Dome Patent L.P. v. Lee , 799 F.3d 1372 ( 2015 )


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  •   United States Court of Appeals
    for the Federal Circuit
    ______________________
    DOME PATENT L.P.,
    Plaintiff-Appellant
    v.
    MICHELLE K. LEE, DIRECTOR, U.S. PATENT AND
    TRADEMARK OFFICE,
    Defendant-Appellee.
    ______________________
    2014-1673
    ______________________
    Appeal from the United States District Court for the
    District of Columbia in No. 1:07-CV-01695.
    ______________________
    Decided: September 3, 2015
    ______________________
    JAMES W. DABNEY, Hughes Hubbard & Reed LLP,
    New York, NY, argued for plaintiff-appellant. Also repre-
    sented by MITCHELL EPNER, STEPHEN S. RABINOWITZ.
    SCOTT WEIDENFELLER, Office of the Solicitor, United
    States Patent and Trademark Office, Alexandria, VA,
    argued for defendant-appellee.   Also represented by
    NATHAN K. KELLEY, WILLIAM LAMARCA.
    ______________________
    Before REYNA, SCHALL, and HUGHES, Circuit Judges.
    2                                   DOME PATENT L.P.   v. LEE
    HUGHES, Circuit Judge.
    Dome owns a patent for making contact-lens material.
    On reexamination, the U.S. Patent and Trademark Office
    found that the claimed method at issue was obvious and
    therefore unpatentable. The district court agreed with
    the Patent Office that the claimed method was unpatent-
    able. On appeal, Dome challenges both the standard of
    review employed by the district court and the court’s
    ultimate conclusion on obviousness. Because we conclude
    that the district court applied the proper legal standard
    and because its factual findings were not clearly errone-
    ous, we affirm.
    I
    Dome owns U.S. Patent No. 4,306,042, which concerns
    the polymer science behind making contact-lens materials
    that are rigid and gas permeable. During the relevant
    time period, contact-lens makers required contact-lens
    materials to be optically clear, sufficiently rigid for ma-
    chining and polishing, oxygen permeable, and hydrophilic.
    To meet these four requirements, contact-lens makers
    used plastic polymers.
    A polymer is a chain or network of molecules called
    monomers. The process of synthesizing a polymer from
    monomers of a single type is called polymerization. When
    two or more different types of monomers are reacted, i.e.,
    copolymerized, a copolymer is formed and the constituent
    compounds are known as comonomers. Polymers or
    copolymers can have many different structures, including
    linear chains, branched chains, cross-linked networks,
    and mixtures thereof.
    Contact-lens makers can produce materials that have
    varying physical properties by varying the types of mon-
    omers used and the resulting polymer’s structure. For
    example, using one type of cross-linking agent over an-
    other may increase the gaps in a polymer’s structure,
    DOME PATENT L.P.   v. LEE                               3
    affecting oxygen permeability.     Or using hydrophilic
    monomers, sometimes referred to as “wetting agents,” in a
    linear polymer chain can increase the polymer’s ability to
    attract or hold water. By contrast, using hydrophobic
    monomers to create a polymer can decrease the polymer’s
    affinity for water.
    The first practical plastic contact lens was made of
    plexiglass, or polymethyl methacrylate (PMMA). Alt-
    hough clear, rigid, and hydrophilic, PMMA was not suffi-
    ciently oxygen permeable to allow users to wear the
    lenses for extended periods of time. After a few hours, a
    user had to remove PMMA lenses to allow the cornea to
    absorb ambient oxygen, which is needed to ensure, among
    other things, that the eye’s cells and nerves remain
    healthy. Given these limitations on PMMA lenses, poly-
    mer scientists began exploring other combinations of
    monomer types and polymer structures to create a mate-
    rial similar to PMMA, but with increased oxygen permea-
    bility.
