 United States Court of Appeals
     for the Federal Circuit
         __________________________

  IN RE ROSUVASTATIN CALCIUM PATENT
                LITIGATION
          __________________________

      ASTRAZENECA UK LIMITED, IPR
         PHARMACEUTICALS INC.,
AND SHIONOGI SEIYAKU KABUSHIKI KAISHA,
            Plaintiffs-Appellees,

                     v.
      AUROBINDO PHARMA LIMITED,
           Defendant-Appellant,

                    AND

     MYLAN PHARMACEUTICALS INC.,
           Defendant-Appellant,

                    AND

             APOTEX CORP.,
            Defendant-Appellant,

                    AND

COBALT PHARMACEUTICALS INC. AND COBALT
          LABORATORIES INC.,
           Defendants-Appellants,

                    AND

 SUN PHARMACEUTICAL INDUSTRIES, LTD.,
          Defendant-Appellant,
ASTRAZENECA   v. AUROBINDO                                2


                             AND

      TEVA PHARMACEUTICALS USA, INC.,
             Defendant-Appellant,

                             AND

           PAR PHARMACEUTICAL, INC.,
                Defendant-Appellant,

                             AND

                     SANDOZ, INC.,
                       Defendant.
               __________________________

 2010-1460,-1461,-1462,-1463,-1464,-1465,-1466,-1467, -
          1468,-1469,-1470,-1471,-1472,-1473
              __________________________

    Appeal from the United States District Court for the
District of Delaware in case nos. 08-MD-1949, 07-CV-0810,
07-CV-0805, 07-CV-0809, 07-CV-0811, 07-CV-0806, 08-CV-
0426, and 07-CV-0808, Judge Joseph J. Farnan, Jr.
                ___________________________

               Decided: December 14, 2012
               ___________________________

    CHARLES E. LIPSEY, Finnegan, Henderson, Farabow,
Garrett & Dunner, LLP, of Reston, Virginia, argued for
plaintiff-appellee. With him on the brief were KENNETH M.
FRANKEL, and YORK M. FAULKNER. Of counsel on the brief
were FORD F. FARABOW, JR., and HOWARD W. LEVINE, of
Washington, DC, MARY K. FERGUSON, of Cambridge, Massa-
chuettes, JOHN D. LIVINGSTONE, of Atlanta, Georgia, MARY
W. BOURKE, Connolly Bove Lodge & Hutz, LLP, of Wilming-
3                                 ASTRAZENECA   v. AUROBINDO


ton, Delaware, HENRY J. RENK, Fitzpatrick, Cella, Harper &
Scinto, of New York, New York, THOMAS STEVENS and JUDY
YUN, AstraZeneca Pharmaceuticals, LP, of Wilmington,
Delaware.

    ROBERT B. BREISBLATT, Katten Muchin Rosenman, LLP,
of Chicago, Illinois, argued for defendant-appellant. With
him on the brief were JEREMY C. DANIEL and CHARLES B.
PARADIS.

    JEFFREY S. WARD, Merchant & Gould, P.C., of Madison,
Wisconsin, argued for defendant-appellant. With him on
the brief were THOMAS P. HENEGHAN, EDWARD J. PARDON,
and SHANE A. BRUNNER.

    STEVEN A. MADDOX, Knobbe, Martens, Olson & Bear,
LLP, of Washington, DC, argued for defendant-appellant.
With him on the brief were PAYSON LEMEILLEUR and JARED
BUNKER, Knobbe, Martens, Olson & Bear, LLP, of Irvine,
California.
              __________________________

    Before NEWMAN, MAYER, and PLAGER, Circuit Judges.
     Opinion of the court filed by Circuit Judge NEWMAN.
    Concurring opinion filed by Circuit Judge PLAGER. Dis-
        senting opinion filed by Circuit Judge MAYER.

NEWMAN, Circuit Judge.

    This patent litigation arises under the Hatch-Waxman
Act, 21 U.S.C. §355, whereby producers of generic pharma-
ceutical products are authorized to challenge the patent
status of a federally registered and approved drug product,
before the generic producer has obtained approval to sell its
counterpart of the approved product. The generic litigant
who succeeds in eliminating the drug patent is granted a
ASTRAZENECA   v. AUROBINDO                                  4


180-day period of exclusivity against other potential provid-
ers of the generic product. 21 U.S.C. §355(j)(5)(B)(iv).

    The drug product here at issue is the “statin” having the
brand name Crestor®, which is federally approved for use in
control of cholesterol and for treatment of atherosclerosis.
In suit is United States Reissue Patent No. 37,314 (“the ’314
patent”), which is a reissue of United States Patent No.
5,260,440 (“the ’440 patent”). The patentee is Shionogi
Seiyaku Kabushiki Kaisha (“Shionogi”) and the exclusive
licensee is Astrazeneca UK and its United States subsidiary
IPR Pharmaceuticals Inc. (collectively “Plaintiffs”).

    The active ingredient of Crestor® is the calcium salt of a
chemical compound whose common name is rosuvastatin, of
the following structural formula:




                        rosuvastatin

Rosuvastatin is one of several statin products that lower
cholesterol production in the liver by inhibiting the enzyme
HMG-CoA reductase. Scientists working at the Shionogi
laboratory in Japan were conducting research in search of a
statin with reduced side effects as compared with the statin
5                                  ASTRAZENECA    v. AUROBINDO


products that were then known. In the course of this re-
search, in 1991 they discovered rosuvastatin and its benefi-
cial properties. Patents were obtained in Japan and other
countries, including the ’314 patent in the United States.

    Federal approval for sale and use in the United States
was granted on August 12, 2003, after over two decades of
development. The product was highly successful, due to its
superior efficacy in lowering low-density (LDL) cholesterol
and elevating high-density (HDL) cholesterol, and its re-
duced side effects, as compared with other commercial
statins. See Peter H. Jones et al., Comparison of the Efficacy
and Safety of Rosuvastatin Versus Atorvastatin, Simvas-
tatin, and Pravastatin Across Doses (STELLAR Trial), 92
Am. J. Cardiology 152 (2003).

    Several generic producers initiated a challenge to the
’314 patent by filing an Abbreviated New Drug Application
(ANDA) accompanied by a Paragraph IV certification, 21
U.S.C. §355(j)(2)(A)(vii)(IV). An ANDA permits a generic
producer to market a drug product based on the federal
approval obtained by the original registrant. Submission of
an ANDA constitutes a statutory act of infringement pursu-
ant to §271(e)(2) of the Patent Act, which provides:

    It shall be an act of infringement to submit an ap-
    plication under [section 355(j) of title 21] . . . for a
    drug claimed in a patent or the use of which is
    claimed in a patent . . . if the purpose of such sub-
    mission is to obtain approval under such Act to en-
    gage in the commercial manufacture, use, or sale of
    a drug, veterinary biological product, or biological
    product claimed in a patent or the use of which is
    claimed in a patent before the expiration of such
    patent.
ASTRAZENECA   v. AUROBINDO                                      6


35 U.S.C. §271(e)(2)(A). If the challenge to the patent fails,
the ANDA cannot be approved until expiration of the pat-
ent. 35 U.S.C. §271(e)(4)(A).

    The infringement suits against the several generic chal-
lengers were consolidated in the United States District
Court for the District of Delaware. The Defendants are
Aurobindo Pharma Ltd., Mylan Pharmaceuticals Inc.,
Apotex Corp., Cobalt Pharmaceuticals Inc. and Cobalt
Laboratories Inc., Sun Pharmaceutical Industries, Ltd.,
Teva Pharmaceuticals USA, Inc., Par Pharmaceuticals, Inc.,
and Sandoz, Inc. The Defendants argued that the ’314
patent is invalid on the ground of obviousness and improper
reissue, and that the patent is unenforceable for inequitable
conduct in the Patent and Trademark Office (“PTO”).

    The district court ruled that the ’314 patent is valid, en-
forceable, and infringed.1 The Defendants all admitted
infringement, except for Apotex Corp. All of the Defendants
appeal the rulings of validity and enforceability.

                                I

                           VALIDITY

    The Defendants challenge patent validity on the ground
of obviousness. Obviousness is decided as a matter of law
based on four basic factual inquiries, as set forth in Graham
v. John Deere Co., 383 U.S. 1, 17–18 (1966), and elaborated
in KSR International, Co. v. Teleflex Inc., 550 U.S. 398, 406–
07 (2007), viz., (1) the scope and content of the prior art, (2)
the level of ordinary skill in the field of the invention, (3) the
differences between the claimed subject matter and the
prior art, and (4) any objective indicia of unobviousness,
    1  In re Rosuvastatin Calcium Patent Litig., 719 F.
Supp. 2d 388 (D. Del. 2010).
7                                ASTRAZENECA   v. AUROBINDO


such as commercial success or long-felt need, or failure of
others.

    The Defendants identified as the closest prior art Euro-
pean Patent Office Publication No. 0 367 895 of the Sandoz
company (“Sandoz”), published May 16, 1990, which de-
scribes numerous pyrimidine-based statin compounds,
including a compound designated as Compound 1b. Com-
pound 1b has two –CH3 (methyl) groups on the amino side
chain, instead of one –CH3 and one –SO2CH3 group as in
rosuvastatin. Compound 1b has the following structural
formula:




                  Sandoz Compound 1b

The Sandoz European application describes Compound 1b
as an “especially preferred embodiment of the invention.”
Sandoz, at *9. The Defendants argued in the district court
that this statement suggests that Compound 1b would be a
good “lead compound” for further research, and that with
this selection as lead compound the change of the –CH3
group to a –SO2CH3 group would have been obvious because
it would make Compound 1b more hydrophilic. The Defen-
dants stated that numerous publications taught that liver-
ASTRAZENECA   v. AUROBINDO                                  8


selective statins may have fewer undesirable side effects,
and that hydrophilic statins are more liver-selective. The
Defendants argued that persons of ordinary skill in this
field would have been motivated to make Sandoz Compound
1b more hydrophilic, and that the C2 position (as marked on
the molecule supra) was the logical place to modify Com-
pound 1b because the other parts of the structure were
known to be essential to statin activity. The Defendants
argued that a person of ordinary skill would have consid-
ered a limited number of common substitutions, including a
sulfonyl “spacer” –SO2– at the C2 position to increase hydro-
philicity. The Defendants argued that a person of ordinary
skill would have predicted that this change would produce a
statin with fewer adverse side effects, thereby rendering the
compound obvious.

