Editing MPEP 2300

{{MPEP Chapter|2200|2400}}

'''<big>Chapter 2300 Interference Proceedings</big>'''

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==2301 Introduction==

An interference is a contest under 35 U.S.C. 135(a) 
between an application and either another application 
or a patent. An interference is declared to assist the 
Director of the United States Patent and Trademark 
Office in determining priority, that is, which party 
first invented the commonly claimed invention within 
the meaning of 35 U.S.C. 102(g)(1). See MPEP § 
2301.03. Once an interference has been suggested 
under 37 CFR 41.202, the examiner refers the suggested 
interference to the Board of Patent Appeals 
and Interferences (Board). An administrative patent 
judge declares the interference, which is then administered 
at the Board. A panel of Board members enters 
final judgment on questions of priority and patentability 
arising in an interference.

Once the interference is declared, the examiner 
generally will not see the application again until the 
interference has been terminated. Occasionally, however, 
the Board may refer a matter to the examiner or 
may consult with the examiner on an issue. Given the 
very tight deadlines in an interference, any action on a 
consultation or referral from the Board must occur 
with special dispatch.

The application returns to the examiner after the 
interference has been terminated. Depending on the 
nature of the judgment in the case, the examiner may 
need to take further action in the application. For 
instance, if there are remaining allowable claims, the 
application may need to be passed to issue. The Board 
may have entered a recommendation for further action 
by the examiner in the case. If the applicant has lost 
an issue in the interference, the applicant may be 
barred from taking action in the application or any 
subsequent application that would be inconsistent 
with that loss.

Given the infrequency, cost, and complexity of 
interferences, it is important for the examiner to consult 
immediately with an Interference Practice Specialist 
(IPS) in the examiner’s Technology Center, see 
MPEP § 2302, once a possible interference is identified. 
It is also important to complete examination 
before the possible interference is referred to the 
Board. See MPEP § 2303.



2301.01Statutory Basis [R-4]

35 U.S.C. 102. Conditions for patentability; novelty and 
loss of right to patent.

A person shall be entitled to a patent unless —






 

(g)(1) during the course of an interference conducted under 
section 135 or section 291, another inventor involved therein 
establishes, to the extent permitted in section 104, that before such 
person’s invention thereof the invention was made by such other 
inventor and not abandoned, suppressed, or concealed, or 



35 U.S.C. 104. Invention made abroad.

(a)IN GENERAL.—

(1)PROCEEDINGS.—In proceedings in the Patent and 
Trademark Office, in the courts, and before any other competent 
authority, an applicant for a patent, or a patentee, may not establish 
a date of invention by reference to knowledge or use thereof, 
or other activity with respect thereto, in a foreign country other 
than a NAFTA country or a WTO member country, except as provided 
in sections 119 and 365 of this title.

(2)RIGHTS.—If an invention was made by a person, 
civil or military—

(A)while domiciled in the United States, and serving 
in any other country in connection with operations by or on behalf 
of the United States,

(B)while domiciled in a NAFTA country and serving 
in another country in connection with operations by or on behalf 
of that NAFTA country, or

(C)while domiciled in a WTO member country and 
serving in another country in connection with operations by or on 
behalf of that WTO member country, that person shall be entitled 
to the same rights of priority in the United States with respect to 
such invention as if such invention had been made in the United 
States, that NAFTA country, or that WTO member country, as the 
case may be.

(3)USE OF INFORMATION.—To the extent that any 
information in a NAFTA country or a WTO member country concerning 
knowledge, use, or other activity relevant to proving or 
disproving a date of invention has not been made available for use 
in a proceeding in the Patent and Trademark Office, a court, or 
any other competent authority to the same extent as such information 
could be made available in the United States, the Director, 
court, or such other authority shall draw appropriate inferences, or 
take other action permitted by statute, rule, or regulation, in favor 
of the party that requested the information in the proceeding.

(b)DEFINITIONS.—As used in this section—

(1)The term “NAFTA country” has the meaning given 
that term in section 2(4) of the North American Free Trade Agreement 
Implementation Act; and

(2)The term “WTO member country” has the meaning 
given that term in section 2(10) of the Uruguay Round Agreements 
Act.

35 U.S.C. 135. Interferences.

(a)Whenever an application is made for a patent which, in 
the opinion of the Director, would interfere with any pending 
application, or with any unexpired patent, an interference may be 
declared and the Director shall give notice of such declaration to 
the applicants, or applicant and patentee, as the case may be. The 
Board of Patent Appeals and Interferences shall determine questions 
of priority of the inventions and may determine questions of 
patentability. Any final decision, if adverse to the claim of an 
applicant, shall constitute the final refusal by the Patent and 
Trademark Office of the claims involved, and the Director may 
issue a patent to the applicant who is adjudged the prior inventor. 
A final judgment adverse to a patentee from which no appeal or 
other review has been or can be taken or had shall constitute cancellation 
of the claims involved in the patent, and notice of such 
cancellation shall be endorsed on copies of the patent distributed 
after such cancellation by the Patent and Trademark Office.







2301.02Definitions [R-4]

37 CFR 41.2. Definitions.

 Unless otherwise clear from the context, the following definitions 
apply to proceedings under this part:

Affidavit means affidavit, declaration under § 1.68 of this title, 
or statutory declaration under 28 U.S.C. 1746. A transcript of an 
ex parte deposition may be used as an affidavit in a contested case.

Board means the Board of Patent Appeals and Interferences 
and includes:

(1)For a final Board action:

(i)In an appeal or contested case, a panel of the Board.

(ii)In a proceeding under § 41.3, the Chief Administrative 
Patent Judge or another official acting under an express delegation 
from the Chief Administrative Patent Judge.

(2)For non-final actions, a Board member or employee acting 
with the authority of the Board.

Board member means the Under Secretary of Commerce for 
Intellectual Property and Director of the United States Patent and 
Trademark Office, the Deputy Under Secretary of Commerce for 
Intellectual Property and Deputy Director of the United States 
Patent and Trademark Office, the Commissioner for Patents, the 
Commissioner for Trademarks, and the administrative patent 
judges.

Contested case means a Board proceeding other than an appeal 
under 35 U.S.C. 134 or a petition under § 41.3. An appeal in an 
inter partes reexamination is not a contested case.

Final means, with regard to a Board action, final for the purposes 
of judicial review. A decision is final only if:

(1)In a panel proceeding. The decision is rendered by a 
panel, disposes of all issues with regard to the party seeking judicial 
review, and does not indicate that further action is required; 
and

(2)In other proceedings. The decision disposes of all issues 
or the decision states it is final.

Hearing means consideration of the issues of record. Rehearing 
means reconsideration.

Office means United States Patent and Trademark Office.

Panel means at least three Board members acting in a panel 
proceeding.

Panel proceeding means a proceeding in which final action is 
reserved by statute to at least three Board members, but includes a 




 

non-final portion of such a proceeding whether administered by a 
panel or not.

Party, in this part, means any entity participating in a Board 
proceeding, other than officers and employees of the Office, 
including:

(1)An appellant;

(2)A participant in a contested case;

(3)A petitioner; and

(4)Counsel for any of the above, where context permits.

37 CFR 41.100. Definitions.

 In addition to the definitions in § 41.2, the following definitions 
apply to proceedings under this subpart:

Business day means a day other than a Saturday, Sunday, or 
Federal holiday within the District of Columbia.

Involved means the Board has declared the patent application, 
patent, or claim so described to be a subject of the contested case.

37 CFR 41.200. Procedure; pendency.

(a)A patent interference is a contested case subject to the 
procedures set forth in subpart D of this part.

(b)A claim shall be given its broadest reasonable construction 
in light of the specification of the application or patent in 
which it appears.

(c)Patent interferences shall be administered such that pendency 
before the Board is normally no more than two years.

37 CFR 41.201. Definitions.

 In addition to the definitions in §§ 41.2 and 41.100, the following 
definitions apply to proceedings under this subpart:

Accord benefit means Board recognition that a patent application 
provides a proper constructive reduction to practice under 35 
U.S.C. 102(g)(1).

Constructive reduction to practice means a described and 
enabled anticipation under 35 U.S.C. 102(g)(1) in a patent application 
of the subject matter of a count. Earliest constructive 
reduction to practice means the first constructive reduction to 
practice that has been continuously disclosed through a chain of 
patent applications including in the involved application or patent. 
For the chain to be continuous, each subsequent application must 
have been co-pending under 35 U.S.C. 120 or 121 or timely filed 
under 35 U.S.C. 119 or 365(a).

 Count means the Board’s description of the interfering subject 
matter that sets the scope of admissible proofs on priority. Where 
there is more than one count, each count must describe a patentably 
distinct invention.

Involved claim means, for the purposes of 35 U.S.C.135(a), a 
claim that has been designated as corresponding to the count.

 Senior party means the party entitled to the presumption under 
§ 41.207(a)(1) that it is the prior inventor. Any other party is a junior 
party.

 Threshold issue means an issue that, if resolved in favor of the 
movant, would deprive the opponent of standing in the interference. 
Threshold issues may include:

(1)No interference-in-fact, and 

(2)In the case of an involved application claim first made 
after the publication of the movant’s application or issuance of the 
movant’s patent:

(i)Repose under 35 U.S.C. 135(b) in view of the 
movant’s patent or published application, or 

(ii)Unpatentability for lack of written description under 
35 U. S.C. 112(1) of an involved application claim where the 
applicant suggested, or could have suggested, an interference 
under § 41.202(a).



2301.03Interfering Subject Matter [R-4]

37 CFR 41.203. Declaration.

(a)Interfering subject matter. An interference exists if the 
subject matter of a claim of one party would, if prior art, have 
anticipated or rendered obvious the subject matter of a claim of 
the opposing party and vice versa.