    In the early 1970’s, major advances in polymer science
    led to the discovery that silicone could be incorporated
    into plastics by mixing siloxane-based compounds with
    methyl methacrylate (MMA), a monomer in PMMA. One
    particular siloxane-based compound known as “Tris,” or
    1,1,1-tris(trimethylsiloxy)methacryloxypropylsilane, was
    identified as a strong candidate because, when mixed
    with MMA, it led to materials with exceptional oxygen
    permeability. A significant drawback to this combination,
    however, was that Tris is hydrophobic, and it caused the
    polymer to be hydrophobic. To offset this drawback,
    polymer scientists in the late 1970’s and the 1980’s would
    combine other hydrophilic comonomers, wetting agents,
    and cross-linking agents with Tris, hoping to strike an
    acceptable balance between oxygen permeability, optical
    clarity, rigidity, and hydrophilicity.
    4                                   DOME PATENT L.P.   v. LEE
    Claim 1 of the ’042 patent covers a method of making
    one such combination. The method comprises making
    Tris and then copolymerizing it with an ester of acrylic or
    methacrylic acid (e.g., MMA), a surface wetting agent,
    and an oxygen permeable siloxane-based cross-linking
    agent (a multifunctional 1 siloxanyl alkyl ester). Claim 1
    recites, in relevant part:
    A method of making an oxygen permeable materi-
    al for the manufacture of contact lens by the syn-
    thesization     of    the     monomer       1,1,1-
    tris(methylsiloxy)methacryloxypropylsilane
    (a siloxanyl alkyl ester) by the following proce-
    dures: . . .
    (f) forming an oxygen permeable contact lens ma-
    terial by copolymerizing from 5% to 90% by
    weight      of   the     1,1,1-tris(trimethylsiloxy)
    methacryloxypropylsilane prepared above; 3% to
    90% by weight of an ester of acrylic or methacrylic
    acid; from 0.05% to 90% by weight of a surface
    wetting agent, from 0.01% to 90% by weight of an
    oxygen permeable crosslinking agent selected
    from the class of multifunctional siloxanyl alkyl
    esters in the presence of a free radical or a photo
    initiator.
    ’042 patent, col. 5 ll. 38–64.
    In December 1997, Dome filed suit against six makers
    of contact lenses for alleged infringement of the ’042
    patent. Shortly after, one defendant requested ex parte
    1   Copolymers with cross-linked networks, such as
    the types covered by the ’042 patent, can be formed by
    employing a “multifunctional” comonomer. Two or more
    ends of a multifunctional comonomer have the ability to
    join with other comonomers to form a cross-link between
    polymer chains, like a rung of a ladder.
    DOME PATENT L.P.   v. LEE                                       5
    reexamination of the ’042 patent. See 35 U.S.C. § 302
    (1994). In June 1999, the Patent Office ordered reexami-
    nation and, as a result, the district court stayed litigation
    pending a final determination in the reexamination
    proceeding. The Patent Office confirmed the patentability
    of claims 2, 3, and 4 of the ’042 patent, but it found claim
    1 obvious under 35 U.S.C. § 103(a) (2006).
    Dome then filed suit in September 2007 against the
    Patent Office in the United States District Court for the
    District of Columbia under 35 U.S.C. §§ 145 and 306
    (2006), requesting that the district court enjoin the Patent
    Office from cancelling claim 1 of the ’042 patent and that
    it direct the Patent Office to issue a reexamination certifi-
    cate under 35 U.S.C. § 307 (2006). Following a bench
    trial, the district court held claim 1 of the ’042 patent
    invalid as obvious under 35 U.S.C. § 103 and entered
    judgment in favor of the Patent Office.
    The district court concluded that the ’042 patent
    would have been obvious to a person of ordinary skill at
    the time of filing in view of the prior art, including U.S.
    Patent Nos. 4,120,570 (Gaylord), 4,152,508 (Ellis), and
    4,235,985 (Tanaka).
    Gaylord discloses a polymer for making rigid, gas-
    permeable contact lenses. Gaylord’s disclosures represent
    a significant breakthrough in contact-lens materials. It is
    one of the first teachings of using siloxane-based mono-
    mers, including Tris, with MMA for the purpose of mak-
    ing contact lenses. In fact, the record indicates that Tris
    and similar siloxane-based compounds became an “indus-
    try standard” in the manufacture of contact lenses follow-
    ing this breakthrough. J.A. 2085.
