ______________________

                      2012-1415
                ______________________

   Appeal from the United States District Court for the
Eastern District of Virginia in No. 10-CV-0115, Judge
Leonie M. Brinkema.
                ______________________

                Decided: October 2, 2013
                ______________________

    MICHAEL A. OAKES, Hunton & Williams, LLP, of
Washington, DC, argued for plaintiff-appellant. With him
on the brief was MICHAEL A. O’SHEA. Of counsel on the
brief was GREGORY N. STILLMAN, of Norfolk, Virginia. Of
counsel was ADAM PRICE and ANDREW DINOVO, DiNovo,
Price Ellwanger & Hardy, LLP, of Austin, Texas.

    STEVEN C. CHERNY, Kirkland & Ellis, LLP, of Wash-
ington, DC, argued for defendants-appellees, Cisco Sys-
tems, Inc., et al. With him on the brief were MICHAEL W.
DE VRIES, of Los Angeles, California, and JOHN C.
O’QUINN, of Washington, DC; JEFFREY K. SHERWOOD and
MEGAN S. WOODWORTH, Dickstein Shapiro LLP, of Wash-
ington, DC, for defendants-appellees, SAP AG, et al;
MICHAEL W. ROBINSON and JEFFRI A. KAMINSKI, Venable
LLP, of Vienna, Virginia, for defendants-appellees, Soft-
ware AG, et al; and HENREY C. BUNSOW and CHRISTINA M.
FINN, Bunsow, De Mory, Smith & Allison, LLP, of San
Francisco, California, for defendant-appellee, Adobe
Systems, Inc.       Of counsel was WILLIAM G. BURGESS,
Kirkland & Ellis, LLP, of Washington, DC.
                   ______________________
TECSEC, INC.   v. INTL BUSINESS MACHINES                   3



     Before MOORE, LINN, and REYNA, Circuit Judges.

    Opinion for the court filed by Circuit Judge LINN.

    Dissenting opinion filed by Circuit Judge REYNA.

LINN, Circuit Judge.

    TecSec, Inc. appeals from the district court’s entry of
judgment that the defendant-appellees (the “defendants”)
do not infringe various claims of three TecSec patents:
U.S. Patent Nos. 5,369,702 (the “’702 Patent”); No.
5,680,452 (the “’452 Patent”); and No. 5,898,781 (the “’781
Patent”). Because the district court incorrectly construed
the claims, this court affirms-in-part, reverses-in-part, and
remands for further proceedings.

                         BACKGROUND

    This case relates to methods and systems that secure
computer data. The ’702, ’452, and ’781 Patents derive
from a common parent application and disclose a method
and a system for providing security in a data network by
nesting encrypted objects into other objects which are also
encrypted. ’702 Patent col. 4. ll. 25–28. This allows a
system to employ different security levels to restrict
access to specific compartments of data. Id.

   Claim 8 of the ’702 Patent is representative of the sys-
tem claims at issue:

     A system for providing multi-level multimedia se-
     curity in a data network, comprising:

     A) digital logic means, the digital logic means
     comprising:

     1) a system memory means for storing data;
4                   TECSEC, INC.   v. INTL BUSINESS MACHINES



    2) an encryption algorithm module, comprising
    logic for converting unencrypted objects into en-
    crypted objects, the encryption algorithm module
    being electronically connected to the system
    memory means for accessing data stored in the
    first system memory;

    3) an object labelling subsystem, comprising logic
    means for limiting object access, subject to label
    conditions, the object labelling subsystem being
    electronically connected to the system memory
    means for accessing data stored in the system
    memory means and the object labelling subsys-
    tem being further electronically connected to the
    encryption algorithm module to accept inputs
    from the encryption algorithm module;

    4) a decryption algorithm module, comprising
    logic for converting encrypted objects into unen-
    crypted objects, the decryption algorithm module
    being electronically connected to the system
    memory means for accessing data stored in the
    system memory means; and

    5) an object label identification subsystem, com-
    prising logic for limiting object access, subject to
    label conditions, the object label identification
    subsystem being electronically connected to the
    system memory means for accessing data stored
    in the system memory means and the object label
    identification subsystem being further electroni-
    cally connected to the decryption algorithm mod-
    ule to accept inputs from the decryption
    algorithm module;

    B) the encryption algorithm module working in
    conjunction with the object labelling subsystem
    to create an encrypted object such that the object
TECSEC, INC.   v. INTL BUSINESS MACHINES                   5



     label identification subsystem limits access to an
     encrypted object.

’702 Patent col. 12 l. 45–col. 13 l. 13 (emphases added).
The parties dispute the construction of the phrase “multi-
level multimedia security,” which appears in every as-
serted claim. The parties also dispute a number of limita-
tions in the ’702 Patent drafted in means-plus-function
format, including the terms “digital logic means” and
“system memory means” recited in independent claim 8,
and fourteen other means-plus-function limitations in
dependent claims 9, 12, 14, and 15.

     TecSec filed suit in the Eastern District of Virginia,
alleging that the defendants’ internet servers and related
software products infringed. In addition to the defend-
ants, TecSec also alleged infringement by International
Business Machines Corp. (“IBM”). Early in the case, the
district court severed TecSec’s claims against IBM and
stayed proceedings against the defendants. It considered
the cross-motions relating to infringement, ultimately
granting IBM’s motion for summary judgment of nonin-
fringement. See TecSec, Inc. v. Int’l Bus. Machs. Corp.,
769 F. Supp. 2d 997 (E.D. Va. 2011) (“Summary Judg-
ment Order”). In granting summary judgment, the court
held that TecSec failed to produce any evidence that IBM
itself ever performed every step of the asserted method
claims or ever made, used, sold or offered for sale within
the United States, or imported into the United States, any
products containing all of the limitations of the asserted
system claims. Because IBM was selling software and
because the claims required both hardware and software,
the district court ruled as a matter of law that TecSec
failed to present a triable issue of fact that IBM’s software
contained every limitation of any asserted claim. The
court also found insufficient evidence of indirect infringe-
ment. Both of those conclusions were independent of the
present disputes about claim construction. As an alter-
6                    TECSEC, INC.   v. INTL BUSINESS MACHINES



nate ground, the district court construed the claims and
concluded, again as a matter of law, that TecSec failed to
show that IBM’s accused software met the relevant limi-
tations of the claims as construed. The court entered final
judgment in IBM’s favor pursuant to Federal Rule of Civil
Procedure 54(b). See id. at 1028.

    TecSec appealed, challenging the district court’s claim
construction as well as its conclusion that TecSec failed to
prove infringement by IBM. This court affirmed the
district court’s judgment without opinion pursuant to
Federal Circuit Rule 36. TecSec, Inc. v. Int’l Bus. Machs.
Corp., 466 F. App’x 882 (Fed. Cir. 2012) (the “IBM ap-
peal”).