A claim of one inventor can be said to interfere 
with the claim of another inventor if they each have a 
patentable claim to the same invention. The Office 
practice and the case law define “same invention” to 
mean patentably indistinct inventions. Case v. CPC 
Int’l, Inc., 730 F.2d 745, 750, 221 USPQ 196, 200 
(Fed. Cir. 1984); Aelony v. Arni, 547 F.2d 566, 570, 
192 USPQ 486, 489-90 (CCPA 1977); Nitz v. Ehrenreich, 
537 F.2d 539, 543, 190 USPQ 413, 416 (CCPA 
1976); Ex parte Card, 1904 C.D. 383, 384-85 
(Comm’r Pats. 1904). If the claimed invention of 
either party is patentably distinct from the claimed 
invention of the other party, then there is no interference-
in-fact. Nitz v. Ehrenreich, 537 F.2d 539, 543, 
190 USPQ 413, 416 (CCPA 1976). 37 CFR 41.203(a) 
states the test in terms of the familiar concepts of 
obviousness and anticipation. Accord Eli Lilly & Co. 
v. Bd. of Regents of the Univ. of Wa., 334 F.3d 1264, 
1269-70, 67 USPQ2d 1161, 1164-65 (Fed. Cir. 2003) 
(affirming the Office’s interpretive rule).

Identical language in claims does not guarantee that 
they are drawn to the same invention. Every claim 
must be construed in light of the application in which 
it appears. 37 CFR 41.200(b). Claims reciting means-
plus-function limitations, in particular, might have 
different scopes depending on the corresponding 
structure described in the written description.

When an interference is declared, there is a description 
of the interfering subject matter, which is called a 
“count.” Claim correspondence identifies claims that 
would no longer be allowable or patentable to a party 
if it loses the priority determination for the count. To 
determine whether a claim corresponds to a count, the 




 

subject matter of the count is assumed to be prior art 
to the party. If the count would have anticipated or 
supported an obviousness determination against the 
claim, then the claim corresponds to the count. 37 
CFR 41.207(b)(2). Every count must have at least one 
corresponding claim for each party, but it is possible 
for a claim to correspond to more than one count.

Example 1

A patent has a claim to a compound in which R is 
an alkyl group. An application has a claim to the 
same compound except that R is n-pentyl, which is 
an alkyl. The application claim, if prior art to the 
patent, would have anticipated the patent claim. 
The patent claim would not have anticipated the 
application claim. If, however, in the art n-pentyl 
would have been an obvious choice for alkyl, then 
the claims define interfering subject matter.

Example 2

An application has a claim to a boiler with a novel 
safety valve. A patent has a claim to just the safety 
valve. The prior art shows that the need for boilers 
to have safety valves is well established. The 
application claim, when treated as prior art, would 
have anticipated the patent claim. The patent 
claim, when treated as prior art and in light of the 
boiler prior art, can be shown to render the application 
claim obvious. The claims interfere.

Example 3

An application has a claim to a reaction using platinum 
as a catalyst. A patent has a claim to the 
same reaction except the catalyst may be selected 
from the Markush group consisting of platinum, 
niobium, and lead. Each claim would have anticipated 
the other claim when the Markush alternative 
for the catalyst is platinum. The claims 
interfere.

Example 4

Same facts as Example 3, except the applicant has 
a Markush group for the catalyst consisting of platinum, 
osmium, and zinc. Each claim would have 
anticipated the other claim when the Markush 
alternative for the catalyst in each claim is platinum. 
The claims interfere.

Example 5

An application has a claim to a protein with a specific 
amino acid sequence shown in SEQ ID NO:1. 
A patent has a claim to the genus of polynucleotides 
defined as encoding the same amino acid 
sequence as the applicant’s SEQ ID NO:1. The 
patent claim would have anticipated the application 
claim since it expressly describes an amino 
acid sequence identical to the protein of the application. 
The application claim would have rendered 
the patent claim obvious in light of a well-established 
relationship between nucleic acids for 
encoding amino acids in protein sequences. The 
claims interfere.

Example 6

A patent has a claim to a genus of polynucleotides 
that encode a protein with a specific amino acid 
sequence. An application has a claim to a polynucleotide 
that encodes a protein with the same 
amino acid sequence. The application claim is a 
species within the genus and thus would have 
anticipated the patent claim. The patent claim 
would not have anticipated or rendered the application 
claim obvious without some explanation of 
why a person having ordinary skill in the art would 
have selected the applicant’s species from the patentee’s 
genus. Generally the explanation should 
include citation to prior art supporting the obviousness 
of the species. Without the explanation, the 
claims do not interfere.

Example 7

A patent and an application each claim the same 
combination including “means for fastening.” The 
application discloses glue for fastening, while the 
patent discloses a rivet for fastening. Despite otherwise 
identical claim language, the claims do not 
interfere unless it can be shown that in this art glue 
and rivets were considered structurally equivalent 
or would have rendered each other obvious.

Example 8

A patent claims a formulation with the surfactant 
sodium lauryl sulfate. An application claims the 
same formulation except no specific surfactant is 
described. The application discloses that it is well 
known in the art to use sodium lauryl sulfate as the 
surfactant in these types of formulations. The 
claims interfere.




 

Example 9

An applicant has a claim to a genus and a species 
within the genus. The interference is declared with 
two counts, one directed to the genus and one 
directed to the species. The species claim would 
correspond to the species count because the count 
would have anticipated the claimed subject matter. 
The genus count would not ordinarily have anticipated 
the species claim, however, so the species 
claim would only correspond to the genus count if 
there was a showing that the genus count would 
have rendered the claimed species obvious. The 
genus claim, however, would have been anticipated 
by both the genus count and the species 
count and thus would correspond to both counts. 



2302Consult an Interference Practice 
Specialist [R-4]

Every Technology Center (TC) has at least one 
Interference Practice Specialist (IPS), who must be 
consulted when suggesting an interference to the 
Board of Patent Appeals and Interferences (Board).

Less than one percent of all applications become 
involved in an interference. Consequently, examiners 
are not expected to become experts in interference 
practices. Instead, examiners are expected to be proficient 
in identifying potential interference and to consult 
with an IPS in their TC on interference matters. 
The IPS, in turn, is knowledgeable about when and 
how to suggest interferences, how to handle inquiries 
to and from the Board before and during interferences, 
and how to handle applications after interferences 
are completed.

An IPS must approve any referral of a suggested 
interference to the Board. The referral must include a 
completed Form PTO-850, which either an IPS or a 
Director of the examiner’s TC must sign.

IPSs consult with administrative patent judges 
(APJs) that declare interferences to stay current in 
interference practice. When necessary, an IPS may 
arrange for a consultation with an APJ to discuss a 
suggested interference or the effect of a completed 
interference. Examiners must promptly address 
inquiries or requests from an IPS regarding a suggested 
interference.




 

Do Not Scan - Predecisional Memorandum
Suggested Interfernce Referral





 

GENERAL PRACTICES

Practice 1. Consult an Interference Practice 
Specialist.

In an effort to maximize uniformity, when an examiner 
first becomes aware that a potential interference 
exists or any other interference issue arises during 
prosecution of an application, the examiner should 
bring the matter to the attention of an IPS in the examiner’s 
TC. 

The IPS in turn will consult with an APJ designated 
from time to time by the Chief Administrative Patent 
Judge.

A plan of action will be developed on a case-by-
case basis.

Practice 2. Party not in condition for allowance.

When:

(A)a first application and a second application 
claim the same patentable invention; and

(B)a first application is in condition for allowance; 
and 

(C)the second application is not in condition for 
allowance, 

then generally a notice of allowance should be entered 
in the first application and it should become a patent.

Without suspending action in the first application 
and after consultation consistent with Practice 1 
above, the examiner may wish to give the second 
applicant a very brief period of time within which to 
put the second application in condition for allowance, 
e.g., by canceling rejected claims thereby leaving only 
allowable claims which interfere with the claims of 
the first application.

When examination of the second application is 
complete, an application versus patent interference 
may be appropriate.

Practice 3. Both in condition for allowance; earliest 
effective filing dates within six months. 

When two applications are in condition for allowance 
and the earliest effective filing dates of the applications 
are within six months of each other, an 
application versus application interference may be 
suggested, provided the applicant with the later filing 
date makes the showing required by 37 CFR 
41.202(d). Note that if the earliest filed application is 
available as a reference (for example, as a published 
application under 35 U.S.C. 102(e)) against the other 
application, then a rejection should be made against 
the other application. Ideally, the rejection would be 
made early in the prosecution, but if it is not and as a 
result the junior application is not in condition for 
allowance, then the senior application should be 
issued. In light of patent term adjustments it is no 
longer appropriate to suspend an application on the 
chance that an interference might ultimately result.

Practice 4. Both in condition for allowance; earliest 
effective filing dates not within six months.

If the applications are both in condition for allowance 
and earliest effective filing dates of the applications 
are not within six months of each other, the 
application with the earliest effective filing date shall 
be issued. The application with the later filing date 
shall be rejected on the basis of the application with 
the earliest effective filing date. Further action in the 
application with the later filing date will be governed 
by prosecution in that application. If the applicant in 
the application with the later filing date makes the 
showing required by 37 CFR 41.202(d), an application 
versus patent interference may be declared. If no 
rejection is possible over the patent issuing from the 
application with the earliest effective filing date, then 
the applicant must still be required under 35 U.S.C. 
132 to make the priority showing required in 37 CFR 
41.202(d).

Practice 5. Suspension discouraged.

Suspension of prosecution pending a possible interference 
should be rare and should not be entered prior 
to the consultation required by Practice 1 above.



2303Completion of Examination [R-4]

37 CFR 41.102. Completion of examination.

 Before a contested case is initiated, except as the Board may 
otherwise authorize, for each involved application and patent:

(a)Examination or reexamination must be completed, and

(b)There must be at least one claim that:

(1)Is patentable but for a judgment in the contested case, 
and

(2)Would be involved in the contested case.