    Gaylord teaches that a suitable polymer can be made
    by combining Tris, MMA, methacrylic acid as a hydro-
    philic wetting agent, and a hydrophilic cross-linking
    agent, such as ethylene glycol dimethacrylate. See Gay-
    lord col. 1 l. 53 – col. 2 l. 44; col. 3 ll. 63–65; col. 5 ll. 39–
    6                                        DOME PATENT L.P.    v. LEE
    51; col. 6 ll. 3–12. But unlike the ’042 patent, Gaylord
    does not teach using a hydrophobic, siloxane-based cross-
    linking agent. See Gaylord col. 6 ll. 3–12.
    Ellis discloses a “silicone-containing hard contact lens
    material” that, like Gaylord, can include Tris, MMA, a
    hydrophilic wetting agent, and a hydrophilic cross-linking
    agent, including ethylene glycol dimethacrylate. Ellis
    col. 1 ll. 1–3; col. 3 ll. 7–24; col. 3 ll. 64–68; col. 4 ll. 24–27;
    col. 4 ll. 4–7. Ellis also teaches the inclusion of a fifth
    monomer called an itaconate ester, which “gives increased
    rigidity, hardness and some degree of wettability.” Ellis
    col. 2 ll. 1–3.
    Tanaka discloses a polymer suitable for continuous-
    wear contact lenses, and it teaches using a variety of
    cross-linking agents. Like Gaylord and Ellis, Tanaka
    teaches using a hydrophilic compound, including ethylene
    glycol dimethacrylate, as a cross-linking agent. Tanaka
    col. 8 ll. 2–6. But Tanaka also teaches, among other
    things, that using hydrophobic siloxane-based compounds
    are preferably employed as cross-linking agents because
    of their ability to enhance oxygen permeability in the
    resulting polymer. Tanaka col. 8 ll. 10–46.
    Tanaka differs from Gaylord in that, rather than us-
    ing Tris, Tanaka teaches using a different siloxane-based
    monomer, containing both hydrophobic alkylsiloxy ester
    groups (siloxane-based groups) and internal hydrophilic
    glycerol or polyether groups. See Tanaka col. 2 l. 64 –
    col. 3 l. 5. Tanaka teaches that this replacement for Tris-
    type monomers can be combined with MMA. See Tanaka
    col. 2 l. 64 – col. 3 l. 5; col. 7 ll. 39–41. According to
    Tanaka, this approach is more effective than using Tris-
    type monomers because simply offsetting the hydrophobic
    properties of Tris by copolymerizing it with hydrophilic
    monomers can lead to an “opaque” product, “a fatal defect
    for use as contact lens materials. Therefore, the polymer-
    ization ratio of the hydrophilic monomer to the [Tris-type]
    DOME PATENT L.P.   v. LEE                                7
    monomer is limited to produce a transparent copoly-
    mer . . . .” Tanaka col. 3 ll. 35–40; see also Tanaka
    col. 3 ll. 6–34. Tanaka suggests that alternatively one
    might reduce the number of siloxane-based molecules in
    the polymer to reduce hydrophobicity, but then the oxy-
    gen permeability of the resulting polymer becomes too
    low. Tanaka col. 3 ll. 41–45. Tanaka explains that “[i]n
    any case, there cannot be obtained a polymer suited for
    preparing a contact lens which can be comfortably worn
    continuously for a long period of time” when Tris-type
    monomers are employed. Tanaka col. 3 ll. 48–51.
    In the district court action, Dome did not dispute that
    the prior art disclosed the compounds recited in claim 1 of
    the ’042 patent. The district court found that a person of
    ordinary skill would have been motivated to combine the
    prior art and that the prior art did not teach away from
    the claimed invention, notwithstanding the disclosures in
    Tanaka regarding Tris-type monomers. Additionally, the
    court found that Dome’s proffered evidence of objective
    indicia did not indicate nonobviousness. Accordingly, the
    court agreed with the Board’s conclusion that claim 1 is
    unpatentable as obvious under 35 U.S.C. § 103. Dome
    appeals.      We have jurisdiction under 28 U.S.C.
    § 1295(a)(4)(C).
    II
    Before reaching Dome’s appeal of the obviousness
    conclusion, we first address Dome’s allegation that the
    district court erred by only requiring the Patent Office to
    show that claim 1 of the ’042 patent is obvious by a pre-
    ponderance of the evidence, rather than by clear and
    convincing evidence. We conclude that the district court
    correctly applied the preponderance of the evidence
    standard.
