Case: 20-1933 Document: 89 Page: 1 Filed: 03/16/2022
United States Court of Appeals
for the Federal Circuit
______________________
BIOGEN INTERNATIONAL GMBH, BIOGEN MA,
INC.,
Plaintiffs-Appellants
v.
MYLAN PHARMACEUTICALS INC.,
Defendant-Appellee
______________________
2020-1933
______________________
Appeal from the United States District Court for the
Northern District of West Virginia in No. 1:17-cv-00116-
IMK-JPM, Judge Irene M. Keeley.
______________________
ON PETITION FOR PANEL REHEARING AND
REHEARING EN BANC
______________________
WILLIAM F. LEE, Wilmer Cutler Pickering Hale and
Dorr LLP, Boston, MA, filed a petition for panel rehearing
and rehearing en banc for plaintiffs-appellants. Also
repre-sented by ANNALEIGH E. CURTIS, MADELEINE C.
LAUPHEIMER, LISA JON PIROZZOLO; SCOTT G. GREENE, New
York, NY; THOMAS SAUNDERS, Washington, DC; PAUL
WILLIAM BROWNING, J. MICHAEL JAKES, JAMES B. MONROE,
JASON LEE ROMRELL, Finnegan, Henderson, Farabow, Gar-
rett & Dunner, LLP, Washington, DC.
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2 BIOGEN INTERNATIONAL GMBH v.
MYLAN PHARMACEUTICALS INC.
NATHAN K. KELLEY, Perkins Coie LLP, Washington,
DC, filed a response to the petition for defendant-appellee.
Also represented by SHANNON BLOODWORTH, BRANDON
MICHAEL WHITE; DAVID LEE ANSTAETT, ANDREW
DUFRESNE, EMILY JANE GREB, Madison, WI; DAN L.
BAGATELL, Hanover, NH; MATTHEW GREINERT, Viatris Inc.,
Canonsburg, PA.
HA KUNG WONG, Venable LLP, New York, NY, for ami-
cus curiae Biotechnology Innovation Organization. Also
represented by KATHERINE ADAMS.
JAMES C. CARVER, The Carver Law Firm, Baton Rouge,
LA, for amicus curiae Chemistry and The Law Division of
the American Chemical Society.
JEFFREY PAUL KUSHAN, Sidley Austin LLP, Washing-
ton, DC, for amicus curiae Pharmaceutical Research and
Manufacturers of America. Also represented by MARY T.
HANNON, STEVEN J. HOROWITZ, Chicago, IL; DAVID EVAN
KORN, Pharmaceutical Research and Manufacturers of
America, Washington, DC.
______________________
Before MOORE, Chief Judge, NEWMAN, LOURIE, DYK,
PROST, O’MALLEY, 1 REYNA, TARANTO, CHEN, and HUGHES,
Circuit Judges. *
LOURIE, Circuit Judge, with whom MOORE, Chief Judge,
and NEWMAN, Circuit Judge, join, dissents from the de-
nial of the petition for rehearing en banc.
1 Circuit Judge O’Malley retired on March 11, 2022,
and participated only in the decision on the petition for
panel rehearing.
* Circuit Judge Stoll and Circuit Judge Cunningham
did not participate.
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BIOGEN INTERNATIONAL GMBH v. 3
MYLAN PHARMACEUTICALS. INC.
PER CURIAM.
ORDER
Biogen International BmbH and Biogen MA, Inc. filed
a combined petition for panel rehearing and rehearing en
banc. A response to the petition was invited by the court
and filed by Mylan Pharmaceuticals Inc. The court also ac-
cepted amicus briefs filed by Biotechnology Innovation Or-
ganization, Chemistry and The Law Division of the
American Chemical Society, and Pharmaceutical Research
and Manufacturers of America. The petition was referred
to the panel that heard the appeal, and thereafter the peti-
tion was referred to the circuit judges who are in regular
active service. The court conducted a poll on request, and
the poll failed.
Upon consideration thereof,
IT IS ORDERED THAT:
The petition for panel rehearing is denied.
The petition for rehearing en banc is denied.
The mandate of the court will issue on March 23, 2022.