    In response, the Plaintiffs pointed out that Sandoz
Compound 1b demonstrated unexpected increased toxicity,
and therefore was not an encouraging lead compound. The
Plaintiffs stated that other compounds in the Sandoz Euro-
pean application, such as Compound 11, demonstrated
better in vitro potency. The Plaintiffs responded to the
argument that in 1991 a scientist would have known that
Compound 1b should be made more hydrophilic, by pointing
to publications that state that lipophilic substituents at the
C2 position, the converse of hydrophilic, can increase statin
potency. The Plaintiffs argued that the prior art provided
no suggestion of rosuvastatin’s unexpectedly superior prop-
erties as compared with Compound 1b or any other known
compound, thus creating no “reasonable expectation of
success.” Pfizer, Inc. v. Apotex, Inc., 480 F.3d 1348, 1361
(Fed. Cir. 2007) (“[T]he burden falls on the challenger of the
patent to show by clear and convincing evidence that a
skilled artisan would have been motivated to combine the
teachings of the prior art references to achieve the claimed
9                                 ASTRAZENECA   v. AUROBINDO


invention, and that the skilled artisan would have had a
reasonable expectation of success in doing so.”).

     The Plaintiffs highlighted the unpredictability that was
associated with statin development. For example, the
pyrrole-based statin corresponding in all other structural
aspects to the pyrimidine-based rosuvastatin displayed toxic
side effects. The Plaintiffs pointed out that at least five
pharmaceutical companies had abandoned their research on
statins with pyrimidine cores, on the prevailing belief that
pyrimidine-based statins were not promising leads to im-
proved products. The Plaintiffs pointed out that no refer-
ence, or combination of references, suggested that the
previously unknown molecule rosuvastatin would have its
advantageous properties. See KSR, 550 U.S. at 421 (“A
factfinder should be aware . . . of the distortion caused by
hindsight bias and must be cautious of arguments reliant
upon ex post reasoning.”); Yamanouchi Pharm. Co. v. Dan-
bury Pharmacal, Inc., 231 F.3d 1339, 1345 (Fed. Cir. 2000)
(finding that “an ordinary medicinal chemist” would not
have expected the specific chemical structure to have the
“most desirable combination of pharmacological properties”)
(internal quotation omitted). The Plaintiffs pointed to
objective indicia of non-obviousness, including commercial
success, long felt but unfilled need, failure of others, and
unexpected results, Graham, 383 U.S. at 17–18, as support
for the district court’s judgment of unobviousness.

    The district court applied the correct standard, that the
challenger must demonstrate by clear and convincing evi-
dence that the invention would have been obvious to a
person of ordinary skill in the field of the invention at the
time the invention was made. Pfizer, 480 F.3d at 1359–60
(“Since we must presume a patent valid, the patent chal-
lenger bears the burden of proving the factual elements of
invalidity by clear and convincing evidence. That burden of
ASTRAZENECA   v. AUROBINDO                                  10


proof never shifts to the patentee to prove validity.”). The
district court discussed the Defendants’ argument that the
insertion of a sulfonyl group at position C2 was one of a
“finite number of identified, predicable solutions” to existing
problems with statins, in the words of KSR, 550 U.S. at 421,
and thus that it would have been obvious to make this
specific compound and test its properties. The district court
found that this situation was similar to that discussed in In
re O'Farrell, 853 F.2d 894 (Fed. Cir. 1988), where the court
explained that obviousness is not shown when “what was
‘obvious to try’ was to explore a new technology or general
approach that seemed to be a promising field of experimen-
tation, where the prior art gave only general guidance as to
the particular form of the claimed invention or how to
achieve it.” Id. at 903. The district court concluded that the
Defendants did not demonstrate the required motivation for
selecting Sandoz Compound 1b as a lead compound, or for
making this specific sulfonyl change in the Compound 1b
molecule. See Eli Lilly & Co. v. Zenith Goldline Pharms.,
471 F.3d 1369, 1379 (Fed. Cir. 2006) (considering whether a
prior art compound would have been chosen as a lead com-
pound).

    We agree that “obvious to try” was negated by the gen-
eral skepticism concerning pyrimidine-based statins, the
fact that other pharmaceutical companies had abandoned
this general structure, and the evidence that the prior art
taught a preference not for hydrophilic substituents but for
lipophilic substituents at the C2 position. See Takeda Chem.
Indus., Ltd. v. Alphapharm Pty., 492 F.3d 1350, 1357 (Fed.
Cir. 2007) (“[I]n cases involving new chemical compounds, it
remains necessary to identify some reason that would have
led a chemist to modify a known compound in a particular
manner to establish prima facie obviousness of a new
claimed compound.”).
11                                ASTRAZENECA   v. AUROBINDO


    The district court correctly held that patent invalidity
on the ground of obviousness had not been shown for the
compound rosuvastatin. That ruling is affirmed.

                             II

                  INEQUITABLE CONDUCT

    The Defendants also argued that the ’314 patent is per-
manently unenforceable because of inequitable conduct
during prosecution of the ’440 patent from which the ’314
patent was reissued. The Defendants attributed the inequi-
table conduct to two employees in Shionogi’s in-house patent
staff in Japan, Ms. Tomoko Kitamura and Mr. Takashi
Shibata, who did not disclose three documents to the PTO
during prosecution of the ’440 patent. The documents were
Bayer Japanese Patent Application No. HI-261377 (filed
Feb. 2, 1989, published Aug. 31, 1989), the Sandoz pub-
lished European application describing Compound 1b, and a
European Patent Office search report that included the
Sandoz application. The Defendants state that all three
documents were highly material to patentability, that they
were intentionally withheld during prosecution of the ’440
patent, and that such inequitable conduct cannot be cured
by a reissue action wherein Shionogi disclosed these patent
documents. The Plaintiffs respond that there was no intent
to deceive or mislead the PTO, and that any error in prose-
cution of the ’440 patent was unintentional and was recti-
fied by prompt filing of the reissue application and
disclosure of the uncited references, as soon as Shionogi
discovered the error.

    To prove inequitable conduct, the challenger must show
by clear and convincing evidence that the patent applicant
(1) misrepresented or omitted information material to
patentability, and (2) did so with specific intent to mislead
ASTRAZENECA   v. AUROBINDO                                12


or deceive the PTO. Therasense, Inc. v. Becton, Dickinson
and Co., 649 F.3d 1276, 1287 (Fed. Cir. 2011) (en banc).
Materiality and intent must be separately established. Id.
at 1290. To establish materiality, it must be shown that the
PTO would not have allowed the claim but for the non-
disclosure or misrepresentation. Id. at 1291. To establish
intent, intent to deceive the PTO must be “‘the single most
reasonable inference able to be drawn from the evidence.’”
Id. at 1290 (quoting Star Scientific, Inc. v. R.J. Reynolds
Tobacco Co., 537 F.3d 1357, 1366 (Fed. Cir. 2008)). The
district court’s findings on materiality and intent are re-
viewed for clear error, and the court’s ultimate decision as
to inequitable conduct is reviewed on the standard of abuse
of discretion. Am. Calcar, Inc. v. Am. Honda Motor Co.,
Inc., 651 F.3d 1318, 1334 (Fed. Cir. 2011).

    There was extensive evidence and argument before the
district court, including the live testimony of the Shionogi
personnel who were accused of acting inequitably. It was
explained that when scientists at Shionogi obtained favor-
able results with certain modified pyrimidine compounds
including rosuvastatin, the Shionogi patent department was
asked to file a patent application on their results. Ms.
Kitamura, then a Shionogi employee, obtained search
reports relating to these products. The reports identified
the Sandoz European application that included Compound
1b, and the Bayer Japanese application that described a
large class of statin compounds that generically included the
rosuvastatin class of substituents, but not showing the
specific compounds that Shionogi submitted for patenting.
Ms. Kitamura testified that because “[t]here were no in-
stances of the same compounds as Shionogi,” she did not
believe that the references created a patentability problem.
J.A. 21458–60. Ms. Kitamura prepared and filed the Japa-
nese patent application and processed the foreign counter-
parts including the United States ’440 application.
13                                ASTRAZENECA   v. AUROBINDO


    The ’440 patent application was filed in the United
States on June 12, 1992. The application described a class
of compounds with a pyrimidine core as HMG-CoA reduc-
tase inhibitors. Table 4 of the application showed that
rosuvastatin had the best HMG-CoA reductase inhibitory
activity. Ms. Kitamura left Shionogi employment about six
weeks after the ’440 application was filed in the United
States, and Mr. Shibata assumed responsibility for these
applications. He received an EPO search report which
identified the Sandoz application as “particularly relevant if
taken alone.” Mr. Shibata asked the Shionogi scientists to
conduct tests to compare the Shionogi compounds with the
preferred compounds described in the Sandoz and Bayer
applications.

     No Information Disclosure Statement (“IDS”) was filed
for the ’440 application, and neither the Sandoz application
nor the Bayer application was provided to the PTO or cited
by the examiner of the ’440 application. The ’440 patent
was issued in the United States on November 9, 1993.

    In the fall of 1997 AstraZeneca and Shionogi began ne-
gotiating a license to rosuvastatin. During the negotiation
it was discovered that no IDS had been filed during prosecu-
tion of the ’440 application, and that the Sandoz and Bayer
applications had not been cited by the examiner. U.S.
patent counsel was consulted, and on November 4, 1997,
Shionogi filed an application to reissue the ’440 patent in
order to file an IDS and to include the Sandoz and Bayer
references in the examination. Shionogi certified to the
PTO that it had erroneously not brought these references to
the examiner’s attention, and that it was through error and
not due to deceptive intent. The reissue examiner then
rejected the generic ’440 claims as obvious in view of the
Bayer reference. In response, Shionogi limited the ’440
patent to the specific compound rosuvastatin and its salts.
ASTRAZENECA   v. AUROBINDO                                 14


The reissue was granted, and the application issued as the
’314 reissue patent on August 7, 2001.

    The Defendants argued that the Sandoz and Bayer ref-
erences were material and that they were deliberately
withheld with deceptive intent, and that such inequitable
conduct could not be cured.

                       1. Materiality

     In the district court, the Defendants argued that the
Bayer and Sandoz applications and EPO search report are
all highly material to patentability. The Defendants pointed
to the reissue examiner’s rejection of the claims as initially
granted, and Shionogi’s retrenchment in claim scope. The
Defendants argued that Shionogi’s prompt filing of the
reissue application itself demonstrated that Shionogi recog-
nized the materiality of these references.

    Although we doubt that the act of taking prompt reme-
dial action is appropriately viewed as an admission of
wrongdoing, the district court found the Sandoz and Bayer
references to be material to the prosecution of the ’440
application. We agree that the reference compounds are
sufficiently similar in structure to warrant citation. Al-
though the references were held by the PTO not to negate
patentability of rosuvastatin, as affirmed ante, we do not
disturb the district court’s finding of materiality.

