  United States Court of Appeals
      for the Federal Circuit
                ______________________

        SHIRE DEVELOPMENT, LLC,
SHIRE PHARMACEUTICAL DEVELOPMENT, INC.,
    COSMO TECHNOLOGIES LIMITED, AND
    GIULIANI INTERNATIONAL LIMITED,
             Plaintiffs-Appellees,

                          v.

       WATSON PHARMACEUTICALS, INC.
      (now known as Actavis, Inc.), WATSON
   LABORATORIES, INC. FLORIDA, WATSON
  PHARMA, INC. (now known as Actavis Pharma,
    Inc.), AND WATSON LABORATORIES, INC.,
                Defendants-Appellants.
                ______________________

                      2013-1409
                ______________________

   Appeal from the United States District Court for the
Southern District of Florida in No. 12-CV-60862, Judge
Donald M. Middlebrooks.
                ______________________

               Decided: March 28, 2014
               ______________________

   EDGAR H. HAUG, Frommer Lawrence & Haug, LLP, of
New York, New York, argued for plaintiffs-appellees.
With him on the brief were JASON A. LIEF, ANDREW S.
WASSON, NICHOLAS F. GIOVE, ELIZABETH MURPHY, and
JONATHAN A. HERSTOFF.
2       SHIRE DEVELOPMENT, LLC    v. WATSON PHARMACEUTICALS,
                                                        INC.




   STEVEN A. MADDOX, Knobbe, Martens, Olson & Bear,
LLP, of Washington, DC, argued for defendants-
appellants. With him on the brief were JONATHAN E.
BACHAND and NEIL M. MCCARTHY. Of counsel was
KRISTIN MARIE COOKLIN, Crowell & Moring, LLP, of
Washington, DC.
                ______________________

    Before RADER, Chief Judge, PROST and HUGHES, Circuit
                          Judges.
HUGHES, Circuit Judge.
    The plaintiffs-appellees (collectively, Shire) own U.S.
Patent No. 6,773,720, which claims a controlled-release
oral pharmaceutical composition for treating inflammato-
ry bowel diseases. Shire markets these oral pharmaceuti-
cal compositions under the brand name LIALDA®. After
the defendants-appellants (collectively, Watson) submit-
ted an Abbreviated New Drug Application (ANDA) seek-
ing approval to sell the bioequivalent of LIALDA®, Shire
sued for infringement of the ’720 patent. After construing
certain relevant claim language, the district court found
that Watson’s product infringed the ’720 patent. We
conclude that the district court’s constructions of “inner
lipophilic matrix” and “outer hydrophilic matrix” imper-
missibly broaden the ordinary meaning of the terms.
Accordingly, we reverse the district court’s claim construc-
tions of “inner lipophilic matrix” and “outer hydrophilic
matrix,” and subsequent finding of infringement, and
remand for further proceedings consistent with this
opinion.
                             I.
    The ’720 patent—entitled “Mesalazine Controlled Re-
lease Oral Pharmaceutical Composition”—concerns
controlled-release oral pharmaceutical compositions for
treating inflammatory bowel diseases, such as Crohn’s
SHIRE DEVELOPMENT, LLC   v. WATSON PHARMACEUTICALS,       3
INC.


disease and ulcerative colitis. ’720 patent col. 1 ll. 9–13.
The active ingredient in these compositions is 5-amino-
salicylic acid, which is also known as mesalazine or
mesalamine (hereinafter, mesalamine).           Mesalamine
treats inflamed areas in the bowel by direct contact with
the intestinal mucosal tissue. J.A. 9054. Thus, mesala-
mine must pass through the stomach and small intestine
without being absorbed into the bloodstream. J.A. 9054.
And, it must be administered throughout the entire
length of the colon so that the mesalamine contacts all
affected tissues. J.A. 9054. Given these requirements,
the oral composition must contain a high percentage, by
weight, of mesalamine. ’720 patent col. 3 ll. 52–56.
     The ’720 patent teaches an inner lipophilic matrix and
an outer hydrophilic matrix to address the limitations of
the prior art systems. 1 According to the ’720 patent, the
combination of a lipophilic and hydrophilic matrix in an
inner-outer matrix system, respectively, is advantageous
because the inner-outer matrix properties cause the
mesalamine to be released in a sustained and uniform
manner. ’720 patent col. 3 ll. 57–59 (“[T]he compositions
of the invention provide a release profile of [mesalamine]
more homogenous than the traditional systems.”); see also
col. 3 l. 60–col. 4 l. 5. The ’720 patent also teaches the
“advantageous characteristic” of a composition with up to
95% active ingredient by weight. ’720 patent col. 3 ll. 52–
56.
    Shire asserts independent claim 1 and dependent
claim 3. Claim 1 recites:



   1     Generally, a lipophilic substance has an affinity
for lipids and a hydrophilic substance has an affinity for
water. Thus, a lipophilic substance resists dissolving in
water, but a hydrophilic substance readily dissolves in
water. See ’720 patent col. 1 ll. 17–26, 32–36.
4     SHIRE DEVELOPMENT, LLC   v. WATSON PHARMACEUTICALS,
                                                     INC.