FOR THE COURT
March 16, 2022 /s/ Peter R. Marksteiner
Date Peter R. Marksteiner
Clerk of Court
Case: 20-1933 Document: 89 Page: 4 Filed: 03/16/2022
United States Court of Appeals
for the Federal Circuit
______________________
BIOGEN INTERNATIONAL GMBH, BIOGEN MA,
INC.,
Plaintiffs-Appellants
v.
MYLAN PHARMACEUTICALS INC.,
Defendant-Appellee
______________________
2020-1933
______________________
Appeal from the United States District Court for the
Northern District of West Virginia in No. 1:17-cv-00116-
IMK-JPM, Judge Irene M. Keeley.
______________________
LOURIE, Circuit Judge, with whom MOORE, Chief Judge,
and NEWMAN, Circuit Judge, join, dissenting from the de-
nial of the petition for rehearing en banc.
On March 2, 2010, this court sitting en banc in Ariad
Pharms., Inc. v. Eli Lilly & Co., reaffirmed the proposition
that “written description” is a requirement that exists in
the patent statute separate and apart from any other re-
quirements for patentability. 598 F.3d 1336, 1351 (Fed.
Cir. 2010). We stated very clearly that “the hallmark of
written description is disclosure.” Id. The test for written
description “requires an objective inquiry into the four cor-
ners of the specification from the perspective of a person of
ordinary skill in the art.” Id. “Based on that inquiry”—
and not based on other considerations—“the specification
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2 BIOGEN INTERNATIONAL GMBH
v. MYLAN PHARMACEUTICALS INC.
must describe an invention understandable to that skilled
artisan and show that the inventor actually invented the
invention claimed.” Id.
We have found lack of written description in a variety
of contexts and circumstances. For example, we found a
lack of written description when a patent specification de-
scribed only rat insulin-encoding cDNA but the claimed mi-
croorganism encompassed human insulin-encoding CDNA.
See Regents of Univ. of Cal. v. Eli Lilly & Co., 119 F.3d
1559, 1568 (Fed. Cir. 1997). We found a lack of written
description when a patent specification identified only one
possible location for controls on a reclining sofa but the
claim recited the controls in a different location. See Gen-
try Gallery, Inc. v. Berkline Corp., 134 F.3d 1473, 1479–80
(Fed. Cir. 1998). In another case, we found a lack of written
description when claims were directed to a method com-
prising administering a compound to achieve a particular
result but the specification failed to disclose any com-
pounds that could be used in the claimed method. See
Univ. of Rochester v. G.D. Searle & Co., 358 F.3d 916, 927
(Fed. Cir. 2004). We also found a lack of written descrip-
tion when a specification disclosed small numbers of spe-
cies of antibodies that did not reasonably represent the
breadth of antibodies encompassed by the claimed genus.
See Abbvie Deutschland GmbH & Co. v. Janssen Biotech,
Inc., 759 F.3d 1285, 1300–01 (Fed. Cir. 2014).
These decisions, and many more like them, are sup-
ported by case law dating back to before this court existed.
See, e.g., In re Ruschig, 379 F.2d 990, 995 (C.C.P.A. 1967)
(finding that the claimed compound was not described in
the specification). Indeed, these decisions are supported by
Supreme Court precedent dating back almost two centuries
when the Court found that Samuel Morse’s eighth patent
claim was invalid because “he claims an exclusive right to
use a manner and process which he has not described and
indeed had not invented, and therefore could not describe
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MYLAN PHARMACEUTICALS INC.
when he obtained his patent.” See O’Reilly v. Morse, 56
U.S. 62, 113 (1853).
But in all that history, this case, in which every claim
limitation is expressly described in the disclosure of the pa-
tent specification, is at the farthest end of the spectrum of
cases where written description has not been found. It is
an outlier.
Today, by denying rehearing en banc, the judges of this
court have let a panel majority opinion stand that imports
extraneous considerations into the written description
analysis and blurs the boundaries between the written de-
scription requirement and the other statutory require-
ments for patentability. In doing so, the court has
contributed to the muddying of the written description re-
quirement. Accordingly, I respectfully dissent from that
denial.
I
Biogen International GmbH (“Biogen”) owns U.S. Pa-
tent 8,399,514 (“the ’514 patent”). Mylan Pharmaceuticals
Inc. (“Mylan”) contended that the claims of the ’514 patent
are invalid for lack of written description support in the
specification. In asserting that challenge, Mylan bore the
burden of proving by clear and convincing evidence that the
disclosure of the ’514 patent specification failed to demon-
strate to a person of ordinary skill in the art that the in-
ventors invented what is claimed. The district court found
that Mylan met its burden. Biogen Int’l GmbH v. Mylan
Pharms. Inc., No. 1:17-cv-116, 2020 WL 3317105 (N.D. W.