                          2. Intent

    The district court found that the Defendants did not es-
tablish that either Ms. Kitamura or Mr. Shibata withheld
the Sandoz and Bayer references with deceptive intent.
Although deceptive intent may be inferred from circumstan-
tial evidence, the inference “must not only be based on
15                                 ASTRAZENECA   v. AUROBINDO


sufficient evidence and be reasonable in light of that evi-
dence, but it must also be the single most reasonable infer-
ence able to be drawn from the evidence to meet the clear
and convincing standard.” Star Scientific, 537 F.3d at 1366;
see also Therasense, 649 F.3d at 1290.

     The Defendants argued that intent to deceive should be
inferred from three situations. First, the Defendants point
to Ms. Kitamura’s possession of the Bayer reference at the
time she filed the ’440 patent application, and her testimony
in the district court that she knew she had a duty to disclose
the Bayer reference to the PTO. Second, the Defendants
point to an internal Shionogi memorandum stating that
“[d]evelopment information on S-4522 [rosuvastatin] must
not be leaked to the outside because it is included in the text
of the published unexamined Bayer patent application . . . .”
 J.A. 2406. Third, the Defendants state that Mr. Shibata
knew about the Bayer and Sandoz references and the EPO
search report, yet failed to disclose them to the United
States examiner. Defendants state that this failure to
disclose was due to deceptive intent, as evidenced by Mr.
Shibata’s delays in processing the patent applications.

     The district court received testimony concerning the
prosecution of the ’440 application from Mr. Shibata, Ms.
Kitamura, and Mr. Tamaki, a third Shionogi employee. Ms.
Kitamura testified that the IDS for the ’440 application was
not due when she left employment at Shionogi. Mr. Shibata
testified that he believed that it had been filed. Mr. Tamaki
testified about the department’s heavy work load and pro-
vided explanation of confusion and error. There was exami-
nation and cross-examination concerning the events at
Shionogi. The district court found that “actions suggestive
of malfeasance become no more than a string of mishaps,
mistakes, misapprehensions and misjudgments on the part
of inexperienced and overworked individuals.” Op. 30. The
ASTRAZENECA   v. AUROBINDO                                16


district court stated that it “is simply not persuaded that
the single most reasonable inference to be drawn from these
circumstances is deceptive intent.” Id. at 24.

    The Defendants argue that the district court clearly
erred when it did not find an inference of deceptive intent.
The Defendants stress that Ms. Kitamura did not remember
details after twenty years, and they also stress her admis-
sion that she knew she had a duty to disclose the Bayer
reference. The Plaintiffs reply that there was no evidence
that she intended to withhold the reference in order to
deceive the PTO, and that deceptive intent is not “the single
most reasonable inference to be drawn from the evidence.”
See Therasense, 649 F.3d at 1290. The Plaintiffs point out
that Ms. Kitamura left Shionogi a month after filing the
’440 application, well before an IDS was due to be filed.

    The district court heard the testimony, considered the
credibility of the witnesses, and concluded that deceptive
intent was not the single most reasonable inference to be
drawn from the evidence. “This court may not reassess, and
indeed is incapable of reassessing, witness credibility and
motive issues on review.” LNP Eng’g Plastics, Inc. v. Miller
Waste Mills, Inc., 275 F.3d 1347, 1361 (Fed. Cir. 2001). The
Defendants have not shown clear error in the district court’s
finding that it was most likely that Ms. Kitamura acted
without deceptive intent.

    The Defendants also argued that the district court
clearly erred in failing to find that Mr. Shibata possessed
deceptive intent. The Defendants argued that Mr. Shibata’s
denials of deceptive intent, his apology and excuses, should
not have been credited by the district court. The Defen-
dants argued that his admission of negligence does not
avoid the inference of intent to deceive, and stress that he
had ordered comparative testing. The Plaintiffs cited a
17                                 ASTRAZENECA   v. AUROBINDO


report by Mr. Shibata dated July 14, 1993, which states (in
the record translation):

     ‘Novelty’ and ‘inventive step’ are examined to de-
     termine patentability. It seems that the examina-
     tion in the U.S. was fairly lenient regarding
     ‘inventive step’. Since we expect a slightly stricter
     examination in Europe and Japan, we are in the
     process of implementing ‘comparative tests’ in the
     laboratory that we can use as countermeasures. If
     the superiority of S-4522 [rosuvastatin] is confirmed
     in these tests, a patent can be obtained in all coun-
     tries in which we have filed.

J.A. 2752. The Plaintiffs argued that this report is not
consistent with an inference of deceptive intent, but instead
reflects his belief that the examination in the United States
had been more “lenient” than was expected in Europe and
Japan. The Plaintiffs argued that by requesting compara-
tive tests Mr. Shibata was preparing to confront the prior
art, not to conceal it.

    The record and argument are extensive. Clear error has
not been shown in the district court’s finding that deceptive
intent was not shown, and was not the single most reason-
able inference based on all of the evidence. See Kingsdown
Med. Consultants, Ltd. v. Hollister Inc., 863 F.2d 867, 873
(Fed. Cir. 1988) (en banc in relevant part) (The evidence
“must be sufficient to require a finding of deceitful intent in
light of all the circumstances.”). The district court observed
the witnesses under examination and cross-examination,
examined the documents, and reasonably found that it was
“equally plausible” that Mr. Shibata believed the require-
ments of the United States patent prosecution had been
met. The district court found that the evidence as a whole
“paints a more innocent explanation of Mr. Shibata as a new
ASTRAZENECA   v. AUROBINDO                                 18


and inexperienced manager attempting to handle an under-
staffed and overworked Patent Department.” Op. 25.

     We agree that clear and convincing evidence did not
show that Ms. Kitamura and Mr. Shibata made a deliberate
decision to withhold references from the PTO. See
Therasense, 649 F.3d at 1290 (“In a case involving nondis-
closure of information, clear and convincing evidence must
show that the applicant made a deliberate decision to with-
hold a known material reference.”) (quoting Molins PLC v.
Textron, Inc., 48 F.3d 1172, 1181 (Fed. Cir. 1995)). The
court in Therasense sought to impart objectivity to the law
of inequitable conduct by requiring that “the accused in-
fringer must prove that the patentee acted with the specific
intent to deceive the PTO,” 649 F.3d at 1290. Recognizing
the complexity of patent prosecution, negligence—even
gross negligence—is insufficient to establish deceptive
intent. See Kingsdown, 863 F.2d at 876 (“a finding that
particular conduct amounts to ‘gross negligence’ does not of
itself justify an inference of intent to deceive”); Lazare
Kaplan Int’l, Inc. v. Photoscribe Techs., Inc., 628 F.3d 1359,
1379 (Fed. Cir. 2010) (“mistake or exercise of poor judgment
. . . does not support an inference of intent to deceive”);
Molins, 48 F.3d at 1181 (“[T]he alleged conduct must not
amount merely to the improper performance of, or omission
of, an act one ought to have performed.”).

   We affirm that unenforceability based on inequitable
conduct was not established.

                             III

                          REISSUE

   The Defendants also argued that the ’314 patent was
improperly reissued, arguing that the statutory reissue
19                                  ASTRAZENECA   v. AUROBINDO


requirement of error without deceptive intent had not been
met. The statute, at the time of the reissue, authorized the
reissue of “inoperative or invalid” patents, as follows:

     Whenever any patent is, through error without any
     deceptive intention, deemed wholly or partly inop-
     erative or invalid, by reason of a defective specifica-
     tion or drawing, or by reason of the patentee
     claiming more or less than he had a right to claim in
     the patent, the Director shall, on the surrender of
     such patent and the payment of the fee required by
     law, reissue the patent for the invention disclosed in
     the original patent . . .

35 U.S.C. §251 (1999).2 The Defendants argued that (1)
there was no error, and (2) there was deceptive intent.

    The Defendants argued that Shionogi deliberately pre-
sented a claim in the ’440 patent that overlapped the prod-
ucts in the Sandoz reference in an attempt to get greater
protection. The Defendants also argued that Shionogi acted
deliberately in obtaining only generic claims in the ’440
patent in order to conceal the rosuvastatin species. The
Plaintiffs pointed out that rosuvastatin was specifically
described in the specification as the most effective of the
four compounds that are described with test data.

    The Defendants also argued that deliberate prosecution
decisions can never be corrected through reissue, citing the

     2  In 2011, Congress modified Section 251 in the
American Invents Act, Pub. L. No. 112-29, to remove the
statutory requirement that the error occur “without any
deceptive intention.” We consider the earlier version of the
statute in this appeal.
ASTRAZENECA   v. AUROBINDO                                 20


statement in In re Serenkin, 479 F.3d 1359, 1362 (Fed. Cir.
2007) that “case law holds that the deliberate action of an
inventor or attorney during prosecution generally fails to
qualify as a correctable error under §251.” However, the
court in Serenkin did not hold that attorney action during
prosecution is not correctable, for a principal purpose of the
reissue statute is to permit correction of erroneous action
during prosecution. Rather, the court held that it is appro-
priate to consider the nature of the action to determine
whether it is a correctable error. The Serenkin court ex-
plained that “the extent to which the reissue statute pre-
vents an applicant from obtaining claims that differ in form
or substance from the cancelled claims ‘necessarily depends
upon the facts in each case and particularly on the reasons
for the cancellation.’” Id. at 1365 (quoting In re Willingham,
282 F.2d 353, 357 (CCPA 1960).

    On the facts of Serenkin, that court held that the pro-
posed “correction” did not comport with the purposes of the
reissue statute. In Serenkin the attorney wished to add
eight sheets of drawings to his pending Patent Cooperation
Treaty (“PCT”) application, which had a filing date of Janu-
ary 28, 1997. For that purpose he filed a petition with the
United States PTO Receiving Office under the PCT, request-
ing that the World Intellectual Property Organization
“republish this application showing a filing date of 17 Feb-
ruary 1998 with no priority claim and the eight sheets of
drawings filed on 17 February 1998.” Id. at 1361. The
attorney had accepted the PTO’s position that he must
choose between keeping the earlier international filing date
without the drawings, or accepting the later date with the
drawings. The attorney chose the later date with the draw-
ings, and the petition was granted. After the United States
patent was issued, Serenkin sought through reissue to
recover the original filing date, stating that its attorney
erred in choosing the later date. The PTO refused, and this
21                                ASTRAZENECA   v. AUROBINDO


court affirmed, stating that Serenkin was impermissibly
“attempting to use the reissue process to undo the conse-
quences of his attorney's conscious decision to give up an
earlier filing date so that certain material, which was con-
sidered important at the time, would be considered with his
PCT application.” Id. at 1365. The court stressed that the
actions had been taken with knowledge of their conse-
quences, and compared these facts with those of In re Wad-
linger, 496 F.2d 1200, 1207 (CCPA 1974), where the court
explained that “error” for reissue purposes encompasses
“inadvertence, accidents, and mistakes,” and “is certainly
inclusive of actions taken in full consciousness.” In Wadlin-
ger the court determined that the reissue claims were
narrower in scope than the original claims, and held that
this was correctable error under §251, “despite the fact that
the cancellation of the original claims was deliberate,” as
explained in Serenkin, 479 F.3d at 1365.

