Sonix Technology Co., Ltd. v. Publications International , 844 F.3d 1370 ( 2017 )


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  •   United States Court of Appeals
    for the Federal Circuit
    ______________________
    SONIX TECHNOLOGY CO., LTD.,
    Plaintiff-Appellant
    v.
    PUBLICATIONS INTERNATIONAL, LTD., SD-X
    INTERACTIVE, INC., ENCYCLOPEDIA
    BRITTANNICA, INC., HERFF JONES, INC.,
    Defendants-Appellees
    ______________________
    2016-1449
    ______________________
    Appeal from the United States District Court for the
    Northern District of Illinois in No. 1:13-cv-02082, Judge
    Amy J. St. Eve.
    ______________________
    Decided: January 5, 2017
    ______________________
    JONATHAN HANGARTNER, X-Patents, APC, La Jolla,
    CA, argued for plaintiff-appellant. Also represented by
    STEVEN P. FALLON, Greer, Burns & Crain, Ltd., Chicago,
    IL.
    JACOB DANIEL KOERING, Miller, Canfield, Paddock, &
    Stone, PLC, Chicago, IL, argued for defendants-appellees.
    Also represented by TERRENCE JOSEPH SHEAHAN, Free-
    born & Peters, LLP, Chicago, IL.
    ______________________
    2                        SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.
    Before LOURIE, O’MALLEY, and TARANTO, Circuit
    Judges.
    LOURIE, Circuit Judge.
    Sonix Technology Co., Ltd. (“Sonix”) appeals from the
    district court’s grant of summary judgment following its
    determination that claims 9, 25, 35–36, 52–55, 57–60, 62–
    64, 66, 68, 71–77, 79–82, and 85–90 (“the asserted
    claims”) of Sonix’s U.S. Patent 7,328,845 (“the ’845 pa-
    tent”) are invalid as indefinite. See Sonix Tech. Co. v.
    Publ’ns. Int’l, Ltd., No. 13-cv-2082, 
    2015 WL 8153600
    , at
    *9–17 (N.D. Ill. Dec. 8. 2015) (“Opinion”). Specifically, the
    district court concluded that the term “visually negligible”
    rendered the asserted claims indefinite under 35 U.S.C.
    § 112 ¶ 2. 1 For the reasons that follow, we reverse the
    determination of indefiniteness and hence the summary
    judgment of invalidity.
    BACKGROUND
    Sonix owns the ’845 patent, which describes a system
    and method for using a “graphical indicator” (e.g., a
    matrix of small dots) to encode information on the surface
    of an object. See ’845 patent, col. 3 ll. 6–43. The surface
    may feature additional information as well; for example,
    illustrations or icons in a children’s book. 
    Id. col. 7
    ll. 1–6.
    The invention also includes an “optical device” that can
    read the graphical indicator and output further infor-
    mation. 
    Id. col. 7
    ll. 18–32. Figure 5 illustrates an
    example:
    1   Because the ’845 patent was filed before the en-
    actment of the Leahy-Smith America Invents Act, Pub. L.
    No. 112-29, § 3, 125 Stat. 284, 285–93 (2011), the prior
    version of § 112 governs. See Fleming v. Escort, Inc., 
    774 F.3d 1371
    , 1374 n.1 (Fed. Cir. 2014).
    SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.                   3
    
    Id. fig.5. In
    this example, an icon showing a person riding
    a horse (511) is printed on the page of a book (51). 
    Id. col. 7
    ll. 1–10. The graphical indicator (512) is printed in the
    same area as the icon. 
    Id. col. 7
    ll. 18–21. The optical
    device (311) captures an image that includes the graph-
    ical indicator. 
    Id. col. 7
    ll. 21–24. The processing device
    (312) retrieves the indicator from the image and outputs
    additional information. 
    Id. In this
    particular example,
    holding the optical device over the horse icon could cause
    the device to output “audio information, such as pronun-
    ciations of horse in English.” 
    Id. col. 7
    ll. 27–32.
    Of course, encoding information on the surface of an
    object is not new. The ’845 patent admits that infor-
    mation has been recorded on the surface of objects
    “[d]ating back to ancient time[s],” 
    id. col. 1
    ll. 15–16, and
    lists a bar code as a “conventional” example of a graphical
    4                        SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.
    indicator, 
    id. col. 9
    ll. 46–57. The ’845 patent purports to
    improve on conventional methods by rendering the graph-
    ical indicator “visually negligible.” 
