  United States Court of Appeals
      for the Federal Circuit
                ______________________

IN RE MARK T. DINSMORE AND DAVID J. CARUSO
            ______________________

                      2013-1637
                ______________________

    Appeal from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in Serial No.
12/137,662.
                 ______________________

                Decided: June 10, 2014
                ______________________

   ORLANDO LOPEZ, Burns & Levinson LLP, of Boston,
Massachusetts, argued for appellants.

    COKE MORGAN STEWART, Associate Solicitor, United
States Patent and Trademark Office, of Alexandria,
Virginia, argued for appellee. With her on the brief were
NATHAN K. KELLEY, Deputy General Counsel for Intellec-
tual Property Law and Solicitor, and KRISTI L. R. SAWERT,
Associate Solicitor.
                  ______________________

 Before TARANTO, BRYSON, and HUGHES, Circuit Judges.
TARANTO, Circuit Judge.
    Mark Dinsmore and David Caruso (“applicants”), who
are the inventors named in U.S. Patent No. 7,236,568,
applied to reissue the ’568 patent under 35 U.S.C. § 251.
During the patent’s prosecution, they had recorded a
2                                           IN RE: DINSMORE




terminal disclaimer in response to rejections for obvious-
ness-type double patenting. The terminal disclaimer
declares that the ’568 patent “shall be enforceable only for
and during such period” as it is commonly owned with the
patent that underlay the double-patenting rejections. In
their reissue application, the applicants sought to modify
the recorded terminal disclaimer to delete the common-
ownership provision, and to modify the claims that gave
rise to the disclaimer, because the two patents are not
and never have been commonly owned. An examiner in
the Patent and Trademark Office rejected the reissue
application, and the Patent Trial and Appeal Board
affirmed. Ex parte Dinsmore, No. 13-6879, 2013 WL
5274029 (Patent Tr. & App. Bd. June 3, 2013). Because
the applicants have not identified an “error” within the
meaning of section 251, we affirm.
                       BACKGROUND
      The ’568 patent, entitled “Miniature x-ray source with
improved output stability and voltage standoff,” issued on
June 26, 2007, with Mr. Dinsmore and Mr. Caruso listed
as inventors and twX, LLC as the sole assignee. During
prosecution, the examiner, in addition to rejecting all the
filed claims on several prior-art grounds, had rejected
claims 1 and 18-20 of the original application—which
eventually became issued claims 1, 16-17, and 21 of the
’568 patent—“on the ground of nonstatutory obviousness-
type double patenting as being unpatentable over claims
. . . of U.S. Patent No. 6,658,086,” J.A. 553, a 2003 patent
listing Mr. Dinsmore as the sole inventor and a firm
called Carl Zeiss as the sole assignee. The applicants
responded by filing a terminal disclaimer over the ’086
patent, disclaiming any term for the ’568 patent beyond
the expiration date of the ’086 patent, and narrowing all
of the filed claims to overcome other rejections that the
examiner had made under 35 U.S.C. §§ 102 & 103. The
’568 patent then issued.
INRE: DINSMORE                                            3



    To file the terminal disclaimer, the applicants com-
pleted and submitted the PTO’s terminal-disclaimer form,
PTO/SB/26, entitled “Terminal Disclaimer To Obviate A
Double Patenting Rejection Over A ‘Prior’ Patent.” As
required by 37 C.F.R. § 1.321(c)—which addresses termi-
nal disclaimers “filed to obviate [a] judicially created
double patenting” rejection—the applicants’ terminal
disclaimer declares that “any patent so granted on the
instant application shall be enforceable only for and
during such period that it and the prior patent are com-
monly owned.” J.A. 579. It says nothing about who then
actually owned, or will in the future own, the ’086 patent
that gave rise to the disclaimer. In filing the disclaimer,
the applicants stated: “The enclosed terminal disclaimer
in compliance with 37 CFR 1.321(c) overcomes the obvi-
ousness-type double patenting rejection.” J.A. 575. In
allowing the claims, the examiner said that the disclaimer
had been reviewed, accepted, and recorded.
     On June 12, 2008, the applicants applied to reissue all
claims of the ’568 patent under 35 U.S.C. § 251, seeking
simply to remove the recorded terminal disclaimer with-
out substituting a new one or amending any of the claims.
Implementing section 251’s precondition of “error” for
reissue, a PTO regulation required the applicants to file a
reissue declaration that, among other things, identified
“[a]t least one error upon which reissue is based.” 37
C.F.R. § 1.175(a)(1). The applicants stated in their (ini-
tial) declaration that they
   inadvertently and without deceptive intent filed a
   Terminal Disclaimer over [the ’086 patent], which
   was not commonly owned by the owners of [the
   ’568 patent] currently at issue.
J.A. 33. In a non-final office action, the examiner denied
the reissue application “as being based upon a defective
reissue declaration,” “because the error which is relied
4                                           IN RE: DINSMORE