    Precedent establishes that for reissue purposes “error is
established where there is no evidence that the appellant
intentionally omitted or abandoned the claimed subject
matter.” Ball Corp. v. United States, 729 F.2d 1429, 1435–
36 (Fed. Cir. 1984). Here, the district court found as fact
that Shionogi erred by failing to file an IDS citing the San-
doz and Bayer references, and by omitting a specific claim to
the preferred species. However, the court found no evidence
of a deliberate choice to omit or abandon the rosuvastatin
species, which was described in the specification as the most
effective product.

    The Defendants’ argument that Shionogi cannot narrow
the claims by reissue has been rejected in a variety of situa-
tions. See, e.g., In re Tanaka, 640 F.3d 1246, 1250 (Fed. Cir.
2011) (“This court also rejects the PTO's assertion that the
omission of a narrower claim from an original patent does
not constitute an error under 35 U.S.C. §251 because the
ASTRAZENECA   v. AUROBINDO                                  22


omission of a dependent claim does not render the patent
inoperative.”); Medtronic, Inc. v. Guidant Corp., 465 F.3d
1360, 1375 (Fed. Cir. 2006) (“An attorney’s failure to appre-
ciate the full scope of the invention is one of the most com-
mon sources of defects in patents, and is generally sufficient
to justify reissuing a patent.”) (citing In re Wilder, 736 F.2d
1516, 1519 (Fed. Cir. 1984)); In re Handel, 312 F.2d 943, 946
n.2 (CCPA 1963) (“adding dependent claims as a hedge
against possible invalidity of original claims is a proper
reason for asking that a reissue be granted”). The district
court’s affirmance of the PTO’s holding that Shionogi had
the right to a reissue in which it claimed only rosuvastatin
and its salts, is in accordance with law.

    Our colleague in dissent cites other cases in which reis-
sue was denied, on other facts and circumstances. While
these cases illustrate the factual nature of a determination
of “intent,” no precedent warrants a finding of deceptive
intent in the situation herein. In In re Youman, 679 F.3d
1335 (Fed. Cir. 2012) the court determined whether the
patentee was attempting to “recapture,” through reissue,
subject matter that had been surrendered during prosecu-
tion. In In re Harita, 847 F.2d 801 (Fed. Cir. 1998) the court
held that reissue was available although, due to gross
negligence, the foreign patent practitioner did not assure
that the PTO was advised of prior art that was discovered
after the patent application was filed; the court held that
“intent to mislead” could not be inferred, even from gross
negligence. In Hewlett-Packard Co. v. Bausch & Lomb, Inc.,
882 F.2d 1556, 1566 (Fed. Cir. 1989) the court held that the
patentee’s submission of false affidavits to the PTO “elimi-
nated the basis for reissue and rendered the ’684 patent
invalid” because the patentee’s explanation of “error” was
“factually untrue.” In In re Hounsfield, 699 F.2d 1320, 1323
(Fed. Cir. 1983) the court held that “lack of ‘intent to claim’
is not an independent basis for denying a reissue application
23                                 ASTRAZENECA    v. AUROBINDO


under section 251,” but only “sheds light upon whether the
claims of the reissue application are directed to the same
invention as the original patent. . . .” In In re Whittelsey, 83
F.2d 894 (CCPA 1936) the court held that the patentee could
not use reissue to obtain claims which “were intentionally
omitted from his original application under the belief that
they could not properly be included therein. . . .” In In re
Murray, 77 F.2d 651, 654–55 (CCPA 1935) the court held
that the patentee could not use reissue to obtain broader
claims to cover “improvements in the art which have oc-
curred since the date of issuance of the original patent” and
were “not intended to be incorporated in the original appli-
cation.” None of these cases supports rejection of a reissue
application for an unintentional failure to file an IDS.

    The district court considered the Defendants’ arguments
directed to both error and deceptive intent, and concluded
that Shionogi did not act intentionally to make the error for
which it seeks reissue. The district court received live
testimony from the purported culprits, and found that “the
evidence adduced in this case shows no such deliberate
choices [as on the facts of Serenkin] and no violations of
rules or statutes that would render the reissue of the ’440
patent improper.” Op. 43. In discussing the scope of the
claims, the district court found that Ms. Kitamura credibly
testified that she was unaware that there was overlap
between the claims of the ’440 application and the prior art
because “the internal Shionogi search report of which she
was aware, did not raise a patentability problem with
respect to Sandoz, and a full copy of the Sandoz reference
was not sent to her.” Op. 41. These internal search reports
do not show the chemical structures of the Sandoz reference.
 J.A. 2211, 2224, 2242. The district court found that the
evidence showed that after Ms. Kitamura’s departure,
Shionogi was not alerted to the need for further attention to
the Sandoz reference because of “chaos, confusion, and
ASTRAZENECA   v. AUROBINDO                                 24


inexperience,” “lack of legal training within the Shionogi
Patent Department, the changing and limited personnel
within that department, . . . the ongoing confusion level,”
and “unintentional miscommunications” between Shionogi’s
patent personnel. Id. These findings have not been shown
to be clearly erroneous. And the Defendants’ charge that
Shionogi deliberately obtained claims in the ’440 patent that
it knew to be invalid is not plausible.

    The district court found that “the Court is ultimately not
convinced that the claims of the ’440 patent that overlapped
the Sandoz reference were the result of some planned strat-
egy or sinister motivation as opposed to mere mistake or
oversight by overworked individuals with limited training
and expertise.” Op. 40. See Hewlett-Packard Co., 882 F.2d
at 1565 (“The language of the current statute, ‘error without
deceptive intent’ . . . encompasses ‘inadvertence, accident or
mistake.’”).

    The Defendants argue that “deceptive intent” in the re-
issue statute requires less rigorous proof than “deceptive
intent” in connection with charges of inequitable conduct.
We discern no sound basis for this distinction, for the com-
plexities of patent solicitation in all its stages have been
shown susceptible to the “plague” of opportunistic accusa-
tions. See Therasense, 649 F.3d at 1289 (“‘[T]he habit of
charging inequitable conduct in almost every major patent
case has become an absolute plague.’”) (quoting Burlington
Indus., Inc. v. Dayco Corp., 849 F.2d 1418, 1422 (Fed. Cir.
1988)). This court has repeatedly held in the context of
inequitable conduct that nondisclosure of prior art by itself
is not enough to create an inference of deceptive intent. See
Larson Mfg. Co. of S.D., Inc. v. Aluminart Prods. Ltd., 559
F.3d 1317, 1340 (Fed. Cir. 2009) (“[N]ondisclosure, by itself,
cannot satisfy the deceptive intent element.”); Dayco Prod-
ucts, Inc. v. Total Containment, Inc., 329 F.3d 1358, 1367
25                                 ASTRAZENECA    v. AUROBINDO


(Fed. Cir. 2003) (“Intent to deceive cannot be inferred sim-
ply from the decision to withhold the reference where the
reasons given for the withholding are plausible.”); Aspex
Eyewear Inc. v. Clariti Eyewear, Inc., 605 F.3d 1305, 1316
(Fed. Cir. 2010) (“Mistake or negligence, even gross negli-
gence, does not support a ruling of inequitable conduct.”);
Kingsdown, 863 F.2d at 876 (en banc in relevant part)
(holding even “‘gross negligence’ does not of itself justify an
inference of intent to deceive”). Here, after considering all
of the evidence, the district court found that the evidence
did not support a finding of deceptive intent. Op. 40 (“To
reach a contrary conclusion in this case would require the
Court to credit a number of inferences, which the Court
finds unsupported by the requisite clear and convincing
standard.”). Id. We find no error.

     “The law does not require that no competent attorney or
alert inventor could have avoided the error sought to be
corrected by reissue.” Scripps Clinic & Res. Found. v.
Genentech, Inc., 927 F.2d 1565 (Fed. Cir. 1991), overruled on
other grounds by Abbott Labs. v. Sandoz, Inc., 566 F.3d 1282
(Fed. Cir. 2009). The Shionogi error in failing to file an IDS
was agreed to be an error, and was rectified promptly upon
its discovery. Our colleague in dissent does not complain
about the speed of the moves to correct the error, but would
hold that the error should have been detected sooner, and
that this failure of detection is fatal to the reissue patent.
However, all of the cited cases relate to the absence of
diligence in correcting the error after it was detected. E.g.,
Principle Bus. Enters., Inc. v. United States, 7 Cl. Ct. 433,
438 (Cl. Ct. 1985) (“The delay of more than seven years after
plaintiffs learned of the alleged error affecting their original
patent is unreasonably long and not justified.”); Gen. Radio
Co. v. Allen B. Dumont Labs., Inc., 129 F.2d 608, 612 (3d
Cir. 1942) (delay of eight years was unreasonable when
“invalidity of the patent should . . . have been clear to any-
ASTRAZENECA   v. AUROBINDO                                  26


one with even a rudimentary knowledge of patent law”);
Miller v. Bridgeport Brass Co., 104 U.S. 350 (1881) (delay of
fifteen years was unreasonable when patentee sought a
broadening reissue to cover newly discovered improvement).
 In contrast, the reissue application here was filed promptly
upon discovery of the error.

     The Defendants, and our colleague in dissent, propose
that Shionogi omitted a claim specific to rosuvastatin from
its application in order to conceal the compound from com-
petitors. However, rosuvastatin was explicitly described in
the Shionogi specification as the preferred compound. It
was specifically identified, including its synthesis and test
results. This is not compatible with concealment. Our
colleague states that “[d]escribing a compound in the exam-
ples contained in the specification, however, is unlikely to be
the ‘red flag’ that narrowly claiming a compound would be,
particularly if that compound is the only one specifically
claimed.” Dissent at 11 n.4. However, this is not a case
where the preferred product was “buried” in massive disclo-
sure, for rosuvastatin was specifically described as the most
potent product. The specification also states that the four
tested compounds are “superior to Mevinolin,” a statin
known to be commercially successful and marketed by
Merck under the brand name Mevacor®. The patentee's
decision to limit the reissue to the compound that was
described in the specification as the most potent of the
compounds specifically described is not evidence that the
most potent compound was deceptively concealed.

    The dissent points to internal Shionogi documents that
caution against “leaking” the discovery of rosuvastatin to
Bayer. Such caution was indeed prudent, but when the
discovery was presented for patenting, it was specifically
identified as the most effective compound. Cautioning
scientists against "leaks" is a distinct matter from the
27                                 ASTRAZENECA    v. AUROBINDO


concern for obtaining valid and strong patents, for specific
claims are more reliable than broad claims that risk the
citation of fringe prior art. The dissent also argues that the
fact that Shionogi narrowed its reissue claims to the com-
pound rosuvastatin, without seeking broader generic scope,
is evidence of deceptive intent. Shionogi states that its
concern was to obtain examination on the uncited refer-
ences, and that limiting the claims to the preferred product
implemented that concern. In view of the circumstances
necessitating the reissue procedure in order to bring the
uncited references before the examiner, it is not clear how
the limitation of the claims to the compound of commercial
interest suggests that the prior flawed procedures were
based on deceptive intent.