    Id. col. 3
    ll. 5–11. The
    patent uses a book cover to illustrate the difference be-
    tween a conventional bar code and the claimed indicator:
    
    Id. figs.12(A) &
    12(B). The graphical indicator (10002) in
    figure 12(B) stores the same information as the bar code
    (10001) in figure 12(A), but in a manner that does not
    “interfere with the other main information on the sur-
    face.” 
    Id. col. 9
    ll. 47–57.
    The “[e]xemplary [d]esign,” 
    id. col. 3
    l. 5, of the
    claimed indicator “includes multiple graphical micro-units
    arranged in a layout.” 
    Id. col. 3
    ll. 14–15. In one embod-
    iment the micro-units are dots, arranged in a matrix. 
    Id. col. 3
    ll. 15–25. Each cell in the matrix either contains or
    does not contain a dot, resulting in a unique pattern that
    can store information. 
    Id. col. 3
    ll. 38–30, col. 4 ll. 13–41.
    The written description also discloses differentiability,
    brightness, and homogeneity “requirements for the graph-
    ical indicators being negligible to human eyes.” 
    Id. col. 4
    ll. 60–61. First, the indicator must be so small that
    “human eyes cannot differentiate one graphical indicator
    from others.” 
    Id. col. 4
    ll. 61–63. The patent indicates
    SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.                    5
    that “[f]or best result, the graphical micro-unit must be so
    tiny that only a microscope apparatus can detect it.” 
    Id. col. 3
    ll. 24–25. Second, the patent advises that the
    number of micro-units should be reduced based on “the
    size of the graphical micro-unit, the pitch between micro-
    unit, and the desired visual effect,” so that they “have
    little influence on the brightness of the surface of the
    object.” 
    Id. col. 4
    l. 67–col. 5 l. 1. Finally, the “number of
    graphical micro-units of each graphical indicator” should
    be “substantially equal to each other,” so that “the graph-
    ical indicators look more homogenous to human eyes and
    become invisible to human eyes.” 
    Id. col. 5
    ll. 1–5.
    The written description also gives two examples of
    visually-negligible indicators. In the first, each square
    centimeter contains 3,000 matrix cells, of which less than
    70% contain graphical micro-units, and where each micro-
    unit occupies less than 80% of the cell. 
    Id. col. 5
    ll. 6–10.
    The second is similar, but requires each square centime-
    ter to include 6,000 cells. 
    Id. col. 5
    ll. 11–15.
    In 2010, Sonix alleged that children’s books using dot
    pattern technology produced by GeneralPlus, a Taiwanese
    company, infringed the ’845 patent. In response, SunPlus
    Technology Co. Ltd. (“SunPlus”), GeneralPlus’s parent
    company, requested ex parte reexamination of the ’845
    patent (“the first reexamination”) by the U.S. Patent and
    Trademark Office (“USPTO”). On December 27, 2011, the
    USPTO confirmed the patentability of, inter alia, asserted
    claims 9, 25, and 35–36, and allowed new, and now as-
    serted, claims 52–55, 57–60, 62–64, 66, 68, 71–77, 79–82,
    and 85–90, among others. J.A. 94–96.
    Less than one month later, GeneralPlus requested
    another ex parte reexamination (“the second reexamina-
    tion”). J.A. 1937. One of the central disputed issues
    during this second reexamination was whether the com-
    bination of U.S. Patent 5,416,312 (“Lamoure”) and U.S.
    Patent 5,329,107 (“Priddy”) would have led to a visually-
    6                       SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.
    negligible indicator, as the examiner initially rejected all
    pending claims over that combination. See, e.g., J.A.
    2328–31. Sonix responded to that rejection with a decla-
    ration from Serjer Serjersen (“Serjersen”), an expert with
    more than thirty years of experience. J.A. 2337. Ser-
    jersen declared that he created graphical indicators using
    the processes described by the ’845 patent and by the
    cited references, and determined that only the indicator
    produced using the process of the ’845 patent was visually
    negligible. J.A. 2338–44, 5313–25. The examiner con-
    firmed the patentability of the asserted claims on the
    basis of Serjersen’s declaration, specifically indicating
    that the combination of cited references did not disclose a
    visually-negligible graphical indicator. J.A. 2362–65.