    1. Controlled-release oral pharmaceutical compo-
    sitions containing as an active ingredient 5-
    amino-salicylic acid, comprising:
        a) an inner lipophilic matrix consisting of sub-
        stances selected from the group consisting of
        unsaturated and/or hydrogenated fatty acid,
        salts, esters or amides thereof, fatty acid
        mono-, di- or triglycerid[e]s, waxes, ceramides,
        and cholesterol derivatives with melting
        points below 90° C., and wherein the active
        ingredient is dispersed both in said the lipo-
        philic matrix and in the hydrophilic matrix;
        b) an outer hydrophilic matrix wherein the
        lipophilic matrix is dispersed, and said outer
        hydrophilic matrix consists of compounds se-
        lected from the group consisting of polymers
        or copolymers of acrylic or methacrylic acid,
        alkylvinyl polymers, hydroxyalkyl celluloses,
        carboxyalkyl celluloses, polysaccharides, dex-
        trins, pectins, starches and derivatives, alginic
        acid, and natural or synthetic gums;
        c) optionally other excipients;
    wherein the active ingredient is present in an
    amount of 80 to 95% by weight of the total compo-
    sition, and wherein the active ingredient is dis-
    persed both in the lipophilic matrix and in the
    hydrophilic matrix.
’720 patent col. 6 ll. 7–30. Claim 3 depends from claim 1
and requires that the composition be in the form of tab-
lets, capsules, or minitablets. ’720 patent col. 6 ll. 35–36.
    The ’720 patent teaches a three-step process to arrive
at the claimed composition. ’720 patent col. 2 ll. 48–59.
SHIRE DEVELOPMENT, LLC   v. WATSON PHARMACEUTICALS,        5
INC.


First, one or more low melting, lipophilic excipients 2 are
mixed with mesalamine during heating. ’720 patent col. 2
ll. 50–53. Second, the mixture is cooled to form the lipo-
philic matrix and then reduced in size into “matrix gran-
ules containing the active ingredient.” ’720 patent col. 2
ll. 54–56. Third, the lipophilic matrix granules are mixed
together with hydrophilic excipients and compressed to
form tablets. ’720 patent col. 2 ll. 50–53, col. 3 ll. 40–45.
     During prosecution of the ’720 patent, the examiner
initially rejected the applicants’ claims as obvious in view
of GB 2 245 492 A (Franco); obvious and anticipated in
view of U.S. Patent No. 5,593,690 (Akiyama); and obvious
in view of the combination of U.S. Patent No. 5,851,555
(Sanghvi) and U.S. Patent No. 6,395,300 (Straub). J.A.
15469–71. The examiner explained that Franco taught a
pharmaceutical composition with an active core, a lipo-
philic coating, and a hydrophilic film. J.A. 15469.
    In response, the applicants stated that Franco dis-
closed a reservoir system where “the active ingredient is
confined within a core which acts as a reservoir from
which the active ingredient is released via the erosion of
the outer coating. However, as to the present invention,
the active ingredient is dispersed in a lipophilic matrix,
not in an isolated core.” J.A. 15480–81.
    The applicants then distinguished Akiyama based on
the claimed invention’s two matrices and high active
ingredient concentration. The applicants argued that
Akiyama “fail[s] to disclose or suggest the two matrices
and the arrangement of the matrices as set forth in the



    2   An excipient is an ingredient other than the active
ingredient, i.e., an ingredient other than mesalamine. See
Shire Dev. LLC v. Watson Pharm., Inc., No. 12-60862,
2013 WL 1912208, at *6 (S.D. Fla. May 9, 2013); see also
J.A. 1425.
6     SHIRE DEVELOPMENT, LLC   v. WATSON PHARMACEUTICALS,
                                                     INC.