upon . . . is not an error upon which a reissue can be
based.” J.A. 51.
    In October 2009, in response to the non-final rejection,
the applicants petitioned the PTO Commissioner to
permit them to replace the recorded terminal disclaimer
with one identical in every material respect except that it
dropped the original provision (required by PTO regula-
tion) that the ’568 patent could be enforced only when
commonly owned with the ’086 patent. Thus, the term of
the ’568 patent would remain tied to the expiration date
of the ’086 patent. In March 2011, the PTO denied the
petition, and then twice more denied the same request for
relief from the applicants; the applicants did not seek
judicial review of those denials.
     Meanwhile, on October 27, 2009, the applicants had
filed a response to the non-final rejection, under 37 C.F.R.
§ 1.111. They submitted a supplemental reissue declara-
tion, which changed their statement of the “error upon
which reissue is based” to read as follows:
    Original [application] claims 1 and 18-20 were re-
    jected on the ground of non-statutory obviousness-
    type double patenting and allowed based on an in-
    effective, invalid terminal disclaimer. The allow-
    ance of issued claims 1 and 18-20 [sic] based on
    the original claims was in error.
J.A. 75. They also cancelled originally filed claims 1 and
18-20 (issued claims 1, 16-17, and 21) and simultaneously
introduced identical claims as “new” claims 22-25. In
April 2011, the examiner, noting that the revised terminal
disclaimer was not accepted, denied the reissue applica-
tion. The applicants then tried again, this time cancelling
the new claims 22-25, but the examiner issued a final
rejection in September 2011.
    On January 30, 2012, the applicants filed a Request
for Continued Examination, during which they amended
INRE: DINSMORE                                              5



their reissue application in three relevant ways. First,
they cancelled all of the issued claims and added new,
narrower claims—identical to the cancelled claims except
for a single, added limitation. They did so, they said, “as
a hedge against unenforceability,” J.A. 234, presumably
because they believed the narrower claims sufficient to
overcome the obviousness-type double-patenting rejection
without a terminal disclaimer. Second, and on that
apparent premise, they again submitted a modified ter-
minal disclaimer that retained the term limit of the ’568
patent as issued but eliminated the declaration limiting
enforceability to times of common ownership—
presumably now treating as inapplicable the regulatory
subsection, 37 C.F.R. § 1.321(c), that requires such a
declaration “when filed to obviate [an obviousness-type]
double patenting rejection.” Finally, they submitted
another (the third) reissue declaration, stating:
    Original [application] claims 1 and 18-20 were re-
    jected on the ground of non-statutory obviousness-
    type double patenting and allowed based on an in-
    effective, invalid terminal disclaimer. The invalid
    terminal disclaimer renders the patent unenforce-
    able. The patentee presents narrower claims
    based on claims that were not rejected on that ba-
    sis.
J.A. 180. Eventually, the examiner issued a final office
action rejecting all of the pending claims in the reissue
application, once again because “the error identified in the
[reissue] declaration is not an error that can support
reissue.” J.A. 246.
     The applicants appealed to the Board, which affirmed
the examiner, because the “voluntary and intentional
filing of a terminal disclaimer to overcome a non-statutory
obviousness-type double patenting rejection during prose-
cution of the original patent is not an ‘error’ correctible by
reissue under 35 U.S.C. § 251.” Ex parte Dinsmore, No.
6                                           IN RE: DINSMORE




13-6879, 2013 WL 5274029, at *9 (Patent Tr. & App. Bd.
June 3, 2013).
    The applicants timely appealed to this court, which
has jurisdiction under 28 U.S.C. § 1295(a)(4)(A).
                       DISCUSSION
    The applicants argue that, because the ’568 and ’086
patents are not and never have been commonly owned,
the recorded terminal disclaimer was “an ineffective,
invalid terminal disclaimer” and its filing therefore was
an “error” within the meaning of the reissue statute, 35
U.S.C. § 251. Section 251, at the relevant time, read:
    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 pa-
    tentee 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 in-
    vention disclosed in the original patent, and in ac-
    cordance with a new and amended application, for
    the unexpired part of the term of the original pa-
    tent. 1




    1    The Leahy-Smith America Invents Act amended
this language by striking “without any deceptive inten-
tion,” a change that neither party argues is material to
deciding this case. See Pub. L. No. 112-29, § 20, 125 Stat
284, 333-34 (2011). The amendments to section 251 took
effect on September 16, 2012, see id. § 20(l), after the
applicants both filed their reissue application (in June
2008) and requested continued examination of that appli-
cation (in January 2012).
INRE: DINSMORE                                            7