    Dome’s appeal arises from an ex parte reexamination
    of the ’042 patent. Ordinarily, the Patent Office in such a
    proceeding must establish by a preponderance of the
    8                                      DOME PATENT L.P.   v. LEE
    evidence that the reexamined claims are not patentable.
    Rambus Inc. v. Rea, 
    731 F.3d 1248
    , 1255 (Fed. Cir. 2013).
    If an ex parte reexamination results in the claims being
    rejected as unpatentable, the decision can be appealed
    directly to this court. See 35 U.S.C. § 141.
    Alternatively, for ex parte reexaminations filed before
    November 29, 1999, a complaint can be filed in district
    court against the Patent Office. See 37 C.F.R. § 1.303(a)
    (2012); 35 U.S.C. § 145 (“The [district] court may adjudge
    that such applicant is entitled to receive a patent for his
    invention, . . . and such adjudication shall authorize the
    Director to issue such patent . . . .”). “The thrust of such a
    complaint is that the decision of the board is erroneous on
    the facts, the law, or both. Indeed, the board’s decision is
    the jurisdictional base for the suit. . . . [I]t is in essence a
    suit to set aside the final decision of the board.” Fregeau
    v. Mossinghoff, 
    776 F.2d 1034
    , 1036–37 (Fed. Cir. 1985).
    Accordingly, if the Patent Office decides after an ex
    parte reexamination that a preponderance of the evidence
    establishes the claimed subject matter is not patentable,
    § 145 authorizes the district court to review whether that
    final decision is correct. The § 145 action in such a case
    does not concern the different question of whether, as part
    of a defense to an infringement action, clear and convinc-
    ing evidence establishes that an issued and asserted
    patent should be held invalid. See 
    id. at 1037
    (“it cannot
    seriously be contended that a § 145 action is other than
    one to overturn the board’s decision”).
    Citing 35 U.S.C. § 282 and Microsoft Corp. v. i4i Ltd.
    Partnership, 
    131 S. Ct. 2238
    (2011), Dome argues that the
    district court erred by refusing to hold the Patent Office to
    the clear and convincing evidence standard of proof.
    According to Dome, the presumption of validity in § 282
    applies to its claimed invention because the district court
    action concerns a claim that the Patent Office previously
    allowed to be patented. Accordingly, Dome argues the
    DOME PATENT L.P.   v. LEE                                    9
    Supreme Court’s holding that “§ 282 requires an invalidi-
    ty defense to be proved by clear and convincing 
    evidence,” 131 S. Ct. at 2242
    , also applies in Dome’s § 145 action.
    The § 145 action before the district court did not in-
    volve a defense to a charge of infringement of an issued
    patent. Section 282 therefore does not apply in this
    instance. See 35 U.S.C. § 282. The district court here was
    reviewing the Patent Office’s reexamination of claimed
    subject matter, and its final determination that the
    subject matter is not patentable, to ascertain whether
    Dome was entitled to receive a patent. Only if the district
    court found in favor of Dome would the Patent Office be
    authorized to issue a patent. See 35 U.S.C. § 145. And
    only after the patent issued would it be entitled to the
    presumption of validity under § 282 and, consequently,
    could not be held invalid absent clear and convincing
    evidence.
    The clear and convincing evidence standard in the lit-
    igation context “stems from our suggestion that the party
    challenging a patent in court ‘bears the added burden of
    overcoming the deference that is due to a qualified gov-
    ernment agency presumed to have done its job.’” Sciele
    Pharma Inc. v. Lupin Ltd., 
    684 F.3d 1253
    , 1260 (Fed. Cir.
    2012) (quoting PharmaStem Therapeutics, Inc. v. ViaCell,
    Inc., 
    491 F.3d 1342
    , 1366 (Fed. Cir. 2007)). But “[i]n
    reexamination proceedings, ‘a preponderance of the
    evidence must show nonpatentability before the [Patent
    Office] may reject the claims of a patent application.’”