    On remand, proceedings resumed as to the defendants
that remained. TecSec then stipulated that it could not
prove infringement by defendants under the claim con-
struction adopted by the district court during the proceed-
ings with IBM. Based on TecSec’s stipulation, the district
court entered judgment of noninfringement as to the
defendants. TecSec, Inc. v. Int’l Bus. Machs. Corp., No.
1:10-cv-00115-LMB/TCB (E.D. Va. Apr. 24, 2012). TecSec
appeals. This court has jurisdiction under 28 U.S.C.
§ 1295(a)(1).

                       DISCUSSION

    The parties agree that claim construction is a legal is-
sue that this court reviews de novo on appeal. Cybor
Corp. v. FAS Techs., Inc., 138 F.3d 1448, 1455–56 (Fed.
Cir. 1998) (en banc). To ascertain the scope and meaning
of the asserted claims, this court looks to the words of the
claims themselves, the specification, the prosecution
history, and, lastly, any relevant extrinsic evidence.
Phillips v. AWH Corp., 415 F.3d 1303, 1315–17 (Fed. Cir.
2005) (en banc).
TECSEC, INC.   v. INTL BUSINESS MACHINES                  7



    Whether claim language invokes § 112, ¶ 6 is an exer-
cise of claim construction and is therefore a question of
law, subject to de novo review. Personalized Media
Commc’ns, LLC v. Int’l Trade Comm’n, 161 F.3d 696, 702
(Fed. Cir. 1998). “If § 112 ¶ 6 is applicable, the determi-
nation of the corresponding structure is also a question of
law.” Linear Tech. Corp. v. Impala Linear Corp., 379 F.3d
1311, 1318 (Fed. Cir. 2004).

    We interpret our own mandate de novo. Laitram
Corp. v. NEC Corp., 115 F.3d 947, 950 (Fed. Cir. 1997).
The application of general collateral estoppel principles is
an issue of regional circuit law. Applied Med. Res. Corp.
v. U.S. Surgical Corp., 435 F.3d 1356, 1360 (Fed. Cir.
2006). The Fourth Circuit reviews de novo the application
of collateral estoppel. Tuttle v. Arlington Cty. Sch. Bd.,
195 F.3d 698, 703 (4th Cir. 1999).

                     I. Claim Construction

    On appeal, the parties dispute whether TecSec may
reargue the claim constructions arrived at by the district
court during the proceeding with IBM and that were at
issue, inter alia, in the IBM appeal. The parties did not
raise this issue below, and the district court did not pass
on the issue.

    The district court made several rulings in granting
IBM’s motion for summary judgment. First, the court
construed a number of claim terms. Summary Judgment
Order, 769 F. Supp. 2d at 1003–09. The court then ad-
dressed TecSec’s direct infringement claims, ruling in
IBM’s favor for two reasons, neither dependent on reject-
ing TecSec’s constructions of the claim terms at issue
here: (1) TecSec “failed to come forward with any evidence
that IBM itself performed any of the steps of the method
claims”; and (2) TecSec failed to adduce any evidence that
IBM “made, used, sold, offered for sale, or imported” the
8                    TECSEC, INC.   v. INTL BUSINESS MACHINES



entire accused system. Id. at 1010–12. The court next
turned to TecSec’s indirect infringement claims and,
again without reliance on rejecting TecSec’s constructions
of the claim terms at issue here, determined that TecSec:
(1) “failed to present even a single instance of a customer
using the accused IBM products in an allegedly infringing
manner”; and (2) failed to provide any evidence that IBM
possessed the requisite mental state to support a claim of
induced or contributory infringement. Id. at 1013–16.
Based on these failures of proof, the district court con-
cluded that summary judgment in favor of IBM on
TecSec’s direct and indirect infringement claims was in
order. As an alternative basis for ruling in favor of IBM,
the district court went on to conclude that TecSec also had
failed to show that IBM’s accused systems met the limita-
tions of the asserted claims under the court’s claim con-
struction. Id. at 1016–22. On appeal from these rulings,
TecSec challenged the district court’s determinations of:
(1) no direct or indirect infringement based on TecSec’s
failure of proof; and (2) its failure to show that IBM’s
systems met the claim limitations, as they properly
should have been construed. We affirmed the district
court’s judgment without opinion pursuant to Rule 36.
The defendants now assert that, under the mandate rule
and the doctrine of collateral estoppel, our Rule 36 judg-
ment precludes TecSec from re-raising its claim construc-
tion arguments.

                    A. Mandate Rule

    The defendants argue that the mandate rule applies
because: (1) the district court’s constructions were within
the scope of its judgment; (2) that judgment was affirmed
in the IBM appeal; and (3) no issues were reserved for
further consideration in the decision in the prior appeal.
TecSec responds that the mandate rule does not apply
because it is impossible to glean which issues this court
decided when we issued the Rule 36 judgment.
TECSEC, INC.   v. INTL BUSINESS MACHINES                    9



    This court agrees with TecSec that the mandate rule
does not bar it from challenging the district court’s claim
construction. After our mandate issues, the mandate rule
“forecloses reconsideration of issues implicitly or explicitly
decided on appeal.” Amado v. Microsoft Corp., 517 F.3d
1353, 1364 (Fed. Cir. 2008). For an issue to be implicitly
decided, it must be “decided by necessary implication.”
Laitram, 115 F.3d at 951. Moreover, in interpreting this
court’s mandate, “both the letter and the spirit of the
mandate must be considered.” Engel Indus., Inc. v. Lock-
former Co., 166 F.3d 1379, 1383 (Fed. Cir. 1999).

     The Rule 36 judgment in the IBM appeal summarily
affirmed the district court’s judgment that IBM did not
directly or indirectly infringe TecSec’s patents. The
district court’s judgment was based on two independent
grounds. The district court first ruled as a matter of law
that TecSec’s direct and indirect infringement claims
failed for failure of proof that IBM itself or any of its
customers performed every claimed step or made, used,
sold, offered for sale, or imported any system containing
all of the limitations of the asserted claims. As the dis-
trict court stated in its opinion, without questioning
TecSec’s construction of the terms now at issue, “TecSec
has utterly failed to come forward with any evidence that
IBM itself performed any of the steps of the method
claims,” and “even if some user-implemented system were
to meet all of the asserted claim limitations—which, as
explained below it cannot . . . —TecSec has provided no
evidence that IBM ever made, used, sold, offered to sell, or
imported that entire claimed system . . . .” Summary
Judgment Order, 769 F. Supp. 2d at 1010, 1012 (first
emphasis added). The district court drew a similar con-
clusion regarding indirect infringement, as to which it
found, as well, insufficient proof of the required intent.
Given the absence of evidence that any steps were per-
formed by IBM or that an entire claimed hard-
ware/software system was ever made, used, sold, offered
10                   TECSEC, INC.   v. INTL BUSINESS MACHINES