“Determining whether an applicant has met the statutory
requirements of 35 U.S.C. § 251 is a question of law,
which we review de novo.” In re Clement, 131 F.3d 1464,
1468 (Fed. Cir. 1997).
    We affirm the Board’s ruling because the applicants
have not identified an “error” underlying the choices made
in the original patent that they now seek to revise. We
begin with the one clear assertion of error in the appli-
cants’ reissue declarations: that the recorded terminal
disclaimer was ineffective or invalid. That assertion,
however, is simply incorrect in the most straightforward
sense.
    The terminal disclaimer promises that the ’568 patent
“shall be enforceable only for and during such period that
it and the prior patent [i.e., the ’086 patent] are commonly
owned.” J.A. 579. That promise, which is clear on its
face, can readily be given effect: the patent will not be
enforced except when owned by the owner of the ’086
patent. And the applicants, by filing the disclaimer,
achieved the immediate effect of overcoming the obvious-
ness-type double-patenting rejection.
    At the same time, the terminal disclaimer was valid.
The applicants identify nothing missing that was required
or anything included that was forbidden. Under the
relevant PTO regulation, “to obviate judicially created
double patenting in a patent application” a terminal
disclaimer must “[i]nclude a provision that any patent
granted on that application . . . shall be enforceable only
for and during such period that said patent is commonly
owned with the . . . patent which formed the basis” for the
rejection. 37 C.F.R. § 1.321(c). The terminal disclaimer
at issue here did just that: it made the required promise
about what would happen if the two patents at issue were
ever separately owned. It thereby fulfilled a purpose of
the bar on obviousness-type double patenting—“to pre-
vent multiple infringement suits by different assignees
8                                            IN RE: DINSMORE




asserting essentially the same patented invention.” In re
Hubbell, 709 F.3d 1140, 1145 (Fed. Cir. 2013).
    At bottom, therefore, the applicants can only be argu-
ing, more broadly, that the disclaimer was “ineffective” in
the sense that it did not produce a patent they could
actually enforce by themselves (without common owner-
ship) and that they erred in producing that result (which
they deem to be inoperativeness) by choosing to file the
terminal disclaimer in order to include in the ’568 patent,
in their final form, the four claims that led to the obvi-
ousness-type double-patenting rejection. This argument,
however, is an insufficient basis for reissue, even if the
condition of present inability to enforce constitutes inop-
erativeness within the meaning of section 251. It is
ultimately no more than a statement of a now-regretted
choice, because the applicants identify no cognizable false
or deficient understanding of fact or law that underlay the
choice. This is not “error” as required by section 251.
    Section 251 requires not only that the original patent
be “wholly or partly inoperative or invalid,” and that the
inoperativeness or invalidity be by reason of a defective
specification or drawing or unduly broad or narrow claim-
ing, but that “error” be the cause of the infirmity. Section
251 often applies to applicants’ choices, i.e., their deliber-
ate decisions about what to say in their patents, not just
slips of the pen. But not every choice that produces
inoperativeness or invalidity by reason of a specification,
drawing, or claiming problem (within the meaning of
section 251) can qualify. Only choices based on “error”
count.
    Our cases indicate that, for purposes of narrowing re-
issue-qualifying choices to those involving “error,” it is
important whether deficient understandings, by the
applicants or their agents, gave rise to the patenting
choice that reissue is being invoked to correct. In the
authorities that the applicants here feature, false or
INRE: DINSMORE                                           9



inadequate understandings about then-existing facts or
law evidently underlay the aspects of the original patent
sought to be altered by reissue. 2 Most reissue cases
involve no dispute about this basis of “error”: the court
has noted that the typical situations are (for a broadening
reissue) the “post-issuance discovery of attorney error in
understanding the scope of the invention” and (for a
narrowing reissue) the “belated discovery of partially
invalidating prior art.” In re Amos, 953 F.2d 613, 616
(Fed. Cir. 1991); see In re Youman, 679 F.3d 1335, 1342
(Fed. Cir. 2012). On the other hand, we have held reissue
unavailable in several cases where the applicants identi-
fied no deficient understanding behind a choice, not even
(as is common) asserting newly noticed potential problems
as to claim breadth or narrowness or other matters affect-
ing the aspects of the original patent that are the subject