claimed invention. The arrangement of the matrices in
the present invention aid[s] in the combined release of an
active ingredient via diffusion from a lipophilic matrix.”
J.A. 15479. The applicants also argued that Akiyama’s
composition contained the “active ingredient . . . in an
amount much lower than that according to the claimed
invention:”—Akiyama taught an active ingredient in
granules in an amount ranging from 0.005–75% by
weight, but the applicants’ amended claim taught 80–
95%. J.A. 15478–79.
     To distinguish Sanghvi and Straub, the applicants
again focused on a lack of two separate matrices: Sanghvi
“fails to disclose a system containing two separate matri-
ces. [It] merely discloses formulations obtained by mixing
together hydrophilic and lipophilic substances into a
single matrix.” J.A. 15481. When discussing the combi-
nation of Sanghvi and Straub, the applicants explained
that “[w]hile the publications might teach the advanta-
geous results of using a lipophilic matrix, the publications
fail to disclose or suggest a composition comprising a
combination of two separate matrices. In fact, there is no
mention or suggestion of a composition utilizing different
control mechanisms.” J.A. 15482.
    The examiner maintained her rejection of the pending
claims as obvious in view of Franco. The examiner also
rejected the claims because “the feature upon which
applicant relies (i.e., the active ingredient is dispersed in
a lipophilic matrix) is not recited in the rejected claims.”
J.A. 15489. Further, the examiner explained that the
limitation-at-the-time—“active ingredient is at least
partly inglobated”—“does not limit the claim to ‘active
ingredient is dispersed in a lipophilic matrix’ as alleged by
the applicant.” J.A. 15489.
    In response, the applicants maintained that Franco
taught a reservoir system, but that the claimed invention
“relates to a ‘multimatrix system’ and not to a reservoir
SHIRE DEVELOPMENT, LLC   v. WATSON PHARMACEUTICALS,       7
INC.


system.” J.A. 15492; see also J.A. 15492 (“FRANCO et al.
do[es] not teach an inner lipophilic matrix or an outer
hydrophilic matrix . . . . The composition taught by
FRANCO et al. is not based on an actual matrix.”). The
applicants also amended their claims to state that the
active ingredient is dispersed in the lipophilic matrix and
added a Markush group 3 for both the inner lipophilic
matrix and the outer hydrophilic matrix. J.A. 15491–92,
96, 99. Following an interview with the examiner, the
claims were amended to require the mesalamine to be
dispersed in the outer hydrophilic matrix and not just the
lipophilic matrix. J.A. 15546–50. The claims were then
allowed and the ’720 patent issued.
    When Watson submitted its ANDA seeking FDA ap-
proval to sell the bioequivalent of LIALDA®, Shire sued
Watson for infringement of the ’720 patent. In January
2013, the district court construed several disputed terms,
including “inner lipophilic matrix” and “outer hydrophilic
matrix.” See Shire Dev. LLC v. Watson Pharm., Inc., No.
12-60862, 2013 WL 174843 (S.D. Fla. Jan. 17, 2013).
    The district court held a bench trial in April 2013 and
issued its opinion a month later, finding that Watson’s
ANDA product infringed claims 1 and 3 of the ’720 patent;
that the claims were not invalid under 35 U.S.C. § 112,
¶ 1; and that Shire was entitled to injunctive relief. Shire
Dev. LLC v. Watson Pharm., Inc., No. 12-60862, 2013 WL
1912208, at *16 (S.D. Fla. May 9, 2013). Specifically, the
district court determined that Watson’s ANDA product
met the limitations of the claims at issue. In considering


   3    “A Markush group lists specified alternatives in a
patent claim, typically in the form: a member selected
from the group consisting of A, B, and C.” Gillette Co. v.
Energizer Holdings, Inc., 405 F.3d 1367, 1372 (Fed. Cir.
2005) (citing to Manual of Patent Examining Procedure
§ 803.2 (2004)).
8     SHIRE DEVELOPMENT, LLC       v. WATSON PHARMACEUTICALS,
                                                         INC.


