Tecsec, Inc. v. Adobe Systems Incorporated , 658 F. App'x 570 ( 2016 )


Menu:
  •        NOTE: This disposition is nonprecedential.
    United States Court of Appeals
    for the Federal Circuit
    ______________________
    TECSEC, INC.,
    Plaintiff-Appellant
    v.
    ADOBE SYSTEMS INCORPORATED,
    Defendant-Appellee
    SAS INSTITUTE, INC., SAP AMERICA, INC., SAP
    AG, CISCO SYSTEMS, INC., SYBASE, INC.,
    SOFTWARE AG, SOFTWARE AG, INC., PAYPAL,
    INC., ORACLE CORPORATION, ORACLE
    AMERICA, INC.,
    Defendants
    ______________________
    2015-1686
    ______________________
    Appeal from the United States District Court for the
    Eastern District of Virginia in No. 1:10-cv-00115-LMB-
    TCB, Judge Leonie M. Brinkema.
    ______________________
    Decided: August 18, 2016
    ______________________
    MICHAEL OAKES, Hunton & Williams LLP, Washing-
    ton, DC, argued for plaintiff-appellant. Also represented
    2              TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED
    by MICHAEL ALFRED O'SHEA; GREGORY N. STILLMAN,
    Norfolk, VA.
    CHARLENE M. MORROW, Fenwick & West, LLP, Moun-
    tain View, CA, argued for defendant-appellee. Also repre-
    sented by VIRGINIA KAY DEMARCHI; PHILLIP JOHN HAACK,
    San Francisco, CA.
    ______________________
    Before PROST, Chief Judge, LINN, and TARANTO, Cir-
    cuit Judges.
    LINN, Circuit Judge.
    TecSec, Inc. (“TecSec”) challenges certain claim
    construction rulings and appeals from a grant of summary
    judgment of non-infringement by Adobe Systems, Inc.
    (“Adobe”) of TecSec’s U.S. Patents Numbers 5,369,702
    (“’702 patent”), 5,680,452 (“’452 patent”), 5,717,755 (“’755
    patent”), and 5,898,781 (“’781 patent”), collectively the
    Distributed Cryptographic Object Method patents
    (“DCOM patents”). TecSec, Inc. v. Int’l Business Machines
    Corp., No. 1:10-cv-115 (E.D. Va. May 7, 2015) (“TecSec
    V”). Adobe contests TecSec’s arguments and asserts a
    number of alternative grounds for affirmance. TecSec
    also requests that the case be reassigned to a different
    district judge on remand.
    Because the district court erred in its construction
    of “selecting a label,” because we find no merit in Adobe’s
    alternate grounds for affirmance, and because we find
    nothing to warrant reassignment on remand, we vacate
    the district court’s summary judgment of non-
    infringement and remand for further proceedings con-
    sistent with this opinion.
    TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED                3
    I. BACKGROUND
    A. History of Proceedings
    In 2010, TecSec filed suit in the Eastern District of
    Virginia seeking to enforce its DCOM patents against
    thirteen defendants. The district court has thus far
    restricted TecSec to proceeding against only one defend-
    ant at a time, beginning with IBM and now Adobe. The
    claims against the other defendants remain in this six-
    year old case for resolution on remand. The extended
    pendency of this litigation raises questions as to the
    efficiency of the district court’s one-defendant-at-a-time
    approach. While the scheduling of proceedings is a mat-
    ter within the sound discretion of the district court, it may
    wish to reconsider the prudence of that approach on
    remand.
    B. TecSec’s DCOM Patents
    TecSec’s DCOM patents are generally directed to
    methods and systems of multi-level encryption that allow
    encrypted files to be nested within other encrypted files.
    In addition to multi-level encryption, the DCOM patents
    further limit access by using labels in the form of a field of
    characters attached to the encrypted files.
    TecSec’s charges of infringement against Adobe are
    focused on Adobe’s “Acrobat” program. TecSec asserted
    both method and system claims of the DCOM patents
    against Adobe. Claim 1 of the ’702 patent is representa-
    tive of the method claims asserted against Adobe, and is
    reproduced below, with emphasis on the primary contest-
    ed claim construction and infringement issues:
    1. A method for providing multi-level multime-
    dia security in a data network, comprising
    the steps of:
    A) accessing an object-oriented key man-
    ager;
    4              TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED
    B) selecting an object to encrypt;
    C) selecting a label for the object;
    D) selecting an encryption algorithm;
    E) encrypting the object according to the en-
    cryption algorithm;
    F) labelling the encrypted object;
    G) reading the object label;
    H) determining access authorization based on
    the object label; and
    I) decrypting the object if access authorization
    is granted.
    ’702 patent, col. 12, ll. 2-15. Claim 1 of the ’755 patent
    includes a modified step F, which reads” “labelling the
    encrypted first object wherein the labelling comprises
    creating a display header.” ’755 patent, col. 11, ll. 61-62.
    Claim 8 of the ’702 patent is representative of system
    claims asserted against Adobe, and is reproduced in
    relevant part below, again emphasizing the primary
    contested issues on appeal:
    8. A system for providing multi-level multimedia
    security in a data network, comprising:
    A) digital logic means, the digital logic means
    comprising:
    1) a system memory means for storing data
    ...
    3) an object labelling subsystem, com-
    prising logic means for limiting object ac-
    cess, subject to label conditions . . .
    5) an object label identification subsys-
    tem, comprising logic for limiting object ac-
    cess, subject to label conditions . . .
    TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED               5
    B) the encryption algorithm module working
    in conjunction with the object labelling sub-
    system to create an encrypted object such
    that the object label identification subsys-
    tem limits access to an encrypted object.
    ’702 patent, col. 12, l. 45 – col. 13, l. 19.
    C. Adobe’s Acrobat Program
    Adobe’s Acrobat program allows users to interact with
    files in portable document format (“PDF”). TecSec V at 5.
    Acrobat allows a PDF author to encrypt the document
    using one of two relevant encryption mechanisms: pass-
    word protection or digital certificate security. Password
    protection grants access to the document upon entry of
    one of two correct passwords—an “owner” password or a
    “user” password. The owner password allows full access
    to the document, e.g. printing and saving, while the user
    password grants access according to the permissions
    assigned by the owner upon encryption. Digital certificate
    security allows the owner to select the digital certificates
    of authorized recipients of the file, and to group the
    recipients into groups with distinct access authorizations.
    When a user initiates the encryption process, a screen
    is displayed, asking which encryption mechanism the user
    wishes to use, and what parts of the document
    to encrypt—“all document contents,” “all document con-
    tents except metadata,” or “only file attachments.”