to sell, or imported by IBM or its customers, the district
court was compelled to find no direct or indirect infringe-
ment. Pennwalt Corp. v. Durand-Wayland, Inc., 833 F.2d
931, 949–50 (Fed. Cir. 1987) (en banc) (“Every Supreme
Court decision which has addressed the issue of infringe-
ment of a patent claim, beginning with Prouty v. Draper,
41 U.S. (16 Pet.) 335, 10 L.Ed. 985 (1842)—and the prece-
dent is voluminous—has held that where a part of the
claimed invention, that is, a limitation of the claim, is
lacking in the accused device exactly or equivalently,
there is no infringement.”) The district court, in finding a
complete failure of proof regarding any act of infringe-
ment by IBM or its customers, did not rely on any rejec-
tion of TecSec’s constructions of the terms at issue here.
Indeed, IBM represented to the court that we could affirm
the district court’s judgment solely based on TecSec’s
“complete failure of proof” and did not “need to get to
claim construction.” TecSec, Inc. v. Int’l Bus. Machs.
Corp., No. 2011-1303, Oral Arg. at 19:30–24:55, available
at
http://oralarguments.cafc.uscourts.gov/default.aspx?fl=20
11-1303.mp3. While the district court also ruled in the
alternative that TecSec failed to show that IBM’s software
met various claim limitations, as construed, our Rule 36
decision does not articulate a basis for affirmance, let
alone an explication on claim construction. On this rec-
ord, it cannot be concluded simply on the basis of this
court’s summary affirmance that we expressly or by
necessary implication decided the claim construction
issues in the IBM appeal. 1


     1  The dissent boldly contends that “[c]laim con-
struction and sufficiency of the evidence showing an act of
infringement are not alternative grounds on which to find
noninfringement,” Dissent at 6, both: (a) ignoring the
distinctions between failures of proof and conventional
rules of infringement, and (b) overlooking the actual
TECSEC, INC.   v. INTL BUSINESS MACHINES                11



    The Supreme Court’s analysis of its summary disposi-
tion procedure is instructive. The Court has explained
that its summary dispositions “affirm[] only the judgment
of the court below, and no more may be read into [its]
action than was essential to sustain that judgment.” Ill.
State Bd. of Elections v. Socialist Workers Party, 440 U.S.
173, 182–83 (1979) (internal citations omitted). Thus,
when the Supreme Court by summary disposition affirms
a decision that rested on multiple grounds, the affirmance
is generally not binding precedent for either ground. See
Akron v. Akron Ctr. for Reproductive Health, Inc., 462
U.S. 416, 433 n.18 (1983).

    Similarly, our Rule 36 judgments only affirm the
judgment of the lower tribunal. “[A] Rule 36 judgment
simply confirms that the trial court entered the correct
judgment. It does not endorse or reject any specific part
of the trial court’s reasoning.” Rates Tech., Inc. v. Medi-
atrix Telecom, Inc., 688 F.3d 742, 750 (Fed. Cir. 2012).
Had claim construction been the only issue in the IBM
appeal, and had that claim construction been essential to
sustaining the judgment of noninfringement, the preclu-
sive effect of our Rule 36 judgment would have been
undeniable. But that was not the case. Here, the man-
date rule does not preclude TecSec from challenging claim
construction.

                     B. Collateral Estoppel

    The defendants also argue that collateral estoppel
precludes TecSec from re-litigating claim construction.
They point out that the district court construed claim
terms that it considered “strictly necessary” to the grant
of summary judgment. See Summary Judgment Order,
769 F. Supp. 2d at 1003. The defendants argue that given

rulings of the district court on the evidentiary record
before it during the IBM phase of this case.
12                   TECSEC, INC.   v. INTL BUSINESS MACHINES



the determination by the district court that the construed
terms were “strictly necessary” to its ruling that the claim
limitations were not met, the existence of alternative
grounds to support the judgment does not deprive the
judgment of preclusive effect.

    TecSec responds by arguing that collateral estoppel
does not apply because the district court’s claim construc-
tions were not necessary to the final judgment, which
rested on multiple, independent grounds. TecSec argues
that, because this court could have affirmed on any
ground, claim construction was not actually determined in
the IBM appeal and was not necessary to this court’s Rule
36 affirmance.

     We agree with TecSec that the defendants have failed
to show that collateral estoppel applies in this case.
Among other elements, the party that seeks to invoke
collateral estoppel must show that the litigated issue was
“actually determined in the prior proceeding” and was a
“critical and necessary part of the decision in the prior
proceeding.” Collins v. Pond Creek Mining Co., 468 F.3d
213, 217 (4th Cir. 2006). A corollary to this requirement
is “where the court in the prior suit has determined two
issues, either of which could independently support the
result, then neither determination is considered essential
to the judgment.” Ritter v. Mount St. Mary’s Coll., 814
F.2d 986, 993 (4th Cir. 1987); see also C.B. Marchant Co.
v. E. Foods, Inc., 756 F.2d 317, 319 (4th Cir. 1985).

    Here, we affirmed without opinion the district court’s
judgment of noninfringement. As recounted above, the
district court’s judgment was independently predicated on
alternative grounds: TecSec’s failure of proof as to IBM’s
and its customers’ acts and as to IBM’s intent, and its
failure to show that IBM’s software met certain limita-
tions of the claims, as construed. The former ground was
not and is not dependent on any claim construction. Even
TECSEC, INC.   v. INTL BUSINESS MACHINES                  13



though the district court stated that its claim construc-
tions were “strictly necessary” to resolving the parties’
summary judgment motions, the judgment based on
TecSec’s failure of proof was independent of the court’s
construction. Because claim construction was neither
actually determined by nor critical and necessary to our
summary affirmance in the IBM appeal, collateral estop-
pel does not preclude the present challenge.

    The Defendants contend, however, that TecSec still
should not be heard because it is re-raising the same
claim construction arguments in the same proceeding.
Relying on Ritter, they argue that collateral estoppel
applies to the district court’s alternative holdings in this
circumstance because otherwise the district court’s rul-
ings would become irrelevancies.

    We disagree. In Ritter, the district court issued two
factual findings, and the plaintiff appealed. 814 F.2d at
988, 993. The appellate court upheld one of the fact
findings but did not address the second finding. Id. The
court then reversed and remanded, concluding that the
district court erred in dismissing some of the plaintiff’s
related civil-rights claims. Id.