the disputed limitations, the district court found that the
mesalamine in Watson’s product was dispersed in both
the lipophilic and hydrophilic matrices because the
mesalamine was present in both the granules and the
spaces outside the granules. Shire, 2013 WL 1912208, at
*7–13. The district court also determined that Watson
failed to prove by clear and convincing evidence that the
patent was invalid under 35 U.S.C. § 112 for lack of
written description or enablement. Id., at *14–16. Wat-
son now appeals issues of claim construction, infringe-
ment, and invalidity. This court has jurisdiction under 28
U.S.C. § 1295(a)(1).
                             II.
    Claim construction is an issue of law reviewed de no-
vo. Lighting Ballast Control LLC v. Philips Elecs. N.A.
Corp., No. 2012-1014, 2014 WL 667499, at *1 (Fed. Cir.
Feb. 21, 2014) (en banc); Cybor Corp. v. FAS Techs., Inc.,
138 F.3d 1448, 1456 (Fed. Cir. 1998) (en banc). When
construing asserted claims, claim terms are given “their
ordinary and accustomed meaning as understood by one
of ordinary skill in the art.” Dow Chem. Co. v. Sumitomo
Chem. Co., 257 F.3d 1364, 1372 (Fed. Cir. 2001); Phillips
v. AWH Corp., 415 F.3d 1303, 1312–13 (Fed. Cir. 2005)
(en banc).
    Intrinsic evidence, such as “the specification, . . . may
shed contextual light” on the ordinary and customary
meaning of a claim term. Aventis Pharm. Inc. v. Amino
Chems. Ltd., 715 F.3d 1363, 1373 (Fed. Cir. 2013). “The
construction that stays true to the claim language and
most naturally aligns with the patent’s description of the
invention will be, in the end, the correct construction.”
Phillips, 415 F.3d at 1316.
    In addition to the specification, this court looks to the
prosecution history. For example, “where the patentee
has unequivocally disavowed a certain meaning to obtain
his patent, the doctrine of prosecution disclaimer attaches
SHIRE DEVELOPMENT, LLC   v. WATSON PHARMACEUTICALS,       9
INC.


and narrows the ordinary meaning of the claim congruent
with the scope of the surrender.” Omega Eng’g, Inc. v.
Raytek Corp., 334 F.3d 1314, 1324 (Fed. Cir. 2003); see
Ekchian v. Home Depot, Inc., 104 F.3d 1299, 1304 (Fed.
Cir. 1997) (“[B]y distinguishing the claimed invention
over the prior art, an applicant is indicating what the
claims do not cover [and] he is by implication surrender-
ing such protection.”). “However, while the prosecution
history can inform whether the inventor limited the claim
scope in the course of prosecution, it often produces ambi-
guities created by ongoing negotiations between the
inventor and the PTO. Therefore, the doctrine of prosecu-
tion disclaimer only applies to unambiguous disavowals.”
Grober v. Mako Prods., Inc., 686 F.3d 1335, 1341 (Fed.
Cir. 2012) (citing Abbott Labs. v. Sandoz, Inc., 566 F.3d
1282, 1289 (Fed. Cir. 2009)). This court reviews the
application of prosecution disclaimer de novo. Ecolab,
Inc. v. FMC Corp., 569 F.3d 1335, 1342 (Fed. Cir. 2009).
                            III.
    The district court construed “inner lipophilic matrix”
to mean “a matrix including at least one lipophilic excipi-
ent, where the matrix is located within one or more sub-
stances.” Shire, 2013 WL 174843, at *5. Similarly, the
district court construed “outer hydrophilic matrix” as “a
matrix of at least one hydrophilic excipient, where the
matrix is located outside the inner lipophilic matrix.” Id.
These constructions do not reflect the ordinary and cus-
tomary meaning of the claim terms in light of the evi-
dence and are impermissibly broad.
                            A.
    When construing the disputed terms, the district
court relied on the specification to first construe “matrix”
to mean “a macroscopically homogeneous structure in all
its volume.” Id., at *4 (quoting ’720 patent col. 3 ll. 42–
45). That construction is correct. But the district court
erred by construing “‘lipophilic matrix’ [as] a matrix that
10    SHIRE DEVELOPMENT, LLC     v. WATSON PHARMACEUTICALS,
                                                       INC.