Va. June 18, 2020) (“District Court Decision”). The panel
majority affirmed. See Biogen Int’l GMBH v. Mylan
Pharms. Inc., 18 F.4th 1333 (Fed. Cir. 2021) (“Panel Maj.
Op.”). I begin by explaining why it should have reversed
and why this court should have granted the petition for re-
hearing en banc.
Claim 1 of the ’514 patent recites:
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4 BIOGEN INTERNATIONAL GMBH
v. MYLAN PHARMACEUTICALS INC.
A method of treating a subject in need of treatment
for multiple sclerosis comprising orally administer-
ing to the subject in need thereof a pharmaceutical
composition consisting essentially of (a) a thera-
peutically effective amount of dimethyl fumarate,
monomethyl fumarate, 1 or a combination thereof,
and (b) one or more pharmaceutically acceptable
excipients, wherein the therapeutically effective
amount of dimethyl fumarate, monomethyl
fumarate, or a combination thereof is about 480 mg
per day.
’514 patent at col. 27 ll. 59–67.
In evaluating whether the written description require-
ment has been met with respect to claim 1, we must look to
what is disclosed in the patent specification. See, e.g., D
Three Enters., LLC v. SunModo Corp., 890 F.3d 1042, 1052
(Fed. Cir. 2018) (“[A]dequate written description . . . asks
what is disclosed.”); Ariad, 598 F.3d at 1351 (“[T]he hall-
mark of written description is disclosure.”). The ’514 pa-
tent sets forth a number of embodiments, including five
methods. Most relevant here, “method 4” includes “meth-
ods of treating a neurological disease.” ’514 patent at col. 8
ll. 35–36. And, pointedly, the title of the patent is “Treat-
ment for Multiple Sclerosis.”
Accordingly, the specification explicitly states that the
neurological disease in method 4 “can [] be multiple sclero-
sis (MS).” See id. at col. 16 ll. 18–22. This disclosure is
consistent with the background section of the patent, which
begins with a specific discussion of multiple sclerosis. The
first sentence of the disclosure states:
1 Dimethyl fumarate and monomethyl fumarate are
often abbreviated as “DMF” and “MMF.”
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Provided are certain compounds for treating neu-
rological diseases, including demyelinating neuro-
logical diseases, such as, e.g., multiple sclerosis.
Id. at col. 1 ll. 12–14. The specification then proceeds to
describe the pathology, symptoms, and available treat-
ments for multiple sclerosis. Id. at col. 1 ll. 15–52. Viewed
from any perspective, including that of a person of ordinary
skill in the art, the ’514 patent describes the invention of a
method for treating multiple sclerosis.
Included within method 4 of the specification are meth-
ods that comprise “administering to the subject in need
thereof at least one compound that is [] structurally similar
to DMF and/or MMF.” Id. at col. 8 ll. 36–38. The patent
notes that the methods comprise administering “a thera-
peutically effective amount of at least one neuroprotective
compound which has Formula I, II, III, or IV, e.g., a fu-
maric acid derivative (e.g., DMF or MMF).” Id. at col. 8
ll. 42–44. And the specification provides details about
what constitutes an effective amount of DMF or MMF, not-
ing that effective doses may vary depending on a number
of factors, and providing examples of effective doses:
For example, an effective dose of DMF or MM[F] to
be administered to a subject orally can be from
about 0.1 g to 1 g per day, 200 mg to about 800 mg
per day (e.g., from about 240 mg to about 720 mg
per day; or from about 480 mg to about 720 mg
per day; or about 720 mg per day).
Id. at col. 18 ll. 58–62 (emphasis added).
To summarize, claim 1 is directed to a method of treat-
ing a particular disease (multiple sclerosis) by administer-
ing particular compounds (DMF or MMF) at a particular
dose (480 mg per day). And that is precisely what the spec-
ification discloses—treatment of multiple sclerosis with a
480 mg per day dose of DMF or MMF. Thus, the specifica-
tion provides sufficient written description under 35 U.S.C.