    J. App’x at 3772. Once the user sets the type of security,
    permissions, and what to encrypt, and clicks “OK,” the
    user is returned to the Acrobat interface. Acrobat does
    not encrypt the data until the user saves the document.
    When saving, Acrobat creates an “encryption dictionary”
    containing all the information necessary to test a user’s
    authorization to access and manipulate the file.
    When the data is secured using password security, the
    encryption dictionary contains a user password key and
    6              TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED
    an owner password key, but not the passwords them-
    selves. The keys are used to test the password entered for
    authorization. When the data is secured using digital
    certificate security, Acrobat creates and encrypts a ran-
    dom number “file key” for each recipient, which acts like
    the password key, and is also stored in the encryption
    dictionary. A user’s digital certificate data is processed
    and the file key is used to test the user’s authorization to
    access the data.
    Acrobat also allows files to nest within a PDF docu-
    ment in what Acrobat calls a PDF envelope. The nested
    files may be in PDF format or any number of other for-
    mats. The nested files may also be separately encrypted.
    If the nested file is a PDF document, it may be encrypted
    using Acrobat. When accessed, nested files open in their
    native program, and, if encrypted, go through their own
    decryption process, which, in the case of a PDF file, can be
    performed through Acrobat.
    D. Proceedings before the District Court
    Prior to the completion of discovery, Adobe moved for
    entry of certain proposed claim constructions and for
    summary judgment of no infringement, contending that
    TecSec cannot show that Acrobat meets the “mult-
    level . . . security,” “object-oriented key manager,” “la-
    bel/labelling,” “object,” “access authorization,” and “dis-
    play header” limitations of the claims. The district court
    limited discovery solely to those issues raised in Adobe’s
    summary judgment motion.
    After briefing, the district court held a hearing on the
    summary judgment motion. At that hearing, the court
    questioned both parties with respect to the proper con-
    struction of the “selecting a label” limitation—and partic-
    ularly whether selecting a label is different from creating
    a label. This, despite the fact that neither party had
    disputed the “selecting a label” limitation or sought a
    ruling on its construction and despite the fact that Adobe
    TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED               7
    had not asserted that element as missing from the ac-
    cused Acrobat program. The district court recognized that
    under the circumstances, supplemental briefing might be
    in order and expressly stated that it was “not opposed to
    giving [the parties] further time to brief it.”
    J. App’x at 3935. Both Adobe and TecSec declined the
    district court’s invitation.
    In its written opinion, the district court addressed
    both the claim construction issues raised by Adobe and
    Adobe’s motion for summary judgment of non-
    infringement. In addressing claim construction, the court
    began by construing “selecting a label for the object.” The
    court noted that while the parties did not propose a
    construction for that limitation and declined the oppor-
    tunity to brief the issue, they clearly disputed whether
    selecting a label includes creating a label or selecting the
    components that go into a label. For that reason, the
    court stated that that it had a duty to resolve that dis-
    pute, citing O2 Micro International, Ltd. v. Beyond Inno-
    vation Technology Co., 
    521 F.3d 1351
    , 1362 (Fed. Cir.
    2008). TecSec V at 19. The court then concluded that
    “before an object can be selected, it must first be created.”
    
    Id. at 20.
    Moreover, it construed the limitation as mean-
    ing “choosing a pre-existing label” and not merely select-
    ing “the components used in its creation.” 
    Id. at 23.
         The district court then turned to the disputed claim
    terms presented in Adobe’s motion and noted that
    “[r]esolution of the meaning of those terms will also assist
    in early resolution of the claims that TecSec asserts
    against the remaining defendants.” 
    Id. The district
    court
    first construed “object oriented key manager” to mean “a
    software component that is capable of performing the
    process of generating, distributing, replacing, storing,
    checking on, and destroying cryptographic keys.” TecSec
    V at 26. The court next construed “label” as having been
    expressly defined in the specification of the “702 patent to
    mean “a series of letters or numbers, separate from but
    8                TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED
    associated with the sending of an object, which identifies
    the person, location, equipment, and/or organization
    which is permitted to receive the associated object.” 
    Id. at 32.
    The court went on to construe “labelling” to mean
    “attaching a label,” 
    id. at 32,
    and “access authorization” to
    mean “authorization to access an object,” 
    id. at 34.
    Final-
    ly, the district court construed “display header” to mean
    “a header for making visually perceptible to a user.” 
    Id. at 35.
         In addressing the merits of Adobe’s motion for sum-
    mary judgment of non-infringement, the district court
    observed that “because failure to generate a genuine issue
    of material fact on a single claim term precludes a finding
    of infringement as a matter of law, the Court will only
    address a subset of those arguments.” 
    Id. at 36.
    It then
    proceeded to address only whether Acrobat met the “mul-
    ti-level . . . security,” “label” and “selecting a label” limita-
    tions.
    It first concluded that there was evidence raising a
    genuine issue of material fact and defeating summary
    judgment of non-infringement as to whether Adobe’s
    Acrobat met the “multi-level . . . security” limitation.
    Specifically, the court cited evidence of “the use of multi-
    ple sessions to provide multiple layers of encryption,”
    noting that Acrobat can be used to encrypt PDFs and nest
    them within other encrypted PDF documents. TecSec V
    at 36-37.
    The district court then turned to the question of
    whether Acrobat’s encryption dictionary met the “label”
    limitation and specifically whether the encryption dic-
    tionary functioned to “identify a person, a location,
    equipment, or an organization” consistent with the court’s
    construction of that limitation. 
    Id. at 37.
    The court
    concluded that the label limitation could not be met when
    using password security because the encryption dictionary
    does not contain either the user or owner passwords and
    TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED               9
    even if it did, such passwords are not linked to the identi-
    ty of a particular user. The court, however, did not reach
    that same conclusion when considering the use of certifi-
    cate security as it found evidence indicating that “the
    certificate IDs identify each of the individual recipients.”
    
    Id. at 38.
    The district court found this to defeat Adobe’s
    argument.
    Finally, the court addressed the “selecting a label”
    limitation. Based on a claim differentiation argument
    centered on a different limitation appearing in claims 1
    and 2, the district court perceived a difference between
    “selecting a label” and “creating a label.” It then conclud-
    ed that before one can select an object, the object must
    pre-exist. It went on to distinguish between selecting a
    label and selecting the components that go into the label,
    concluding that the limitation required that the label
    itself and not merely the label components must be select-
    ed. Accordingly, it construed the limitation to mean
    “choosing a pre-existing label.” It then concluded that
    using either encryption scheme, Acrobat does not meet
    the “selecting a label” limitation because Adobe’s encryp-
    tion dictionary does not exist when the type of encryption
    (password protection or digital certificate security) and
    the information to be encrypted are selected, and because
    the encryption dictionary is “not created until the user
    saves the file.” 
