Ex Parte Reexamination: How to Request It and What Happens Next

Reexamination began on July 1, 1981 and is "essentially ex parte": the proceedings after the order are "very similar to regular examination procedures in patent applications" (MPEP § 2209). The statute sets the steps:

1. Request. "Any person at any time may file a request for reexamination by the Office of any claim of a patent on the basis of any prior art cited under the provisions of section 301," with the fee (§ 302). The request must set out each substantial new question and explain how the cited art applies to every claim for which reexamination is requested (37 C.F.R. § 1.510(b)).
2. Decision within three months. The Director decides whether the request raises a substantial new question of patentability affecting any claim (§ 303(a)). A refusal may be challenged only by petition to the Director within one month; otherwise it is "final and nonappealable" (§ 303(c); 37 C.F.R. § 1.515(c)).
3. Order, statement and reply. If reexamination is ordered, the patent owner has at least two months to file a statement, with any amendments; a third-party requester may reply within two months of service, but only if the patent owner files a statement (§ 304; 37 C.F.R. §§ 1.530(b), 1.535).
4. Examination. Reexamination then proceeds "according to the procedures established for initial examination" (§ 305) and, with any appeal to the PTAB, "with special dispatch."
5. Certificate. When the proceeding ends and the time for appeal has passed or any appeal has ended, the Director issues a certificate "canceling any claim of the patent finally determined to be unpatentable, confirming any claim of the patent determined to be patentable, and incorporating in the patent any proposed amended or new claim determined to be patentable" (§ 307(a)).

Sources: 35 U.S.C. §§ 302-307; 37 C.F.R. § 1.510, § 1.515, § 1.530, § 1.535; MPEP § 2209.

The MPEP reads "any person" literally: "there are no types of ‘persons’ who are excluded," including corporations and government entities, and the patent owner may request reexamination of its own patent (MPEP § 2212). The rule allows a request "at any time during the period of enforceability of a patent" (37 C.F.R. § 1.510(a)), which the MPEP says is generally the expiration date plus six years, longer if litigation is pending (MPEP § 2211).

The one exclusion is IPR and PGR estoppel: once an IPR or PGR on a claim ends in a final written decision, the petitioner, its real party in interest and privies may not request a USPTO proceeding on that claim on any ground they raised or reasonably could have raised (35 U.S.C. § 315(e)(1); MPEP § 2212). A third-party requester must certify that this estoppel does not bar the request (37 C.F.R. § 1.510(b)(6)).

Anonymity. Unlike an IPR petition, which must name all real parties in interest (§ 312(a)(2)), a reexamination request does not have to say who is behind it. The MPEP lists "attorneys without identification of their real client in interest" among the usual requesters, though "the name of the person who files the request will not be maintained in confidence" (MPEP § 2212). Two 2026 developments:

• Previously challenged patents (notice of Feb. 4, 2026, 1544 OG 128). A real party in interest may stay anonymous through a registered practitioner. But if any claim of the patent received a final written decision in an IPR or PGR, the anonymous request should affirmatively state that the requester and every other real party in interest are not that proceeding’s petitioner, real party in interest or privy, and identify the proceedings and their parties. Without that statement, the request’s filing date may be vacated.
• Proposed rule (July 22, 2026). The USPTO proposed requiring every third-party request to identify all real parties in interest, in a statement that would be kept confidential on request (RIN 0651-AD94, 91 FR 46038). Comments closed August 21, 2026. On October 18, 2026 the Federal Register showed only the proposed rule, not a final one.

Sources: 35 U.S.C. § 302, § 312(a)(2), § 315(e)(1); 37 C.F.R. § 1.510; MPEP §§ 2211, 2212; Filing Anonymous Requests for Ex Parte Reexamination Directed to Previously-Challenged Patents, 1544 OG 128 (Mar. 3, 2026); Requirement To Identify All Real Parties in Interest, 91 FR 46038 (proposed July 22, 2026); USPTO patent related notices, 2026.