    The plaintiff’s civil-rights claims required proof of the
same underlying facts that were at issue in the first trial.
Id. at 993–94. On remand, the district court held that the
plaintiff could not re-litigate both fact findings, and the
court of appeals affirmed. Id. The court held that even
though its prior decision only mentioned the first fact
finding, to allow re-litigation of the second fact finding in
the same case against the same defendant “would consti-
tute an abandonment of serious judicial reasoning and
decision-making in exchange for the wooden application of
judge-made rules designed to protect litigants in circum-
stances where they need protection.” Id. at 994.
14                     TECSEC, INC.   v. INTL BUSINESS MACHINES



    We decline to extend Ritter to the facts of this case.
The Fourth Circuit has recognized that Ritter “essentially
appl[ied] a law-of-the-case principle” to hold that collat-
eral estoppel should apply in that case. In re Microsoft
Antitrust Litig., 355 F.3d 322, 328 (4th Cir. 2004). For the
reasons underlying our decision that the mandate rule
does not apply in this case, we conclude that the law of
the case doctrine does not bar TecSec from rearguing
claim construction in this appeal. See Tronzo v. Biomet,
Inc., 236 F.3d 1342, 1348 n.1 (Fed. Cir. 2001) (explaining
that the law of the case doctrine is a “corollary to the
mandate rule”) (citing United States v. Polland, 56 F.3d
776, 779 (7th Cir. 1995)). Moreover, unlike Ritter, our
Rule 36 judgment did not address any of the issues ruled
on below that TecSec had appealed. We did not endorse
or reject any of the district court’s specific holdings. For
collateral estoppel to apply to a court’s claim construction,
the construction “had to be the reason for the loss,” Jack-
son Jordan, Inc. v. Plasser Am. Corp., 747 F.2d 1567, 1577
(Fed. Cir. 1984), a conclusion that does not apply here.
We thus decline to hold that collateral estoppel applies in
this case.

     II. Construction of “Multi-Level Multimedia Security”

     The parties dispute the construction of the term “mul-
ti-level multimedia security.” That term appears in every
asserted claim.

    The district court ruled that the term requires “multi-
ple layers of encryption” because TecSec defined the term
during prosecution and the specification repeatedly de-
scribes that the method encrypts an object and then nests
or embeds that object within other encrypted objects.
Summary Judgment Order, 769 F. Supp. 2d at 1003–09.
The court also concluded that the term was limited to
securing multimedia information and construed the term
“multimedia” as “a computer technology that displays
TECSEC, INC.   v. INTL BUSINESS MACHINES                15



information using a combination of full-motion video,
animation, sound, graphics and text with a high degree of
user interaction.” Id. at 1008–09. The court concluded
that the patentee had advocated for this definition during
prosecution. Id.

               A. Multiple Layers of Encryption

    TecSec argues that the district court erroneously re-
quired multiple layers of encryption because the term
“security” is broader than “encryption” and encompasses
access control. TecSec specifically asserts that the claim
language does not require multiple layers of encryption
because claim 1 recites encrypting a single object, not
multiple objects, and dependent claim 3 recites encrypting
multiple objects. TecSec argues that the specification
discloses embodiments in which the method utilizes one
layer of encryption to secure data.

    The defendants respond that the district court correct-
ly required multiple layers of encryption. They contend
that the inventors explained in prosecution that “multi-
level security” refers to encrypted objects that may be
“nested within other objects which are also encrypted.”
J.A. 427, 436; ’702 Patent col. 4 ll. 25–28. They argue
that TecSec’s claim differentiation argument fails because
the court’s construction does not render any claims super-
fluous—the dependent claims that require two levels of
encryption also require selecting a second label. They
assert that the specification only discloses encrypted data
contained within an encrypted container.

    We are not persuaded by TecSec’s arguments. It may
be true that the ordinary meaning of “multi-level” securi-
ty is not limited to two layers of encryption but can en-
compass one level of encryption coupled with a second
layer of security, such as access control. And TecSec is
correct that the asserted patents disclose encryption and
16                   TECSEC, INC.   v. INTL BUSINESS MACHINES



password protection as different types of security. E.g.,
’702 Patent col. 1 ll. 32–35, ll. 46–48 (disclosing encryp-
tion and password protection).

     But the prosecution history mandates a narrower con-
struction. During prosecution, the PTO rejected the
claims because the term “multi-level multimedia security”
was “unclear.” J.A. 434. In response, the inventor
amended the specification and explained that the inven-
tion achieves “multi-level multimedia security” in two
ways: (1) it achieves “multi-level security” because “en-
crypted objects may be nested within other objects which
are also encrypted”; and (2) it achieves “multimedia
security” because the “objects are encrypted.” J.A. 427;
see also ’702 Patent col. 4 ll. 25–34. “Thus, the nesting of
individually encrypted objects provides security that is
multi-level and multimedia.” J.A. 427; see also ’702
Patent col. 4 ll. 32–34. Through these statements the
inventor defined the term “multi-level multimedia securi-
ty” to require multiple layers of encryption.

    This definition of the term “multi-level multimedia se-
curity” is sufficient to overcome TecSec’s claim differentia-
tion argument. Claim differentiation is not a rigid rule
and it cannot overcome a construction required by the
prosecution history. Regents of Univ. of Cal. v. Dakocyto-
mation Cal., Inc., 517 F.3d 1364, 1375 (Fed. Cir. 2008).
Here, the inventor’s definition of “multi-level multimedia
security” governs. Thus, the district court correctly
construed “multi-level multimedia security” as requiring
multiple layers of encryption.

                  B. Multimedia Objects

    TecSec argues that the court erroneously construed
“multimedia” as a noun identifying the types of objects
that may be encrypted, rather than an adjective describ-
ing the type of security that the invention employs. It
TECSEC, INC.   v. INTL BUSINESS MACHINES                    17



contends that the claims and specification show that
security can be applied to any “object,” regardless of the
media type.

     The defendants assert that the inventor defined the
term during prosecution when he referred to a dictionary
definition of “multimedia.” Thus, the defendants contend
that the district court correctly construed the claims when
it simply adopted the inventor’s definition.

     We agree with TecSec that the court erred when it
limited the encrypted data to objects in multimedia form.
The ordinary meaning of “multi-level multimedia securi-
ty” relates to the type of “security” employed and does not
limit the type of data that may be encrypted. Indeed, the
claims and specification convey that any type of data may
be encrypted, not just multimedia. E.g., ’702 Patent
claim 1, col. 3 l. 42–col. 4 l. 34. For example, the specifica-
tion describes the encrypting and decrypting of text,
memos, letters, spreadsheets, and sound. Id. col. 3 l. 58–
col. 4 l. 22, col. 7 l. 63–col. 11 l. 11.

    The prosecution history of the ’702 Patent does not
limit the claims to the encryption and decryption of mul-
timedia data. “[F]or prosecution disclaimer to attach, our
precedent requires that the alleged disavowing actions or
statements made during prosecution be both clear and
unmistakable.” Omega Eng’g, Inc. v. Raytek Corp., 334
F.3d 1314, 1325–26 (Fed. Cir. 2003). The prosecution
history at issue here does not rise to that level.

     During prosecution, the inventor explained that the
portion he added to the specification relating to multi-
level encryption described “multi-level multimedia securi-
ty.” J.A. 435. He also cited to a dictionary for the propo-
sition that those terms—“multi-level,” “multimedia,” and
“security”—were well known in the art. Id. He did not
argue that the dictionary definition showed that “multi-
18                     TECSEC, INC.   v. INTL BUSINESS MACHINES



media security” required encryption of multimedia ob-
jects. Nor did the inventor characterize his claims as
limited to encrypting multimedia objects. He did not
distinguish his invention from the prior art on that basis.
In these circumstances, we cannot say that the inventor
clearly and unmistakably limited his claims to encrypting
multimedia objects. Thus, we hold that the district court
erred when it limited the term “multi-level multimedia
security” to require that secured data be multimedia data.