     We also take note of the dissent’s concern that “[b]y fail-
ing to act promptly to narrow its overbroad claim, Shionogi
deprived the public of the right to experiment with, and to
improve upon, the compounds encompassed by claim 1.”
Dissent at 15. However, patenting does not deprive the
public of the right to experiment with and improve upon the
patented subject matter. As discussed in J.E.M. Ag Supply,
Inc. v. Pioneer Hi-Bred Int’l, Inc., 534 U.S. 124, 142 (2001),
“[t]he disclosure required by the Patent Act is ‘the quid pro
quo of the right to exclude,’” quoting Kewanee Oil Co. v.
Bicron Corp., 416 U.S. 470, 484 (1974). It is not necessary
to wait for the patent to expire before the knowledge con-
tained in the patent can be touched. The patent’s right to
exclude was explained by Justice Story in Whittemore v.
Cutter, 29 F. Cas. 1120 (C.C.D.Mass. 1813):

     [I]t could never have been the intention of the legis-
     lature to punish a man who constructed such a ma-
     chine merely for philosophical experiments, or for
     the purpose of ascertaining the sufficiency of the
     machine to produce its described effects.
ASTRAZENECA   v. AUROBINDO                                28


Id. at 1121; see Chesterfield v. United States, 159 F. Supp.
371 (Ct. Cl. 1958) (experimental study is not infringement).

    In sum, the district court correctly found that reissue
was available, and that the scope of the reissue was in
accordance with law.

                             IV

                      INFRINGEMENT

     With the exception of Apotex Corp. (herein “Apotex
U.S.”), all of the Defendants admit infringement of claims 6
and 8 of the ’314 patent. Apotex U.S. is a United States
affiliate of the Canadian company Apotex Inc. (herein
“Apotex Canada”). Apotex U.S. stated in the district court
that it is a defendant to this action only because it signed
and filed the ANDA on behalf of Apotex Canada. Apotex
U.S. stated that it did not “submit” the ANDA within the
meaning of §271(e)(2)(A) and thus cannot infringe the U.S.
patent. Apotex U.S. also stated that Apotex Canada cannot
be liable for infringement in this action because it is not a
party to this suit.

    The district court found Apotex U.S. to be the ANDA
“submitter” because Apotex U.S. filed the ANDA and ac-
tively participated with Apotex Canada in preparation of
the ANDA, and that Apotex U.S. intends to directly benefit
from the ANDA by selling the drug product in the United
States upon approval of the ANDA. The court found that
Apotex U.S. acts as the marketing and distribution arm of
Apotex Canada in the United States, a relationship that was
not disputed. Apotex Canada is not a party to this suit only
because the infringement case against Apotex Canada was
transferred to the Southern District of Florida at the re-
quest of Apotex Canada, which pled the absence of personal
29                                ASTRAZENECA   v. AUROBINDO


jurisdiction in Delaware. In re Rosuvastatin Calcium Patent
Litigation, MDL No. 08-1949, 2010 WL 661559 (D. Del. Feb.
19, 2010).

     Apotex U.S. argues that it cannot be bound by the dis-
trict court’s judgment of infringement because it only signed
and filed the ANDA as the agent of Apotex Canada. The
district court ruled that Apotex U.S. can be liable for in-
fringement under §271(e)(2)(A), not only because Apotex
U.S. is the entity that signed and filed the ANDA, but also
because it intends to benefit from the application by selling
the rosuvastatin product manufactured by its Canadian
relative. The district court referred to testimony by the
President of Apotex U.S., who stated that Apotex Canada
“made the decision to ‘develop Rosuvastatin calcium as a
generic product for the United States, for Apotex U.S. to sell
in the United States. . . .’” The district court found that
Apotex U.S. actively participated in activities related to the
ANDA submission in conjunction with Apotex Canada, and
referred to activities of Mr. Kiran Krishnan, manager of
regulatory affairs for Apotex U.S., at the headquarters of
Apotex Canada in preparing the ANDA in consultation with
the regulatory staff of Apotex Canada. Mr. Krishnan signed
the ANDA on behalf of Apotex U.S., as the authorized U.S.
agent. The district court concluded that Apotex U.S. may be
held liable for infringement under Section 271(e)(2)(A) as a
“submitter” of an ANDA.

     Responding to the Apotex argument that the Hatch-
Waxman Act does not provide a definition of “submit,” the
district court adopted the legal standard for a “submitter”
set forth in In re Rosuvastatin Calcium Patent Litig., 2008
WL 5046424, at *10 (D. Del. Nov. 24, 2008) (“Rosuvastatin
I”), and in AstraZeneca Pharms. LP v. Aurobindo Pharma
Ltd., 2009 WL 483131, at *3 (D. Del. Feb. 25, 2009). In
those cases the district court held that
ASTRAZENECA   v. AUROBINDO                                  30


   a wholly-owned subsidiary of a foreign ANDA appli-
   cant, which signs an ANDA as the agent of its par-
   ent-applicant, and which intends to benefit directly
   if the ANDA is approved by participating in the
   manufacture, importation, distribution and/or sale
   of the generic drug [i]s subject to suit under §271(e)
   as the one who has “submitted” the ANDA.

Rosuvastatin I at *10. Other courts have also applied
liability to the ANDA “submitter” who signs the ANDA and
intends to directly benefit from the ANDA. See Wyeth v.
Lupin Ltd., 505 F. Supp. 2d 303, 306–07 (D. Md. 2007);
Aventis Pharma Deutschland GmbH v. Lupin Ltd., 403 F.
Supp. 2d 484, 492–94 (E.D. Va. 2005); see generally Cepha-
lon, Inc. v. Watson Pharms., Inc., 629 F. Supp. 2d 338, 349
(D. Del. 2009); In re Cyclobenzaprine Hydrochloride Ex-
tended-Release Capsule Patent Litig., 693 F. Supp. 2d 409,
417 (D. Del. 2010).

    Apotex U.S. argues that 21 U.S.C. §355(j) identifies the
applicant as “the person or entity who submits an ANDA,
establishes what the applicant must do to submit an ANDA,
creates incentives to encourage ANDA submission, and
provides a means to obtain patent certainty.” Apotex Br. 15.
 Apotex U.S. argues that 35 U.S.C. §271(e)(2)(A) incorpo-
rates §355(j), and consequently defines who submits an
ANDA. Apotex U.S. explains that the Hatch-Waxman Act
similarly defines an applicant in its section related to new
drug applications, which states “[t]he applicant shall file
with the application the patent number and the expiration
date of any patent which claims the drug for which the
applicant submitted the application. . . .” 21 U.S.C.
§355(b)(1) (emphasis by Apotex U.S.). Apotex U.S. argues
that §271(e)(2)(A) makes no mention of “active involve-
ment,” “parent-subsidiary,” “principal-agent,” or intent to
31                                 ASTRAZENECA   v. AUROBINDO


benefit from ANDA approval, and argues that these factors
are irrelevant to the “submitter” issue.

     Apotex U.S. argues that FDA regulations identify the
applicant as the person or entity who submits an ANDA,
citing 21 C.F.R. §314.3(b) (“Applicant means any person
who submits an application or abbreviated application or an
amendment or supplement to them under this part to obtain
FDA approval of a new drug or an antibiotic drug and any
person who owns an approved application or abbreviated
application.”). Apotex U.S. states that Apotex Canada made
the Paragraph IV certification, that a Paragraph IV certifi-
cation is the infringing act under §271(e)(2), and therefore
that Apotex U.S. cannot be bound by any judgment of patent
infringement.

    Apotex U.S. also argues that the district court’s ruling is
unfair because its orders can affect the interests of Apotex
Canada, who is not before the Delaware court, and thus that
the district court violated the due process rights of Apotex
Canada. Apotex U.S. also argues that Apotex Canada is a
necessary party to the suit against Apotex U.S.

     The district court properly deemed these arguments un-
persuasive. The court found that the interests of Apotex
Canada in this action are represented by its agent and
subsidiary, Apotex U.S., and that Apotex U.S. participated
in preparation of the ANDA and represented that it would
sell the product in the United States. That relationship is
not denied.

    We conclude that the district court did not err in holding
that Apotex U.S. is properly named as a defendant in this
action. The judgment of infringement against all of the
Defendants is affirmed.
ASTRAZENECA   v. AUROBINDO        32


                       AFFIRMED
United States Court of Appeals
    for the Federal Circuit
         __________________________

  IN RE ROSUVASTATIN CALCIUM PATENT
                LITIGATION
          __________________________

      ASTRAZENECA UK LIMITED, IPR
         PHARMACEUTICALS INC.,
AND SHIONOGI SEIYAKU KABUSHIKI KAISHA,
            Plaintiffs-Appellees,
                     v.
      AUROBINDO PHARMA LIMITED,
           Defendant-Appellant,
                    AND

     MYLAN PHARMACEUTICALS INC.,
           Defendant-Appellant,
                    AND

             APOTEX CORP.,
            Defendant-Appellant,
                    AND

COBALT PHARMACEUTICALS INC. AND COBALT
          LABORATORIES INC.,
           Defendants-Appellants,
                    AND

 SUN PHARMACEUTICAL INDUSTRIES, LTD.,
          Defendant-Appellant,
                    AND
ASTRAZENECA   v. AUROBINDO                                 2


       TEVA PHARMACEUTICALS USA, INC.,
              Defendant-Appellant,
                             AND

           PAR PHARMACEUTICAL, INC.,
                Defendant-Appellant,
                             AND

                     SANDOZ, INC.,
                       Defendant.
               __________________________

 2010-1460,-1461,-1462,-1463,-1464,-1465,-1466,-1467, -
          1468,-1469,-1470,-1471,-1472,-1473
              __________________________

    Appeal from the United States District Court for the
District of Delaware in case nos. 08-MD-1949, 07-CV-
0810, 07-CV-0805, 07-CV-0809, 07-CV-0811, 07-CV-0806,
08-CV-0426, and 07-CV-0808, Judge Joseph J. Farnan, Jr.
              __________________________

PLAGER, Circuit Judge, concurring.
    I join the opinion of Judge Newman.
     I write to clarify my understanding of why Apotex
U.S. should be treated as having “submit[ted]” an applica-
tion for an ANDA, and therefore be held liable as an
infringer under 35 U.S.C. § 271(e)(2). The question is
whether, under the statute, Apotex U.S. “submit[ted] an
application . . . for a drug . . . claimed in a patent or the
use of which is claimed in a patent before the expiration
of such patent.” If so, the statute deems that to be an act
of infringement. Id.
    Apotex U.S. argues that, in filing the application for
the ANDA, it was simply an agent for the true applicant,
3                                ASTRAZENECA   v. AUROBINDO