    In 2013, Sonix alleged that Publications Internation-
    al, Ltd., SD-X Interactive, Inc., Encyclopedia Brittannica,
    Inc., and Herff Jones, Inc. (collectively, “Appellees”)
    infringed the asserted claims. Appellees’ initial invalidity
    contentions identified twenty-six claim limitations that
    they believed to be indefinite; however, that list did not
    include the term “visually negligible.” See J.A. 2637–41.
    In their final invalidity contentions, Appellees contended
    that two additional claim limitations were indefinite, but
    again did not question “visually negligible.” J.A. 3031.
    During claim construction, Appellees initially asked
    the district court to construe “visually negligible,” J.A.
    2430, but, when they retained new counsel, proposed that
    the term be given its ordinary meaning, J.A. 2434–36.
    Sonix agreed with an ordinary-meaning construction, and
    so the district court did not construe “visually negligible.”
    Even so, “visually negligible” was used repeatedly in
    the expert reports.       For example, Sonix’s expert,
    Dr. Ashok, opined that the accused products included
    visually-negligible indicators, J.A. 3087–88, and that the
    cited prior art did not, J.A. 3539–41, 3547. Appellees’
    expert, Dr. Engels, also applied “visually negligible”
    SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.                   7
    throughout his reports, and even agreed that “the dot
    patterns in the specific products reviewed by Dr. Ashok in
    his Report are visually negligible . . . .” J.A. 4210–11. On
    validity, Dr. Engels repeatedly opined that the indicators
    disclosed in Lamoure and Priddy—the same references at
    issue in the second reexamination—were visually negligi-
    ble. See J.A. 5348–49, 5355–56, 5418, 5430–31. But Dr.
    Engels did not opine that “visually negligible” was indefi-
    nite. See 
    id. Elsewhere in
    his report, Dr. Engels contend-
    ed that alternatives to the claimed invention would have
    been available because “it would be a simple matter to
    ensure that any pattern being used would be printed in a
    manner that would be visually negligible compared to the
    main information on a page.” J.A. 4228.
    At Dr. Ashok’s deposition, after the close of fact dis-
    covery and after the parties agreed to an ordinary mean-
    ing for “visually negligible,” he was asked to explain
    “what does [‘visually negligible’] mean to you?” J.A. 4755
    at 46:25–47:1. Dr. Ashok indicated that he understood it
    “to mean that if these dot patterns are imprinted on a
    surface, with a cursory look, I will not notice that.” 
    Id. at 47:2–7.
    Dr. Ashok was then asked whether there was
    “any sort of objective standard” for visual negligibility.
    J.A. 4756 at 49:11. Dr. Ashok explained that visibility
    depended on the ink used, the printing pattern, and the
    size of the dot, but that there “is not a universal standard
    by any means because it depends on the visual acuity of
    the observer.” 
    Id. at 50:24–51:4.
    Even so, Dr. Ashok
    indicated that his “method of determining visual negligi-
    bility would be [to] print at the magnification desired and
    look at it,” because he “would imagine that would be
    representative of most people looking at it.” 
    Id. at 51:5–8.
        In response, Dr. Engels asserted at his deposition that
    “visually negligible” was subjective because “there is no
    objective test to define the boundary between visually
    negligible and visually non-negligible.” Dr. Engels did not
    analyze the intrinsic evidence, and did not provide any
    8                        SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.
    detail explaining his conclusion. J.A. 3709. On the basis
    of the two expert depositions, Appellees amended their
    invalidity contentions and moved for summary judgment
    of indefiniteness.
    The district court ultimately held that the claims are
    invalid as indefinite. Opinion, 
    2015 WL 8153600
    , at *9–
    17. Reasoning that “visually negligible” is “purely subjec-
    tive” and that the claim language does not provide guid-
    ance on its meaning, the court turned to the other
    intrinsic evidence. 
    Id. at *13.
    The court determined that
    the written description does not provide a person of
    ordinary skill in the art “with a meaning that is reasona-
    bly certain and defines objective boundaries” of the claim
    scope. 
    Id. The court
    rejected Sonix’s argument that
    “visually negligible” means “something that may be
    visible, but does not interfere with the user’s perception of
    other visual information on a surface,” concluding that
    defining the term “as reliant on the user’s perception
    provides no objective standard by which to measure the
    scope of the term—the user’s perception becomes the
    measure and this is insufficient.” 