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6 BIOGEN INTERNATIONAL GMBH
v. MYLAN PHARMACEUTICALS INC.
§ 112. Whatever shortcomings exist in this unfocused pa-
tent specification, failure of written description with re-
spect to claim 1 is not one of them.
II
Both the panel majority and the district court began
their analyses by correctly recognizing that “it is the spec-
ification itself that must demonstrate possession” of the
claimed invention. See Panel Maj. Op., 18 F.4th at 1342
(quoting the district court). Yet, despite the clear written
description support in the specification itself, neither the
panel majority nor the district court resolved the written
description inquiry in favor of the patentee, Biogen. It is
thus important to explain what I believe are the errors
made by the panel majority and the district court.
As a general matter, the panel majority and the district
court erred by analyzing factual and legal considerations
that are not properly contained within the written descrip-
tion analysis. More specifically, I identify four individual
points of error that the en banc court should have cor-
rected. First, the panel majority and the district court
overly emphasized unclaimed disclosures in the specifica-
tion. Second, they erroneously imposed a heightened bur-
den on the patentee to show that the specification proves
efficacy. Third, they imported legal factors from other pa-
tentability requirements. And fourth, they were influenced
by irrelevant extrinsic evidence. I will address each of
these points of error in turn.
A
The first point of error is the undue emphasis that the
panel majority and the district court placed on unclaimed
disclosures in the specification. Although they acknowl-
edged that the subject matter of the claims—treatment of
multiple sclerosis with 480 mg per day of DMF or MMF—
was, in fact, disclosed in the patent specification, the panel
majority and the district court engaged in irrelevant
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MYLAN PHARMACEUTICALS INC.
comparisons between the amount of disclosure of the
claimed subject matter versus the unclaimed subject mat-
ter.
For example, while conceding that “MS may arguably
constitute an important element of the disclosure from the
start,” the panel majority focused on the fact that the spec-
ification “covers a broad array of nearly three dozen neuro-
logical disorders.” Panel Maj. Op., 18 F.4th at 1342; see
also District Court Decision, 2020 WL 3317105, at *10 (“MS
is merely one such disease ‘among a slew of competing pos-
sibilities.’”). As another example, the panel majority em-
phasized that the 480 mg per day dose “is listed only once
in the entire specification,” finding this to be “a significant
fact that cuts against Biogen’s case.” Panel Maj. Op. 18
F.4th at 1343; see also District Court Decision, 2020 WL
3317105, at *10 (noting that column 18 is “the only part of
the specification that mentions 480 mg/day of DMF”). The
panel majority contrasted this one express disclosure of
480 mg per day with the “series of ranges” disclosed in the
specification, noting that the 480 mg dose “appears at the
end of one range.” Panel Maj. Op. 18 F.4th at 1343.
As Judge O’Malley’s panel dissent noted, the district
court justified its focus on unclaimed subject matter by
looking to our precedent requiring that a specification con-
tain “blaze marks” that point a person of ordinary skill to
the claimed species of a disclosed genus. See 18 F.4th at
1350–51 (O’Malley, J., dissenting). Blaze mark analysis
originated in In re Ruschig, where, unlike here, the speci-
fication failed to disclose a claimed species within a dis-
closed genus. See 379 F.2d 990, 994–95 (C.C.P.A. 1967).
Although Biogen argued that the district court misapplied
that blaze mark precedent, the panel majority dismissed
that concern as “superfluous.” Panel Maj. Op., 18 F.4th at
1345.
This court has developed a body of precedent to govern
the genus/species relationship in the context of the written
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8 BIOGEN INTERNATIONAL GMBH
v. MYLAN PHARMACEUTICALS INC.