                           *****

    The term “multi-level multimedia security” requires
multiple levels of encryption but is not limited to securing
only multimedia objects. Based on the parties’ stipula-
tion, TecSec may be able to prove infringement against
every defendant except PayPal. J.A. 2640, 2645–46.
Thus, we affirm the court’s noninfringement judgment as
to PayPal but otherwise reverse the court’s summary
judgment of noninfringement and remand for further
proceedings.

     III. Construction of Means-Plus-Function Limitations

    The parties’ dispute relates to sixteen claim limita-
tions that employ the term “means.” The district court
treated these limitations as 35 U.S.C. § 112, ¶ 6 expres-
sions and held that TecSec failed to identify correspond-
ing structure for any of these limitations. Summary
Judgment Order, 769 F. Supp. 2d at 1020–22. It conclud-
ed that none of the “structure” that TecSec pointed to was
sufficient to perform any of the recited functions and that
TecSec could not prove infringement as a matter of law.
Id. We discuss these limitations below.
TECSEC, INC.   v. INTL BUSINESS MACHINES                     19



   A. System Memory Means and Digital Logic Means

    TecSec argues that the district court erred when it
concluded that the terms “system memory means” and
“digital logic means” were means-plus-function limita-
tions. It argues that both terms recite sufficient structure
to avoid treatment under § 112, ¶ 6 because “system
memory” is a structural element and the claim provides
that the “digital logic means” comprises specific struc-
tures, including “a system memory means,” two “subsys-
tems,” and two “modules.”

    The defendants argue that the district court correctly
concluded that the “system memory means” and the
“digital logic means” are means-plus-function limitations.
They argue that a “system memory means” invokes
§ 112, ¶ 6 because a “system memory” is insufficient
structure to overcome the presumption that the term is a
means-plus-function limitation. Similarly, they argue
that the “digital logic means” is a means-plus-function
limitation because the “modules,” “systems,” and “means”
recited in the claim are generic structures.

    We agree with TecSec that the “system memory
means” and the “digital memory means” do not invoke
§ 112, ¶ 6. The use of the term “means” triggers a rebut-
table presumption that § 112, ¶ 6 applies. TriMed, Inc. v.
Stryker Corp., 514 F.3d 1256, 1259 (Fed. Cir. 2008). One
way in which this presumption can be overcome is if “the
claim recites sufficient structure for performing the
described functions in their entirety.” Id. To determine if
the claim recites sufficient structure, “it is sufficient if the
claim term is used in common parlance or by persons of
skill in the pertinent art to designate structure, even if
the term covers a broad class of structures and even if the
term identifies the structures by their function.” Lighting
World, Inc. v. Birchwood Lighting, Inc., 382 F.3d 1354,
1359–60 (Fed. Cir. 2004).
20                   TECSEC, INC.   v. INTL BUSINESS MACHINES



    A “system memory” is sufficient structure to perform
the “storing data” function. To those skilled in the art, a
system memory is a specific structure that stores data.
Consistent with this understanding, for example, the
specification discloses a computer that contains random
access memory (RAM) to store data. ’720 Patent col. 7 l.
37 (disclosing a “486 50 MHz DX” computer system with
“16 megabytes of RAM”).

   The defendants rely on Chicago Board Options Ex-
change v. International Securities Exchange, 677 F.3d
1361, 1367 n.1 (Fed. Cir. 2012), in arguing that a “system
memory means” can be a means-plus-function limitation.
This argument fails for two reasons.

     First, we did not hold in Chicago Board that a “sys-
tem memory means” was a means-plus-function limita-
tion. Instead, we held that the patentee had waived its
right to argue that a “system memory” was sufficient
structure to avoid the application of § 112, ¶ 6 because
“[t]he parties expressly agreed during claim construction
that ‘system memory means’ is a means-plus-function
limitation.” Chicago Board, 677 F.3d at 1366–67. We
then noted that “[e]ven if this argument was not waived,
the presumption that ‘system memory means’ is a means-
plus-function limitation is not overcome.” Id. at 1366–67
n.1. This statement was not a holding; it was expressly
dictum and thus not binding. Zoltek Corp. v. United
States, 672 F.3d 1309, 1319–20 (Fed. Cir. 2012).

    Second, the “system memory means” at issue in Chi-
cago Board performed a more specific function than
simply storing data. It required the system memory
means to “stor[e] allocating parameters for allocating
trades between the incoming order or quotation and the
previously received orders and quotations.” Chicago
Board, 677 F.3d at 1365. The sufficient structure inquiry
focuses on whether the claim recites sufficient structure
TECSEC, INC.   v. INTL BUSINESS MACHINES                 21



to perform “the functions in question.” TriMed, 514 F.3d
at 1260. Here, it is beyond question that those of skill in
the art would understand that a system memory is suffi-
cient structure to perform the general function of “storing
data.” Accordingly, we hold that the district court erred
when it concluded that the term “system memory means
for storing data” was a means-plus-function limitation.

    The term “digital logic means” is also not subject to
§ 112, ¶ 6. As an initial matter, the claims do not recite a
function for the digital logic means to perform. Claim 8 of
the ’702 Patent simply recites a “digital logic means, the
digital logic means comprising” a number of claim ele-
ments. In addition, the term “digital logic” designates
structure to skilled artisans—namely digital circuits that
perform Boolean algebra. The claim also recites that the
digital logic means is comprised of structural elements,
including a system memory and specific modules and
subsystems. While the defendants assert that those
elements are purely generic, we see no reason to hold that
those elements are so devoid of structure as to implicate
§ 112, ¶ 6. Thus, the district court erred when it held that
the term “digital logic means” was a means-plus-function
limitation.

 B. Computer-Implemented Means-Plus-Function Terms

    TecSec argues that the district court erred when it
concluded that the fourteen other means-plus-function
terms in the asserted claims of the ’702 Patent lacked
sufficient corresponding structure in the specification.
These terms all recite computer-implemented functions in
the overall claimed system. For example, claim 12 re-
quires a “means for selecting an object to encrypt.”
TecSec contends that Examples 1–3 in the specification
disclose specific software applications and describe how
these software applications operate to perform the recited
functions.
22                   TECSEC, INC.   v. INTL BUSINESS MACHINES



    The defendants respond that the district court correct-
ly concluded that the computer-implemented means-plus-
function terms lack corresponding structure in the specifi-
cation. They contend that the software programs recited
in the specification are not sufficient to perform the
recited functions because they are generic disclosures of
software, not specific algorithms to implement the
claimed functions.