    Id. (citing Datamize,
    LLC v. Plumtree Software, Inc., 
    417 F.3d 1342
    , 1351 (Fed.
    Cir. 2005)).
    The district court also rejected Sonix’s attempts to re-
    ly on other portions of the written description. For exam-
    ple, the court determined that the instruction that the
    graphical micro-units “must be so tiny that only a micro-
    scope apparatus can detect it,” ’845 patent, col. 3 ll. 24–25,
    failed to provide reasonable certainty because the written
    description “contains no information . . . regarding what
    type of microscope apparatus or what level of magnifica-
    tion the user would need.” Opinion, 
    2015 WL 8153600
    , at
    *14. The court similarly rejected Sonix’s reliance on the
    differentiability, brightness, and homogeneity require-
    ments because they lacked “the necessary detail to make
    [them] meaningful.” 
    Id. Finally, the
    court rejected the
    SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.                  9
    prosecution and reexamination history as not providing
    additional guidance. 
    Id. at *15.
        Although the district court determined that it was
    “not necessary” to consult the extrinsic evidence, it none-
    theless concluded that the extrinsic evidence “highlights
    the problem with the subjective nature of the ‘visually
    negligible’ claim term.” 
    Id. The court
    noted, for example,
    that although the experts applied the term to the prior
    art, they did not provide any standard by which to meas-
    ure negligibility aside from their “subjective belief.” 
    Id. The district
    court then reviewed recent cases from the
    Supreme Court and this court, and determined that the
    present case was more similar to those concluding that
    claims were invalid as indefinite than to those holding
    otherwise. See 
    id. at *15–17
    (citing Nautilus v. Biosig
    Instruments, Inc., 
    134 S. Ct. 2120
    , 2129 (2014); Interval
    Licensing LLC v. AOL, Inc., 
    766 F.3d 1364
    , 1368–74 (Fed.
    Cir. 2014); Enzo Biochem, Inc. v. Applera Corp., 
    599 F.3d 1325
    , 1336 (Fed. Cir. 2010); 
    Datamize, 417 F.3d at 1349
    –
    54).
    The district court therefore entered judgment against
    Sonix and for Appellees on December 8, 2015. J.A. 1–2.
    Sonix timely appealed. We have jurisdiction pursuant to
    28 U.S.C. § 1295(a)(1).
    DISCUSSION
    At the outset, there is a dispute relating to the stand-
    ard of review to be applied to the present case. Sonix
    argues that our review is entirely de novo, because the
    district court indicated that it was unnecessary to address
    the extrinsic evidence and did not make any factual
    findings based thereon. Appellees respond that the
    district court made underlying findings that “visually
    negligible” is subjective and that it lacks an objectively-
    measurable standard.
    10                      SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.
    We agree with Sonix that we review a district court’s
    determination that a claim is invalid as indefinite under
    35 U.S.C. § 112 ¶ 2 de novo, although, as with claim
    construction, any factual findings by the district court
    based on extrinsic evidence are reviewed for clear error.
    Cox Commc’ns, Inc. v. Sprint Commc’n Co., 
    838 F.3d 1224
    , 1228 (Fed. Cir. 2016) (citing Teva Pharm. USA, Inc.
    v. Sandoz, Inc., 
    135 S. Ct. 831
    , 840–42 (2015) (“Teva I”)).
    To trigger clear error review, “it is not enough that the
    district court may have heard extrinsic evidence during a
    claim construction proceeding—rather, the district court
    must have actually made a factual finding . . . .” Card-
    Soft, LLC v. VeriFone, Inc., 
    807 F.3d 1346
    , 1350 (Fed. Cir.
    2015) (citations omitted). Moreover, “[a] party cannot
    transform into a factual matter the internal coherence
    and context assessment of the patent simply by having an
    expert offer an opinion on it. The internal coherence and
    context assessment of the patent, and whether it conveys
    claim meaning with reasonable certainty, are questions of
    law.” Teva Pharm. USA, Inc. v. Sandoz, Inc., 
    789 F.3d 1335
    , 1342 (Fed. Cir. 2015) (“Teva II”).