    Id. at 40.
    Because the district court’s
    construction of “selecting a label” required a “pre-existing”
    label—an element missing from the Acrobat program—
    the district court concluded that Adobe was entitled to
    summary judgment of non-infringement.
    E. The Present Appeal
    TecSec appeals the district court’s summary judge-
    ment of non-infringement, claiming error: (a) in the
    district court’s basing of its grant on the sua sponte con-
    struction of the “selecting a label” limitation; (b) in erro-
    neously construing the “selecting a label” limitation to
    10              TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED
    require that the label be pre-existing; (c) in adopting an
    unnecessarily narrow construction of the “label” limita-
    tion; and (d) in holding that the encryption dictionary
    with password security is not a label. In a second set of
    arguments, TecSec appeals the district court’s claim
    construction of the “object-oriented key manager” and
    “display header” claim constructions—even though it
    recognized that those limitations did not form the basis of
    the district court's summary judgment decision—and
    contests a statement made by the district court in footnote
    23 of its opinion with regard to the “labelling” limitation.
    Finally, it requests that the case be reassigned to a differ-
    ent judge on remand.
    Adobe asserts as alternative grounds for affirmance
    that Acrobat does not meet: (a) the “object-oriented key
    manager” limitation; (b) the “display header” limitation;
    (c) the requirement for certain memory hardware as
    required by the asserted system claims; (d) the “label”
    limitation under either construction asserted by the
    parties; and (e) the “multi-level . . . security” limitation.
    Adobe also contends that the district court provided an
    alternative basis for summary judgment of non-
    infringement in footnote 23 of its opinion, i.e. that Acrobat
    did not infringe because it did not satisfy the “labelling
    the encrypted object” limitation. Finally, Adobe argues
    that no basis exists to reassign this case to a different
    judge.    This court has jurisdiction under 28 U.S.C.
    § 1295(a)(1).
    II. Discussion
    A. Standards of Review
    The Fourth Circuit reviews the grant of summary
    judgment de novo, viewing the facts and drawing all
    reasonable inferences in favor of the non-moving party,
    and asking whether there is a genuine issue of material
    fact. PBM Prods., LLC v. Mead Johnson Co., 
    639 F.3d 111
    , 119 (4th Cir. 2011). At summary judgment, claim
    TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED            11
    construction is reviewed de novo as an issue of law when
    based on intrinsic evidence without underlying factual
    findings. Teva Pharm. USA, Inc. v. Sandoz, Inc., 
    135 S. Ct. 831
    , 841 (2015). We review subsidiary district court
    fact-finding, if any, for clear error. 
    Id. B. Asserted
    Procedural Error
    TecSec first contends that the district court commit-
    ted serious procedural error when it granted summary
    judgment on the basis of its sua sponte construction of
    selecting a label, without providing proper notice. Be-
    cause we vacate the district court’s summary judgment on
    the merits, we need not and do not address TecSec’s
    assertion of procedural error, but instead turn directly to
    the issues raised.
    C. The Issues Raised by TecSec
    We begin by addressing the principal issues raised by
    TecSec. We address TecSec’s second set of arguments,
    
    noted, supra
    , in our analysis of Adobe’s alternative
    grounds for affirmance.
    1. “Selecting a Label”
    The principal argument raised in this appeal is
    whether the district court properly construed the “select-
    ing a label” limitation and whether, under the proper
    construction, Adobe is entitled to summary judgment of
    no infringement. TecSec asserts that the district court
    both erred in its claim construction and in granting
    summary judgment of non-infringement, even under the
    district court's claim construction.
    TecSec argues that the meaning of this term was nev-
    er in dispute, that the plain and ordinary meaning should
    have been adopted, and that no construction should have
    been provided. It further argues that the district court
    improperly read into the limitation a “pre-existing” re-
    quirement not supported by the intrinsic record. Accord-
    12              TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED
    ing to TecSec, the district court added its pre-existing
    requirement based on a flawed claim differentiation
    argument relating to a different limitation. It also argues
    that selecting a label means selecting components for a
    label.
    Adobe contends that the district court’s claim con-
    struction correctly reflects the common sense understand-
    ing that one cannot “select” something that does not yet
    exist. Adobe cites a number of dictionary definitions to
    support its argument and refers to examples in the speci-
    fication that explain that a user creates an object before
    selecting it for preview. It also argues that in a prior case
    involving two of the asserted DCOM patents, TecSec took
    the position that the plain meaning of the term “selecting”
    is “choosing.” Adobe further argues support based on the
    district court’s claim differentiation analysis and contends
    that there is no support in the specification for TecSec’s
    assertion that selecting a label means selecting compo-
    nents for a label.
    The district court construed “selecting a label for the
    object” as “choosing a pre-existing label,” TecSec V at 5,
    explaining that in the context of the patent, “selecting a
    label” is necessarily distinct from creating a label. The
    primary basis for the district court’s construction was its
    understanding of claim differentiation. In addition to the
    step of “selecting a label,” claim 1 of the ’702 patent
    contains the additional step of “selecting an object to
    encrypt.” ’702 patent, col. 12, l. 5 (emphasis added).
    Dependent claim 2 adds the step of “creating an object in
    an application prior to accessing the object-oriented key
    manager,” ’702 patent, col. 12, ll. 16-20 (emphasis added).
    The district court reasoned that under the doctrine of
    claim differentiation, “selecting an object” in claim 1
    cannot mean “creating an object” as in claim 2 and neces-
    sarily excludes “creating that object.” The court then
    concluded that selecting must mean the same thing in
    both the “selecting an object” and “selecting a label”
    TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED             13
    limitations and that, therefore, “selecting a label” cannot
    include “creating a label.” See TecSec V at 19-20.
    The problem with this reasoning is that first, the “se-
    lecting an object” and “selecting a label” limitations are
    separate and different limitations. Moreover, while the
    doctrine of claim differentiation requires that the limita-
    tions in a parent claim be construed to be different in
    scope from those in dependent claims, it does not neces-
    sarily mean that they are mutually exclusive. The only
    requirement is that the limitation in the parent be at
    least broad enough to encompass the limitation in the
    dependent claim. Tr. of Columbia Univ. in City of New
    York v. Symantec Corp., 
    811 F.3d 1359
    , 1370 (Fed. Cir.