An interference should rarely be suggested until 
examination is completed on all other issues. Each 




 

pending claim must be allowed, finally rejected, or 
canceled. Any appeal from a final rejection must be 
completed, including any judicial review. Any petition 
must be decided.

Example 1

An applicant has one allowed claim directed to 
invention A, which is the same invention of 
another inventor within the meaning of 35 U.S.C. 
102(g)(1), and has rejected claims directed to different 
invention B. If the rejection is contested, the 
application is not yet ready for an interference. 
Restriction of the application to invention A, followed 
by cancellation of the claims directed to 
invention B would remove this impediment to 
declaring an interference.

Example 2

A patent has a claim to a species. An applicant has 
claims to the species and to a genus that includes 
the species. The examiner has allowed the species 
claim, but rejected the genus claim. The applicant 
suggests an interference with the patent. The interference 
will generally not be declared until the 
applicant resolves the status of the genus claim by, 
for example, appealing the rejection or canceling 
the rejected claim. An applicant may expedite the 
process of having the interference declared by canceling 
the genus claim from the application.

Two grounds of unpatentability receive particularly 
close scrutiny before an interference is declared. 
Enforcement of the written description requirement 
under 35 U.S.C. 112, first paragraph and the late 
claiming bars under 35 U.S.C. 135(b) are important to 
preserve the efficiency and integrity of interferences. 
37 CFR 41.201, “Threshold issue.” See, e.g., Berman 
v. Housey, 291 F.3d 1345, 1354, 63 USPQ2d 1023, 
1029 (Fed. Cir. 2002).

RESTRICTION IN APPLICATIONS WITH 
INTERFERING CLAIMS

Ordinarily restrictions are limited to situations 
where (A) the inventions are independent or distinct 
as claimed, and (B) there would be a serious burden 
on the examiner if restriction is not required (see 
MPEP §
 
803). Potential interferences present an additional 
situation in which a restriction requirement may 
be appropriate. Specifically, restriction of interfering 
claims from non-interfering claims, or from unpatentable 
claims whose further prosecution would unduly 
delay initiation of an interference, can be an appropriate 
use of restrictions under 35 
U.S.C. 121. An Interference 
Practice Specialist (IPS) should be consulted 
in making and resolving restrictions under this heading. 
An applicant may, of course, also choose to cancel 
claims and refile them in a continuation 
application without waiting for the restriction requirement.


A.Non-Interfering Claims

Patent term adjustments are available for patents 
whose issuance has been delayed for an interference. 
35 
U.S.C. 154(b)(1)(C)(i). A claim that does not interfere, 
by definition, is directed to a patentably distinct 
invention compared to a claim that does interfere. 
Leaving a non-interfering claim in an application 
going into an interference creates an unwarranted 
delay in the issuance of claims to the non-interfering 
subject matter. As far as the public and the Office are 
concerned, there is no justification for not issuing the 
non-interfering claims promptly. An exception exists 
if the claims are already term limited, as would be the 
case for an application subject to a terminal disclaimer 
or a reissue application (see 35 
U.S.C. 
154(b)(1)(C) (referring to issuance of the original 
patent)).

If an application contains both interfering and non-
interfering claims, a restriction requirement should be 
made between the two. If the applicant traverses the 
restriction requirement, depending on the reasons for 
the traversal, the restriction may be maintained or the 
traversal may be treated as a concession that the non-
interfering claims should be designated as corresponding 
to the count.

B.Unpatentable Claims

Ordinarily restriction of claims simply because they 
are not patentable would not be appropriate. If, however, 
(A)
 
prosecution of the unpatentable claims to 
completion would unduly delay initiation of the interference 
and (B)
 
the delay would create prejudice to 
another stakeholder, such as another applicant or the 
public, a restriction requirement may be appropriate. 
Approval of an IPS is required before this restriction 
requirement may be made.




 

Example

An applicant has both broad and narrow claims. 
The narrow claims are plainly supported, but the 
support for the broad claims is contested. A patent 
with claims to the narrow invention issues to 
another inventor with a much later earliest effective 
filing date. Delay of the interference until the 
patentability of the broader claims is resolved may 
unduly prejudice the patentee and the public by 
leaving a cloud of doubt hanging over the patent 
claims.

If the unpatentable application claims are eventually 
prosecuted to allowance, the examiner should 
consult with the IPS regarding the status of the 
interference in case the claims would be affected 
by the outcome of the interference.

C.Reissue Applications

As explained above, reissue applications are not 
subject to patent term adjustments. Applicants sometimes, 
however, file reissue applications to amend 
patent claims in response to events occurring in the 
interference. To maintain parity with other applicants, 
the Board does not permit reissue applicants to add 
claims that would not correspond to a count. Winter v. 
Fujita, 53 
USPQ2d 1234, 1249 (Bd. Pat. App. & 
Inter. 1999). Since the burden lies with the reissue 
applicant to comply with Winter, the examiner need 
not require restriction of the non-interfering claims. 
Practice under Winter, however, may explain why 
some reissue applicants file more than one reissue 
application for the same patent.

Form paragraph 23.01 may be used to acknowledge 
a request for interference that is premature since 
examination of the application has not been completed.


¶ 23.01 Request for Interference Premature; Examination 
Not Completed

The request for interference filed [1] is acknowledged. However, 
examination of this application has not been completed as 
required by 37 CFR 41.102(a). Consideration of a potential interference 
is premature. See MPEP § 2303.





2303.01Issuance and Suspension [R-4]

Since applicants may be eligible for patent term 
adjustments to offset delays in examination, 35 U.S.C. 
154(b)(1), it is important that suspensions should 
rarely, if ever, be used and that applications with 
allowed claims be issued to the greatest extent possible.


Example 1

A claim of patent A and a claim of application B 
interfere. Examination of application B is completed. 
An interference may not be declared 
between two patents. 35 U.S.C. 135(a). Consequently, 
the interfering claim in application B 
should not be passed to issue, even if it has an earlier 
effective filing date than patent A. Instead, an 
interference should be suggested.

Example 2

Two applications, C and D, with interfering claims 
are pending. Examination of application C is completed 
and all claims are allowable. Examination 
of application D is not completed. Application C 
should be issued promptly. If application C has an 
earlier effective U.S. filing date when issued as 
patent C, or when published as application publication 
C, it may be available as prior art under 35 
U.S.C. 102(e) against application D. However, 
even if application C’s effective filing date is later 
than application D’s effective filing date, application 
C should issue. Until examination of application 
D is completed, it is not known whether 
application D should be in interference with application 
C, so suspension of application C will 
rarely, if ever, be justified.

Example 3

Two applications, E and F, with interfering claims 
are pending. Both are ready to issue. (Such ties 
should be extremely rare; suspensions must not be 
used to create such ties.) If the applications have 
their earliest effective filing dates within six 
months of each other, then an interference may be 
suggested. If, however, application E’s earliest 
effective filing date is more than six months before 
application F’s earliest effective filing date, then 
application E should issue. If application E (or the 
resulting patent E) is available as prior art (under 
35 U.S.C. 102(a) or 102(e)) against application F, 
then a rejection should be made. If not, a requirement 
under 37 CFR 41.202(d) to show priority 
should be made. See MPEP § 2305.




 



2303.02Other Outstanding Issues with 
Patents [R-4]

Patents that are undergoing reexamination or reissue 
are subject to the requirement of 37 CFR 41.102that examination be completed. Patents may, however, 
be the subject of other proceedings before the Office. 
For instance, a patent may be the subject of a petition 
to accept a late maintenance fee, 35 U.S.C. 41(c), or a 
request for disclaimer or correction. 35 U.S.C. 253 to 
256. Such issues must be resolved before an interference 
is suggested because they may affect whether or 
how an interference may be declared.

Example 1

A patent maintenance fee has not been timely paid. 
By operation of law, 35 U.S.C. 41(b), the patent is 
considered to be expired. An interference cannot 
be declared with an expired patent. 35 U.S.C. 
135(a). Consequently, if a petition to accept 
delayed payment is not granted, 37 CFR 1.378, 
then no interference can be declared.

Example 2

A disclaimer under 35 U.S.C. 253, is filed for the 
sole patent claim directed to the same invention as 
the claims of the applicant. Since the patentee and 
applicant must both have claims to the same invention, 
35 U.S.C. 102(g)(1), no interference can be 
declared.

Example 3

Similar to Example 2, a request for correction 
under 35 U.S.C. 254 or 255, is filed that results in 
a change to the sole patent claim such that it is no 
longer directed to the same invention as any claim 
of the applicant. Again, since the patentee and 
applicant must both have claims to the same invention, 
35 U.S.C. 102(g)(1), no interference can be 
declared.

Example 4

Inventorship is corrected such that the inventors 
for the patent and the application are the same. 
Since 35 U.S.C. 102(g)(1) requires the interference 
to be with “another inventor,” the correction 
eliminates the basis for an interference. Other 
rejections, such as a double-patenting rejection 
may be appropriate.



2304Suggesting an Interference [R-4]

The suggestion for an interference may come from 
an applicant or from an examiner. Who suggests the 
interference determines what must be done and shown 
prior to declaration of an interference. In either circumstance, 
the examiner must consult with an Interference 
Practice Specialist (IPS), who may then refer 
the suggested interference to the Board of Patent 
Appeals and Interferences.



2304.01Preliminaries to Referring an 
Interference to the Board [R-4]





2304.01(a)Interference Search [R-4]

When an application is in condition for allowance, 
an interference search must be made by performing a 
text search of the “US-PGPUB” database in EAST or 
WEST directed to the comprehensive inventive features 
in the broadest claim. If the application contains 
a claim directed to a nucleotide or peptide sequence, 
the examiner must submit a request to STIC to perform 
an interference search of the sequence. If the 
search results identify any potential interfering subject 
matter, the examiner will review the application(s) 
with the potential interfering subject to determine 
whether interfering subject matter exists. If interfering 
subject matter does exist, the examiner will follow the 
guidance set forth in this chapter. If there is no interfering 
subject matter then the examiner should prepare 
the application for issuance. A printout of only 
the database(s) searched, the query(ies) used in the 
interference search, and the date the interference 
search was performed must be made of record in the 
application file. The results of the interference search 
must not be placed in the application file.