Under the MPEP, prior patents or printed publications raise a substantial question "where there is a substantial likelihood that a reasonable examiner would consider the prior art patent or printed publication important in deciding whether or not the claim is patentable." The question is new unless the same question has already been decided in a final federal-court holding of invalidity after all appeals, decided in an earlier concluded examination or review of the patent by the Office (including an IPR or PGR), or raised in a pending reexamination or supplemental examination (MPEP § 2242).

• No prima facie case needed. The decision on the request does not decide patentability, so "no prima facie case of unpatentability need be found to grant an order for reexamination" (MPEP § 2240).
• Old art can qualify, if seen in a new light. "The existence of a substantial new question of patentability is not precluded by the fact that a patent or printed publication was previously cited by or to the Office or considered by the Office" (§ 303(a)). But the request must show "a new, non-cumulative technological teaching," or old art "presented in a new light or a different way that escaped review during earlier examination" (MPEP § 2216).
• Only patents and printed publications. Public use, on-sale activity and "conduct by parties" will not be considered (MPEP § 2209); new or amended claims are also examined under § 112 (37 C.F.R. § 1.552(a)).
• Section 325(d). The Director may reject a request because "the same or substantially the same prior art or arguments previously were presented to the Office" (35 U.S.C. § 325(d)). Such issues go to the appropriate Supervisory Patent Reexamination Specialist or the Director of the Central Reexamination Unit (MPEP § 2209) and are taken up after the substantial-new-question determination (1545 OG 217).

In practice the bar has been low: of 15,998 decisions on requests through September 30, 2025, 92.7% granted reexamination. Filings have risen: 491 in fiscal year 2025, and 831 ex parte requests in the first three quarters of fiscal year 2026 alone.

Sources: 35 U.S.C. § 303, § 325(d); 37 C.F.R. § 1.552; MPEP §§ 2209, 2216, 2240, 2242; 1545 OG 217 (Apr. 28, 2026); Ex Parte Reexamination Filing Data (Sept. 30, 2025); Reexamination operational statistics (quarter ending June 30, 2026).

The streamlined format means 40 or fewer pages, double or one-and-a-half line spacing, a non-script font of at least 12 points, compliant margins and clear reproduction; copies of the art, the patent and the required certifications do not count toward the 40 pages (§ 1.20(c)(1)). The fee schedule notes that third-party filers are not eligible for the micro entity fee. These are government fees only; our official sources do not quantify attorney costs.

Sources: 37 C.F.R. § 1.20(c), § 1.26(c); USPTO fee schedule (updated Aug. 14, 2026).

By rule, the patent owner may not file a statement before the decision on the request (37 C.F.R. § 1.530(a)). A notice signed April 1, 2026 (1545 OG 217) waives that rule for requests filed on or after April 5, 2026:

• Pre-order paper. The patent owner may file a paper of 30 pages or fewer arguing that, despite the teachings the request cites, the Office should keep its earlier decision of patentability. It must be filed no later than 30 days after service of the request, and that time cannot be extended. It may not address matters not raised in the request or argue for denial under § 325(d), and arguments that a teaching is not new should be saved for after the order.
• Requester response only by exception. A requester ordinarily may not respond; in exceptional cases, such as misrepresentations, it may file a 10-page paper with a grantable petition under 37 C.F.R. § 1.182 and fee, within 15 calendar days of service of the patent owner’s paper.

After an order, the patent owner’s statement must "clearly point out why the subject matter as claimed is not anticipated or rendered obvious" by the art, alone or in reasonable combinations (§ 1.530(c)), and may propose amendments and new claims. No amendment may enlarge the scope of the claims or add new matter, and none may be proposed in an expired patent (§ 305; § 1.530(j)). If the owner files a statement, the requester has two months to reply, with no extensions, and may cite additional art; after that reply the requester may file nothing further (MPEP § 2251).