description requirement of 35 U.S.C. § 112. In cases in-
volving claims to a genus, “a sufficient description of a ge-
nus [] requires the disclosure of either a representative
number of species falling within the scope of the genus or
structural features common to members of the genus so
that one of skill in the art can ‘visualize or recognize’ the
members of the genus.” Ariad, 598 F.3d at 1350 (quoting
Regents of the Univ. of Cal. v. Eli Lilly & Co., 119 F.3d
1559, 1568–69 (Fed. Cir. 1997)). On the other hand, “[i]n
cases where the specification describes a broad genus and
the claims are directed to a single species or a narrow sub-
genus, we have held that the specification must contain
‘“blaze marks” that would lead an ordinarily skilled inves-
tigator toward such a species among a slew of competing
possibilities.’” Novartis Pharms. Corp. v. Accord
Healthcare, Inc., 21 F.4th 1362, 1370 (Fed. Cir. 2022) (quot-
ing Novozymes A/S v. DuPont Nutrition Biosciences APS,
723 F.3d 1336, 1349 (Fed. Cir. 2013)).
As we recently clarified in Novartis, however, “‘[b]laze
marks’ are not necessary where the claimed species is ex-
pressly described in the specification.” Id. Such is the case
here. The ’514 patent does not merely disclose the genus
“neurological diseases” without reference to the claimed
species “multiple sclerosis.” Rather, the patent expressly
states that the neurological disease in method 4 can be
“multiple sclerosis.” ’514 patent at col. 16 ll. 18–21; see also
id. at col. 16 l. 44 (listing additional neurological diseases
“in addition to MS”). Similarly, with respect to doses, the
patent explicitly includes “480 mg per day” as an end point
of a limited number of dose ranges. Id. at col. 18 ll. 52–64.
In this case, where the claimed species—i.e., “multiple
sclerosis” within the genus “neurological diseases”—is ex-
pressly described in the specification, the written descrip-
tion requirement is satisfied regardless of the
specification’s additional disclosure of other unclaimed
neurological diseases. See Scriptpro, LLC v. Innovation As-
socs., Inc., 762 F.3d 1355, 1359 (Fed. Cir. 2014) (“It is
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common, and often permissible, for particular claims to
pick out a subset of the full range of described features,
omitting others.”). Moreover, written description support
for the claimed 480 mg per day dose is not undermined by
the fact that it only appears one time in the specification or
by the fact that the patent also discloses unclaimed dose
ranges. See Vanda Pharms. Inc. v. W.-Ward Pharms. Int’l
Ltd., 887 F.3d 1117, 1137 (Fed. Cir. 2018) (“The disclosure
of a dose outside of the claimed range does not compel a
finding that the asserted claims lack adequate written de-
scription.”). Once is enough.
The panel majority opinion implies that a patent fails
the written description requirement of 35 U.S.C. § 112
when it contains too much disclosure beyond the claimed
invention, which is incorrect. The opinion implies that a
patentee must disclose the claimed subject matter more
than once, which is also incorrect. And the opinion implies
that a court may arbitrarily count the number of times the
claimed subject matter is disclosed in the specification rel-
ative to the number of times unclaimed subject matter is
disclosed, which is incorrect. The en banc court should
have intervened to correct these incorrect propositions.
B
The second point of error is the panel majority’s erro-
neous imposition of a burden of proof on the patentee to
show that the specification proves the efficacy of the
claimed pharmaceutical composition. Under our prece-
dent, “it is unnecessary to prove that a claimed pharma-
ceutical compound actually achieves a certain result.”
Nuvo Pharms. (Ir.) Designated Activity Co. v. Dr. Reddy’s
Lab’ys Inc., 923 F.3d 1368, 1384 (Fed. Cir. 2019). That is
the province of the United States Food and Drug Admin-
istration. See In re Brana, 51 F.3d 1560, 1567 (Fed. Cir.
1995) (delineating between “the requirements under the
law for obtaining a patent with the requirements for ob-
taining government approval to market a particular drug
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10 BIOGEN INTERNATIONAL GMBH
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for human consumption”); see also Scott v. Finney, 34 F.3d
1058, 1063 (Fed. Cir. 1994) (“Testing for the full safety and
effectiveness of a prosthetic device is more properly left to
the Food and Drug Administration (FDA). Title 35 does
not demand that such human testing occur within the con-
fines of Patent and Trademark Office (PTO) proceedings.”).
Yet the panel majority affirmed the district court’s decision
that the patent fails the written description requirement
because “nothing in [the specification] teaches a [person of
ordinary skill in the art] that a 480 mg/day dose of DMF []
is therapeutically effective for treating MS.” District Court
Decision, 2020 WL 3317105, at *11; see also Panel Maj. Op.,
18 F.4th at 1343–44 (“What matters for purposes of the in-
quiry in this case is whether, at the time of filing the dis-
closure, . . . a skilled artisan could deduce simply from
reading the specification that DMF480 would be a thera-
peutically effective treatment for MS.”).