    2016) (“Thus, in a situation where dependent claims have
    no meaningful difference other than an added limitation,
    the independent claim is not restricted by the added
    limitation in the dependent claim. In such situations,
    construing the independent claim to exclude material
    covered by the dependent claim would be inconsistent.”);
    Aspex Eyewear, Inc. v. Marchon Eyewear, Inc., 
    672 F.3d 1335
    , 1348 (Fed. Cir. 2012) (holding that an independent
    claim including the limitation “magnetic member” in-
    cludes ferromagnetic material in addition to a magnet, in
    light of dependent claim limiting “magnetic member” to a
    magnet); Am. Med. Sys., Inc. v. Biolitec, Inc., 
    618 F.3d 1354
    , 1360 (Fed. Cir. 2010) (concluding that “[u]nder the
    doctrine of claim differentiation, those dependent claims
    [reciting the use of particular wavelengths] give rise to a
    presumption that the broader independent claims [recit-
    ing that laser radiation be ‘absorbed substantially com-
    pletely’] are not confined to that range”).
    Here, the district court’s reliance on the doctrine of
    claim differentiation is flawed. The addition of the limita-
    tion “creating an object” in claim 2 signals that the “se-
    lecting an object” limitation in claim 1 must be at least
    broad enough to cover an object that has already been
    created, not that selecting an object necessarily excludes
    14              TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED
    an object that will be created after it is selected. Moreo-
    ver, it is beyond cavil that the plain and ordinary mean-
    ing of the term “selecting” can naturally refer to a choice
    of a not-yet extant object. Parties regularly select any
    number of things that do not exist when the selection is
    made and are only later made to order.
    The district court also relied on the portion of the
    specification that “requires a user to actively choose a pre-
    existing label.” TecSec V at 21. This too was error. First,
    as the district court acknowledged, it is improper to
    import limitations from the specification into the claims.
    Second, the specification does not in any way indicate or
    suggest that one cannot select a label that does not yet
    exist, such as a label identifying the location of a terminal
    that is not yet connected. Nothing in the intrinsic record
    precludes such a possibility, or limits the meaning of
    “selecting a label” to the selection of pre-existing labels.
    Adobe’s assertion that TecSec’s argument on appeal is
    contrary to TecSec’s prior position that “selecting” means
    “choosing” is inapposite. “Choosing” no more requires
    that the chosen label already exists than does “selecting.”
    Lastly, while the district court is correct that “select-
    ing a label” is not the same as “selecting components for a
    label,” the distinction is of no consequence given our
    elimination of the district court’s “pre-existing” require-
    ment.
    We thus agree with TecSec that “selecting a label for
    the object” in the DCOM patents should be given its plain
    meaning, without a requirement that the label exist prior
    to being selected. Under the proper construction of this
    limitation, the district court’s conclusion that Adobe is
    entitled to summary judgement of non-infringement
    cannot be sustained.
    TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED                15
    2. “Label”
    The district court construed the term “label” to mean
    “a series of letters or numbers, separate from but associ-
    ated with the sending of an object, which identifies the
    person, location, equipment, and/or organization which is
    permitted to receive the associated object.” TecSec V at
    32. The court’s construction is based on the following
    passage from the background section of the specification
    of the ’702 patent:
    A file ‘label’ for purposes of this invention means a
    series of letters or numbers, which may or may not
    be encrypted, separate from but associated with the
    sending of a message, which identifies the person,
    location, equipment, and/or organization which is
    permitted to receive the associated message. Using
    a secure labelling regimen, a network manager or
    user can be assured that only those messages
    meant for a certain person, group of persons,
    and/or location(s) are in fact received, decrypted,
    and read by the intended receiver.
    * * *
    A system such as that described above is disclosed
    in U.S. patent application Ser. No. 08/009,741, the
    specification of which is incorporated by reference
    herein.
    ’702 patent, col. 2, ll. 34-61 (emphasis added). The district
    court replaced “associated with the sending of a message”
    and “permitted to receive the associated message” in the
    first paragraph, with “associated with an object,” and
    “permitted to receive the associated object,” respectively.
    TecSec argues that the district court’s construction of
    “label” was error and that the term properly should be
    construed simply to mean “an identifier associated with
    an object.” It contends that the district court improperly
    imported a limited definition from the background section
    16             TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED
    of the specification that is merely descriptive of the mean-
    ing of “label” in the prior art and that was not intended as
    a definition by the patentee. TecSec further argues: (1)
    that the label definition in the first paragraph does not
    apply to the invention described in the written description
    but instead refers to the prior art patent application cited
    in the second paragraph above; (2) the passage associates
    the label with “the sending of a message,” not an object,
    and sending a message does not make sense in the con-
    text of the DCOM patents; (3) the claims here have no
    requirement for “sending” the object, as described in the
    passage; and (4) the patent uses the phrase “the present
    invention” to define the scope of the invention, but the
    first paragraph above uses the phrase “this invention.”
    TecSec also asserts that the specification in the ‘452
    patent uses “label” in a broader and more flexible way
    than the meaning adopted by the district court and that
    its definition is consistent with the plain and ordinary
    meaning of the term and the intrinsic record.
    Adobe counters by arguing that the district court’s
    construction was correct based on the express definition
    set forth in the specification of the DCOM patents and the
    incorporation by reference in the ’702, ’755, and ’781
    patents of the same express definition appearing in U.S.
    Patent Application Serial No. 08/009,741.
    TecSec’s arguments are unconvincing. “[O]ur cases
    recognize that the specification may reveal a special
    definition given to a claim term by the patentee that
    differs from the meaning it would otherwise possess.”
    Phillips v. AWH Corp., 
    415 F.3d 1303
    , 1316 (Fed. Cir.
    2005) (en banc). To give a term a special meaning, “the
    patentee must clearly express an intent to redefine the
    term.” Thorner v. Sony Comp. Entm’t Am. LLC, 
    669 F.3d 1362
    , 1365 (Fed. Cir. 2012) (internal quotes omitted). The
    DCOM patents here clearly manifest such an intent by
    using archetypal language of definition: “A file ‘label’ for
    purposes of this invention means . . . .” The most natural
    TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED                  17
    reading of the passage is as an indicator of the intended
    scope of the claims using that term. “Where, as here, the
    patentee has clearly defined a claim term, that definition
    ‘usually . . . is dispositive; it is the single best guide to the
    meaning of a disputed term.’” Jack Guttman, Inc. v.