     We agree with TecSec that the specification discloses
sufficient corresponding structure for the computer-
implemented means-plus-function limitations.           The
parties agree that for these limitations to avoid indefi-
niteness, the specification must disclose a special purpose
computer as corresponding structure—i.e., a computer
programmed to perform a disclosed algorithm. Ergo
Licensing, LLC v. CareFusion 303, Inc., 673 F.3d 1361,
1364–65 (Fed. Cir. 2012). We allow a patentee to express
an algorithm “in any understandable terms including as a
mathematical formula, in prose, or as a flow chart, or in
any other manner that provides sufficient structure.”
Finisar Corp. v. DirecTV Grp., Inc., 523 F.3d 1323, 1340
(Fed. Cir. 2008) (internal citation omitted). However,
“[s]imply reciting ‘software’ without providing some detail
about the means to accomplish the function is not
enough.” Id. at 1340–41. The party alleging that the
specification fails to disclose sufficient corresponding
structure must make that showing by clear and convinc-
ing evidence. Budde v. Harley-Davidson, Inc., 250 F.3d
1369, 1380–81 (Fed. Cir. 2001).

    The defendants have failed to show by clear and con-
vincing evidence that the ’702 Patent specification fails to
disclose corresponding structure for the fourteen comput-
er-implemented means-plus-function limitations.         The
specification discloses the specific software products and
how to use those products to implement the claimed
functions, which include “selecting an object to encrypt,”
TECSEC, INC.   v. INTL BUSINESS MACHINES                  23



“selecting an encryption algorithm,” and “encrypting the
object,” among others.

     The specification provides three examples of using the
software to perform these functions. The first example
describes securing an object in a word processor applica-
tion such as WordPerfect® or Microsoft Word® using an
Object-Oriented Key Manager (OOKeyMan), which is a
specific stand-alone application in Microsoft Windows®.
’702 Patent col. 6 ll. 40–46, col. 7 l. 62–col. 9 l. 4. The
example describes how a user interacts with the software
applications to cause them to select an object to encrypt,
select a label for the object, select an encryption algo-
rithm, encrypt the object, and label the encrypted object.
Id. col. 7 l. 63–col. 8 l. 37. The example then details how
the software determines if the user is authorized to view
the object and, if so, decrypts the object. Id. col. 8 l. 37–
col. 9 l. 3. While the details of the example focus on the
encryption and labeling of a single object, the specification
explains that the example “shows the ability for OOK-
eyMan to securely manage and track single or multiple
embedded encrypted objects within other encrypted
objects.” Id. col. 7 ll. 50-52. The second and third exam-
ples show how the OOKeyMan software manages and
tracks encrypted objects that may be transmitted between
different applications, such as between WordPerfect® and
Microsoft Word®. Id. col. 7 ll. 54-61, col. 9 l. 4–col. 11 l.
11.

     The defendants contend that these examples only dis-
close generic software and not a specific algorithm. We
disagree. It is true that “black box” disclosures of soft-
ware are often too generic to provide corresponding struc-
ture for computer-implemented means-plus-function
limitations. E.g., Blackboard, Inc. v. Desire2Learn Inc.,
574 F.3d 1371, 1383 (Fed. Cir. 2009) (“The ACM is essen-
tially a black box that performs a recited function. But
how it does so is left undisclosed.”); ePlus, Inc. v. Lawson
24                    TECSEC, INC.   v. INTL BUSINESS MACHINES



Software, Inc., 700 F.3d 509, 518 (Fed. Cir. 2012) (holding
that “black box” labeled “Purchase Orders” was insuffi-
cient structure to perform the “generate purchase orders”
function). But the examples here provide detailed prose
that shows how the specific software products operate to
implement the claimed functions. “This court does not
impose a lofty standard in its indefiniteness cases.”
Finisar, 523 F.3d at 1341. Short of providing source code,
it is difficult to envision a more detailed disclosure.
Accordingly, we reverse the district court’s conclusion that
the ’702 Patent specification failed to provide sufficient
structure corresponding to these means-plus-function
limitations.

                        CONCLUSION

    We have considered the parties’ remaining arguments
and have found them unpersuasive. For the foregoing
reasons, the district court’s judgment is

 AFFIRMED-IN-PART, REVERSED-IN-PART, AND
               REMANDED

                           COSTS

     Each party shall bear its own costs.
 United States Court of Appeals
     for the Federal Circuit
            ______________________

               TECSEC, INC.,
              Plaintiff-Appellant,

                       v.

   INTERNATIONAL BUSINESS MACHINES
       CORPORATION AND EBAY INC.,
              Defendants,

                     AND

CISCO SYSTEMS, INC., SAS INSTITUTE INC., SUN
  MICROSYSTEMS, INC. (now known as Oracle
  America, Inc.), ORACLE CORPORATION, AND
                  PAYPAL, INC.,
               Defendants-Appellees,

                     AND

SAP AMERICA, INC., SAP, AG, AND SYBASE, INC.,
           Defendants-Appellees,

                     AND

   SOFTWARE AG and SOFTWARE AG, INC.,
           Defendants-Appellees,

                     AND

           ADOBE SYSTEMS, INC.,
             Defendant-Appellee.
2                    TECSEC, INC.   v. INTL BUSINESS MACHINES



                  ______________________

                        2012-1415
                  ______________________

   Appeal from the United States District Court for the
Eastern District of Virginia in No. 10-CV-0115, Judge
Leonie M. Brinkema.
                ______________________

REYNA, Circuit Judge, dissenting.
    This case raises an important issue concerning the
court’s practice of issuing judgments pursuant to Federal
Circuit Rule 36 (“Rule 36”).
    The majority concludes that the district court miscon-
strued various claim terms from three TecSec, Inc. pa-
tents. It reaches this conclusion notwithstanding that the
same claim terms, same constructions, same arguments,
and same summary judgment order were previously
before this court and reviewed on January 9, 2012. See
TecSec, Inc. v. Int’l Bus. Mach. Corp. (“TecSec I”), 466 Fed.
App’x 882 (Fed. Cir. 2012). In TecSec I, this court sum-
marily affirmed the district court’s grant of summary
judgment of noninfringement pursuant to Rule 36. Id.
After TecSec lost its case against IBM, and without offer-
ing any additional evidence against the other defendants
now before us, TecSec stipulated to noninfringement and
has once again appealed the same district court’s claim
constructions to this court. I respectfully dissent because
I believe that entertaining this appeal gives TecSec a
second bite at the apple and undermines the utility of
Rule 36.
TECSEC, INC.   v. INTL BUSINESS MACHINES                       3



                               I.
     Rule 36 allows this court to “enter a judgment of af-
firmance without opinion” under specific circumstances. 1
Because there is no opinion, a Rule 36 judgment simply
affirms the prior tribunal’s judgment. Rates Tech., Inc. v.
Mediatrix Telecom, Inc., 688 F.3d 742, 751 (Fed. Cir.
2012). It does not endorse or sustain any specific part of
the prior tribunal’s reasoning, but it does impart finality
on issues underlying the district court’s judgment at least
as it relates to “claim preclusion, issue preclusion, judicial
estoppel, law of the case, and the like.” Id. (quoting Fed.
Cir. R. 32.1(c)); see also Fed. Cir. Internal Operating
Procedure 9 ¶ 8 (Nov. 14, 2008).