The claims specify precisely the amount that they
claim would be “therapeutically effective,” namely, “480 mg
per day.” ’514 patent col. 27 ll. 65–67. And the patent spec-
ification leaves nothing for the skilled artisan to deduce; it
expressly states that 480 mg per day is an effective
amount.
C
The third point of error is the panel majority’s impor-
tation of extraneous legal considerations into the written
description analysis. In Ariad, we stated that the first par-
agraph of 35 U.S.C. § 112 “contains two separate descrip-
tion requirements: a ‘written description [i] of the
invention, and [ii] of the manner and process of making and
using [the invention].” Ariad, 598 F.3d at 1344 (quoting 35
U.S.C. § 112, emphasis and brackets original). The panel
majority’s focus on the efficacy of the claimed pharmaceu-
tical composition runs afoul of that precedent.
Questions about the operability of a claimed inven-
tion—i.e., whether or not the claimed invention actually
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works—can be relevant to patentability. “But written de-
scription is about whether the skilled reader of the patent
disclosure can recognize that what was claimed corre-
sponds to what was described; it is not about whether the
patentee has proven to the skilled reader that the inven-
tion works, or how to make it work, which is an enablement
issue.” Alcon Rsch. Ltd. v. Barr Lab’ys, Inc., 745 F.3d 1180,
1191 (Fed. Cir. 2014); see also Miles Lab’ys, Inc. v. Shandon
Inc., 997 F.2d 870, 875 (Fed. Cir. 1993) (noting that opera-
bility is relevant “to the enablement requirement of § 112”).
The enablement requirement has its own legal test and its
own substantial body of precedent separate and apart from
the written description requirement. See, e.g., In re Wands,
858 F.2d 731 (Fed. Cir. 1988). 2 By focusing on whether the
patentee proved that 480 mg per day is an effective
amount to treat multiple sclerosis—as distinct from
whether the ’514 patent specification discloses that 480
mg per day is an effective amount to treat multiple sclero-
sis—the panel majority and the district court erroneously
imported operability considerations into the written de-
scription analysis.
In addition to blurring the lines between written de-
scription and enablement, the panel majority and the dis-
trict court also considered factors relevant to the
inventorship of the ’514 patent. For example, the district
court went into detail about the inventors’ “respective
roles” in developing the patented technology. District
Court Decision, 2020 WL 3317105, at *12. Similarly, the
panel majority focused on what could be extrapolated from
2 Operability is also relevant for the utility require-
ment of 35 U.S.C. § 101. See, e.g., Newman v. Quigg, 877
F.2d 1575, 1581 (Fed. Cir. 1989) (holding that under the
utility requirement of 35 U.S.C. § 101, a claimed invention
must “operate to produce what [the patentee] claims it
does”).
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12 BIOGEN INTERNATIONAL GMBH
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each inventor’s research as of the time the patent applica-
tion was filed. See Panel Maj. Op., 18 F.4th at 1339–40
(citing testimony from inventor Lukashev about whether
clinical doses of DMF was the focus of his work); id. at 1344
(discussing when inventor O’Neill may have conceived the
idea for the invention). But again, the specification itself
discloses that 480 mg per day of DMF is an effective dose
in a method for treating multiple sclerosis. To the extent
Mylan argued, or could have argued, that there was an in-
ventorship problem with the ’514 patent, that is a separate
issue from written description under 35 U.S.C. § 112.
The district court also imported aspects of a “best
mode” requirement into the written description analysis.
The district court stated that “on reading the specification,
a POSA would be drawn to, if anything, the 720mg/day
dose of DMF included in each dosing example.” District
Court Decision, 2020 WL 3317105, at *11 (emphasis
added). The court then relied on testimony that a person
of ordinary skill reading the specification “would not know
which dose provided in Column 18 would be most effective
for treating MS.” Id. (emphasis added). But there is no
requirement that the written description be sufficient to
“draw” a person of ordinary skill toward the claimed em-
bodiment and away from unclaimed embodiments. And
there is certainly no requirement that patent claims be lim-
ited to only the “most effective” embodiment disclosed in
the specification. See ScriptPro LLC v. Innovation Assocs.,
Inc., 833 F.3d 1336, 1341 (Fed. Cir. 2016) (“[A] specifica-
tion’s focus on one particular embodiment or purpose can-
not limit the described invention where that specification
expressly contemplates other embodiments or purposes.”).