    
    Rambus, 731 F.3d at 1255
    (quoting Ethicon, Inc. v. Quigg,
    
    849 F.2d 1422
    , 1427 (Fed. Cir. 1988)). This standard is
    “substantially lower than in a civil case, . . . [and] there is
    no presumption of validity.” In re Swanson, 
    540 F.3d 1368
    , 1377 (Fed. Cir. 2008) (citations omitted).
    “[A]n examiner is not attacking the validity of a pa-
    tent, but is conducting a subjective examination of claims
    in the light of prior art.” In re Etter, 
    756 F.2d 852
    , 857–58
    10                                  DOME PATENT L.P.   v. LEE
    (Fed. Cir. 1985); see also 
    id. at 857
    (“litigation and reex-
    amination are distinct proceedings, with distinct parties,
    purposes, procedures, and outcomes”). When the Patent
    Office institutes ex parte reexamination, it reopens prose-
    cution to determine whether the claimed subject matter
    should have been allowed in the first place. At that point,
    there is no need to presume that the Patent Office had
    “done its job” in the previous examination. Accordingly,
    the presumption of validity is no longer applicable.
    Our conclusion aligns with the purpose of the reexam-
    ination process, which includes allowing the Patent Office
    to take a second look at “patents thought ‘doubtful.’” In re
    
    Etter, 756 F.2d at 857
    (quoting H.R. Rep. No. 66-1307, at
    3–4 (1980), reprinted in 1980 U.S.C.C.A.N. 6460, 6462).
    “In a very real sense, the intent underlying reexamination
    is to ‘start over’” in the Patent Office. 
    Id. We would
    hinder this intent if we required the district court here to
    presume that the reexamined claim is valid because of the
    Patent Office’s previous determination and, consequently,
    to impose a burden to defend its own subsequent reexam-
    ination decision by clear and convincing evidence. Thus,
    the district court did not err by requiring the Patent
    Office to show by a preponderance of the evidence that the
    reexamined claim is obvious.
    III
    We now address the district court’s obviousness de-
    terminations. A patent may not issue “if the differences
    between the subject matter sought to be patented and the
    prior art are such that the subject matter as a whole
    would have been obvious at the time the invention was
    made to a person having ordinary skill in the art.” 35
    U.S.C. § 103(a) (2006). 2 Obviousness is a question of law
    2   Because the application for the ’042 patent was
    filed before March 16, 2013, the pre-Leahy-Smith America
    DOME PATENT L.P.   v. LEE                                 11
    based on underlying factual findings, including: “(1) the
    scope and content of prior art; (2) differences between
    prior art and claims; (3) the level of ordinary skill in the
    art; and (4) objective indicia of nonobviousness.” Par
    Pharm., Inc. v. TWI Pharm., Inc., 
    773 F.3d 1186
    , 1193
    (Fed. Cir. 2014) (citing Graham v. John Deere Co., 
    383 U.S. 1
    , 17–18 (1966)). We review the ultimate conclusion
    of obviousness de novo and the underlying factual find-
    ings for clear error. Medichem, S.A. v. Rolabo, S.L., 
    437 F.3d 1157
    , 1164 (Fed. Cir. 2006).
    A
    If all elements of a claim are found in the prior art, as
    is the case here, the factfinder must further consider the
    factual questions of whether a person of ordinary skill in
    the art would be motivated to combine those references,
    and whether in making that combination, a person of
    ordinary skill would have had a reasonable expectation of
    success. 
    Id. at 1164.
    The Supreme Court has cautioned,
    however, that an obviousness determination cannot be
    confined by formalistic rules. KSR Int’l Co. v. Teleflex
    Inc., 
    550 U.S. 398
    , 419 (2007). Rather, courts must take
    an “expansive and flexible approach” to the question of
    obviousness. 
    Id. at 415.
        Evidence of a motivation to combine prior art refer-
    ences may flow from “‘the nature of the problem to be
    solved.’” Tokai Corp. v. Easton Enters., Inc., 
    632 F.3d 1358
    , 1371 (Fed. Cir. 2011) (quoting Ruiz v. A.B. Chance
    Co., 
    357 F.3d 1270
    , 1276 (Fed. Cir. 2004)). Here, the
    record supports the district court’s finding that a person
    of ordinary skill understood that high oxygen permeabil-
    ity in contact-lens materials was desirable. And this
    understanding would have motivated a person of ordinary
    Invents Act, Pub. L. No. 112-29, 125 Stat. 284 (2011),
    version of 35 U.S.C. § 103 applies.