    Kopykake Enterprises, Inc., 
    302 F.3d 1352
    , 1360-61 (Fed.
    Cir. 2002) (quoting Vitrionics Corp. v. Conceptronic, Inc.,
    
    90 F.3d 1576
    , 1582 (Fed. Cir. 1996)).
    The “system such as that described above . . .” passage
    does not change the express definition, or indicate that
    the definition should not apply to the ’702 patent. Nor is
    the explicit definitional language of the passage defeated
    by the message/object disparity. The heart of the defini-
    tion is the role of the label in restricting access, and that
    definition is consistent with the use of label in the assert-
    ed patent. Finally, there is no indication in the patent
    that only the phrase, “the present invention,” shall be
    used as a definition, and the phrase “this invention” shall
    be used informationally. Both can be strong indicators of
    a patentee’s lexicographic intent.
    TecSec’s argument that the broader description of la-
    bel in the ’452 patent undermines the definition above is
    also unavailing. See ’452 patent, col. 5, ll. 16-27. 1 We
    1    “A label is a field of characters attached to the en-
    crypted file. The label may define a group of people that
    may have access to the file. The label may define the
    device at which the file may be accessed. The device may
    define a single person who may have access. A label may
    also define the type of access, that is, read only, write
    only, read and write, print only, etc., that authorized
    persons may have. A label may also define any combina-
    tion of authorized people, devices, objects, and/or access
    type. Thus, the label is a flexible, powerful way to set
    forth with great specificity all conditions that must be
    fulfilled in order to gain the defined access to the file.”
    18              TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED
    agree with the district court that the bulk of that excerpt
    is wholly consistent with the definition set forth in the
    ’702 patent and discussed above. Moreover, the defini-
    tional language in the ’702 patent is also present in the
    ’452 patent. See ’452 patent, col. 3, ll. 1-7. We also agree
    with the district court that because the ’452 patent was
    filed after the ’702 patent issued, the excerpt in the ’452
    patent cannot change the express definition in the ’702
    patent. See TecSec V at 29. Finally, we note that neither
    party has argued that the word “label” should take on a
    different meaning in the ‘452 patent than in the other
    DCOM patents. We thus agree with the district court’s
    claim construction of “label” as meaning “a series of
    letters or numbers, separate from but associated with the
    sending of an object, which identifies the person, location,
    equipment, and/or organization which is permitted to
    receive the associated object.”
    TecSec also asserts that the district court erred in
    concluding that the encryption dictionary is not a label
    when Acrobat is used with password security, even under
    the district court’s construction. The district court rea-
    soned that because Acrobat stores keys and not passwords
    and because “the user and owner passwords are not
    linked to the identity of a particular user,” the encryption
    dictionary does not “identif[y] the person . . . permitted to
    receive the object,” as required to meet the “label” limita-
    tion. TecSec argues that Acrobat’s encryption dictionary
    contains two different keys—a user key, and an owner
    key—and that Acrobat’s ability to distinguish between the
    two identifies the individual either as a “user” or an
    “owner,” which is all that is required to meet the claim
    limitation.
    We agree with TecSec. The district court, in applying
    its claim construction to the password security feature of
    the Acrobat program, required the label to identify a
    “particular person,” as opposed to a group of persons
    authorized to have access. But nothing in the intrinsic
    TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED             19
    record requires that the label identify a “particular”
    person. See ’702 patent, col. 2, ll. 40-44 (“Using a secure
    labelling regimen, a network manager or user can be
    assured that only those messages meant for a certain
    person, group of persons, and/or locations(s) are in fact
    received, decrypted, and read by the intended receiver.”)
    (emphasis added). The district court’s construction of
    “label,” with which we agree, is broad enough to encom-
    pass a label which identifies different classes or groups of
    users authorized to access the object. And while some
    labels may limit access to particular people, it does not
    necessarily follow that all claimed labels must do so.
    Moreover, the fact that the encryption dictionary contains
    password “keys” and not the passwords themselves is
    inapposite—nothing in the district court’s construction or
    the intrinsic record indicates that the passwords them-
    selves must be stored in the dictionary. It is sufficient
    that Acrobat’s encryption dictionary stores the infor-
    mation needed to provide appropriate access to individu-
    als having a proper owner or user password.
    The court’s construction thus does not foreclose read-
    ing the label limitation on the user and owner keys stored
    in the encryption dictionary when using password securi-
    ty in the Acrobat program. For this reason, the district
    court erred in ruling in Adobe’s favor on its argument for
    summary judgement of non-infringement with respect to
    the password security option of the Acrobat program. The
    district court’s determination in that regard is therefore
    vacated.
    D. Adobe’s Alternative Grounds for Affirmance
    Adobe presents a number of alternative grounds for
    affirmance. TecSec contends that several of the district
    court’s claim construction rulings relevant to these alter-
    native grounds for affirmance were incorrect. We address
    each of these arguments in turn.
    20              TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED
    1. “Object-oriented Key Manager”
    Before the district court, Adobe argued that the term
    “object-oriented key manager” should be construed to
    mean “a software component that manages the encryption
    of an object, on an object-by-object basis, to achieve multi-
    level security, including the process of generating, dis-
    tributing, changing, replacing, storing, checking on, and
    destroying cryptographic keys.” TecSec argued that the
    term means “software that controls access to the algo-
    rithm used to encrypt and decrypt objects.” The district
    court largely agreed with Adobe. Finding the intrinsic
    record clear and unambiguous, with no need to resort to
    extrinsic evidence, the district court construed “object-
    oriented key manager” as “a software component that is
    capable of performing the process of generating, distrib-
    uting, changing, replacing, storing, checking on, and
    destroying cryptographic keys.” TecSec V at 23-26. The
    term appears only in the asserted method claims.
    Adobe does not challenge the district court’s claim con-
    struction but argues that under that construction, Adobe
    is entitled to summary judgment of non-infringement as a
    matter of law because Acrobat does not store or distribute
    any keys. According to Adobe’s expert, “the key is not
    saved.     The key is re-derived from the password.”
    JA3574, 120:5-10. Adobe thus contends that because
    there is no evidence that Acrobat meets this limitation,
    the district court’s judgment of non-infringement may be
    affirmed on this ground.
    TecSec asserts that the district court was correct in
    not citing this limitation as a basis to find no infringe-
    ment. Moreover, it contends that the term properly
    should have been given an even broader meaning and
    that the district court erred in not adopting the construc-
    tion TecSec proffered before the district court.