    The district court expressly explained that the extrin-
    sic evidence was “not necessary for [its] consideration” of
    the indefiniteness issue. Opinion, 
    2015 WL 8153600
    , at
    *15. Moreover, the district court’s conclusions of subjec-
    tivity and lack of an objective standard are not findings
    subject to clear error review; instead, they are conclusions
    relating to the meaning of the intrinsic evidence, and
    whether it conveys claim meaning with reasonable cer-
    tainty. See Teva 
    II, 789 F.3d at 1342
    . Such conclusions
    cannot be transformed into factual matters “simply by
    having an expert offer an opinion on [them].” 
    Id. I. INDEFINITENESS
        Sonix argues that the district court erred in conclud-
    ing that “visually negligible” renders the asserted claims
    invalid as indefinite. Specifically, Sonix argues that the
    SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.                11
    requirements and examples in the written description
    would have allowed a skilled artisan to know the scope of
    the claimed invention with reasonable certainty and
    establish that the term depends on human perception, not
    opinion. This conclusion is supported, Sonix contends, by
    the consistent manner in which “visually negligible” has
    been applied during initial examination, both reexamina-
    tions, and the majority of the district court litigation.
    Appellees respond that visual negligibility does not
    have an objective standard because it depends on the
    “vagaries of any one person’s opinion,” 
    Datamize, 417 F.3d at 1350
    , and is therefore indefinite. Appellees contend
    that the written description would not allow a skilled
    artisan to understand the scope of the claims with rea-
    sonable certainty, and that the ability of experts to apply
    the term does not provide an objective standard.
    We agree with Sonix that a skilled artisan would un-
    derstand, with reasonable certainty, what it means for an
    indicator in the claimed invention to be “visually negligi-
    ble.” The intrinsic evidence supports, and the extrinsic
    evidence is consistent with, this conclusion.
    Section 112 requires that a patent specification “con-
    clude with one or more claims particularly pointing out
    and distinctly claiming the subject matter which the
    applicant regards as his invention.” The Supreme Court
    has read this provision to require that “a patent’s claims,
    viewed in light of the specification and prosecution histo-
    ry, inform those skilled in the art about the scope of the
    invention with reasonable certainty.” 
    Nautilus, 134 S. Ct. at 2129
    . Indefiniteness must be proven by clear and
    convincing evidence. See Teva 
    II, 789 F.3d at 1345
    .
    The § 112 ¶ 2 requirement strikes a “delicate balance”
    between “the inherent limitations of language” and
    providing “clear notice of what is claimed.” 
    Nautilus, 134 S. Ct. at 2129
    (internal citations omitted). Even so, the
    Supreme Court has recognized that “absolute precision is
    12                     SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.
    unattainable.” 
    Id. “[T]he certainty
    which the law re-
    quires in patents is not greater than is reasonable, having
    regard to their subject-matter.” 
    Id. (quoting Minerals
    Separation, Ltd. v. Hyde, 
    242 U.S. 261
    , 270 (1916) (inter-
    nal quotation marks omitted)).
    Because language is limited, we have rejected the
    proposition that claims involving terms of degree are
    inherently indefinite. Interval 
    Licensing, 766 F.3d at 1370
    . Thus, “a patentee need not define his invention
    with mathematical precision in order to comply with the
    definiteness requirement.” Invitrogen Corp. v. Biocrest
    Mfg., L.P., 
    424 F.3d 1374
    , 1384 (Fed. Cir. 2005) (citation
    omitted). Indeed, “[c]laim language employing terms of
    degree has long been found definite where it provided
    enough certainty to one of skill in the art when read in
    the context of the invention.” Interval 
    Licensing, 766 F.3d at 1370
    (citing Eibel Process Co. v. Minn. & Ont. Paper
    Co., 
    261 U.S. 45
    , 65–66 (1923)).
    Accordingly, we have held that the clause “not inter-
    fering substantially” did not render a claim invalid as
    indefinite. 
    Enzo, 599 F.3d at 1336
    . 2 In that case, we
    reasoned that the intrinsic evidence provided guidance as
    to the scope of the claims, including, inter alia, examples
    of noninterfering structures and criteria for their selec-
    tion. 
    Id. at 1334–35.
    This guidance allowed a skilled
    artisan to compare a potentially infringing product “with
    the examples in the specification to determine whether
    interference . . . is substantial.” 