Apotex Canada. As an agent for the applicant, Apotex
U.S. argues that it is not an applicant and therefore
cannot be deemed an infringer. The question of whether
an agent-filer-submitter such as Apotex U.S. can be a
party liable for infringement under § 271(e)(2) is a ques-
tion of first impression in this court.
    The statute nowhere addresses the question of agency
in the submission of an application under § 271(e). How-
ever, in creating the artificial act of infringement by the
submission of an ANDA, the statute does add the follow-
ing qualifier related to the applicant’s purpose in making
the submission: “It shall be an act of infringement to
submit an application . . . if the purpose of such submis-
sion is to obtain approval . . . to engage in the commercial
manufacture, use, or sale of a drug . . . claimed in a pat-
ent . . . .” Id. (emphasis added). The phrasing leaves
unclear what the consequences are if the party who
submits the application is not the same as the principal
party who will “engage in” the manufacture of the drug at
issue.
    Thus the question becomes whether the statute is in-
tended to include within its scope 1) any agent who sim-
ply submits (i.e., files) an application for another who is
the principal commercial manufacturer; or 2) an agent
who files on behalf of such another, but who has a finan-
cial interest beyond simply acting for the commercial
manufacturer, and in this latter situation, what qualifies
as a sufficient financial interest.
    With regard to the first, there can be no doubt that
many applications are in fact submitted to the FDA by
attorneys or others acting as agents for the real party in
interest, i.e., the commercial manufacturer of the generic
drug at issue. It would make little sense to read the
statute as making such agents liable for the artificial “act
ASTRAZENECA   v. AUROBINDO                                 4


of infringement” created therein. Though presumably an
attorney or other agent representing a principal commer-
cial manufacturer could fashion some sort of hold-
harmless provision in the employment contract, such
unnecessary complication and the potential mischief
associated therewith cannot be what Congress had in
mind. An agent who simply prepares and submits the
application as such is not an applicant; it is the real party
in interest—the commercial manufacturer—who is the
statutory applicant who “submit[s]” the application and
commits the act of infringement. In the case before us,
there is no doubt that Apotex Canada is the principal
party in interest and intends “to engage in the commercial
manufacture, use, or sale” of the drug, and thus is an
applicant under the statute.
    But there remains the second inquiry. What of the
agent who has a financial interest in the manufacture or
distribution of the drug that is the subject of the ANDA?
Here, Apotex U.S. did indeed assist Apotex Canada in the
planning, preparation, and submission of the application,
but as discussed above, that alone cannot create liability.
In this case, however, there is more—it is clear from the
record that Apotex U.S. is not merely an agent who as-
sisted the manufacturer in submitting an application
under the statute.
    The record indicates that Apotex U.S., by virtue of the
relationships between itself and Apotex Canada, both
corporate and otherwise, will become the entity—indeed,
a real party in interest—that will use and sell the drug in
the United States. The trial court found, based on the
testimony of the President of Apotex U.S., that Apotex
U.S. is the marketing arm of Apotex Canada and that
Apotex Canada made the decision “to develop [the drug]
as a generic product for the United States, for Apotex U.S.
to sell in the United States . . . .” See Op. at 12. Fur-
5                               ASTRAZENECA   v. AUROBINDO


thermore, in its brief to this court, Apotex U.S. acknowl-
edged this relationship: “Apotex [U.S.] hopes to market
the product described in the ANDA some day . . . [and]
desire[s] to one day market the product described in the
ANDA . . . .” Appellant’s Reply Br. at 12.
    The district court applied the following legal standard
for determining liability for submission of an ANDA:
    a wholly-owned subsidiary of a foreign ANDA ap-
    plicant, which signs an ANDA as the agent of its
    parent-applicant, and which intends to benefit di-
    rectly if the ANDA is approved -- by participating
    in the manufacture, importation, distribution
    and/or sale of the generic drug -- [is] subject to
    suit under § 271(e) as one who has “submitted” an
    ANDA.
Slip Op. at 8-9 (modification in original). This was a
standard derived from the approach several other district
courts had taken.
    There is some logic to the position that, when such a
related agent expects to financially benefit from the
approval of the ANDA in a significant way, for example by
becoming a major if not sole distributor of the generic
product in the United States, the statute can be under-
stood broadly enough to include such an agent as a statu-
tory “submit[ter].”    Such an agent could thus be
considered a party who may be held liable for the statu-
tory act of infringement by virtue of submission of the
application.1

    1    Apotex U.S.’s effort to divert attention away from
§ 271(e) to other parts of the statutes—including the
provision regarding Paragraph IV certifications and 21
U.S.C. § 355, relating to the New Drug Approval process,
misses the point—it is the scope of “submit” in § 271 that
is the issue.
ASTRAZENECA   v. AUROBINDO                                 6


    Although Apotex U.S. is not a wholly-owned subsidi-
ary of Apotex Canada, they are closely related through a
complex corporate structure.2 Both the statutory analy-
sis suggested here and the evidentiary record in this case
support the district court in bringing Apotex U.S. within
the ambit of the party who submits an ANDA and thus is
subject to liability as a deemed infringer.
    More directly, however, in this case Apotex U.S.
clearly intends to engage in, and presumably submitted
the ANDA for the purpose of, selling the approved drug in
the United States. The statute speaks not only in terms
of engaging in commercial manufacture, but, disjunc-
tively, in terms of engaging in the drug’s “use or sale.” As
an acknowledged sales agent for the primary applicant,
Apotex U.S. can be treated as simply having “submit[ted]”
an application for an ANDA for the purpose of “engag[ing]
in the commercial . . . sale of [the] drug . . . claimed in a
patent.” Under either analysis, the district court did not
err in concluding that Apotex U.S. is liable for an act of
infringement.3




    2    See the district court opinion at 11 for a descrip-
tion of the corporate structure involved.
    3    In finding Apotex U.S. liable as an infringer under
the statute by virtue of its having “submit[ted]” the appli-
cation for the ANDA, we make no judgment regarding
Apotex Canada, who was not a party to this law suit; any
rights or obligations it may have when and if it is brought
into a law suit involving the product that is the subject of
this case are questions for another time.
United States Court of Appeals
    for the Federal Circuit
         __________________________

  IN RE ROSUVASTATIN CALCIUM PATENT
                LITIGATION
          __________________________

      ASTRAZENECA UK LIMITED, IPR
         PHARMACEUTICALS INC.,
AND SHIONOGI SEIYAKU KABUSHIKI KAISHA,
            Plaintiffs-Appellees,
                     v.
      AUROBINDO PHARMA LIMITED,
           Defendant-Appellant,
                    AND

     MYLAN PHARMACEUTICALS INC.,
           Defendant-Appellant,
                    AND

             APOTEX CORP.,
            Defendant-Appellant,
                    AND

COBALT PHARMACEUTICALS INC. AND COBALT
          LABORATORIES INC.,
           Defendants-Appellants,
                    AND

 SUN PHARMACEUTICAL INDUSTRIES, LTD.,
          Defendant-Appellant,
                    AND
ASTRAZENECA   v. AUROBINDO                                2


       TEVA PHARMACEUTICALS USA, INC.,
              Defendant-Appellant,
                             AND

           PAR PHARMACEUTICAL, INC.,
                Defendant-Appellant,
                             AND

                     SANDOZ, INC.,
                       Defendant.
               __________________________

 2010-1460,-1461,-1462,-1463,-1464,-1465,-1466,-1467, -
          1468,-1469,-1470,-1471,-1472,-1473
              __________________________

    Appeal from the United States District Court for the
District of Delaware in case nos. 08-MD-1949, 07-CV-
0810, 07-CV-0805, 07-CV-0809, 07-CV-0811, 07-CV-0806,
08-CV-0426, and 07-CV-0808, Judge Joseph J. Farnan, Jr.
              __________________________

MAYER, Circuit Judge, dissenting.
    I respectfully dissent. There can be no infringement
of U.S. Reissue Patent No. 37,314 (the “’314 patent”)
because that patent is invalid for improper reissue.
Reissue is available under 35 U.S.C. § 251 to rectify an
“error” resulting from inadvertence, accident, or mistake.
No such error was present in U.S. Patent No. 5,260,440
(the “’440 patent”), so there is no basis upon which it
could properly be reissued. Furthermore, Shionogi Sei-
yaku Kabushiki Kaisha (“Shionogi”) has forfeited the
right to obtain reissue by its failure to exercise due dili-
gence in seeking to rectify the alleged defect in the ’440
patent.
3                                 ASTRAZENECA   v. AUROBINDO


                             I.
     “Congress limited reissue to instances where the pat-
entee could demonstrate an ‘error without any deceptive
intention.’” In re Youman, 679 F.3d 1335, 1342 (Fed. Cir.
2012) (quoting 35 U.S.C. § 251); see also In re Serenkin,
479 F.3d 1359, 1363 (Fed. Cir. 2007) (concluding that
reissue was not available where a patentee’s attorney
made a “conscious decision” to accept a later filing date for
his application); Hewlett-Packard Co. v. Bausch & Lomb,
Inc., 882 F.2d 1556, 1565 (Fed. Cir. 1989) (emphasizing
that a party seeking reissue must establish “inadver-
tent error in conduct”); In re Hounsfield, 699 F.2d 1320,
1323 (Fed. Cir. 1983) (explaining that reissue is designed
to “correct an inadvertent error in the original patent”); In
re Whittelsey, 83 F.2d 894, 895 (C.C.P.A. 1936) (conclud-
ing that reissue was improper where “there was no inad-
vertence or mistake” in a patentee’s decision to omit
certain claims from his original application); In re
Murray, 77 F.2d 651, 655 (C.C.P.A. 1935) (explaining that
a patent may not be reissued “for the purpose of correct-
ing errors of judgment”). Prior to 1952, the reissue stat-
ute specifically provided that defects correctible through
reissue were those that had resulted from “inadvertence,
accident, or mistake.” 35 U.S.C. § 64 (1946); In re Weiler,
790 F.2d 1576, 1582 (Fed. Cir. 1986). When it enacted
section 251, the current reissue provision, Congress
intended to retain the “inadvertence, accident, or mis-
take” standard that had existed under the earlier stat-
ute.1 Hewlett-Packard, 882 F.2d at 1565; see In re

    1   Section 251, during the relevant time period, pro-
vided:
    Whenever any patent is, through error without
    any deceptive intention, deemed wholly or partly
    inoperative or invalid, by reason of a defective
    specification or drawing, or by reason of the pat-
ASTRAZENECA   v. AUROBINDO                                 4