The search for interfering applications must not be 
limited to the class or subclass in which the application 
is classified, but must be extended to all classes, 
in and out of the Technology Center (TC), in which it 
has been necessary to search in the examination of the 
application. See MPEP § 1302.08.




 



2304.01(b)Obtaining Control Over Involved 
Files [R-4]

Ordinarily applications that are believed to interfere 
should be assigned to the same examiner.

I.IN DIFFERENT TECHNOLOGY CENTERS


If the interference would be between two applications, 
and the applications are assigned to different 
Technology Centers (TCs), then one application must 
be reassigned. Ordinarily the applications should both 
be assigned to the TC where the commonly claimed 
invention would be classified. After termination of the 
interference, further transfer may be appropriate 
depending on the outcome of the interference.

II.PAPERS NOT CONVERTED TO IMAGE 
FILE WRAPPER FILES

Although the official records for most applications 
have been converted into Image File Wrapper (IFW) 
files, some records exist only in paper form, particularly 
older benefit application files. Even IFW files 
may have artifact records that have not been converted. 
Complete patent and benefit files are necessary 
for determining whether benefit should be 
accorded for purposes of 35 U.S.C. 102(g)(1). A suggested 
interference must not be referred to the Board 
of Patent Appeals and Interferences (Board) if all 
files, including benefit files, are not available to the 
examiner in either IFW format or paper.

If a paper file wrapper has been lost, it must be 
reconstructed before the interference is referred to the 
Board.

III.PATENT COOPERATION TREATY APPLICATION 
FILES

Generally, a separate application file for a Patent 
Cooperation Treaty (PCT) application is not required 
for according benefit because the PCT application is 
included in a national stage application file that is 
itself either the application involved in the interference 
or a benefit file. Occasionally, however, the PCT 
application file itself is required for benefit. For 
instance, if benefit is claimed to the PCT application, 
but not to a national stage application in which it is 
included, then the PCT application file must be 
obtained.



2304.01(c)Translation of Foreign Benefit 
Application [R-4]

A certified translation of every foreign benefit 
application or Patent Cooperation Treaty (PCT) application 
not filed in English is required. 35 U.S.C. 
119(b)(3) and 372(b)(3) and 37 CFR 1.55(a)(4). If no 
certified translation is in the official record for the 
application, the examiner must require the applicant 
to file a certified translation. The applicant should 
provide the required translation if applicant wants the 
application to be accorded benefit of the non-English 
language application. Any showing of priority that 
relies on a non-English language application is prima 
facie insufficient if no certified translation of the 
application is on file. 37 CFR 41.154(b) and 
41.202(e).

Form paragraph 23.19 may be used to notify applicant 
that a certified English translation of the priority 
document is required.

¶ 23.19 Foreign Priority Not Substantiated

Should applicant desire to obtain the benefit of foreign priority 
under 35 U.S.C. 119(a)-(d) prior to declaration of an interference, 
a certified English translation of the foreign application must be 
submitted in reply to this action, 37 CFR 41.154(b) and 41.202(e).

Failure to provide a certified translation may result in no benefit 
being accorded for the non-English application.





2304.01(d)Sorting Claims [R-4]

An applicant may be entitled to a day-for-day 
patent term adjustment for any time spent in an interference. 
If an applicant has several related applications 
with interfering claims intermixed with claims 
that do not interfere, the examiner should consider 
whether the interfering claims should be consolidated 
in a single application or whether an application 
should be restricted to claims that do not interfere. 
This way examination can proceed for any claims that 
do not interfere without the delay that will result from 
the interference.

Interfering claims of an applicant are “conflicting 
claims” within the meaning of 37 CFR 1.78(b). The 




 

examiner may require consolidation of such claims 
into any disclosure of the applicant that provides support 
for the claims. 35 U.S.C. 132(a).

Similarly, the examiner should require an applicant 
to restrict an application to the interfering claims, 35 
U.S.C. 121, in which case the applicant may file a 
divisional application for the claims that do not interfere.


Sorting of claims may not be appropriate in all 
cases. For instance, a claim should not be consolidated 
into an application that does not provide support 
under 35 U.S.C. 112, first paragraph for the claim.



2304.02Applicant Suggestion [R-4]

37 CFR 41.202. Suggesting an interference.

(a)Applicant. An applicant, including a reissue applicant, 
may suggest an interference with another application or a patent. 
The suggestion must:

(1)Provide sufficient information to identify the application 
or patent with which the applicant seeks an interference,

(2)Identify all claims the applicant believes interfere, 
propose one or more counts, and show how the claims correspond 
to one or more counts,

(3)For each count, provide a claim chart comparing at 
least one claim of each party corresponding to the count and show 
why the claims interfere within the meaning of § 41.203(a),

(4)Explain in detail why the applicant will prevail on priority,


(5)If a claim has been added or amended to provoke an 
interference, provide a claim chart showing the written description 
for each claim in the applicant’s specification, and

(6)For each constructive reduction to practice for which 
the applicant wishes to be accorded benefit, provide a chart showing 
where the disclosure provides a constructive reduction to practice 
within the scope of the interfering subject matter.



(d)Requirement to show priority under 35 U.S.C. 
102(g). (1) When an applicant has an earliest constructive 
reduction to practice that is later than the apparent earliest 
constructive reduction to practice for a patent or published 
application claiming interfering subject matter, the applicant 
must show why it would prevail on priority.

(2)If an applicant fails to show priority under paragraph 
(d)(1) of this section, an administrative patent judge may nevertheless 
declare an interference to place the applicant under an 
order to show cause why judgment should not be entered against 
the applicant on priority. New evidence in support of priority will 
not be admitted except on a showing of good cause. The Board 
may authorize the filing of motions to redefine the interfering subject 
matter or to change the benefit accorded to the parties.



When an applicant suggests an interference under 
37 CFR 41.202(a), an examiner must review the suggestion 
for formal sufficiency. As explained in MPEP 
§ 2304.02(c), the examiner is generally not responsible 
for determining the substantive adequacy of any 
priority showing. The examiner may, however, offer 
pertinent observations on any showing when the suggested 
interference is referred to the Board of Patent 
Appeals and Interferences. The observations may be 
included as an attachment to the Form PTO-850.

Form paragraphs 23.06 to 23.06.06 may be used to 
acknowledge applicant’s suggestion for interference 
under 37 CFR 41.202(a) that failed to comply with 
one or more of paragraphs (a)(1) to (a)(6) of 37 CFR 
41.202.

¶ 23.06 Applicant Suggesting an Interference 

Applicant has suggested an interference pursuant to 37 CFR 
41.202(a) in a communication filed [1].

Examiner Note:

1.Use this form paragraph if applicant has suggested an interference 
under 37 CFR 41.202(a) and applicant has failed to comply 
with one or more of paragraphs (a)(1) to (a)(6) of 37 CFR 
41.202. 

2.In bracket 1, insert the date of applicant’s communication.

3.This form paragraph must be followed by one or more of 
form paragraphs 23.06.01 to 23.06.03 and end with form paragraph 
23.06.04.

¶ 23.06.01 Failure to Identify the Other Application or 
Patent

Applicant failed to provide sufficient information to identify 
the application or patent with which the applicant seeks an interference. 
See 37 CFR 41.202(a)(1) and MPEP § 2304.02(a).

¶ 23.06.02 Failure to Identify the Counts and 
Corresponding Claims

Applicant failed to (1) identify all claims the applicant believes 
interfere, and/or (2) propose one or more counts, and/or (3) show 
how the claims correspond to one or more counts. See 37 CFR 
41.202(a)(2) and MPEP § 2304.02(b).

¶ 23.06.03 Failure to Provide Claim Chart Comparing At 
Least One Claim

Applicant failed to provide a claim chart comparing at least 
one claim of each party corresponding to the count. See 37 CFR 
41.202(a)(3) and MPEP § 2304.02(c).

¶ 23.06.04 Failure to Explain in Detail Why Applicant Will 
Prevail on Priority

Applicant failed to provide a detailed explanation as to why 
applicant will prevail on priority. See 37 CFR 41.202(a)(4), (a)(6), 
(d) and MPEP § 2304.02(c).




 

¶ 23.06.05 Claim Added/Amended; Failure to Provide 
Claim Chart Showing Written Description

Claim [1] has been added or amended in a communication filed 
on [2] to provoke an interference. Applicant failed to provide a 
claim chart showing the written description for each claim in the 
applicant’s specification. See 37 CFR 41.202(a)(5) and MPEP § 
2304.02(d).

¶ 23.06.06 Time Period for Reply

Applicant is given ONE MONTH or THIRTY DAYS, whichever 
is longer, from the mailing date of this communication to correct 
the deficiency(ies). THE PROVISIONS OF 37 CFR 1.136DO NOT APPLY TO THE TIME SPECIFIED IN THIS 
ACTION.





2304.02(a)Identifying the Other Application 
or Patent [R-4]

37 CFR 41.202. Suggesting an interference.

(a)Applicant. An applicant, including a reissue applicant, 
may suggest an interference with another application or a patent. 
The suggestion must:

(1)Provide sufficient information to identify the application 
or patent with which the applicant seeks an interference,



Usually an applicant seeking an interference will 
know the application serial number or the patent number 
of the application or patent, respectively, with 
which it seeks an interference. If so, providing that 
number will fully meet the identification requirement 
of 37 CFR 41.202(a)(1).

Occasionally, an applicant will believe another 
interfering application exists based only on indirect 
evidence, for instance through a journal article, a 
“patent pending” notice, or a foreign published application. 
In such cases, information about likely named 
inventors and likely assignees may lead to the right 
application. The applicant should be motivated to help 
the examiner identify the application since inadequate 
information may prevent the declaration of the suggested 
interference.