    1   Rule 36 is as effective as it is simple:

    ENTRY OF JUDGMENT – JUDGMENT OF
    AFFIRMANCE WITHOUT OPINION
    The court may enter a judgment of affirmance without
    opinion, citing this rule, when it determines that any
    of the following conditions exist and an opinion would
    have no precedential value:
    (a) the judgment, decision, or order of the trial court
    appealed from is based on findings that are not clearly
    erroneous;
    (b) the evidence supporting the jury’s verdict is suffi-
    cient;
    (c) the record supports summary judgment, directed
    verdict, or judgment on the pleadings;
    (d) the decision of an administrative agency warrants
    affirmance under the standard of review in the statute
    authorizing the petition for review; or
    (e) a judgment or decision has been entered without an
    error of law.

Fed. Cir. R. 36.
4                    TECSEC, INC.   v. INTL BUSINESS MACHINES



     Rule 36 is premised, in part, on the recognition that
“[t]he workload of the appellate courts precludes prepara-
tion of precedential opinions in all cases.” Fed. Cir.
Internal Operating Procedure 10 ¶ 1 (Jul. 7, 2010).
Indeed, unnecessary nonprecedential dispositions with
full opinions only impede the rendering of decisions and
delay the preparation of precedential opinions in cases
that merit such effort. See id.
    This is not to say that there is no value in a Rule 36
judgment. “Appeals whose judgments are entered under
Rule 36 receive the full consideration of the court, and are
no less carefully decided than the cases in which we issue
full opinions.” U.S. Surgical Corp. v. Ethicon, Inc., 103
F.3d 1554, 1556 (Fed. Cir. 1997). I have no reason to
doubt that this court in TecSec I gave the appeal before it
its full consideration and attention. Based on these
propositions, I am troubled by the majority’s decision to
reach the claim construction issues on this appeal.
    The majority reasons that the district court’s judg-
ment in TecSec I could have been affirmed on multiple
grounds—failure of proof of an act of infringement by IBM
or its customers or, alternatively, failure to show that
IBM’s accused machines meet the claim limitations as
construed. The majority therefore reasons that this
court’s Rule 36 affirmance in TecSec I has no preclusive
effect, either under the mandate rule or collateral estop-
pel and, in so concluding, it ignores that implicit in its
reasoning is the false premise that claim construction is
not a necessary part of a noninfringement determination.
    An act of infringement occurs when all the elements
of a claimed product or method are met by the accused
device or process. See Akamai Techs., Inc. v. Limelight
Networks, Inc., 692 F.3d 1301, 1337–38 (Fed. Cir. 2012)
(en banc) (Linn, J., dissenting) (“[T]he existence of an act
of direct infringement under [35 U.S.C.] § 271(a), [re-
quires] that all steps of a claimed method be prac-
TECSEC, INC.   v. INTL BUSINESS MACHINES                      5



ticed . . . .”). This is the familiar “all elements” rule. 2 Our
cases hold that before the “all elements” rule can be
deployed, however, the claims must first be construed.
Specifically, an “[e]valuation of a summary judgment of
noninfringement requires two steps: claim construc-
tion . . . and comparison of the properly construed claims
to the accused product . . . .” Abbott Labs. v. Sandoz, Inc.,
566 F.3d 1282, 1288 (Fed. Cir. 2009); Markman v.
Westview Instruments, Inc., 52 F.3d 967, 976 (Fed. Cir.
1995) (en banc), aff’d, 517 U.S. 370 (1996); see also Baron
Servs. v. Media Weather Innovations LLC, 717 F.3d 907,
914 n.13 (Fed. Cir. 2013) (“A determination of patent
infringement, even on summary judgment, requires a two-
step analysis, the first of which is claim construction.”).


    2   Under the “all elements” rule, the accused device
must contain each limitation of the claim, either literally
or by an equivalent, to be infringing. TIP Sys., LLC v.
Phillips & Brooks/Gladwin, Inc., 529 F.3d 1364, 1379
(Fed. Cir. 2008) (quoting Freedman Seating Co. v. Am.
Seating Co., 420 F.3d 1350, 1358 (Fed. Cir. 2005)). Most
often, the “all elements” rule serves to prevent vitiation of
a claim limitation when the infringement theory is based
on the doctrine of equivalents, but that is not the case
here. Trading Techs. Int’l, Inc. v. eSpeed, Inc., 595 F.3d
1340, 1355 (Fed. Cir. 2010) (quoting in Warner-Jenkinson
Co., Inc. v. Hilton Davis Chemical Co., 520 U.S. 17, 39 n.8
(1997)); see also TIP, 529 F.3d at 1379; Freedman, 420
F.3d at 1358; Pennwalt Corp. v. Durand-Wayland, Inc.,
833 F.2d 931, 949-50 (Fed. Cir. 1987) (en banc) (Nies, J.,
additional views). Relevant to this case, literal infringe-
ment “occurs when every limitation recited in the claim
appears in the accused device, i.e., when ‘the properly
construed claim reads on the accused device exactly.’”
Demarini Sports v. Worth, 239 F.3d 1314, 1331 (Fed. Cir.
2001) (quoting Amhil Enters., Ltd. v. Wawa, Inc., 81 F.3d
1554, 1562 (Fed. Cir. 1996)).
6                    TECSEC, INC.   v. INTL BUSINESS MACHINES



Claim construction and sufficiency of the evidence show-
ing an act of infringement are not alternative grounds on
which to find noninfringement. They are part of a singu-
lar analysis. Baron, 717 F.3d at 914 (“[A] district court
should not avoid construing relevant terms in the assert-
ed claims as part of its infringement analysis.”). Only
after the claims are properly construed can the court
determine that there is no evidence of an act of infringe-
ment when there has been no showing that the accused
products meet all of the limitations of the properly con-
strued claims. See Burke, Inc. v. Bruno Indep. Living
Aids, Inc., 183 F.3d 1334, 1338 (Fed. Cir. 1999). It is
during this second step of the infringement analysis that
the “all elements” rule is deployed to determine whether
there has been an act of infringement. See supra note 2.
    In this case, the district court’s summary judgment
opinion follows the proper infringement analysis. First,
the court construed the claims of TecSec’s patents to
determine their meaning and scope. TecSec, Inc. v. Int’l
Bus. Mach. Corp., 769 F. Supp. 2d 997, 1003–09 (E.D. Va.
2011); see Cordis Corp. v. Boston Sci. Corp., 658 F.3d
1347, 1354 (Fed. Cir. 2011). Second, the district court
determined whether the evidence offered by TecSec,
which compared the claims to the accused products,
raised a triable issue of material fact. TecSec, 769 F.
Supp. 2d at 1010–22; see Computer Docking Station Corp.
v. Dell, Inc., 519 F.3d 1366, 1373 (Fed. Cir. 2008). Given
that this court affirmed (under Rule 36) the district
court’s judgment as based on findings that were not
clearly erroneous, that the record supported summary
judgment, and that the judgment was entered without an
error of law, the district court’s claim construction must
have been critical and necessary to the decision to issue
the Rule 36 affirmance. See Fed. Cir. R. 36(a), (c), (e); cf.
Burke,183 F.3d at 1338 (“Summary judgment should
ordinarily be vacated or reversed, however, if it is based
TECSEC, INC.   v. INTL BUSINESS MACHINES                  7