Wadlinger, 496 F.2d 1200, 1207 (C.C.P.A. 1974) (empha-
sizing that when Congress substituted the word “error”
for the words “inadvertence, accident, or mistake,” it did
not intend to make “a substantive change”).
     Here, Shionogi made an error in judgment when it
elected to prosecute a broad genus claim which covered
trillions of pyrimidine compounds and which clearly
overlapped with a known prior art reference, European
Published Application No. 0367895 (“Sandoz”). There is
no evidence that the overlap between claim 1 of the ’440
patent and Sandoz was the result of ignorance or inadver-
tence, rather than a deliberate attempt to obtain patent
rights that were as broad in scope as possible. Not a
single inventor or patent prosecutor testified that he or
she unknowingly or inadvertently introduced the overlap
between Sandoz and claim 1. Indeed, the only inventor to
testify at trial, Haruo Koike, stated that he did not believe
that there was any error in the ’440 patent. Joint App.
22763-65.
    It is undisputed that Shionogi was aware of Sandoz
when it prosecuted and obtained the broad claims of the
’440 patent. A June 1991 Shionogi internal search report
identified Sandoz as relevant prior art. In October 1992,

    entee claiming more or less than he had a right to
    claim in the patent, the Director shall, on the sur-
    render of such patent and the payment of the fee
    required by law, reissue the patent for the inven-
    tion disclosed in the original patent, and in accor-
    dance with a new and amended application, for
    the unexpired part of the term of the original pat-
    ent. No new matter shall be introduced into the
    application for reissue.
35 U.S.C. § 251 (emphasis added). Pursuant to the
Leahy-Smith America Invents Act, Pub. L. No. 112-29,
§ 20(d), 125 Stat. 284, 333 (2011), the words “without any
deceptive intention” were deleted from the statute.
5                                ASTRAZENECA   v. AUROBINDO


Shionogi received a European Patent Office (“EPO”)
search report with an attached copy of Sandoz. This
report identified Sandoz as an “X” reference, meaning
that the reference was “particularly relevant if taken
alone.” Shionogi received the EPO search report a second
time when the European counterpart to the ’440 patent
was published in January 1993.
     Tomoko Kitamura, the Shionogi employee who filed
the ’440 application, testified at trial, but never stated
that she misapprehended the Sandoz disclosure or that
she failed to appreciate the overlap between it and claim 1
of the ’440 patent. To the contrary, the record shows that
Shionogi was well aware of Sandoz at the time Kitamura
filed the ’440 application. A November 1991 internal
search report listed Sandoz as relevant prior art and
explained that it disclosed a “pyrimidine skeleton” with
statin activity. Given the obvious overlap between San-
doz and claim 1, it defies credulity to accept that Kita-
mura, who had had several years of experience preparing
and prosecuting patent applications and who holds a
degree in organic chemical synthesis, would fail to appre-
ciate that claim 1 was directed to subject matter previ-
ously disclosed in Sandoz.2
    When Kitamura left Shionogi in July 1992, Takashi
Shibata assumed primary responsibility for prosecution of
the ’440 application. Shibata received the EPO search
report declaring Sandoz to be “particularly relevant”
stand-alone prior art. Shibata, moreover, specifically

    2   At trial, Kitamura stated that she believed that
none of the prior art cited in internal search reports
raised “patentability concerns” with respect to Shionogi’s
pyrimidine statins. Joint App. 21458. Contrary to the
majority’s assertions, ante at 21, however, Kitamura
never testified that she failed to appreciate that claim 1 of
the ’440 patent overlapped with Sandoz.
ASTRAZENECA   v. AUROBINDO                                  6


instructed Shionogi scientists to test and compare the
preferred compounds disclosed in Sandoz with those
disclosed in the ’440 application. Although Shibata
testified at trial, he, like Kitamura, never stated that he
failed to appreciate the scope of the invention disclosed in
the ’440 patent or that he was unaware of the obvious
overlap between claim 1 and Sandoz.
    In 1997, Shionogi and Zeneca Limited (“Zeneca”)3 en-
tered into discussions regarding a licensing agreement
that would allow Zeneca to commercialize rosuvastatin,
the most promising compound disclosed in the ’440 pat-
ent. During these negotiations, Zeneca raised concerns
that Sandoz was potentially invalidating prior art. Joint
App. 2285-86. In response, Shionogi conceded that it “had
been aware of [Sandoz] . . . prior to filing the [’440 appli-
cation]” and that there was an overlap between claim 1 of
the ’440 patent and “the disclosure and claims of [San-
doz].” Id. at 2290. Shionogi asserted, however, that “not
so much attention was paid” to Sandoz because it believed
that rosuvastatin “did not fall within the scope of [San-
doz].” Id. Significantly, when responding to Zeneca’s
invalidity concerns, Shionogi did not assert that it had
previously misunderstood the scope of the Sandoz disclo-
sure or that it had unintentionally or inadvertently intro-
duced the overlap between Sandoz and claim 1.
    A patentee cannot establish correctible “error” under
section 251 simply by demonstrating that his original
patent contains a defect. Hewlett-Packard, 882 F.2d at
1565 (emphasizing that the fact that a patent is “defec-
tive” does not “give[] rise to an inference of ‘oversight’’’);
Weiler, 790 F.2d at 1582-83 (concluding that reissue was

    3   Zeneca is the predecessor to AstraZeneca UK Lim-
ited.
7                                ASTRAZENECA   v. AUROBINDO


not permitted where a patentee failed to establish that he
had unintentionally omitted subject matter from his
original claims); In re Mead, 581 F.2d 251, 257 (C.C.P.A.
1978) (holding that a “conscious choice” not to file a con-
tinuing application did not constitute correctible error); In
re Byers, 230 F.2d 451, 454 (C.C.P.A. 1956) (emphasizing
that the deliberate amendment of a claim did not consti-
tute correctible error). Instead, reissue is warranted only
where a patentee “supplies . . . facts indicating how . . .
ignorance,” accident, or mistake caused an error in his
claims:
    [The patentee’s] reliance on allegations of the in-
    ventors’ ignorance of drafting and claiming tech-
    nique and counsel’s ignorance of the invention is
    unavailing. Those allegations could be frequently
    made, and, if accepted as establishing error,
    would require the grant of reissues on anything
    and everything mentioned in a disclosure. [The
    patentee] supplies no facts indicating how the ig-
    norance relied on caused any error . . . . [Section]
    251 does not authorize the patentee to re-present
    his application.
Weiler, 790 F.2d at 1583 n.4 (emphasis added); see also In
re Wittry, 489 F.2d 1299, 1302 (C.C.P.A. 1973) (holding
reissue claims invalid where “the declarations [did] not
present any reasonable explanation of any errors in the
original claims which the reissue would overcome”).
    Serenkin, 479 F.3d at 1362-65, is instructive on this
issue. There, a prosecuting attorney chose to accept a
later filing date in exchange for being allowed to include
additional drawings with his application. The patentee
later sought reissue, arguing that his attorney had “made
the wrong procedural choice” by accepting the later filing
date. Id. at 1362. We rejected this argument, explaining
ASTRAZENECA   v. AUROBINDO                               8


that reissue is appropriate where there has been “a genu-
ine error,” but not where a patentee or his attorney has
made “a deliberate, but subsequently found to be disad-
vantageous, choice.” Id. at 1364.
     A similar analysis applies here. Shionogi made an er-
ror in judgment when it prosecuted and maintained a
broad genus claim that clearly overlapped with a known
prior art reference. Absent any evidence showing that
this overlap was the result of inadvertence or mistake,
however, Shionogi had no right to invoke the reissue
process in order to remedy its “deliberate, but subse-
quently found to be disadvantageous, choice.” Id.; Hew-
lett-Packard, 882 F.2d at 1566 (rejecting the argument
that “an error in conduct must be presumed, absent
affirmative evidence that the defect in the patent which is
asserted in the reissue application was intentional”); see
also Youman, 679 F.3d at 1343 (explaining that section
251’s “error” requirement covers “inadvertence or mis-
take,” not “deliberate” choices made by the patentee). As
we have previously made clear, section 251 “was not
enacted as a panacea for all patent prosecution problems,
nor as a grant to the patentee of a second opportunity to
prosecute de novo his original application.” Weiler, 790
F.2d at 1582.
     On appeal, Shionogi argues that the overlap with
Sandoz must have been unintentional because “no ra-
tional patent applicant would intentionally pursue claims
known to be invalid.” This argument is unpersuasive for
two reasons. First, the fact that claim 1 overlapped with
Sandoz did not necessarily render that claim invalid. A
subset of a broad genus of prior art compounds is poten-
tially patentable. See Eli Lilly & Co. v. Bd. of Regents,
334 F.3d 1264, 1270 (Fed. Cir. 2003). Indeed, during the
negotiations with Zeneca, Shionogi’s U.S. patent attorney
stated that claim 1 of the ’440 patent was not necessarily
9                                 ASTRAZENECA   v. AUROBINDO


invalid in view of Sandoz “because it [could] be said that
ours is a selection invention from within the genus of
[Sandoz].” Joint App. 5187.
    Second, patentees not infrequently intentionally draft
very broad independent claims, but “hedge” against
invalidity by drafting narrower dependent claims. See In
re Tanaka, 640 F.3d 1246, 1249-51 (Fed. Cir. 2011). Here,
Shionogi believed that even if the broad genus claim
contained in claim 1 was subsequently found to be invalid,
subgenus claims 2 and 3, which did not overlap with
Sandoz, would protect rosuvastatin, its most important
compound. See Joint App. 20513-15; 8532-37; 20208-09.
                            II.
     In concluding that the ’440 patent was properly reis-
sued, the majority conflates the issue of whether Shionogi
was guilty of inequitable conduct with the question of
whether it met the requirements for reissue under section
251. Shionogi failed to cite any relevant prior art to the
United States Patent and Trademark Office (“PTO”) when
it prosecuted the ’440 application. Indeed, the record
suggests that Shionogi acted with intent to deceive the
PTO when it failed to disclose the highly material Bayer
application, see Japanese Published Patent Application
No. 1989-261377, and the EPO search report identifying
Sandoz as a highly relevant stand-alone prior art refer-
ence. Prior to Therasense, Inc. v. Becton, Dickinson & Co.,
649 F.3d 1276, 1290-93 (Fed. Cir. 2011) (en banc), this
conduct would surely have been censored as fraud on the
patent office. Even accepting arguendo that Shionogi’s
malfeasance was insufficient to satisfy the standard for
inequitable conduct articulated in Therasense, however,
this does not mean that the ’440 patent was validly reis-
sued. Whether Shionogi intended to deceive the PTO by
failing to disclose Sandoz is a wholly separate issue from
ASTRAZENECA   v. AUROBINDO                              10