    We begin by addressing TecSec’s claim construction
    argument. TecSec argued that the term means “software
    TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED               21
    that controls access to the algorithm used to encrypt and
    decrypt objects.” TecSec bases its argument on several
    parts of the intrinsic record. During prosecution of the
    ’702 patent, TecSec submitted the following in response to
    an indefiniteness rejection directed at the phrase “key
    manager”:
    Various methods have evolved to manage the dis-
    tribution of keys. Such methods of distribution
    are collectively referred to as ‘key management.’
    [a] The function of key management is to perform
    the process of generating, distributing, changing,
    replacing, storing, checking on, and destroying
    cryptographic keys. [b] Under normal circum-
    stances, the key manager begins and ends a cryp-
    tographic session by controlling access to the
    algorithm used to encrypt and decrypt plain text
    objects. Thus, a user who wants to encrypt an ob-
    ject or decrypt an object must first access the key
    manager so that an encryption algorithm may be
    chosen.
    J. App’x 3719-3720 (bracketed lettering added). TecSec
    also amended the specification of the ’702 patent to incor-
    porate this language. ’702 patent, col. 1, l.61 – col.2, l. 4.
    TecSec urges that the passage quoted above distin-
    guishes “key management” and “key manager,” and that a
    key manager need only perform the functions described in
    sentence [b] above, and not all the key management
    functions described in [a]. Adobe argues that the district
    court construction was correct, and that TecSec’s proposed
    construction would result in a key manager that does not
    perform key management.
    TecSec is correct that there is a distinction between
    “key management” and a “key manager,” but TecSec’s
    reference to the observation that a key manager “begins
    and ends a cryptographic session by controlling access to
    the algorithm used to encrypt and decrypt plan text
    22              TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED
    objects” does little to aid in an understanding of what a
    “key manager” is. We agree with the district court that a
    key manager performs key management and that accord-
    ing to the definitional statement added to the specifica-
    tion of the DCOM patents, key management includes
    generating, distributing, changing, replacing, storing,
    checking on, and destroying cryptographic keys. It is that
    functionality that controls access to the encryption and
    decryption algorithm. But that is not to say that a key
    manager must perform all of those functions. We find no
    basis in the intrinsic record to support that strict a re-
    quirement.
    The district court found no support in the written de-
    scription for Adobe’s inclusion of the requirement that the
    key manager “manages the encryption of an object, on an
    object-by-object basis, to achieve multi-level security.”
    For that reason, the district court did not include that
    part of Adobe’s proffer in its claim construction. But even
    if the district court was correct not to include the full text
    requested by Adobe because of a lack of support in the
    written description, it was error to ignore the words
    “object-oriented,” which are part of the claimed expression
    itself.
    We therefore modify the district court’s claim con-
    struction and construe the term “object-oriented key
    manager” to mean “a software component that manages
    the encryption of an object by performing one or more of
    the functions of generating, distributing, changing, re-
    placing, storing, checking on, and destroying cryptograph-
    ic keys.”
    Adobe argues that it is entitled to summary judgment
    of non-infringement as a matter of law because Acrobat
    does not store or distribute any keys. TecSec points to
    evidence in the record that Adobe’s Acrobat products
    include a security handler in the form of a software mod-
    ule which implements various aspects of the encryption
    TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED             23
    process and controls access to the contents of encrypted
    documents. More specifically, this evidence shows that
    the security handler generates a key for encryption upon
    saving of a PDF document following a user’s selection of a
    security method.
    In light of this evidence, we cannot conclude as a mat-
    ter of law that Adobe is entitled to summary judgment of
    non-infringement as failing to meet the properly con-
    strued “object-oriented key manager” limitation.
    2. “Display Header”
    Adobe argues that it is entitled to summary judgment
    of non-infringement as a matter of law because Acrobat
    does not show a “display header” to the user. The district
    court construed “display header” as “a header for making
    visually perceptible to a user.” 
    Id. Adobe argues
    that to
    meet the limitation as construed by the district court, the
    display header must be capable of being shown to the
    user, something it contends is not done using Acrobat.
    The only support for Adobe’s position is the testimony
    of its corporate representative, Mr. Kaufman, that it is
    not possible to view the content of the encryption diction-
    ary. J. App’x at 3574. TecSec argues that Acrobat’s
    security properties dialog box “can display label attrib-
    utes,” J. App’x at 3797, which are “derived from the
    information in the encryption dictionary,” TecSec Reply
    Br. at 18, such as a “listing of various permission levels,”
    whether a document is encrypted and document re-
    strictions, and enables modifying security settings, J.
    App’x at 3797.
    Adobe has not explained why the security properties
    dialog box does not meet the “display header” limitation,
    and therefore has failed to show a lack of a genuine issue
    of material fact with respect to this limitation.
    TecSec argues that the district court erred in not giv-
    ing this limitation its plain and ordinary meaning. We
    24             TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED
    disagree and find the district court’s construction fully
    supported by the intrinsic record.
    3. Memory Hardware
    Adobe makes a cursory argument that Acrobat does
    not include the memory hardware required by all asserted
    system claims, a fact Adobe contends TecSec never dis-
    puted. TecSec argues that the district court struck Ado-
    be’s argument regarding memory hardware and that it
    therefore had no reason to oppose it. See TecSec V at 35
    n.20. TecSec also argues that Acrobat is installed on
    computers having memory, thus supporting TecSec’s
    charge of infringement. In particular, TecSec points to
    the testimony of Adobe’s corporate witness that he en-
    crypted a PDF file within another encrypted PDF file
    using Acrobat installed on a computer, see J. App’x at
    3565, and points to a blog post describing those same
    steps, see J. App’x at 3683. Adobe’s cursory argument on
    this issue has no merit.
    4. “Label” with Respect to Certificate Security
    Adobe argues that even under the district court’s con-
    struction of the term “label,” the district court erred in
    concluding that a genuine issue of material fact was
    presented when using digital certificate security. Adobe
    reasons that TecSec’s infringement theory identifies one
    “object” to be labelled—the strings and streams in the
    body of a PDF file—and a different object to be encrypt-
    ed—the entire PDF file, including the header and the
    trailer. Because the claims require that the same object
    be labelled and encrypted, Adobe argues that Acrobat
    cannot infringe as a matter of law regardless of the type
    of security used.
    We disagree with Adobe. All the encryption infor-
    mation is contained in the encryption dictionary, the part
    of the PDF that TecSec identifies as the label. Adobe does
    not explain the asserted disconnect between the object
    TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED             25
    encrypted and the object labelled, apart from citing
    TecSec’s claim charts. However, TecSec’s claim charts
    allege that the same thing is given a label and encrypted.