    Id. at 1336.
       We have found terms of degree indefinite, however,
    when such guidance is lacking. For example, Datamize
    2   Although Enzo was decided before the introduc-
    tion of the “reasonable certainty” standard, we have relied
    on it in our post-Nautilus decisions. See, e.g., Interval
    
    Licensing, 766 F.3d at 1370
    .
    SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.                  13
    involved claims to an “aesthetically pleasing” look and feel
    for interface 
    screens. 417 F.3d at 1348
    –49. We deter-
    mined that such language rendered the claim indefinite
    because, although the written description did detail
    various elements that might affect whether a screen was
    aesthetically pleasing (such as button styles and sizes), it
    “provide[d] no guidance to a person making aesthetic
    choices such that their choices will result in an ‘aestheti-
    cally pleasing’ look and feel of an interface screen.” 
    Id. at 1352.
    Without such guidance, the claim did “not just
    include a subjective element, it [wa]s completely depend-
    ent on a person’s subjective opinion.” 
    Id. Similarly, Interval
    Licensing involved a claim related
    to displaying content “in an unobtrusive manner that does
    not distract a 
    user.” 766 F.3d at 1368
    . We observed that
    the term was “a term of degree,” 
    id. at 1370,
    “purely
    subjective,” 
    id. at 1371,
    and that the claim language
    offered “no objective indication of the manner in which
    content images are to be displayed to the user,” 
    id. We refused
    to limit the “facially subjective claim term” to the
    single example in the written description because, with-
    out more information, “a skilled artisan is still left to
    wonder what other forms of display are unobtrusive and
    non-distracting . . . thus leaving the skilled artisan to
    consult the ‘unpredictable vagaries of any one person’s
    opinion.’” 
    Id. at 1373–74
    (quoting 
    Datamize, 417 F.3d at 1350
    ).
    As indefiniteness analysis involves general claim con-
    struction principles, we begin with the language of the
    claims of the ’845 patent. See Enzo, 
    599 F.3d 1332
    . We do
    agree with the district court that the claim language itself
    does not unmistakably make clear the scope of “visually
    negligible”; however, we disagree with the conclusion, and
    Appellees’ argument, that the term is “purely subjective,”
    Opinion, 
    2015 WL 8153600
    , at *13, in the same manner
    as “aesthetically pleasing” in Datamize and “in an unob-
    14                     SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.
    trusive manner that does not distract a user” in Interval
    Licensing.
    Datamize and Interval Licensing involved terms that
    were subjective in the sense that they turned on a per-
    son’s tastes or opinion. “Aesthetically pleasing” impli-
    cates matters of taste or preference; whether something is
    aesthetically pleasing is a value judgment that inherently
    varies from person to person. “In an unobtrusive manner
    that does not distract” similarly implicates a person’s
    individual focus, concentration, attentiveness, or similar
    mental state at a given moment, or even opinions, affect-
    ing what is or is not distracting. The question whether
    something is “visually negligible” or whether it interferes
    with a user’s perception, however, involves what can be
    seen by the normal human eye. This provides an objec-
    tive baseline through which to interpret the claims. See
    Warsaw Orthopedic, Inc. v. NuVasive, Inc., 
    778 F.3d 1365
    ,
    1371 (Fed. Cir. 2015), cert. granted, judgment vacated sub
    nom. Medtronic Sofamor Danek USA, Inc. v. NuVasive,
    Inc., 
    136 S. Ct. 893
    (2016), and opinion reinstated in
    relevant part, 
    824 F.3d 1344
    , 1346 (Fed. Cir. 2016). Thus,
    although the term may be a term of degree, it is not
    “purely subjective.”
    We turn next to the written description, to determine
    whether there is some standard in the written description
    for measuring visual negligibility. See 
    Enzo, 599 F.3d at 1332
    . Our prior cases establish that the written descrip-
    tion is key to determining whether a term of degree is
    indefinite. In Enzo, for example, the written description
    included examples of noninterfering structures and the
    procedures for selecting them; we reasoned that the
    examples and procedures provided guidance and points of
    comparison for skilled artisans. 
    Id. at 1335–36.