whether it deliberately introduced an overlap between
Sandoz and the ’440 patent.
    Shionogi asserts that it failed to disclose material
prior art to the PTO because of the “chaos” and “confu-
sion” that ensued after Kitamura resigned in July 1992.
AstraZeneca Pharms. LP v. Mylan Pharms. Inc., 719 F.
Supp. 2d 388, 400 (D. Del. 2010). Kitamura, however, had
already filed the ’440 application—with its overlap with
Sandoz—when she left Shionogi. There is no evidence
that there was any confusion or chaos in the Shionogi
patent department before Kitamura’s departure. Thus,
while confusion within the Shionogi patent department
may have led to the failure to disclose material prior art,
there is no evidence that it led to the overlap between
Sandoz and claim 1.
                             III.
     When Shionogi submitted its reissue application, it
filed a declaration stating that it had “claimed more than
[it] had a right to claim by reason of the disclosure of
[Sandoz].” Joint App. 2812. Shionogi could have reme-
died the overlap with Sandoz by simply revising claim 1.
Instead, however, Shionogi ultimately cancelled all of the
claims of the ’440 patent—including claims 2 and 3 which
did not overlap with Sandoz—and replaced them with
new claims narrowly directed to rosuvastatin. If the
overlap with Sandoz were the result of inadvertence or
mistake and Shionogi was merely attempting to rectify
this alleged error, it presumably would have simply
revised claim 1 and left claims 2 and 3 intact.
    Shionogi’s initial failure to obtain a narrow claim di-
rected to rosuvastatin was not the result of error or mis-
take, but was instead part of a deliberate effort to avoid
alerting Bayer, its competitor, of its interest in the com-
pound. Shionogi was very concerned that if Bayer discov-
11                               ASTRAZENECA   v. AUROBINDO


ered that Shionogi was focusing on rosuvastatin it would
try to include that compound in the claims of its pending
patent application. In a November 1991 memorandum,
for example, Shionogi advised its employees to be “on
maximum alert” to prevent “leaks of secrets relating to
the status of the Shionogi [rosuvastatin] development”
because “Bayer might make an effort to assert” that
rosuvastatin was included within the claims of its pend-
ing application. Joint App. 2241. Indeed, at trial Shibata
acknowledged that Shionogi was concerned “that if Bayer
found out that Shionogi was focusing on [rosuvastatin],
Bayer would try to cover [rosuvastatin] in their pending
. . . application.” Joint App. 20760.
    There is no evidence that the failure to include a
claim directed to rosuvastatin was the result of “error” or
mistake. Instead, the record contains strong evidence
that Shionogi failed to specifically claim rosuvastatin in
order to avoid “tipping off” Bayer about its interest in the
compound.4 It was only after the Bayer application had
been withdrawn that Shionogi decided to add narrow
claims directed to rosuvastatin and its salts.
    Contrary to the majority’s assertions, ante at 19, the
situation presented here is far different from that pre-
sented in Tanaka. There, we concluded that reissue was
proper where a patentee retained his original claims, but
added a narrow dependent claim. 640 F.3d at 1249-51.

     4  Shionogi presents no plausible alternative expla-
nation for its failure to specifically claim rosuvastatin.
Instead, Shionogi argues that it did not attempt to conceal
rosuvastatin from Bayer because rosuvastatin was de-
scribed in the ’440 patent’s specification. Describing a
compound in the examples contained in the specification,
however, is unlikely to be the “red flag” that narrowly
claiming a compound would be, particularly if that com-
pound is the only one specifically claimed.
ASTRAZENECA   v. AUROBINDO                                12


In Tanaka, however, the inventor supported his claim of
error by filing a declaration explaining that he “did not
fully appreciate the process of claiming according to U.S.
practice . . . .” Id. at 1247. Here, by contrast, there is no
evidence that the overlap with Sandoz was due to any
misunderstanding of PTO requirements or procedures.
Shionogi had extensive experience prosecuting U.S.
patents. Indeed, before November 1993 when the ’440
patent issued, Shionogi had applied for and received more
than 200 U.S. patents. Significantly, at approximately
the same time that Kitamura filed the application for the
pyrimidine compounds disclosed in the ’440 patent, she
also filed an application directed to pyrrole statin com-
pounds. This pyrrole application contained a narrow
claim directed to the preferred pyrrole compound. Kita-
mura, therefore, clearly understood how to draft a claim
specifically directed to a preferred compound and yet
failed to do so when she filed the ’440 application.
    “Reissue is an extraordinary procedure and must be
adequately supported by the circumstances detailed in
[section 251].” Ball Corp. v. United States, 729 F.2d 1429,
1435 (Fed. Cir. 1984) (footnote omitted); see also Hewlett-
Packard, 882 F.2d at 1566 (concluding that reissue was
not permitted where a patentee failed to provide an
adequate “explanation of what his error was and how and
why it occurred” (emphasis omitted)). Thus, a reissue
patent is invalid where, as here, a patentee fails to sub-
stantiate assertions of “error” in the original claims. See
Hewlett-Packard, 882 F.2d at 1565 (“[A] reissue applicant
does not make a prima facie case of error in conduct
merely by submitting a sworn statement which parrots
the statutory language.”); Wittry, 489 F.2d at 1302 (con-
cluding that reissue was improper where “the declara-
tions [did] not present any reasonable explanation of any
errors in the original claims which the reissue would
13                               ASTRAZENECA   v. AUROBINDO


overcome”). Here, Shionogi obtained claims which obvi-
ously overlapped with a known prior art reference and
intentionally failed to seek a claim directed to its pre-
ferred compound in order to gain a competitive advantage
in the marketplace. Such machinations constitute an
abuse of the reissue process and are wholly contrary to
the objectives of section 251, a statute predicated “on
fundamental principles of equity and fairness,” Weiler,
790 F.2d at 1579; see also Serenkin, 479 F.3d at 1362
(emphasizing that “the remedial function of the [reissue]
statute is not without limits” and “the deliberate action of
an inventor or attorney during prosecution generally fails
to qualify as a correctable error under § 251”); In re
Harita, 847 F.2d 801, 809 (Fed. Cir. 1988) (“In any given
case, the [reissue] statute should be so applied to the facts
that justice will be done both to the patentee and the
public.”).
    The claims of a validly-issued patent serve an impor-
tant notice function, alerting the public of the metes and
bounds of an inventor’s discovery. See Superior Fireplace
Co. v. Majestic Prods. Co., 270 F.3d 1358, 1371 (Fed. Cir.
2001) (“This court has previously noted the propriety of
independently considering the public notice function in
interpreting the patent statutes.”). This public notice
function will be subverted if the “error” requirement is
read out of the reissue statute and patentees are given
free reign to rewrite their claims whenever they find it
expedient to do so. See Hester Indus., Inc. v. Stein, Inc.,
142 F.3d 1472, 1484 (Fed. Cir. 1998) (“[H]ere, the second
attorney draft[ed] the [reissue] claims nearly a decade
later and with the distinct advantage of having before
him the exact product offered by the now accused in-
fringer.”).
ASTRAZENECA   v. AUROBINDO                               14


                              IV.
    Equity dictates that a patentee exercise due diligence
in seeking to rectify a defect in his patent. See Miller v.
Bridgeport Brass Co., 104 U.S. 350, 351 (1881) (explaining
that where a “mistake was so obvious as to be instantly
discernible on opening the letters-patent,” any right to
have the patent reissued “was abandoned and lost by
unreasonable delay”); Gen. Radio Co. v. Allen B. Dumont
Labs., Inc., 129 F.2d 608, 612 (3d Cir. 1942) (“It has long
been settled that due diligence must be exercised in
discovering a mistake in a patent and that an unreason-
able delay in making application for reissue invalidates
the reissue patent.”). The reasons for requiring prompt
action to correct a patent defect “may be just as great in a
case where the patentee seeks to narrow his claims as
where he seeks to broaden them.” Gen. Radio, 129 F.2d
at 613. Where a patentee unjustifiably delays seeking
reissue of overly broad claims, he “usurp[s] the right of
the public to graze in the field erroneously claimed as a
private preserve.” Principle Bus. Enters., Inc. v. United
States, 7 Cl. Ct. 433, 438 (Cl. Ct. 1985) (citations and
internal quotation marks omitted); Gen. Radio, 129 F.2d
at 613 (emphasizing that failure to take prompt action to
narrow overly broad claims gives a patentee an “unwar-
ranted claim of monopoly”).
    Here, Shionogi learned of the Sandoz reference no
later than June 1991 when an internal search report
issued in connection with the ’440 application identified
Sandoz as relevant prior art. The importance of Sandoz
to the claims of the ’440 patent was made clear when
Shionogi received, in October 1992, the EPO search report
that identified Sandoz as a “particularly relevant” stand-
alone prior art reference. On February 21, 1996, the EPO
rejected many of the claims in the European counterpart
to the ’440 patent based upon Sandoz. Shionogi thereaf-
15                                ASTRAZENECA   v. AUROBINDO


ter narrowed claim 1 in the European application and
added a claim specific to rosuvastatin. It waited for over
two years, however, until August 1998, to seek reissue of
the ’440 patent. Thus, Shionogi maintained the broad
claims of the ’440 patent for more than seven years after
learning of the Sandoz reference, for more than six years
after receiving the EPO report identifying Sandoz as
particularly relevant stand-alone prior art, for more than
five years after issuance of the ’440 patent, and for two
years after surrendering the corresponding claims in the
European application due to the Sandoz reference.5 It has
proffered no adequate justification for its failure to rectify
the alleged error in the ’440 patent in a timely manner.
    “The privilege of correcting an acknowledged error in
[an] original patent may in the public interest be validly
conditioned upon the patentee proceeding promptly.”
Gen. Radio, 129 F.2d at 613. During the years when
Shionogi maintained its overbroad claim, there was
strong and widespread interest in the development of new
and more effective statins. Joint App. 20148-51; 1755-57.
By failing to act promptly to narrow its overbroad claim,
Shionogi deprived the public of the right to experiment
with, and to improve upon, the compounds encompassed
by claim 1.6 Because Shionogi’s delay in seeking to rem-

     5  On appeal, Shionogi asserts that it was not aware
of the overlap between Sandoz and claim 1 until October
1997. This contention is belied by the record. Testimony
at trial established that Shionogi was already aware of
the overlap between Sandoz and claim 1 when it received
the October 1997 letter from Zeneca pointing out this
overlap. Joint App. 20463.
    6   The doctrine of “intervening rights,” see 35 U.S.C.
§ 252, does nothing to protect “the rights of others un-
known who wrongfully may have been deterred because of
the apparent expansiveness of the patent,” Principle Bus.,
7 Cl. Ct. at 438.
ASTRAZENECA   v. AUROBINDO                           16


edy the alleged defect in the ’440 patent was unreason-
able, it has forfeited the right to obtain reissue under
section 251.