    12                                   DOME PATENT L.P.   v. LEE
    skill to combine the Tris monomer disclosed in Gaylord
    with the Tris-type cross-linking agent disclosed in Tanaka
    to increase the oxygen permeability of a contact lens.
    Gaylord, for example, teaches that the previously
    used contact-lens material, PMMA, is rigid and durable
    but relatively impermeable to oxygen. Gaylord col. 1
    ll. 24–30. Gaylord explained it would be “highly desira-
    ble” to provide a contact-lens material that has “increased
    oxygen permeability, is wettable,” and has improved
    mechanical properties. Gaylord col. 1 ll. 39–44. To meet
    that need, Gaylord discloses using siloxane-based com-
    pounds, including Tris-type monomers. See Gaylord col. 1
    ll. 44–51; col. 2 ll. 32–44. Similarly, Ellis teaches that
    oxygen permeability is “directly related” to the silicone
    content in contact lenses. Ellis col. 1 ll. 29–30. And
    Tanaka explains that contact lenses with poor oxygen
    permeability would make it “impossible to wear them
    continuously for a long period of time.” Tanaka col. 1 ll.
    30–32. Tanaka therefore “preferably employed” siloxane-
    based cross-linking agents, including some that are
    hydrophobic, because the oxygen permeabilities of the
    obtained cross-linked copolymers are high. Tanaka col. 8
    ll. 10–46.
    The testimonies from Dome’s experts also support the
    district court’s conclusion. Dr. Mark Melamed testified
    that “it’s essential that there be an adequate flow of
    oxygen either through the lens or around the lens.” J.A.
    1805; see also J.A. 1804–05 (“it’s essential that there be a
    constant flow of oxygen to the entry surface of the cornea
    in order for a contact lens to be worn safely for a period of
    time”). A “chief” issue during Dr. Melamed’s practice was
    “the ability to get oxygen across a contact lens,” while
    “maintaining a nice even tear film over the contact lens
    and over the cornea,” i.e., hydrophilicity, was considered a
    “secondary problem” related to contact lens comfort levels.
    J.A. 1807. And another of Dome’s experts, Dr. Timothy
    Long, testified that those in the field were turning to
    DOME PATENT L.P.   v. LEE                                 13
    siloxane-based compounds to enhance a polymer’s oxygen
    permeability. See J.A. 1746 (“It has great oxygen perme-
    ability. It’s one of the big driving forces for people in the
    contact lens field to use it.”). Accordingly, the district
    court did not clearly err in finding that the evidence
    disclosed a motivation to combine the prior art.
    B
    Dome argues that a person of ordinary skill would not
    have been motivated to combine Gaylord with Tanaka
    because the prior art teaches away from using Tris with
    siloxane-based cross-linking agents. To improve Gay-
    lord’s disclosures, Dome asserts, a person of ordinary skill
    would have been inclined to introduce hydrophilic cross-
    linking agents, instead of hydrophobic siloxane-based
    cross-linking agents, to offset the hydrophobicity of Tris,
    but Tanaka warned against this approach. As an alterna-
    tive, Tanaka suggested designing a new amphiphilic or
    hydrophilic monomer to replace Tris altogether.
    “[W]hen the prior art teaches away from combining
    certain known elements, discovery of a successful means
    of combining them is more likely to be nonobvious.” 
    KSR, 550 U.S. at 416
    . A reference teaches away from a claimed
    invention when a person of ordinary skill, “upon reading
    the reference, would be discouraged from following the
    path set out in the reference, or would be led in a direc-
    tion divergent from the path that was taken by the appli-
    cant.” In re Gurley, 
    27 F.3d 551
    , 553 (Fed. Cir. 1994).
    But “[t]he degree of teaching away will of course depend
    on the particular facts.” Id.; see also 
    id. (“A known
    or
    obvious composition does not become patentable simply
    because it has been described as somewhat inferior to
    some other product for the same use.”). And “there is no
    rule that a single reference that teaches away will man-
    date a finding of nonobviousness.” 