2304.02(b)Counts and Corresponding 
Claims [R-4]

37 CFR 41.202. Suggesting an interference.

(a)Applicant. An applicant, including a reissue applicant, 
may suggest an interference with another application or a patent. 
The suggestion must:



(2)Identify all claims the applicant believes interfere, propose 
one or more counts, and show how the claims correspond to 
one or more counts,

(3)For each count, provide a claim chart comparing at 
least one claim of each party corresponding to the count and show 
why the claims interfere within the meaning of § 41.203(a),



The applicant must identify at least one patentable 
claim from every application or patent that interferes 
for each count. A count is just a description of the 
interfering subject matter, which the Board of Patent 
Appeals and Interferences uses to determine what evidence 
may be used to prove priority under 35 U.S.C. 
102(g)(1).

The examiner must confirm that the applicant has 
(A) identified at least one patentable count, (B) identified 
at least one patentable claim from each party for 
each count, and (C) has provided a claim chart comparing 
at least one set of claims for each count. The 
examiner need not agree with the applicant’s suggestion. 
The examiner’s role is to confirm that there are 
otherwise patentable interfering claims and that the 
formalities of 37 CFR 41.202 are met.



2304.02(c)Explaining Priority [R-4]

37 CFR 41.202. Suggesting an interference.

(a)Applicant. An applicant, including a reissue applicant, 
may suggest an interference with another application or a patent. 
The suggestion must:



(4)Explain in detail why the applicant will prevail on priority,




(6)For each constructive reduction to practice for which 
the applicant wishes to be accorded benefit, provide a chart showing 
where the disclosure provides a constructive reduction to practice 
within the scope of the interfering subject matter.



(d)Requirement to show priority under 35 U.S.C. 
102(g). (1) When an applicant has an earliest constructive 
reduction to practice that is later than the apparent earliest 
constructive reduction to practice for a patent or published 
application claiming interfering subject matter, the applicant 
must show why it would prevail on priority.

(2)If an applicant fails to show priority under paragraph 
(d)(1) of this section, an administrative patent judge may never





 

theless declare an interference to place the applicant under an 
order to show cause why judgment should not be entered against 
the applicant on priority. New evidence in support of priority will 
not be admitted except on a showing of good cause. The Board 
may authorize the filing of motions to redefine the interfering subject 
matter or to change the benefit accorded to the parties.



A description in an application that would have 
anticipated the subject matter of a count is called a 
constructive reduction-to-practice of the count. One 
disclosed embodiment is enough to have anticipated 
the subject matter of the count. If the application is 
relying on a chain of benefit disclosures under any of 
35 U.S.C. 119, 120, 121 and 365, then the anticipating 
disclosure must be continuously disclosed through the 
entire benefit chain or no benefit may be accorded.

If the application has an earlier constructive reduction-
to-practice than the apparent earliest constructive 
reduction-to-practice of the other application or 
patent, then the applicant may simply explain its entitlement 
to its earlier constructive reduction-to-practice. 
Otherwise, the applicant must (A) antedate the 
earliest constructive reduction-to-practice of the other 
application or patent, (B) demonstrate why the other 
application or patent is not entitled to its apparent earliest 
constructive reduction-to-practice, or (C) provide 
some other reason why the applicant should be considered 
the prior inventor.

The showing of priority may look similar to showings 
under 37 CFR 1.130-1.132, although there are 
differences particularly in the scope of what must be 
shown. In any case, with the exception discussed 
below, the examiner is not responsible for examining 
the substantive sufficiency of the showing.

I.REJECTION UNDER 35 U.S.C. 102(a) or 
102(e)

If an application claim is subject to a rejection 
under 35 U.S.C. 102(a) or 102(e) and the applicant 
files a suggestion under 37 CFR 41.202(a) rather than 
a declaration under 37 CFR 1.130-1.132, then the 
examiner must review the suggestion to verify that the 
applicant’s showing, taken at face value, is sufficient 
to overcome the rejection. If the examiner determines 
that the showing is not sufficient, then the examination 
is not completed, 37 CFR 41.102, the rejection 
should be maintained and the suggestion should not 
be referred to the Board of Patent Appeals and Interferences 
(Board) for an interference.

II.COMPLIANCE WITH 35 U.S.C. 135(b)

If an application claim interferes with a claim of a 
patent or published application, and the claim was 
added to the application by an amendment filed more 
than one year after issuance of the patent, or the application 
was not filed until more than one year after 
issuance of the patent (but the patent is not a statutory 
bar), then under the provisions of 35 U.S.C. 135(b), 
an interference will not be declared unless at least one 
of the claims which were in the application, or in a 
parent application, prior to expiration of the one-year 
period was for “substantially the same subject matter” 
as at least one of the claims of the patent.

If the applicant does not appear to have had a claim 
for “substantially the same subject matter” as at least 
one of the patent claims prior to the expiration of the 
one-year period, the examiner may require, 35 U.S.C. 
132, that the applicant explain how the requirements 
of 35 U.S.C. 135(b) are met. Further, if the patent 
issued from an application which was published under 
35 U.S.C. 122(b), note the one year from publication 
date limitation found in 35 U.S.C. 135(b)(2) with 
respect to applications filed after the date of publication.


The obviousness test is not the standard for determining 
whether the subject matter is the same or substantially 
the same. Rather the determination turns on 
the presence or absence of a different material limitation 
in the claim. These tests are distinctly different. 
The analysis focuses on the interfering claim to determine 
whether all material limitations of the interfering 
claim necessarily occur in a prior claim. In re 
Berger, 279 F.3d 975, 61 USPQ2d 1523 (Fed. Cir. 
2002). If none of the claims which were present in the 
application, or in a parent application, prior to expiration 
of the one-year period meets the “substantially 
the same subject matter” test, the interfering claim 
should be rejected under 35 U.S.C. 135(b). In re 
McGrew, 120 F.3d 1236, 43 USPQ2d 1632 (Fed. Cir. 
1997). Note that the expression “prior to one year 
from the date on which the patent was granted” in 35 
U.S.C. 135(b) includes the one-year anniversary date 
of the issuance of a patent. Switzer v. Sockman, 333 
F.2d 935, 142 USPQ 226 (CCPA 1964).




 

Form paragraph 23.14 may be used to reject a claim 
as not being made prior to one year of the patent issue 
date. Form paragraph 23.14.01 may be used to reject a 
claim as not being made prior to one year from the 
application publication date.

¶ 23.14 Claims Not Copied Within One Year of Patent 
Issue Date 

 Claim [l] rejected under 35 U.S.C. 135(b)(1) as not being 
made prior to one year from the date on which U.S. Patent No. [2] 
was granted. See In re McGrew, 120 F.3d 1236, 1238, 43 USPQ2d 
1632, 1635 (Fed. Cir. 1997) where the Court held that 35 U.S.C. 
135(b) may be used as a basis for ex parte rejections.

¶ 23.14.01 Claims Not Copied Within One Year Of 
Application Publication Date 

Claim [l] rejected under 35 U.S.C. 135(b)(2) as not being made 
prior to one year from the date on which [2] was published under 
35 U.S.C. 122(b). See In re McGrew, 120 F.3d 1236, 1238, 43 
USPQ2d 1632, 1635 (Fed. Cir. 1997) where the Court held that 35 
U.S.C. 135(b) may be used as a basis for ex parte rejections.

Examiner Note:

1.In bracket 2, insert the publication number of the published 
application.

2.This form paragraph should only be used if the application 
being examined was filed after the publication date of the published 
application.





2304.02(d)Adequate Written Description[R-4]

37 CFR 41.202. Suggesting an interference.

(a)Applicant. An applicant, including a reissue applicant, 
may suggest an interference with another application or a patent. 
The suggestion must:



(5)If a claim has been added or amended to provoke an 
interference, provide a claim chart showing the written description 
for each claim in the applicant’s specification, and



An applicant is not entitled to an interference simply 
because applicant wants one. The interfering 
claim must be allowable, particularly with respect to 
the written description supporting the interfering 
claim.

Historically, an applicant provoked an interference 
by copying a claim from its opponent. The problem 
this practice created was that differences in the underlying 
disclosures might leave the claim allowable to 
one party, but not to the other; or despite identical 
claim language differences in the disclosures might 
require that the claims be construed differently.

Rather than copy a claim literally, the better practice 
is to add (or amend to create) a fully supported 
claim and then explain why, despite any apparent differences, 
the claims define the same invention. 37 
CFR 41.203(a). The problem of inadequate written 
description in claims added or amended to provoke an 
interference is so great that the issue has been singled 
out for heightened scrutiny early in the course of an 
interference. 37 CFR 41.201, under “Threshold 
issue.”



2304.03Patentee Suggestion [R-4]

37 CFR 41.202. Suggesting an interference.



(b)Patentee. A patentee cannot suggest an interference 
under this section but may, to the extent permitted under § 1.99and § 1.291 of this title, alert the examiner of an application 
claiming interfering subject matter to the possibility of an interference.




A patentee may not suggest an interference unless it 
becomes an applicant by filing a reissue application. 
A patentee may, however, to the limited extent permitted 
under 37 CFR 1.99 and 1.291, alert an examiner 
to the existence of interfering claims in an 
application. See MPEP § 1134 and § 1901.



2304.04Examiner Suggestion [R-4]

37 CFR 41.202. Suggesting an interference.



(c)Examiner. An examiner may require an applicant to add 
a claim to provoke an interference. Failure to satisfy the requirement 
within a period (not less than one month) the examiner sets 
will operate as a concession of priority for the subject matter of 
the claim. If the interference would be with a patent, the applicant 
must also comply with paragraphs (a)(2) through (a)(6) of this 
section. The claim the examiner proposes to have added must, 
apart from the question of priority under 35 U.S.C. 102 (g):




 

(1)Be patentable to the applicant, and

(2)Be drawn to patentable subject matter claimed by 
another applicant or patentee.