By incorporating extraneous legal standards into the
analysis, the panel majority opinion creates confusion for
future patent applicants and litigants regarding what is re-
quired to meet the written description requirement of 35
U.S.C. § 112. The en banc court should have corrected the
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panel majority’s errors and restored the proper and estab-
lished boundaries of the written description inquiry.
D
The fourth point of error is the consideration of extrin-
sic evidence. The test for written description “requires an
objective inquiry into the four corners of the specification.”
Ariad, 598 F.3d at 1351. Yet, the panel majority affirmed
a district court decision that is replete with reasoning that
extends far beyond the confines of the disclosure contained
in the patent specification.
To be fair, because the written description inquiry is
conducted from the perspective of a person of ordinary skill
in the art, extrinsic evidence regarding how a person of or-
dinary skill would understand what is disclosed in the pa-
tent specification can, at times, be relevant. See, e.g.,
Forest Lab’ys, LLC v. Sigmapharm Lab’ys, LLC, 918 F.3d
928, 937–38 (Fed. Cir. 2019) (affirming sufficient written
description based on expert testimony about how a specifi-
cation’s disclosure would have been understood in view of
what was known in the art); Space Sys./Loral, Inc. v. Lock-
heed Martin Corp., 405 F.3d 985, 988–90 (Fed. Cir. 2005)
(considering expert testimony regarding how the disclosure
of the patent specification would have been interpreted by
a skilled artisan). But, importantly, such extrinsic evi-
dence should be used only as part of an objective inquiry
into what is meant by the disclosure in the patent specifi-
cation. Where the disclosure in a patent’s specification
plainly corresponds to what is claimed, extrinsic evidence
should not be used to cast doubt on the meaning of what is
disclosed.
Meaning is not in question in this case. The ’514 patent
contains a disclosure that corresponds to what is claimed—
treatment of multiple sclerosis with 480 mg per day of
DMF. In my view, the extrinsic evidence does not render
that disclosure inadequate to support what is claimed.
Case: 20-1933 Document: 89 Page: 17 Filed: 03/16/2022
14 BIOGEN INTERNATIONAL GMBH
v. MYLAN PHARMACEUTICALS INC.
The district court, however, went far beyond limiting
its use of extrinsic evidence to interpreting what is dis-
closed in the patent. Under the guise of considering what
a person of ordinary skill in the art would have known as
of the claimed priority date, the district court placed con-
siderable weight on whether Biogen’s clinical trials before
the filing date would have been sufficient to show the effi-
cacy of particular doses of DMF to treat multiple sclerosis.
See District Court Decision, 2020 WL 3317105, at *11
(“Based on the results of Biogen’s Phase II study, . . . a
POSA would have known that 720mg/day of DMF [] is a
therapeutically effective dose for treating MS, and that
lower doses, such as 360mg/day of DMF [] and 120mg/day
of DMF [], are not.”). The court also considered the disclo-
sures contained in later-filed Biogen patent applications
and compared them to the disclosures of the ’514 patent.
Id. at *13–14. The court went so far as to posit explana-
tions for why the disclosures differed between the patent
applications, including speculating about Biogen’s motiva-
tions for its patent prosecution decisions based on the tim-
ing of Biogen’s clinical trials and possible desires to avoid
prior art. Id. at *14. And the court concluded its decision
by considering the arguments Biogen made in a Patent
Trial and Appeal Board proceeding while defending
against Mylan’s inter partes review petitions. Id. at *15.
Simply put, none of that is relevant to the question
whether the ’514 patent specification contains sufficient
written description to support what is claimed. The en
banc court should have granted the petition for review to
make that clear.
CONCLUSION
I recognize the hesitance to go en banc simply to correct
errors in one case. But this case involves more than that.
Here, the panel majority has affirmed a district court’s er-
roneous broadening of the written description inquiry. In
denying rehearing en banc, the court has lost an
Case: 20-1933 Document: 89 Page: 18 Filed: 03/16/2022
BIOGEN INTERNATIONAL GMBH v. 15
MYLAN PHARMACEUTICALS INC.
opportunity to provide clarity for future litigants by reaf-
firming the proper boundaries of the written description re-
quirement in 35 U.S.C. § 112.
I therefore dissent from the court’s decision not to re-
hear this case en banc.