    For example, for the “selecting a label” limitation, TecSec
    states that “Adobe Acrobat applies passwords to and/or
    sets permission levels for an object, such as a PDF
    file/document.” J. App’x at 4089. The same object, “a
    PDF file” is identified as capable of being “encrypted with
    a password.” J. App’x at 4090. The object identified
    throughout is a PDF file or a PDF document, regardless of
    whether the element being discussed is the label or the
    encryption. Adobe has failed to show a lack of a genuine
    issue of material fact as to the same. This argument thus
    fails to provide an alternative ground for affirmance.
    5. “Multi-level . . . Security”
    We have previously construed ‘multi-level . . . securi-
    ty” in the preamble to be restrictive, and to require multi-
    ple layers of encryption, based primarily on TecSec’s
    prosecution history. TecSec, Inc. v. Int’l Bus. Mach. Corp.,
    
    731 F.3d 1336
    , 1345-46 (Fed. Cir. 2013). Adobe argues
    that Acrobat cannot nest an encrypted PDF within anoth-
    er encrypted PDF within a single session of Acrobat, and
    therefore Acrobat does not meet the claim limitation. 2
    Adobe also argues that Acrobat can only encrypt one level
    of information because the encryption of the PDF enve-
    lope treats the encrypted data in a nested object in line
    with the data of the PDF envelope.
    2   Adobe also frames the multiple-sessions require-
    ment through the lens of divided infringement, i.e. that
    Adobe is not responsible for the infringement because the
    user opens up multiple sessions of Acrobat, and Adobe
    does not direct or control the user’s actions. This argu-
    ment is incorrect for the same reasons described in the
    analysis that follows.
    26             TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED
    TecSec’s position is that Acrobat performs multi-level
    security when a user encrypts a PDF, then attaches it to a
    separate PDF, and then encrypts that PDF. TecSec
    argues that the claim does not require that all this be
    performed within a single session window of Acrobat.
    The district court agreed with TecSec and denied
    Adobe’s motion, finding that the multi-window sequence
    described above provides evidence that Acrobat could be
    used to allow multi-level security. The district court also
    noted that “TecSec has also presented evidence that
    Adobe has instructed its customers that Acrobat could be
    used in that manner.” TecSec V at 37.
    We agree. To access the data in the nested PDF, a
    user would have to decrypt the PDF envelope, followed by
    decrypting the nested PDF. That Acrobat uses multiple
    windows to accomplish the nesting does not place Acrobat
    outside the scope of the limitation. Claim 1 recites “A
    method for providing multi-level multimedia security in a
    data network.”     Adobe’s envelope feature “provid[es]
    multi-level multimedia security in a data network.” That
    the mechanism provided requires multiple sessions of the
    accused product does not preclude infringement. There is
    at least a genuine issue of material fact whether Acrobat
    PDF envelopes infringe the multi-layer security limita-
    tion.
    Relatedly, Adobe argues that because two sessions of
    Acrobat are required, each “object” at each level does not
    have its own “label.” We agree with the district court that
    TecSec has presented ample evidence to defeat summary
    judgment of non-infringement of this element. To take
    just one example, Mr. Kaufman, Adobe’s 30(b)(6) witness
    confirmed that an encrypted PDF attached to another
    PDF which was then encrypted, would yield separate
    encryption dictionaries (the alleged “label”), and could
    have     different   passwords    or    security     types.
    J. App’x at 3629.
    TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED               27
    We see no error in the district court’s conclusion that
    genuine issues of material fact preclude summary judg-
    ment of non-infringement on the basis of the multi-level
    security limitation.
    6. Labelling and Footnote 23
    In considering the “selecting a label” limitation, the
    district court added the following seemingly gratuitous
    footnote regarding a separate limitation directed to label-
    ling:
    Although not briefed by the parties, there are oth-
    er aspects of the DCOM Patents that Acrobat does
    not perform. For example, each asserted claim re-
    quires some form of “labelling.” At TecSec's urg-
    ing, “labelling” has been construed to mean
    “attaching a label.” Acrobat does not attach an en-
    cryption dictionary to an encrypted PDF docu-
    ment; instead, it inserts the encryption dictionary
    into the (pre-existing) trailer for that file. Jones
    Dec. 68. Indeed, far from being attached to the
    encrypted object, “[t]he encryption dictionary is
    part of the trailer portion of a PDF document.” 
    Id. Thus, what
    TecSec alleges is a label is not “at-
    tached to” the object, it is part of the object.
    TecSec V at 40 n.23.
    TecSec argues that the district court’s footnote is pro-
    cedurally flawed because TecSec was not permitted dis-
    covery on this issue and was never given an opportunity
    to respond, in violation of Federal Rules of Civil Proce-
    dure 56(f). TecSec also contends that the substantive
    basis for the district court’s decision is also flawed, be-
    cause first, the system claims do not have a “labelling”
    limitation, but claim a distinct “object labelling subsys-
    tem,” see Section E.1 infra at 29-30, and second, Acrobat
    meets the labelling limitation when the encryption dic-
    28             TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED
    tionary is attached to a PDF file’s trailer, which is itself
    attached to the encrypted PDF content.
    Adobe finds no procedural fault with the district
    court’s footnote and asserts it as an alternative basis for
    affirmance. It also contends that the district court was
    substantively correct. According to Adobe, Acrobat in-
    serts the data for the encryption dictionary into a pre-
    existing trailer in the PDF, making the encryption dic-
    tionary a part of the encrypted PDF file and not an at-
    tachment thereto. It therefore contends that Acrobat
    cannot meet the “labelling the encrypted object” limita-
    tion.
    Federal Rule of Civil Procedure 56(f) allows a district
    court to grant summary judgment on a ground not raised
    by a party “[a]fter giving notice and a reasonable time to
    respond.” See also U.S. Dev. Corp. v. Peoples Fed. Sav. &
    Loan Ass'n, 
    873 F.2d 731
    , 735 (4th Cir. 1989) (explaining
    that the exercise of a district court’s power to enter sum-
    mary judgment sua sponte is contingent on giving the
    losing party a reasonable opportunity to demonstrate
    genuine issue of material fact); Matthews v. Thomas, 385
    F. App’x 283, 288 (4th Cir. 2010). It undisputed that the
    district court failed to provide TecSec with any opportuni-
    ty to respond with respect to the “labelling” limitation. In
    this regard, the district court procedurally erred in mak-
    ing the statements set forth in footnote 23. We give that
    footnote no weight and do not address whether a genuine
    issue of material fact exists as to whether Acrobat meets
    the labelling limitation when it inserts the encryption
    dictionary into the trailer of the PDF document.