2304.04(a)Interfering Claim Already in 
Application [R-4]

If the applicant already has a claim to the same subject 
matter as a claim in the application or patent of 
another inventor, then there is no need to require the 
applicant to add a claim to have a basis for an interference.


The examiner may invite the applicant to suggest 
an interference pursuant to 37 CFR 41.202(a). An 
applicant may be motivated to do so in order to 
present its views on how the interference should be 
declared.

If the applicant does not suggest an interference, 
then the examiner should work with an Interference 
Practice Specialist (IPS) to suggest an interference to 
the Board of Patent Appeals and Interferences 
(Board). The suggestion should include an explanation 
of why at least one claim of every application or 
patent defines the same invention within the meaning 
of 37 CFR 41.203(a). See MPEP § 2301.03 for a discussion 
of interfering subject matter. The examiner 
must also complete Form PTO-850.

The examiner should be prepared to discuss why 
claims interfere, whether the subject matter of other 
claims would have been anticipated or rendered obvious 
if the interfering claims are treated as prior art, 
and whether an applicant or patentee is entitled to 
claim the benefit of an application as a constructive 
reduction-to-practice. The IPS may require the examiner 
to prepare a memorandum for the Board on any 
of these subjects. The IPS may require the examiner 
to participate in a conference with the Board to discuss 
the suggested interference.



2304.04(b)Requiring a Claim [R-4]

35 U.S.C. 132. Notice of rejection; reexamination.

(a)Whenever, on examination, any claim for a patent is 
rejected, or any objection or requirement made, the Director shall 
notify the applicant thereof, stating the reasons for such rejection, 
or objection or requirement, together with such information and 
references as may be useful in judging of the propriety of continuing 
the prosecution of his application; and if after receiving such 
notice, the applicant persists in his claim for a patent, with or 
without amendment, the application shall be reexamined. No 
amendment shall introduce new matter into the disclosure of the 
invention.



The examiner may, pursuant to 35 U.S.C. 132(a), 
require an applicant to add a claim that would interfere 
with the claim of another application or patent. 
For example, the requirement may be made to obtain 
a clearer definition of the interfering subject matter or 
to establish whether the applicant will pursue claims 
to the interfering subject matter. When the requirement 
is based on a published application with allowed 
claims or a patent, the examiner must identify the 
published application or the patent in making the 
requirement.

Given the cost and complexity of interferences, a 
requirement to add a claim under 37 CFR 41.202(c) 
should not be lightly made. Before making the 
requirement, the examiner should consult with an 
Interference Practice Specialist (IPS). The following 
principles should guide the examiner in exercising 
discretion to make this requirement:

(A)An interference should generally not be suggested 
if examination of the application is not otherwise 
completed.

(B)The required claim must not encompass prior 
art or otherwise be barred.

(C)The application must provide adequate support 
under 35 U.S.C. 112, first paragraph for the subject 
matter of the required claim.

(D)A claim should not be required when the 
applicant expressly states that the commonly 
described subject matter is not the applicant’s invention.


(E)A claim based on a claim from a published 
application should not be required unless the claim 
from the published application has been allowed.

Example 1

A patent is 35 U.S.C. 102(b) prior art against any 
possible interfering claim. No interfering claim 
should be required.

Example 2

The patent issued more than one year ago and the 
applicant did not previously have a claim to the 




 

same subject matter. Any added claim would most 
likely be time barred under 35 U.S.C. 135(b)(1). 
No interfering claim should be required.

Example 3

An application describes work that attributes to 
another inventor, but also describes and claims an 
improvement. The other inventor has received a 
patent for original work. The applicant may in 
some sense have 35 U.S.C. 112, first paragraph 
support for an interfering claim to the other inventor’s 
work. Nevertheless, the applicant has indicated 
that the commonly described subject matter 
is not the applicant’s invention. No interfering 
claim should be required.

Example 4

An application has support for both a generic 
claim G and a species claim G1. The applicant 
only claims the genus G. A patent discloses and 
claims only G1. Under the facts of this example, 
there is no evidence that genus G would have rendered 
the species G1 obvious. If for some reason 
the patent is not available as a reference against the 
application, the examiner may require the applicant 
to add a claim to species G1 after consulting 
with an IPS.

Example 5

Published application H and application I both 
support a claim to H1. Published application H 
contains a claim to H1, but application I does not. 
The claim to H1 in the published application is 
under rejection. Applicant I should not ordinarily 
be required to add the claim.

Form paragraph 23.04 may be used to require 
applicant to add a claim to provoke interference. 

¶ 23.04 Requiring Applicant to Add Claim to Provoke 
Interference

The following allowable claim from [1]is required to be added 
for the purpose of an interference:

[2]

The claim must be copied exactly.

Applicant is given ONE MONTH or THIRTY DAYS, whichever 
is longer, from the mailing date of this communication to add 
the claim. Refusal to add a required claim will operate as a concession 
of priority for the subject matter of the required claim, but 
will not result in abandonment of this application. See 37 CFR 
41.202(c) and MPEP § 2304.04(b). THE PROVISIONS OF 37 
CFR 1.136 DO NOT APPLY TO THE TIME SPECIFIED IN 
THIS ACTION.

If the interference would be with a patent, applicant must also 
comply with 37 CFR 41.202(a)(2) to (a)(6).

Examiner Note:

1.In bracket 1, insert the published application number if the 
claim is an allowed claim from a U.S. application publication or 
the patent number if the claim is from a U.S. patent.

2.In bracket 2, insert the claim which applicant is required to 
add to provoke an interference.

APPLICANT MUST ADD THE CLAIM

If required to add a claim under 37 CFR 41.202(c), 
the applicant must do so. Refusal to add a required 
claim will operate as a concession of priority for the 
subject matter of the required claim. The applicant 
would then be barred from claiming, not only the subject 
matter of the required claim, but any subject matter 
that would have been anticipated or rendered 
obvious if the required claim were treated as prior art. 
In re Ogiue, 517 F.2d 1382, 1390, 186 USPQ 227, 235 
(CCPA 1975).

While complying with the requirement to add a 
claim, an applicant may also express disagreement 
with the requirement several ways, including:

(A)Identifying a claim already in its application, 
or another of its applications, that provides a basis for 
the proposed interference;

(B)Adding an alternative claim and explaining 
why it would provide a better basis for the proposed 
interference (such as having better support in the 
applicant’s disclosure); or

(C)Explaining why the required claim is not patentable 
to the applicant.

The examiner may withdraw the requirement if persuaded 
by the reasons the applicant offers.



2304.05Common Ownership [R-4]

37 CFR 41.206. Common interests in the invention.

An administrative patent judge may decline to declare, or if 
already declar ed the Board may issue judgment in, an interference 
between an application and another application or patent that 
are commonly owned.

An interference is rarely appropriate between two 
applications or an application and patent that belong 
to the same owner. The owner should ordinarily be 
able to determine priority and is obligated under 37 
CFR 1.56 to inform the examiner about which application 
or patent is entitled to priority. The examiner 




 

may require an election of priority between the application 
and other application or patent. 35 U.S.C. 
132(a).

In making the election, the owner must eliminate 
the commonly claimed subject matter. This may be 
accomplished by canceling the interfering application 
claims, disclaiming the interfering patent claims, 
amending the application claims such that they no 
longer interfere, or filing a reissue application to 
amend the patent claims such that they no longer 
interfere.

Example 1

Two corporations have applications that claim the 
same invention. After a merger of the corporations, 
the resulting corporation owns both applications. 
The new corporation is obligated to 
investigate priority. Once the corporation has had 
an opportunity to determine which application is 
entitled to priority, the corporation must elect 
between the applications or otherwise eliminate 
the need for an interference.

Example 2

J files an application in which J is the sole inventor 
and assignee. K files an application in which J and 
K are named as inventors and co-assignees. 
Although J is an owner of both applications, an 
interference may nevertheless be necessary if J and 
K disagree about which application is entitled to 
priority.



2305Requiring a Priority Showing [R-4]

37 CFR 41.202. Suggesting an interference.



(d)Requirement to show priority under 35 U.S.C. 102(g). 
(1) When an applicant has an earliest constructive reduction to 
practice that is later than the apparent earliest constructive reduction 
to practice for a patent or published application claiming 
interfering subject matter, the applicant must show why it would 
prevail on priority.



(e)Sufficiency of showing. (1) A showing of priority under 
this section is not sufficient unless it would, if unrebutted, support 
a determination of priority in favor of the party making the showing.


(2)When testimony or production necessary to show priority 
is not available without authorization under § 41.150(c) or § 
41.156(a), the showing shall include:

(i)Any necessary interrogatory, request for admission, 
request for production, or deposition request, and

(ii)A detailed proffer of what the response to the 
interrogatory or request would be expected to be and an explanation 
of the relevance of the response to the question of priority.



Whenever the application has an earliest constructive 
reduction-to-practice that is later than the earliest 
constructive reduction-to-practice of a published 
application having allowed claims or a patent with 
which it interferes, the applicant must make a priority 
showing under 37 CFR 41.202(d)(1).

There are two typical situations in which a showing 
under 37 CFR 41.202(d)(1) is filed without a requirement 
from the examiner. First, the applicant may be 
complying with 37 CFR 41.202(a)(2) in order to suggest 
an interference under 37 CFR 41.202(a) or as part 
of complying with a requirement under 37 CFR 
41.202(c). Second, the applicant may file the showing 
to overcome a rejection based on 35 U.S.C. 102(a) or 
102(e) when an affidavit is not permitted under 37 
CFR 1.131(a)(1) because the applicant is claiming 
interfering subject matter.

