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2209 Ex Parte Reexamination [R-07.2022]

Procedures for reexamination of issued patents began on July 1, 1981, the date when the reexamination provisions of Public Law 96-517 came into effect.

The reexamination statute, 35 U.S.C. 302, and rules permit any person to file a request for an ex parte reexamination containing certain elements and the appropriate fee under 37 CFR 1.20(c)(1) or (c)(2). The Office initially determines if “a substantial new question of patentability” (35 U.S.C. 303(a)) is presented. If such a new question has been presented, reexamination will be ordered. The reexamination proceedings which follow the order for reexamination are very similar to regular examination procedures in patent applications; however, there are notable differences. For example, there are certain limitations as to the kind of rejections which may be made in a reexamination ordered under 35 U.S.C. 304, special reexamination forms to be used, and time periods set to provide “special dispatch.” When the prosecution of a reexamination proceeding is terminated, a reexamination certificate is issued which indicates the status of all claims following the reexamination.

The following sections of this chapter explain the details of reexamination.

The intent of the reexamination procedures covered in this chapter include the following:

  • (A) To provide procedures for reexamination of patents;
  • (B) To implement reexamination in an essentially ex parte manner;
  • (C) To minimize the processing costs and complexities of reexamination;
  • (D) To maximize respect for the reexamined patent;
  • (E) To provide procedures for prompt and timely determinations by the Office in accordance with the “special dispatch” requirements of 35 U.S.C. 305.

The basic characteristics of ex parte reexamination are as follows:

  • (A) Anyone can request reexamination at any time during the period of enforceability of the patent;
  • (B) In ex parte reexaminations ordered under 35 U.S.C. 304, prior art considered during reexamination is limited to prior art patents or printed publications applied under the appropriate parts of 35 U.S.C. 102 and 103. Patents may also be applied in a double patenting rejection as discussed in MPEP § 2258 subsection I.D. (However, in ex parte reexaminations ordered under 35 U.S.C. 257, the prior art considered during reexamination is not limited. See MPEP § 2801);
  • (C) A substantial new question of patentability must be present for reexamination to be ordered;
  • (D) If ordered, the actual reexamination proceeding is ex parte in nature;
  • (E) Decision on a request for reexamination submitted under 35 U.S.C. 302 must be made no later than 3 months from its filing, and the remainder of the proceeding must proceed with “special dispatch” within the Office. (Similarly, a decision on a request for supplemental examination submitted under 35 U.S.C. 257 must be made no later than 3 months from its filing (see MPEP § 2815), and any ex parte reexamination proceeding ordered as a result of a supplemental examination proceeding must proceed with “special dispatch” within the Office);
  • (F) If ordered, a reexamination proceeding will normally be conducted to its conclusion and the issuance of a reexamination certificate;
  • (G) The scope of a claim cannot be enlarged by amendment;
  • (H) All reexamination and patent files are open to the public, but see paragraph (I) below;
  • (I) The reexamination file is scanned into IFW to provide an electronic format copy of the file. All public access to and copying of the reexamination file may be made from the electronic format copy available through Patent Center. Any remaining paper files are not available to the public. Images of non-patent literature (NPL) cited in public files are not available for either viewing or downloading through Patent Center. Certified copies of the full contents of the files, including NPL, are available from the Patent and Trademark Copy Fulfillment Branch of the Public Records Division, and may be ordered online through the Certified Copy Center storefront at

For a discussion of public access to papers filed in a supplemental examination proceeding, see MPEP § 2803.02.

Parties are cautioned that the reexamination statute, regulations, and published examining procedures do not countenance so-called “litigation tactics” in reexamination proceedings. The parties are expected to conduct themselves accordingly. For example, it is expected that submissions of papers that are not provided for in the reexamination regulations and/or appear to be excluded by the regulation will either be filed with an appropriate petition to accept the paper and/or waive the regulation(s), or not filed at all. Parties are advised that multiple submissions, such as a reply to a paper opposing a petition and a sur-reply directed to such a reply are not provided for in the reexamination regulations or examining procedures. It is expected that the parties will adhere to the provisions of 37 CFR 11.18(b) throughout the course of a reexamination proceeding.



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Last Modified: 02/16/2023 12:58:21