    Adobe also argues that the district court erred in its
    claim construction of “labelling,” and that under the
    proper claim construction—“labelling the encrypted
    object” means “attachment of a label to an object by
    software after encryption of that object,” J. App’x at
    2468—Acrobat does not meet this limitation because no
    TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED              29
    label is attached to a single encrypted object but to a
    group of encrypted and non-encrypted data. Adobe’s
    argument is convoluted and not persuasive. Adobe does
    not explain the presence of the temporal “after” in its
    construction, why the admittedly encrypted PDF content
    could not be considered a single encrypted object, or why
    the presence of unencrypted PDF components disallowed
    the labelling of the encrypted object. We therefore reject
    this ground as an alternative basis for affirmance.
    E. Considerations on Remand
    1. System and Method Claims
    In granting summary judgment, the district court
    grouped the method and system claims together with
    respect to the selecting a label limitation, despite the fact
    that the system claims do not include that limitation, in
    haec verba. The system claims require an “object label-
    ling subsystem” and an “object identification subsystem.”
    The district court treated these limitations as necessarily
    containing the “selecting a label” limitation from the
    method claims. Without analysis, the court stated that
    “the [system] claims use only ‘slightly different language
    to describe substantially the same invention [as the
    method claims].’” TecSec V at 39 n.22 (quoting Ohio
    Willow Wood Co. v. Alps South, LLC., 
    735 F.3d 1333
    , 1342
    (Fed. Cir. 2013)). The court also determined that TecSec
    waived any distinction between the claim types by group-
    ing its infringement arguments together under method
    claim 1 as representative of all of the asserted claims.
    TecSec argues that treating the system and method
    claims together was improper, and failed to give meaning
    to the explicit difference in claim language. Adobe coun-
    ters that TecSec equated the “object labelling subsystem”
    language in the system claims to the “selecting a label”
    limitation in the method claims by explaining in its
    infringement contentions that Acrobat practiced the
    “object labelling subsystem” of the systems claims because
    30             TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED
    “Adobe Acrobat products select a label for an object.”
    J. App’x at 2208.
    We agree with TecSec that equating the limitations
    was improper. There is no indication that TecSec’s argu-
    ment in its infringement contentions used “selecting a
    label” as a term of art or to reference the meaning of that
    phrase in the method claims, rather than using it for its
    colloquial meaning. In other words, although the district
    court departed from an ordinary meaning of “selecting a
    label” in construing the method claims, TecSec has no-
    where indicated that the distinct “object labelling subsys-
    tem” in the system claims should be bound by the same
    construction.
    Adobe also argues that TecSec equated the two
    phrases in TecSec’s brief in response to Adobe’s summary
    judgment motion, in which TecSec put forth claim 1, a
    method claim, as representative of the DCOM patents.
    However, that statement was made before “selecting a
    label” was at issue because Adobe had not raised it in its
    opening brief, and it was first raised sua sponte by the
    district court at the summary judgment hearing. TecSec V
    at 19. TecSec was never confronted with a reason to
    explicitly consider the equivalence of the system and
    method claims with respect to the two terms. Moreover,
    the district court concluded that the scope of the system
    and method claims was identical without analysis of the
    relative claim scope. Determining the relative claim
    scope here is not an easy issue admitting of such a cursory
    conclusion. Cf., e.g., CLS Bank Int’l v. Alice Corp., 
    717 F.3d 1269
    , 1288-1292 (Fed. Cir. 2013) (en banc) (Lourie,
    J., concurring).
    On remand, TecSec will have the opportunity to sepa-
    rately argue infringement of the method and system
    claims with respect to these limitations.
    TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED             31
    2. Doctrine of Equivalents
    Adobe argues that TecSec has waived its opportunity
    to argue infringement of the “selecting a label” limitation
    under the doctrine of equivalents. We disagree. As
    explained above, that limitation entered this case via sua
    sponte consideration by the district court. TecSec was
    under no obligation to assert the doctrine of equivalents
    with respect to a limitation that Adobe did not even
    dispute was literally met by the accused product.
    3. Reassignment
    TecSec urges us to reassign this case to a different
    judge on remand. TecSec argues that Judge Brinkema
    has repeatedly held against TecSec, has raised dispositive
    issues sua sponte, has been reversed on appeal for many
    of those issues, and has pre-judged a § 101 issue that has
    not yet been raised.
    Reassignment is only appropriate in exceptional cir-
    cumstances. Here, reassignment is governed by Fourth
    Circuit law, which applies a three factor test for reas-
    signment: 1) whether the judge would be reasonable
    expected to have substantial difficulty putting her views
    that were held to be incorrect out of her mind; 2) whether
    reassignment is necessary to preserve the appearance of
    justice; and 3) the degree of waste of judicial resources
    and duplication if the case were reassigned. See United
    States v. Guglielmi, 
    929 F.2d 1001
    , 1007 (4th Cir. 1991).
    Nothing in this case merits reassignment on remand.
    Though Judge Brinkema has indeed ruled against TecSec
    several times, there is no indication that these rulings are
    biased, or are based on anything other than the exercise
    of her reasoned judgment and appropriate judicial discre-
    tion. Though Judge Brinkema has indeed raised more
    than one dispositive issue sua sponte, the Federal Rules of
    Civil Procedure specifically empower district courts to do
    so, subject to certain procedural requirements. See Fed.
    32              TECSEC, INC.   v. ADOBE SYSTEMS INCORPORATED
    R. Civ. P. Rule 56(f). Moreover, given the six-year journey
    of this case through the judicial system, and its multi-
    party complexity, reassignment would create significant
    unnecessary waste of judicial resources. Here, we are not
    persuaded that any of the factors in the Fourth Circuit’s
    test are met. Reassignment thus is not appropriate in
    this case.
    III. CONCLUSION
    For the foregoing reasons, we modify the district
    court’s construction of “selecting a label,” affirm its con-
    struction of the term “label,” vacate its determination that
    Acrobat’s password security option cannot meet the
    “label” limitation, and vacate the grant of summary
    judgment of non-infringement. We also modify the dis-
    trict court’s construction of “object-oriented key manager”
    and deny each of Adobe’s alternative grounds for affir-
    mance. We reject Adobe’s request that the case be reas-
    signed and remand the case for further proceedings
    consistent with this opinion.
    VACATED AND REMANDED
    IV. COSTS
    Costs are awarded to TecSec.