If no showing has been filed, and the application’s 
earliest constructive reduction-to-practice is later than 
the earliest constructive reduction-to-practice of a 
patent or published application, then the examiner 
must require a showing of priority. This showing is 
necessary because an insufficient showing (including 
no showing at all) can trigger a prompt judgment 
against the applicant in an interference. 37 CFR 
41.202(d)(2). The applicant may choose to comply 
with a requirement under 37 CFR 41.202(d)(1) by 
suggesting an interference under 37 CFR 41.202(a).

Example

Application L has claims that interfere with claims 
of patent M. Application L was filed in June 2001. 
The application that resulted in patent M was filed 
in November 2001, but has an earliest constructive 
reduction-to-practice in a foreign application filed 
in December 2000. Assuming no rejection is available 
under 35 U.S.C. 102(e), the examiner must 
require a showing under 37 CFR 41.202(d)(1) in 
application L.




 

I.RELATIONSHIP TO 37 CFR 1.131 AFFIDAVIT


Ordinarily an applicant may use an affidavit of 
prior invention under 37 CFR 1.131 to overcome a 
rejection under 35 U.S.C. 102(a) or 102(e). An exception 
to the rule arises when the reference is a patent or 
application published under 35 U.S.C. 122(b) and the 
reference has claims directed to the same patentable 
invention as the application claims being rejected. 37 
CFR 1.131(a)(1). The reason for this exception is that 
priority is determined in an interference when the 
claims interfere. 35 U.S.C. 135(a). In such a case, the 
applicant must make the priority showing under 37 
CFR 41.202(d) instead. In determining whether a 37 
CFR 1.131 affidavit is permitted or not, the examiner 
should keep the purpose of the exception in mind. If 
an interference would not be possible at the time the 
affidavit would be submitted, then the affidavit should 
be permitted. This situation could arise two ways.

First, the claims that matter for the purposes of 37 
CFR 1.131 are not the published claims but the currently 
existing claims. For example, if the claims that 
were published in a published application have been 
significantly modified during subsequent examination, 
they may no longer interfere with the rejected 
claims. Similarly, the patent claims may have been 
subsequently corrected or amended in a reissue application 
or a reexamination. Since an interference no 
longer exists between the current claims in the patent 
or published application and the rejected claims, an 
affidavit under 37 CFR 1.131 may be submitted.

Similarly, if a published application contains claims 
to the same invention, but the claims in the published 
application are not in condition for allowance, then no 
interference is yet possible. 37 CFR 41.102. Since the 
claims in the published application might never be 
allowed in their present form, it is not appropriate to 
proceed as though an interference would be inevitable. 
Consequently, an affidavit under 37 CFR 1.131may be submitted.

II.NOT A PRIORITY STATEMENT

A priority showing under 37 CFR 41.202(d)(1), 
which is presented during examination, is not the 
same as a priority statement under 37 CFR 41.204(a), 
which is filed during an interference. A priority statement 
is a notice of what a party intends to prove on 
the issue of priority during an interference. A priority 
showing under 37 CFR 41.202(d)(1) must, however, 
actually prove priority assuming that the opposing 
party did not oppose the showing. 37 CFR 
41.202(e)(1). Generally speaking, while a priority 
statement might be more detailed in some respects, it 
will not be sufficient to make the necessary showing 
of priority for the purposes of 37 CFR 41.202.

An applicant presenting a priority showing must 
establish through the showing that it would prevail on 
priority if an interference is declared and the opponent 
does not oppose the showing. The requirement for a 
priority showing is intended to spare a senior party 
patentee the burden of an interference if the junior 
party applicant cannot establish that it would prevail 
in an interference even if the senior party does nothing. 
Kistler v. Weber, 412 F.2d 280, 283-85, 162 
USPQ 214, 217-19 (CCPA 1969) and Edwards v. 
Strazzabosco, 58 USPQ2d 1836 (Bd. Pat. App. & 
Inter. 2001).

The consequence of an inadequate showing may be 
serious for the applicant. If an interference is declared 
and the Board of Patent Appeals and Interferences 
(Board) finds the priority showing insufficient 
(thereby issuing an order to show cause why judgment 
should not be entered against the applicant), the 
applicant will not be allowed to present additional 
evidence to make out a priority showing unless the 
applicant can show good cause why any additional 
evidence was not presented in the first instance with 
the priority showing before the examiner. 37 CFR 
41.202(d)(2); Huston v. Ladner, 973 F.2d 1564, 23 
USPQ2d 1910 (Fed. Cir. 1992); Hahn v. Wong, 892 
F.2d 1028, 13 USPQ2d 1313 (Fed. Cir. 1989); 
Edwards v. Strazzabosco, 58 USPQ2d 1836 (Bd. Pat. 
App. & Inter. 2001). The principles which govern 
review of a priority showing are discussed in Basmadjian 
v. Landry, 54 USPQ2d 1617 (Bd. Pat. App. & 
Inter. 1997) (citing former 37 CFR 1.608(b)).



2306Secrecy Order Cases [R-4]

37 CFR 5.3. Prosecution of application under secrecy 
orders; withholding patent.



(b)An interference will not be declared involving a national 
application under secrecy order. An applicant whose application is 
under secrecy order may suggest an interference (§ 41.202(a) of 




 

this title), but the Office will not act on the request while the application 
remains under a secrecy order.



Once an interference is declared, an opposing party 
is entitled to access to the application and benefit 
applications. 37 CFR 41.109. See MPEP § 2307.02. 
Consequently, an interference should not be suggested 
for an application under a secrecy order. See MPEP § 
120 and § 130. When a secrecy order expires or is 
rescinded, if the examination is otherwise completed, 
37 CFR 41.102, then the need for an interference may 
be reconsidered.

If an application not under a secrecy order has 
allowable claims that interfere with allowable claims 
of an application that is under a secrecy order, then the 
application that is not under the secrecy order should 
be passed to issue as a patent. An interference may be 
suggested with the application and the patent (unless 
the patent has expired) once the secrecy order has 
been lifted.

Example

Application L discloses and claims a transistor that 
is useful in a commercial context. Application M 
discloses the same transistor in the context of a 
missile control circuit, but claims only the transistor. 
A secrecy order is placed on application M. 
Once examination of application L is completed 
and the transistor claim is allowable, application L 
should pass to issue.



2307Action During an Interference[R-4]

37 CFR 41.103. Jurisdiction over involved files.

 The Board acquires jurisdiction over any involved file when 
the Board initiates a contested case. Other proceedings for the 
involved file within the Office are suspended except as the Board 
may order.

Once a patent or application becomes involved in 
an interference, the Board of Patent Appeals and 
Interferences (Board) has jurisdiction over the file. 
The examiner may not act on an involved patent or 
application except as the Board may authorize.

The Board may occasionally consult with the 
examiner, for instance, on a question regarding the 
technology at issue in an involved application or 
patent.

The Board retains jurisdiction over the interference 
until the interference is terminated. The Director has 
defined termination to occur after a final Board judgment 
in the interference and the period for seeking 
judicial review has expired or, if judicial review is 
sought, after completion of judicial review including 
any further action by the Board. 37 CFR 41.205(a).



2307.01Ex Parte Communications [R-4]

37 CFR 41.11. Ex parte communications in inter partes 
proceedings.

 An ex parte communication about an inter partes reexamination 
(subpart C of this part) or about a contested case (subparts D 
and E of this part) with a Board member, or with a Board 
employee assigned to the proceeding, is not permitted.

Since an interference involves two or more parties, 
the integrity of the process requires the opportunity 
for the opposing party to participate in communications 
or actions regarding any involved application or 
patent. Once an interference is declared, any attempt 
by a party to communicate with the Board of Patent 
Appeals and Interferences (Board) through the examiner 
or to have the examiner act in an involved patent 
or application without Board authorization should be 
promptly reported to the Board. Board action may 
include a sanction in the interference or referral of a 
patent practitioner to the Office of Enrollment and 
Discipline.



2307.02Access to Related Files [R-4]

37 CFR 41.109. Access to and copies of Office records.

(a)Request for access or copies. Any request from a party 
for access to or copies of Office records directly related to a contested 
case must be filed with the Board. The request must precisely 
identify the records and in the case of copies include the 
appropriate fee set under § 1.19(b) of this title.

(b)Authorization of access and copies. Access and copies 
will ordinarily only be authorized for the following records:

(1)The application file for an involved patent;

(2)An involved application; and

(3)An application for which a party has been accorded 
benefit under subpart E of this part.



In addition to any access permitted to a member of 
the public under 37 CFR 1.11 and 1.14 (see MPEP § 
103), an opposing party may be authorized under 37 
CFR 41.109 to have access to or a copy of the record 
for any involved patent or application, and for any 




 

application for which benefit has been accorded. The 
availability of a file to an opposing party under 37 
CFR 41.109 has no bearing on whether a file is otherwise 
available under 37 CFR 1.11 or 1.14.



2307.03Suspension of Related 
Examinations [R-4]

Although the examiner may not act in a patent or an 
application directly involved in an interference, 37 
CFR 41.103, examination may continue in related 
cases, including any benefit files. Once examination 
is completed, the examiner should consult with an 
Interference Practice Specialist (IPS) to determine 
whether and how further action should proceed. The 
IPS may consult with the Board of Patent Appeals and 
Interferences (Board) to determine whether the application 
claims would be barred in the event the applicant 
loses the interference.

Suspension may be necessary if the claims would 
be barred by a loss in the interference. Steps should be 
considered to minimize the effect of any patent term 
adjustment that would result from the suspension. For 
instance, the examiner could require restriction, 35 
U.S.C. 121, of the application to only the claims that 
do not interfere so that they can be issued. The applicant 
may then file a divisional application with the 
interfering claims, which may be suspended.



2307.04Additional Parties to Interference 
[R-4]

During the course of an interference, the examiner 
may come across applications or patents of parties 
that claim the same invention, but are not already 
involved in the interference. If so, the examiner 
should consult with an Interference Practice Specialist 
(IPS) and prepare a referral of the suggested interference 
to the Board of Patent Appeals and Interferences 
in the same way that a referral is prepared in the first 
instance.