Sources: Pre-order Procedure regarding Substantial New Question determination, 1545 OG 217 (Apr. 28, 2026); 37 C.F.R. § 1.530, § 1.535; 35 U.S.C. §§ 304, 305; MPEP §§ 2249, 2251.

• Pace. Office actions usually set a two-month shortened period for response (MPEP § 2263), and the patent owner gets at least 30 days (37 C.F.R. § 1.550(b)). Reexaminations are "special" throughout, and those involved in litigation have priority over all other cases (MPEP § 2261). Overall pendency from filing to certificate was 25.2 months on average and 18.9 months at the median (USPTO data as of September 30, 2025).
• Claim construction. In deciding whether to order reexamination, the Office gives unexpired claims "their broadest reasonable interpretation consistent with the specification"; claims of an expired patent get their ordinary and customary meaning under Phillips (MPEP §§ 2240, 2258).
• Outcomes. Of certificates issued through September 30, 2025, 22.2% confirmed all requested claims, 14.5% cancelled all requested claims and 63.3% changed claims; for third-party requests the figures were 22.9%, 16.1% and 61.0%. The analysis covers requested claims only and counts merged reexaminations once.
• Appeal. The patent owner may appeal adverse decisions to the PTAB and then to the Federal Circuit (§ 306; § 141(b)). "A third party requester of an ex parte reexamination may not seek judicial review" (MPEP § 2279).
• Intervening rights. Amended or new claims that come out of reexamination have the same effect as reissued claims under § 252 on the rights of anyone who, before the certificate, made, purchased or used within the United States, or imported, what they cover, or made substantial preparation to do so (§ 307(b)).
• Litigation. If the patent is in litigation, the Director decides whether to suspend the reexamination (37 C.F.R. § 1.565(b)). A court decision upholding a claim "does not necessarily mean that no new question is present," because of "the different standards of proof" in court and at the Office (MPEP § 2286).

Sources: 35 U.S.C. § 306, § 307, § 141(b); 37 C.F.R. § 1.550, § 1.565; MPEP §§ 2240, 2258, 2261, 2263, 2279, 2286; Ex Parte Reexamination Filing Data (Sept. 30, 2025); USPTO Central Reexamination Unit.

Supplemental examination (35 U.S.C. § 257) is a different, owner-only proceeding. A patent owner may ask the Office "to consider, reconsider, or correct information believed to be relevant to the patent." Within three months the Office issues a certificate stating whether the information raises a substantial new question; if it does, reexamination is ordered (§ 257(a)-(b)).

No amendment may be filed during the supplemental examination itself (37 C.F.R. § 1.620(f)), and if the Office finds that a material fraud may have been committed, it refers the matter to the Attorney General (§ 257(e)).

Sources: 35 U.S.C. § 257; 37 C.F.R. § 1.601, § 1.605, § 1.610, § 1.620, § 1.625, § 1.20(k); USPTO fee schedule.

• Rehashing the examiner’s art. A request that only asks the Office to look again at art already considered, without a new teaching or a new light, will not raise a substantial new question (MPEP § 2216).
• Arguing public use or sales. Those grounds are outside reexamination (MPEP § 2209). A patent owner who wants wider consideration of issues such as prior public use or on sale may file a reissue application or, where appropriate, request supplemental examination (MPEP § 2212).
• Forgetting the estoppel statement. An anonymous request against a patent with an IPR or PGR final written decision should include the affirmative statement the February 2026 notice describes, or the filing date may be vacated.
• Expecting to steer the examination. After its one reply the requester has no further say, and it cannot appeal a confirmation. In our view, request reexamination only on art you are prepared to see confirmed or amended around, since a certificate can leave the patent stronger.

Sources: MPEP §§ 2209, 2212, 2216, 2251, 2279; 1544 OG 128 (Mar. 3, 2026); 35 U.S.C. § 301, § 306, § 307. Follow the PTAB and USPTO guidance we track on our PTAB hub and PTAB guidance topic page; trials at the Board are covered in our inter partes review guide.