   2     See In re Tanaka, 640 F.3d 1246, 1247-48 (Fed.
Cir. 2011) (applicant’s declaration stated that he misun-
derstood “the process of claiming according to U.S. prac-
tice”); Medrad, Inc. v. Tyco Healthcare Grp. LP, 466 F.3d
1047, 1052-53 (Fed. Cir. 2006) (applicant did not realize
that a supplemental declaration was required); In re Oda,
443 F.2d 1200, 1206 (CCPA 1971) (reissue declaration,
made by all four inventors, stated that errors were made
while translating from corresponding Japanese applica-
tions); see also Grant v. Raymond, 31 U.S. 218 (1832)
(allowing correction of a patent where the inventor mis-
takenly thought specification adequately described inven-
tion); In re Rosuvastatin Calcium Patent Litigation, 703
F.3d 511 (Fed. Cir. 2012) (reissue approved where appli-
cants originally claimed too broadly after not properly
reacting to invalidating prior art, with the error coming
because of “chaos, confusion, and inexperience,” “lack of
legal training” in the patent department, “the changing
and limited personnel within that department,” and
“unintentional miscommunications” between personnel).
10                                          IN RE: DINSMORE




of reissue. In such cases, the reissue application was held
inadequate as being no more than an effort to reverse a
later-regretted choice made in obtaining the original
patent. 3
    A focus on the understandings behind a patentee’s
choices during the patenting process may not resolve all
“error” issues. But that focus suits this case. Here, the
applicants have not identified any deficient understand-
ing as leading to the issuance of original claims 1, 16-17,
and 21 with the terminal disclaimer.
    Thus, the applicants simply have not alleged or shown
that they had a mistaken belief as to the invalidity of
those claims on the cited ground of obviousness-type
double patenting in the absence of the disclaimer or,
therefore, the choice they faced: cancel or sufficiently
modify those claims to avoid the rejection; or file the
disclaimer. They have not alleged or shown that they did,
let alone reasonably could, misunderstand the plain
meaning of the disclaimer. They also have not alleged or
shown that their choice in favor of filing the disclaimer


     3   See In re Serenkin, 479 F.3d 1359, 1364 (Fed. Cir.
2007) (denying reissue where applicant was “fully alert”
to the underlying facts and still “intentionally and know-
ingly surrendered his right to a claim of priority”); In re
Mead, 581 F.2d 251, 257 (CCPA 1978) (no cognizable
error where applicant “knew” or at least “should have
known” of intervening-art risk of choice to break chain of
copendency); In re Orita, 550 F.2d 1277, 1280 (CCPA
1977) (where applicant knowingly acquiesced in re-
striction, no error in resulting patent; later failure “to
timely file a divisional application covering the originally
non-elected subject matter” immaterial to issued patent).
See also Miller v. Bridgeport Brass Co., 104 U.S. 350, 355
(1881) (reissue “can only be done when an actual mistake
has occurred; not from a mere error of judgment”).
INRE: DINSMORE                                           11



resulted from any mistaken belief that the ’568 and ’086
patents were in fact commonly owned. The applicants
never declared, and do not show here, that they believed
that such common ownership existed when they filed the
terminal disclaimer to obtain the ’568 patent.
    From all that appears, the applicants—knowing that
the patents were not commonly owned—intentionally
surrendered a possible right (the ability to obtain all or
some of the ’568 patent claims in a form enforceable
independently of the ’086 patent) in exchange for a benefit
(overcoming an obviousness-type double-patenting rejec-
tion of several of the proposed claims). See, e.g., J.A. 575
(arguing to the examiner that the “terminal disclaimer in
compliance with [37 C.F.R. § 1.321(c)] overcomes the
obviousness-type double patenting rejection”). On the
record of this case, applicants are ultimately seeking
simply to revise a choice they made, not to remedy the
result of a mistaken belief. Theirs is not an error remedi-
able under the reissue statute.
    The applicants argue otherwise by stating that a
“terminal disclaimer is akin to a contract” and that “the
incorrect terminal disclaimer . . . suffers from antecedent
impossibility,” with the “modern designation of anteced-
ent impossibility being either mutual mistake or unilat-
eral mistake.”     Appellants’ Brief at 9-10.      But the
applicants gain nothing from this argument. “A mistake
is a belief that is not in accord with the facts,” Restate-
ment (Second) of Contracts § 151, and nowhere do appli-
cants claim that they filed the terminal disclaimer based
on such a belief. In fact, to the extent that the applicants
were to argue (though they do not) that their error was in
predicting the future behavior of the owner of the ’086
patent, the invocation of mutual-mistake law would
undermine, rather than aid, their case. See id. Comment
a (“A party’s prediction or judgment as to events to occur
in the future, even if erroneous, is not a ‘mistake’ as that
word is defined here.”); Lakeshore Eng’g Servs., Inc. v.
12                                          IN RE: DINSMORE




United States, 2014 WL 1394949, at *8 (Fed. Cir. Apr. 11,
2014).
    The reissue application here does not meet the “error”
requirement of section 251. We therefore need not ad-
dress broader questions about the intersection of reissue
standards and terminal disclaimers.
                       CONCLUSION
    The Board’s decision rejecting the application for reis-
sue is affirmed.
                       AFFIRMED