2307.05Board Action on Related Files[R-4]

Occasionally, the Board may order that a paper be 
filed in a related application. Generally, the paper will 
notify the examiner of a fact, such as a party admission 
or prior art, that may be relevant to examination 
of the related case.



2307.06Action at the Board [R-4]

Action at the Board of Patent Appeals and Interferences 
(Board) during an interference is beyond the 
scope of this Chapter. For further information, see 37 
CFR part 41, subparts A, D, and E; see also the 
Board’s Contested Case Practice Guide. A Standing 
Order and other orders, which further direct the conduct 
of the parties, are also entered in each interference.




2308Action After an Interference [R-4]

37 CFR 41.127. Judgment.

(a)Effect within Office—(1) Estoppel. A judgment disposes 
of all issues that were, or by motion could have properly been, 
raised and decided. A losing party who could have properly 
moved for relief on an issue, but did not so move, may not take 
action in the Office after the judgment that is inconsistent with 
that party’s failure to move, except that a losing party shall not be 
estopped with respect to any contested subject matter for which 
that party was awarded a favorable judgment.

(2)Final disposal of claim. Adverse judgment against a 
claim is a final action of the Office requiring no further action by 
the Office to dispose of the claim permanently.



(c)Recommendation. The judgment may include a recommendation 
for further action by the examiner or by the Director. If 
the Board recommends rejection of a claim of an involved application, 
the examiner must enter and maintain the recommended 
rejection unless an amendment or showing of facts not previously 
of record is filed which, in the opinion of the examiner, overcomes 
the recommended rejection.



Jurisdiction over an application returns to the 
examiner once the interference has terminated. If 
there is a recommendation for further action in the 
application, the examiner must reopen prosecution to 
consider the recommendation. The examiner must 
enter any recommended rejection, and must maintain 
the rejection unless the applicant by amendment or 
submission of new evidence overcomes the rejection 
to the examiner’s satisfaction.

If there is no recommendation in the judgment, the 
examiner should update the search and may, but is not 




 

required to, reopen prosecution for any claim not disposed 
of in the judgment.

An interference judgment simply resolves any 
question of priority between the two parties to the 
interference. The judgment does not prevent the 
examiner from making a rejection in further examination 
in the same application or a different application. 
If a party loses on an issue in the interference, the 
examiner should reject any claim for which allowance 
would be inconsistent with the interference judgment.

Form paragraph 23.02 may be used to resume ex 
parte prosecution.

¶ 23.02 Ex Parte Prosecution Is Resumed

Interference No. [1] has been terminated by a decision [2] to 
applicant. Ex parte prosecution is resumed.

Examiner Note:

1.In bracket 1, insert the interference number.

2.In bracket 2, insert whether favorable or unfavorable.





2308.01Final Disposal of Claims [R-4]

Judgment against a claim in an interference, including 
any judgment on priority or patentability, finally 
disposes of the claim. No further action is needed 
from the examiner on that claim. If no claim remains 
allowable to the applicant, a notice of abandonment 
should be issued.



2308.02Added or Amended Claims [R-4]

An applicant may file a motion during the interference 
to add or amend a claim. A patentee may file a 
reissue application in support of a motion to add or 
amend a claim. A copy of the paper adding or amending 
the claim will be placed in the official record of 
the application, but not entered. A decision on the 
motion is entered in the official record of the application. 
The examiner may enter the added claim or 
amended claim into the application only if, and only 
to the extent, authorized by the Board of Patent 
Appeals and Interferences, typically in the decision on 
the motion. The decision authorizing entry of the 
added or amended claim does not prevent the examiner 
from rejecting the claim during further prosecution.




2308.03Estoppel Within the Office [R-4]

If a party loses on an issue, it may not re-litigate the 
issue before the examiner or in a subsequent Board of 
Patent Appeals and Interferences (Board) proceeding. 
The time for the party to make all pertinent arguments 
is during the interference, unless the Board expressly 
prevented the party from litigating the issue during 
the interference.

There are two main types of interference estoppel. 
First, a losing party is barred on the merits from seeking 
a claim that would have been anticipated or rendered 
obvious by the subject matter of the lost count. 
In re Deckler, 977 F.2d 1449, 24 USPQ2d 1448 (Fed. 
Cir. 1992); Ex parte Tytgat, 225 USPQ 907 (Bd. Pat. 
App. & Inter. 1985). Second, a losing party is procedurally 
barred from seeking from the examiner relief 
that could have been--but was not--sought in the interference. 
37 CFR 41.127(a)(1); Ex parte Kimura, 55 
USPQ2d 1537 (Bd. Pat. App. & Inter. 2000) (reissue 
applicant estopped to claim compound when patentability 
of that compound could have been put in issue 
in interference where opponent’s application also 
described compound).

The examiner should consult with an Interference 
Practice Specialist (IPS) before allowing a claim to a 
losing party that was added or amended during post-
interference examination.

Example 1

The applicant lost on priority for a count drawn to 
subject matter X. The Board’s judgment automatically 
disposed of all of the applicant’s claims corresponding 
to the count. The applicant files a 
continuing application with a claim to subject matter 
X. The claim must be rejected as estopped on 
the merits by the applicant’s loss in the interference.


Example 2

Same facts as Example 1 except the applicant files 
a continuing application with a claim generic to 
subject matter X. Since the generic claim encompasses 
subject matter lost in the interference, the 
generic claim must be rejected as estopped on the 
merits by the loss in the interference.




 

Example 3

Same facts as Example 1 except the applicant files 
a continuing application with a claim to subject 
matter that would have been obvious in view of 
subject matter X. The claim must be rejected as 
estopped on the merits by the applicant’s loss in 
the interference, but the examiner must demonstrate 
why the claim would have been obvious if 
subject matter X is assumed to be prior art.

Example 4

Same facts as Example 1 except the applicant files 
a continuing application with a claim identical to a 
claim that corresponded to the count of the interference. 
The applicant also files a showing of why 
the claim should not have corresponded to the 
count. The claim should be rejected as procedurally 
estopped. Whether the showing is adequate or 
not, it is too late. The time to make the showing 
was during the interference.

Example 5

Same facts as Example 4 except that during the 
interference the applicant timely requested, but 
was not permitted, to show the claim did not correspond 
to the count. The examiner may determine 
in light of the new showing whether the lost count 
would have anticipated or rendered obvious the 
subject matter of the claim. The procedural estoppel 
does not apply if, through no fault of the applicant, 
the Board prevented the applicant from 
seeking relief during the interference.

Example 6

The applicant’s claim 1 was held unpatentable during 
the interference. The applicant could have 
moved, but did not move, to amend the claim. The 
applicant files a continuing application with an 
amended claim 1. If the subject matter of the 
amended claim would have been anticipated or 
obvious in view of a count of the interference, it 
must be rejected as procedurally estopped. 
Whether the amendment is sufficient to overcome 
the ground for unpatentability or not, the time to 
have amended the claim was during the interference.


Example 7

Same situation as Example 6 except the applicant 
did move to amend the claim, but the motion was 
denied. The result is the same as in Example 6. If 
the subject matter of the amended claim would 
have been anticipated or obvious in view of a 
count of the interference, it must be rejected as 
procedurally estopped. The applicant’s lack of success 
on the motion does not prevent the estoppel 
from applying to the claim.

Example 8

Same facts as Example 6 except the applicant filed 
a late request during the interference to amend the 
claim to overcome the basis for unpatentability. 
The request was denied as untimely. The claim 
must be rejected as procedurally estopped. Even 
though the applicant was not permitted to amend 
the claim during the interference, the estoppel still 
applies because the applicant’s inability to obtain 
relief in the interference was the result of the applicant’s 
failure to seek timely relief.



2308.03(a)Losing Party [R-4]

A party is barred (estopped) from raising an issue if 
the party lost on the issue during the interference. A 
party may lose on one issue, yet not lose on a different 
issue.

Example

The applicant lost the interference on a count drawn 
to a compound, but the opponent lost on a count 
drawn to methods of using the compound. The applicant 
may continue to pursue claims to the method of 
using the compound, but not claims to the compound 
itself.



2308.03(b)No Interference-in-Fact [R-4]

A judgment of no interference-in-fact means that 
no interference is needed to resolve priority between 
the parties. Neither party has lost the interference for 
the purpose of estoppel, 37 CFR 41.127(a)(1), even if 
one of the parties suggested the interference.

A judgment of no interference-in-fact bars any further 
interference between the same parties for claims 
to the same invention as the count of the interference.





 



2308.03(c)No Second Interference [R-4]

No second interference should occur between the 
same parties on patentably indistinct subject matter. If 
the Board of Patent Appeals and Interferences held 
that there is no interference-in-fact between the parties 
for the subject matter of the count, that holding 
may not be reopened in further examination. If a party 
that lost the earlier interference is again claiming the 
same invention as the count, the interfering claims 
should be rejected as estopped.



2309National Aeronautics and Space 
Administration or Department of 
Energy [R-4]

Ownership of an invention made pursuant to a U.S. 
government contract may be vested in the contracting 
government agency. The Board of Patent Appeals and 
Interferences (Board) determines two such ownership 
contests using interference procedures: for the 
National Aeronautics and Space Administration 
(NASA), 42 U.S.C. 2457 (inventions having significant 
utility in aeronautical or space activity), and for 
the Department of Energy (DoE), 42 U.S.C. 2182 
(inventions relating to special nuclear material or 
atomic energy). 

An applicant with an application covered by these 
Acts must file a statement regarding the making or 
conception of the invention and any relation to a contract 
with NASA or DoE. See MPEP § 150 and § 151. 
The examiner should work in coordination with 
Licensing and Review and one of the Technology 
Centers Interference Practice Specialists in suggesting 
these cases to the Board. Although these cases are not 
interferences, the interference practices in this chapter 
generally apply to NASA and DoE ownership contests 
as well.