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 Intellectual 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 obviousness-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 commonownership 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 obviousnesstype 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 completed 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 terminal 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 commonly 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 obviousness-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 without 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 (initial) 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 regulation) 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 declaration, which changed their statement of the “error upon 

which reissue is based” to read as follows: 

Original [application] claims 1 and 18-20 were rejected on the ground of non-statutory obviousnesstype double patenting and allowed based on an ineffective, invalid terminal disclaimer. The allowance 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 application. 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 terminal 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 rejected on the ground of non-statutory obviousnesstype double patenting and allowed based on an ineffective, invalid terminal disclaimer. The invalid 

terminal disclaimer renders the patent unenforceable. The patentee presents narrower claims 

based on claims that were not rejected on that basis. 

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 prosecution 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 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, and in accordance with a new and amended application, for 

the unexpired part of the term of the original patent.1

1 The Leahy-Smith America Invents Act amended 

this language by striking “without any deceptive intention,” 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 application (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 applicants’ 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 obviousness-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 prevent 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 arguing, 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 ownership) 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 obviousness-type double-patenting rejection. This argument, 

however, is an insufficient basis for reissue, even if the 

condition of present inability to enforce constitutes inoperativeness 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 claiming, but that “error” be the cause of the infirmity. Section 

251 often applies to applicants’ choices, i.e., their deliberate 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 reissue-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 identified 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 affecting 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 misunderstood “the process of claiming according to U.S. practice”); 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 applications); see also Grant v. Raymond, 31 U.S. 218 (1832)

(allowing correction of a patent where the inventor mistakenly thought specification adequately described invention); In re Rosuvastatin Calcium Patent Litigation, 703 

F.3d 511 (Fed. Cir. 2012) (reissue approved where applicants 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 understanding 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 knowingly 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 restriction, 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 rejection 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 remediable 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 antecedent impossibility being either mutual mistake or unilateral 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,” Restatement (Second) of Contracts § 151, and nowhere do applicants 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 address broader questions about the intersection of reissue

standards and terminal disclaimers. 

CONCLUSION

The Board’s decision rejecting the application for reissue is affirmed.

AFFIRMED