MPEP 2303
Completion of Examination

Ninth Edition of the MPEP, Revision 07.2022, Last Revised in February 2023

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2303    Completion of Examination [R-08.2017]

37 C.F.R. 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 pre-AIA 35 U.S.C. 102(g)(1) and pre-AIA 35 U.S.C. 291, 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(a), and the late claiming bars under pre-AIA 35 U.S.C. 135(b) are important to preserve the efficiency and integrity of interferences. See 37 CFR 41.201, "Threshold issue." See, e.g., Berman v. Housey, 291 F.3d 1345, 1354, 63 USPQ2d 1023, 1029 (Fed. Cir. 2002).


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 may be available for patents whose issuance has been delayed for an interference. See pre-AIA 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 pre-AIA 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.


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. See 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.