    The one
    example provided in the written description at issue in
    Interval Licensing, in contrast, was not accompanied by
    sufficient detail to render the claim scope reasonably
    
    certain. 766 F.3d at 1372
    . In Datamize, the written
    SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.                   15
    description did not contain any examples of an “aestheti-
    cally pleasing” interface, nor did it “explain what factors a
    person should consider when selecting a feature” to lead
    to an aesthetically pleasing 
    result. 417 F.3d at 1352
    .
    On the other hand, the ’845 patent contains consider-
    ably more detail than Datamize or Interval Licensing. As
    explained previously, the written description of the ’845
    patent includes: (1) a general exemplary design for a
    visually-negligible indicator, ’845 patent, col. 3 ll. 13–20;
    (2) “requirements for the graphical indicators being
    negligible to human eyes,” 
    id. col. 4
    l. 60–col. 5 l. 5; and
    (3) two specific examples of visually-negligible indicators,
    
    id. col. 5
    ll. 6–15. That there are examples at all distin-
    guishes this case from Datamize, and that the written
    description contains an additional example and specific
    requirements distances this case from Interval Licensing.
    Instead, the level of detail provided in the written de-
    scription is closer to that provided in Enzo: These are
    statements that provide guidance on how to create visual-
    ly-negligible indicators, and specific examples that pro-
    vide points of comparison for the result.
    Appellees criticize what they see as the written de-
    scription’s low level of detail. Specifically, they argue that
    the examples and requirements in the written description
    cannot be translated to an objective standard for the
    claim’s scope because they, too, are subjective. We disa-
    gree. Just as the patent in Enzo included “examples of
    suitable linkage 
    groups,” 599 F.3d at 1334
    , the ’845 pa-
    tent includes examples of visually-negligible indicators,
    ’845 patent, col. 5 ll. 6–15. Just as the patent in Enzo
    provided “some criteria for selecting [linkage groups that
    did not substantially 
    interfere],” 599 F.3d at 1334
    , the
    ’845 patent includes the differentiability, brightness, and
    homogeneity “requirements for the graphical indicators
    being negligible to human eyes,” ’845 patent, col. 4 l. 60–
    col. 5 l. 5. The guidance in Enzo allowed a skilled artisan
    to compare a potentially infringing product “with the
    16                       SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.
    examples in the specification to determine whether inter-
    ference . . . is 
    substantial,” 599 F.3d at 1336
    ; similarly, an
    accused infringer could compare the examples and criteria
    from the written description of the ’845 patent to deter-
    mine whether an indicator is visually negligible. Moreo-
    ver, Appellees have not provided evidence that human
    perception varies so significantly that reliance on it as a
    standard renders the claims indefinite. See 
    Warsaw, 778 F.3d at 1371
    . Thus, as in Enzo, the written description of
    the ’845 patent supports the conclusion that a skilled
    artisan would have understood the term with reasonable
    certainty.
    Other aspects of this case also make reversal compel-
    ling. The prosecution history of the ’845 patent, which
    includes the reexamination history, see Info-Hold, Inc. v.
    Applied Media Techs. Corp., 
    783 F.3d 1262
    , 1266 (Fed.
    Cir. 2015), supports that conclusion. No one involved in
    either the first or the second reexamination had any
    apparent difficulty in determining the scope of “visually
    negligible.” During the first reexamination, SunPlus
    repeatedly argued that the prior art disclosed visually-
    negligible graphical indicators without any apparent
    uncertainty as to the meaning or scope of the term, and no
    apparent difficulty applying it to the references at issue.
    See, e.g., J.A. 795, 800, 801, 811, 823, 835, 844, 849–50,
    854, 864, 876. During the second reexamination, the
    examiner was able to understand and apply the term in
    performing a search for prior art and make an initial
    rejection. See J.A. 2312–13. Moreover, Serjersen was
    able to understand both the claims and written descrip-
    tion with sufficient certainty to (1) replicate the claimed
    indicator; and (2) opine regarding whether it, and the
    indicators of Lamoure and Priddy, were visually negligi-
    ble. See J.A. 2338–44, 5313–25. Thus, he was readily
    able to differentiate between which indicators were and
    which were not visually negligible. Finally, the examiner
    understood the import of Serjersen’s results well enough
    SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.                 17
    to withdraw the rejections in response, indicating that he
    was able to differentiate between indicators as well. J.A.
    2363–65. Again, GeneralPlus, Sonix, and the USPTO did
    not express any uncertainty as to the scope of “visually
    negligible,” or encounter any apparent difficulty in apply-
    ing the term to the references.