includes at least one lipophilic excipient.” Id. That
construction erroneously focuses on the lipophilic proper-
ties of an excipient in the matrix, rather than the proper-
ties of the matrix itself.
     A review of the intrinsic evidence as a whole reveals
that the district court’s construction of “inner lipophilic
matrix”—and thus, “outer hydrophilic matrix”—is overly
broad. Looking first to the language of the claims, “lipo-
philic” is an adjective that modifies matrix. The parties
stipulated that “lipophilic” means “poor affinity towards
aqueous fluids.” J.A. 216. Thus, the matrix—not just an
excipient within the matrix—must exhibit the stipulated-
to lipophilic characteristic.
    This conclusion is bolstered by the specification. The
Background of the Invention explains that a lipophilic
matrix is one “in which the main component of the matrix
structure” exhibits certain lipophilic properties. ’720
patent col. 1 ll. 17–20. And, the specification teaches that
a lipophilic matrix “generally entail[s] non-linear, but
esponential [sic] release of the active ingredient.” ’720
patent col. 1 ll. 32–33. Thus, a “lipophilic matrix” is more
than just a matrix with at least one lipophilic excipient—
the matrix itself must exhibit lipophilic characteristics.
The ’720 patent teaches that this occurs when “the main
component of the matrix structure” is lipophilic. ’720
patent col. 1 ll. 17–18.
                            B.
    In construing the matrix terms, the district court re-
jected Watson’s position that the inner matrix and outer
matrix must be “separate and distinct.” Shire, 2013 WL
174843, at *5. Watson based its arguments on alleged
disclaimers by the applicants during the prosecution. See
Appellants’ Br. 37–38. The district court acknowledged
that the applicants described their matrices as “separate”
to distinguish over the prior art references, but found that
“no where in the prosecution history, claims, or specifica-
SHIRE DEVELOPMENT, LLC   v. WATSON PHARMACEUTICALS,      11
INC.


tion does the term ‘separate and distinct’ appear.” Shire,
2013 WL 174843, at *5. Explaining that the prosecution
history is an ongoing negotiation and that there must be
clear and unambiguous disavowal, the district court could
not “say that the claim was clearly limited or disclaimed
during the prosecution.” Id.
    The district court correctly found no prosecution dis-
claimer because the statements in the prosecution history
were not “unambiguous disavowals.” Grober, 686 F.3d at
1341. During prosecution, Shire carefully characterized
the prior art as not having separate matrices but never
actually stated that the claimed invention does have
separate matrices. See, e.g., J.A. 15482 (“While the publi-
cations might teach the advantageous results of using a
lipophilic matrix, the publications fail to disclose or sug-
gest a composition comprising a combination of two
separate matrices.” (emphasis added)). Although the
prosecution history statements do not rise to the level of
unmistakable disavowal, they do inform the claim con-
struction.
     The prosecution history, the structure of the claim it-
self, the ordinary meaning of the claim terms, including
the Markush group limitations, and the patent’s descrip-
tion of the invention compel a claim construction which
requires that the inner lipophilic matrix is separate from
the outer hydrophilic matrix. Phillips, 415 F.3d at 1316
(“The construction that stays true to the claim language
and most naturally aligns with the patent’s description of
the invention will be, in the end, the correct construc-
tion.”).
    Looking to the claim structure itself, the claims re-
quire the inner lipophilic matrix to be separate, if not
distinct, from the outer hydrophilic matrix. Element (a)
of claim 1 recites “an inner lipophilic matrix.” Element
(b) of claim 1 separately recites “an outer hydrophobic
matrix.” The separation of these elements within the
12    SHIRE DEVELOPMENT, LLC   v. WATSON PHARMACEUTICALS,
                                                     INC.


claims indicates that the claim requires two separate
matrices.
    Shire even admits that the structure of the claim lan-
guage requires two separate matrices. Oral Argument at
17:23–17:50, Shire Dev., LLC v. Watson Pharms., Inc., No.
2013-1409 (Fed. Cir. Dec. 2, 2013), available at
http://oralarguments.cafc.uscourts.gov/default.aspx?fl=20
13-1409.mp3 (Q: “It sounds like then, even though you
opposed having the separate and distinct, that you agree
that there has to be two different matrices? A: Correct,
separate, yes. . . . They’re separate because by the claim,
itself, it says an inner and an outer, so we’re talking about
two different matrices. For sure, one is lipophilic, one is
hydrophilic. They’re separate. No question.”); Appellees’
Br. 34 (“[T]o the extent there is a ‘separation’ of matrices,
the claim language addresses that by defining two matri-
ces as opposed to one.”).
    Moreover, the logical reading of the claim requires
separation between the matrices because the matrices are
defined by mutually exclusive spatial characteristics—one
inner, one outer—and mutually exclusive compositional
characteristics—one hydrophilic, one lipophilic. Accord-
ing to the ordinary and customary meanings of these
characteristics, one matrix cannot be both inner and outer
in relation to a second matrix. Nor can one matrix be
both hydrophilic and lipophilic. Thus, considering matrix
is properly construed as “a macroscopically homogenous
structure in all its volume,” the construction of “inner
lipophilic matrix” requires the inner volume to be sepa-
rate from the outer volume. See Phillips, 415 F.3d at
1314 (“In some cases, the ordinary meaning of claim
language as understood by a person of skill in the art may
be readily apparent even to lay judges, and claim con-
struction in such cases involves little more than the
application of the widely accepted meaning of commonly
understood words.”).
SHIRE DEVELOPMENT, LLC   v. WATSON PHARMACEUTICALS,       13
INC.