    Medichem, 437 F.3d at 1165
    ; see also 
    KSR, 550 U.S. at 421
    (“Rigid preventative
    rules that deny factfinders recourse to common sense . . .
    14                                        DOME PATENT L.P.    v. LEE
    are neither necessary under our case law nor consistent
    with it.”). Additionally, just because “better alternatives”
    may exist in the prior art “does not mean that an inferior
    combination is inapt for obviousness purposes.” In re
    Mouttet, 
    686 F.3d 1322
    , 1334 (Fed. Cir. 2012) (citing
    
    Gurley, 27 F.3d at 553
    ).
    Here, Tanaka discloses potential disadvantages asso-
    ciated with using Tris-type monomers. It explains that,
    outside of certain unspecified limits, if hydrophilic mono-
    mers are copolymerized with hydrophobic Tris-type
    monomers to offset hydrophobicity, the copolymer “is
    liable to become opaque.” Tanaka col. 3 ll. 6–36. Tanaka
    explains that opacity is a “fatal defect” for the copolymer’s
    use as a material for contact lenses, and thus offsetting
    hydrophobic Tris-type monomers with hydrophilic mono-
    mers “is limited.” Tanaka col. 3 ll. 36–41. Tanaka does
    not further identify the mentioned limits, but it goes on to
    disclose an alternative for Tris-type monomers. See
    Tanaka col. 3 ll. 52–59.
    The record, however, supports the district court’s find-
    ing that other prior art references disclose roadmaps on
    how to offset the disadvantages associated with using
    Tris-type monomers to obtain a material suitable for
    contact lenses.
    Ellis acknowledges that “[i]t has been difficult to ob-
    tain high oxygen permeability while still maintaining
    other properties . . . when oxygen permeability is derived
    from the silicone content” in a polymer. Ellis col. 1 ll. 30–
    34. Ellis then teaches how to effectively overcome this
    difficulty without compromising the resulting material’s
    clarity. Ellis teaches several examples of using Tris with
    hydrophilic monomers in varying concentrations and
    concludes that “[i]n all cases, the polymers are optically
    clear and meet required standards of contact lenses.”
    Ellis col. 7 ll. 15–17; see also 
    id. col. 5
    l. 50 – col. 7 l. 13; 
    id. col. 7
    ll. 19–21. Ellis also discloses that “many variations
    DOME PATENT L.P.   v. LEE                                  15
    are possible within the scope of keeping the physical
    properties,” stating that “[f]or example, two or more
    siloxanyl alkyl ester monomers can be used instead of a
    single such monomer for that component of the system.”
    Ellis col. 7 ll. 30–36.
    Gaylord similarly acknowledges the issues identified
    by Tanaka and then sets out a solution, one that does not
    compromise the resulting polymer’s use as a material for
    contact lenses. Gaylord teaches that “[w]hile some of the
    copolymers are inherently wettable by human tears, it
    may be necessary to improve the wettability of others.”
    Gaylord col. 5 ll. 39–41. For example, “wettability can be
    imparted to the copolymer by the addition of from about
    0.1% to about 10% by weight of one or more hydrophilic
    monomers to the copolymerization mixture” or by other
    treatments, including corona discharge, oxidizing, or
    soaking in aqueous solutions. 
    Id. col. 5
    ll. 42–58. Gaylord
    also lists examples “illustrat[ing] the preparation and
    properties of copolymers containing varying proportions of
    a siloxanyl monomer, [MMA], and a hydrophilic monomer
    (hydroxyethyl methacrylate).” Gaylord col. 9 l. 67 –
    col. 10 l. 2. Many of these examples resulted in “trans-
    parent” materials. See Ellis col. 9 l. 66 – col. 10 l. 24.
    The district court found that while Tanaka warns that
    constructing a lens with Tris-type materials can be diffi-
    cult, the other two references plainly teach that Tris could
    be used effectively to make contact lenses. Accordingly,
    the district court concluded that a person of ordinary skill
    would not have been dissuaded from combining the prior
    art, particularly in light of Gaylord and Ellis. The record
    supports these factual findings.