on a claim construction that this court determines to be
erroneous.”).
    Despite the district court’s two-step infringement
analysis, the majority suggests that the district court
could have found either a failure of proof of an act of
infringement, or alternatively, no infringement under
“conventional rules of infringement” where the properly
construed claims are compared to the accused products.
Maj. Op. 10 n.1. In order to find a failure of proof of an
act of infringement, the district court, under the “all
elements” rule, needed to identify a missing element or
elements from the accused products. 3 Demarini, 239 F.3d
at 1331. The majority points to a portion of the district
court’s opinion, which it asserts is a separate, independ-
ent determination of failure of proof. The majority, how-
ever, overlooks the fact that the district court identifies
only two missing elements from the accused products in
that section and the reasoning that the district court gives
for why those elements are missing is that the accused
products lack those limitations under its own claim con-
struction, which is the second step in a traditional in-
fringement analysis. TecSec, 769 F. Supp. 2d at 1011
(“[The accused products] cannot infringe the [asserted
patents] because . . . those products alone are not capable
of encrypting and decrypting the same object, as is re-
quired by the [the district court’s construction]. See infra
at III.B.3.C”); id. at 1012 (“[E]ven if some user-
implemented system were to meet all of the asserted
claim limitations - which, as explained below, it cannot,



    3  This is not a case in which the district court inti-
mated that there had been a failure of proof irrespective
of which constructions it adopted. Instead, the district
court rejected TecSec’s proposed constructions initially
and made no mention of them in its failure of proof analy-
sis.
8                    TECSEC, INC.   v. INTL BUSINESS MACHINES



see infra at III.B.3, TecSec has provided no evidence that
IBM ever made, used, sold, offered to sell, or imported
th[e] entire claimed system . . . .”). Rather than being a
separate, independent analysis, the district court’s de-
scription of TecSec’s failure of proof is merely the second
step of its infringement analysis after the claims were
construed in the first step.
    This court previously refused to affirm summary
judgment of noninfringement where the district court did
not perform a “traditional infringement analysis” when it
“did not conduct the first step of that analysis—
construing the disputed claim language”—even though
the accused infringer alternatively asserted that there
was a failure of proof on infringement.          See Eagle
Comtronics, Inc. v. Arrow Commc’n Labs., Inc., 305 F.3d
1303, 1317 (Fed. Cir. 2002). It follows that a failure of
proof of an act of infringement is not an alternative to
“conventional rules of infringement,” but rather consti-
tutes the second step of a traditional infringement analy-
sis performed after the court completes the first necessary
step of construing the claims.
                            II.
     Having concluded that the district court’s claim con-
struction was critical and necessary to our prior Rule 36
affirmance, it is a straightforward step for me to conclude
that TecSec is precluded from relitigating those issues it
lost on in TecSec I. This outcome holds true under either
the mandate rule or collateral estoppel.
    According to the mandate rule, “[u]nless remanded by
this court, all issues within the scope of the appealed
judgment are deemed incorporated within the mandate
and thus are precluded from further adjudication.” Engel
Indus., Inc. v. Lockformer Co., 166 F.3d 1379, 1383 (Fed.
Cir. 1999). Specifically, “issues actually decided—those
within the scope of the judgment appealed from, minus
TECSEC, INC.   v. INTL BUSINESS MACHINES                  9



those explicitly reserved or remanded by the court—are
foreclosed from further consideration.” Id.
    Here, the majority reasons that the claim construction
issues were not “actually decided” because the TecSec I
panel could have affirmed on the “independent” ground of
failure of proof without “implicitly or explicitly” reaching
the claim construction issues. This reasoning is contrary
to our precedent that claim construction and evaluation of
the evidence to determine a failure of proof are not inde-
pendent grounds; they are two steps necessary to reach a
single noninfringement judgment. E.g., Abbott Labs., 566
F.3d at 1288. Accordingly, the claim construction issues
that TecSec advanced in TecSec I are within the scope of
the Rule 36 affirmance in that case, and the mandate rule
precludes TecSec from relitigating them in this appeal.
     For collateral estoppel, the majority disputes whether
the claim construction issues were “actually determined”
and “critical and necessary to the judgment.” Yet, there is
no question that the district court actually determined the
claim construction issues in TecSec I. See TecSec, 769 F.
Supp. 2d at 1003–09. For the TecSec I panel to have
affirmed the district court’s judgment of noninfringement,
it necessarily decided those issues as well or, at a mini-
mum, the claim construction issues were critical and
necessary to the affirmance of the district court’s sum-
mary judgment decision. See Abbott Labs., 566 F.3d at
1288. Thus, I find that collateral estoppel precludes
TecSec from relitigating the claim construction issues it
lost in TecSec I on appeal before this court.
                           *   *   *
    As a practitioner, I once bore distaste for Rule 36 af-
firmances. I accepted that under a Rule 36 judgment, one
party lost and another won, and that the decision of the
district court was deemed not erroneous. What bothered
me was that the “how” and the “why” behind the affir-
mance, the actual reasoning that would enable me to
10                   TECSEC, INC.   v. INTL BUSINESS MACHINES



assist and guide a client, was lacking. The court’s silence
on its analysis and reasoning thundered loudly.
     As a judge on this court, I fully understand and ap-
preciate the role of Rule 36 judgments in the overall
process of our work. And it is precisely this understand-
ing that triggers my dissent in this case. When we explic-
itly or implicitly assume that a prior panel of this court
overlooked controlling precedent and narrowly circum-
scribe a prior judgment issued under Rule 36, we fail to
honor the principle that those cases “receive the full
consideration of the court, and are no less carefully decid-
ed than the cases in which we issue full opinions.” U.S.
Surgical, 103 F.3d at 1556. Allowing a party to relitigate
an issue it previously lost by summary affirmance will
erode the confidence that underpins Rule 36, that such
cases are no less carefully reviewed. Perhaps, as I once
believed, this court should revisit its frequent use of Rule
36. Yet, that would be a drastic step, and would only
impede the rendering of decisions and delay the prepara-
tion of precedential opinions in cases that merit such
effort. A far better course would be to accord Rule 36
affirmances their appropriate weight, see Rates Tech., 688
F.3d at 751, and apply the preclusion doctrines that
would prevent second bites at the apple. The majority’s
disposition in this case allows TecSec two bites at the
claim construction apple. Accordingly, I respectfully
dissent.