    The compositions of the inner volume and outer vol-
ume, i.e., inner matrix and outer matrix, respectively, are
further limited by the Markush groups. During prosecu-
tion, the applicants added Markush groups to claim 1 to
overcome the examiner’s rejection of the claims as obvious
over Franco. J.A. 15491–92. For example, the inner
lipophilic matrix is limited by a Markush group “consist-
ing of unsaturated and/or hydrogenated fatty acid, salts,
esters or amides thereof, fatty acid mono-, di- or triglycer-
id[e]s, waxes, ceramides, and cholesterol derivatives with
melting points below 90° C.” ’720 patent col. 6 ll. 11–14.
The outer hydrophilic matrix is similarly limited by a
Markush group consisting of hydrophilic components. See
’720 patent col. 6 ll. 20–25. The lack of overlap of the
components of the two Markush groups supports the
requirement that the volumes be separate. Accordingly,
the correct construction requires that the inner volume
contain substances from the group described for the inner
lipophilic matrix (which are all lipophilic substances), and
that the outer volume separately contain substances from
the group described for the outer hydrophilic matrix
(which are all hydrophilic).
    The ’720 patent specification also teaches “separate”
matrices. The specification describes five examples of
forming discrete lipophilic matrix granules and compress-
ing those granules together with the hydrophilic matrix.
See, e.g., ’720 patent col. 3 ll. 31–45. The specification
explains that a lipophilic matrix “opposes some resistance
to the penetration of the solvent due to the poor affinity
towards aqueous fluids.” ’720 patent col. 1 ll. 17–20. And
under the stipulated meaning of “lipophilic,” the lipophilic
matrix must have a “poor affinity towards aqueous flu-
ids.” J.A. 216. Thus, the matrix that is deemed the
“lipophilic” matrix cannot have hydrophilic properties.
But, a matrix comprised of only one lipophilic substance
and several hydrophilic substances—and thus capable of
exhibiting hydrophilic properties—would meet the district
14    SHIRE DEVELOPMENT, LLC   v. WATSON PHARMACEUTICALS,
                                                     INC.


court’s construction of “lipophilic matrix.” Such a result
contradicts the customary and ordinary meaning of “lipo-
philic” and “hydrophilic.”
     Furthermore, under the district court’s construction, a
single mixed matrix with both hydrophilic and lipophilic
components—such as the one disclosed in the Sanghvi
reference, which the applicants described as “mixing
together hydrophilic and lipophilic substances into a
single matrix”—could contain both an “inner lipophilic
matrix” and an “outer hydrophilic matrix.” J.A. 15481.
Indeed, any arbitrarily selected volume in a single mixed
matrix would satisfy the district court’s construction of
“inner lipophilic matrix” because that volume would
necessarily contain “at least one lipophilic excipient” and
it would be “inside” the surrounding volume. Similarly,
under the district court’s construction, that same arbitrar-
ily selected volume would constitute an “outer hydrophilic
matrix” because it would contain “at least one hydrophilic
excipient” and would be “outside” the inner lipophilic
matrix. The claims, however, require two matrices with a
defined spatial relationship.
    Shire argues that the intrinsic evidence does not de-
scribe any particular degree of separation and thus, such
a construction would create ambiguity. Shire’s argument
misses the point. A court must identify “[t]he construc-
tion that stays true to the claim language and most
naturally aligns with the patent’s description of the
invention.” Phillips, 415 F.3d at 1316. Whether or not a
composition infringes when there is a trace of hydrophilic
molecules in the inner volume because of the mixing step
inherent in the manufacturing process, for example, is a
question for the fact finder. That this question may need
to be resolved does not compel a claim construction that
departs from the customary and ordinary meaning of the
claims, i.e., that the matrices must be “separate” such
that they retain their claimed properties and are con-
sistent with their respective Markush group limitations.
SHIRE DEVELOPMENT, LLC   v. WATSON PHARMACEUTICALS,    15
INC.


                            IV.
    Accordingly, we reverse the district court’s construc-
tions of “inner lipophilic matrix” and “outer hydrophilic
matrix,” and subsequent infringement determination, and
remand for proceedings consistent with this opinion.
            REVERSED AND REMANDED