    While Dome’s argument that the claimed subject mat-
    ter would not have been obvious in light of Tanaka’s
    disclosures is plausible, “[t]he burden of overcoming the
    district court’s factual findings is, as it should be, a heavy
    one.” Polaroid Corp. v. Eastman Kodak Co., 
    789 F.2d 16
                                       DOME PATENT L.P.   v. LEE
    1556, 1559 (Fed. Cir. 1986). Our standard of review
    requires that we uphold the district court’s factual find-
    ings on this point, rather than revisiting them de novo. In
    this case, the district court did not clearly err in finding a
    person of ordinary skill would have been motivated to
    combine the identified prior art to arrive at the claimed
    invention, notwithstanding Tanaka’s disclosures regard-
    ing Tris-type compounds.
    C
    Dome also challenges the district court’s handling of
    evidence relating to objective indicia of nonobviousness.
    Dome argues first that the district court erred by improp-
    erly shifting the burden onto Dome to prove nonobvious-
    ness once the Patent Office established a prima facie case
    of obviousness.
    While we have held that a district court has erred “by
    making its finding that the patents in suit were obvious
    before it considered the objective considerations and by
    shifting the burden of persuasion to [the patentee],” In re
    Cyclobenzaprine Hydrochloride Extended-Release Capsule
    Patent Litig., 
    676 F.3d 1063
    , 1075 (Fed. Cir. 2012), the
    legal framework used by the district court in this case was
    not improper.
    Before reaching its ultimate conclusion of obvious-
    ness, the district court first considered whether the Pa-
    tent Office had demonstrated that a person of ordinary
    skill would have been motivated to combine the com-
    pounds recited in claim 1 of the ’042 patent and that there
    would have been a reasonable expectation of success. The
    court also considered whether the prior art taught away
    from the claimed invention. After finding in favor of the
    Patent Office on these points, the court agreed with Dome
    that a product, the Boston IV contact lens, embodies claim
    1 of the ’042 patent and that the Boston IV contact lens
    achieved some commercial success. Nevertheless, the
    court found that the evidence relating to the Boston IV
    DOME PATENT L.P.   v. LEE                               17
    contact lens was not particularly strong. Next, after
    considering the parties’ arguments and making the rele-
    vant findings of fact, the court concluded that claim 1 of
    the ’042 patent is obvious as a matter of law. Indeed, the
    court’s opinion, when read as a whole, shows that the
    court considered and made factual findings on all evi-
    dence relating to objective indicia before reaching its
    ultimate conclusion on obviousness.
    Dome also argues that the district court erred by re-
    fusing to consider Dome’s proffer of evidence relating to
    objective indicia of nonobviousness. We have consistently
    stated that “all evidence pertaining to the objective indi-
    cia of nonobviousness must be considered before reaching
    an obviousness conclusion.” Plantronics, Inc. v. Aliph,
    Inc.,724 F.3d 1343, 1355 (Fed. Cir. 2013). The district
    court here did not refuse to consider Dome’s evidence.
    Rather, the court found that Dome was entitled to a
    presumption that the commercial success of the Boston IV
    contact lens relates to the claimed invention. Nonethe-
    less, the court found that the evidence was “not particu-
    larly strong.” J.A. 57. The court also gave “little weight”
    to testimony relating to the reasons for the Boston IV
    contact lens’s commercial success. J.A. 6 n.4. Moreover,
    the court found that Dome’s own expert testified that the
    commercial success of the Boston IV contact lens was in
    part due to other economic and commercial factors not
    related to the allegedly novel aspects of the claimed
    invention. Dome does not challenge these findings.
    After having accepted all evidence relating to the four
    Graham factors—including evidence relating to commer-
    cial success—the district weighed the evidence and then
    made findings of fact. Only after considering all of the
    evidence did the court reach its obviousness conclusion.
    Thus, we conclude that the court did not err in its consid-
    eration of the evidence relating to objective indicia of
    nonobviousness.
    18                                 DOME PATENT L.P.   v. LEE
    IV
    We have considered Dome’s remaining arguments and
    find them unpersuasive. Because the district court did
    not commit reversible error in its determination that the
    claimed subject matter would have been obvious to a
    person of ordinary skill during the relevant time period,
    we affirm.
    AFFIRMED