    Appellees challenge this evidence as well, arguing
    that the fact that the experts applied the term does not
    mean that they used or could determine an objective
    standard. Although Appellees are correct that application
    by the examiner and an expert do not, on their own,
    establish an objective standard, they nevertheless provide
    evidence that a skilled artisan did understand the scope
    of this invention with reasonable certainty.
    The extrinsic evidence, to the extent that it is neces-
    sary in this case, does not counsel otherwise. Appellees
    apparently understood the meaning of “visually negligi-
    ble” from the beginning of the litigation. Their initial
    invalidity contentions did not argue that the “visually
    negligible” was indefinite, and neither did their final
    contentions. Indeed, at no point before Dr. Ashok’s depo-
    sition did they contend that “visually negligible” was
    indefinite, even though they contended that twenty-eight
    other terms were indefinite. That Appellees themselves
    did not question the clarity of “visually negligible” in the
    first several years of litigation supports the conclusion
    that the term could be understood with reasonable cer-
    tainty.
    Appellees’ other actions during litigation also reflect
    that they understood “visually negligible.” They initially
    argued for a specific construction of the term, but later
    abandoned their attempt in favor of an ordinary-meaning
    construction. The parties’ experts also had no difficulty in
    applying “visually negligible.” Dr. Ashok and Dr. Engels
    repeatedly applied the term to the references and the
    accused products. Although Appellees again argue that
    18                      SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.
    this does not establish an objective standard, continued
    application by the experts in this case further supports
    the conclusion that a skilled artisan did understand the
    term with reasonable certainty.
    Appellees’ repeatedly cite Dr. Ashok’s responses dur-
    ing his deposition. Appellees asked Dr. Ashok to define
    “visually negligible,” a term for which he had given no
    previous definition, and which Appellees had previously
    agreed did not need a construction. But it is unsurprising
    that Dr. Ashok indicated that he was unaware of a “tech-
    nical standard” for the term, J.A. 4756 at 51:9–11; as
    Appellees had agreed to an ordinary-meaning construc-
    tion, there was no reason for him to attempt to determine
    one. Even so, Dr. Ashok did not opine that a skilled
    artisan would have any trouble understanding the term
    or that the claims were indefinite, and he observed that
    he thought that his assessment of what was visually
    negligible would likely be representative. See J.A. 4755–
    56. Dr. Engels, Appellees’ own expert, also did not opine
    that the claims were indefinite or that a skilled artisan
    would not have understood the term; instead, he provided
    a one-sentence statement that “visually negligible” is
    subjective and that there was no objective test to define it.
    See J.A. 3709. Dr. Engels did not detail any basis for this
    conclusion, instead simply stating that it was “based on
    Dr. Ashok’s testimony.” 
    Id. In light
    of the intrinsic
    evidence, this ambiguous testimony is not persuasive.
    Our holding in this case does not mean that the exist-
    ence of examples in the written description will always
    render a claim definite, or that listing requirements
    always provide sufficient certainty. Neither does the fact
    that an expert has applied a contested claim term without
    difficulty render a claim immune from an indefiniteness
    challenge. As always, whether a claim is indefinite must
    be judged “in light of the specification and prosecution
    history” of the patent in which it appears. Interval Li-
    
    censing, 766 F.3d at 1369
    . We simply hold that “visually
    SONIX TECH. CO.   v. PUBL’NS INT’L, LTD.               19
    negligible” is not a purely subjective term and that, on
    this record, the written description and prosecution
    history provide sufficient support to inform with reasona-
    ble certainty those skilled in the art of the scope of the
    invention. The examiner’s knowing allowance of claims
    based on the term that is now questioned, plus the ac-
    ceptance of the term by both parties’ experts, force us to
    the conclusion that the term “visually negligible” is not
    indefinite. Accordingly, we reverse the district court’s
    conclusion that the asserted claims are invalid as indefi-
    nite.
    Because we hold that the district court erred in con-
    cluding that the asserted claims are indefinite, we need
    not, and do not, reach Sonix’s alternative arguments for
    reversal.
    CONCLUSION
    We have considered the remaining arguments, but
    find them unpersuasive. For the foregoing reasons, the
    decision of the district court is reversed.
    REVERSED