Post-grant review (PGR)

1. PetitionA person who is not the owner of the patent files a petition with the USPTO and pays the fee¹. The petition may be considered only if it identifies all real parties in interest and identifies, in writing and with particularity, each claim challenged, the grounds and the supporting evidence, including copies of the patents and printed publications relied on⁵. It may be filed not later than 9 months after the grant of the patent or the issuance of a reissue patent¹.
2. Preliminary responseThe patent owner has the right to file a preliminary response, within a time period set by the Director, setting out reasons why no review should be instituted because the petition fails to meet a requirement of the chapter⁶.
3. Institution decisionThe Director may not authorize a review unless the information in the petition, if not rebutted, would demonstrate that it is more likely than not that at least 1 challenged claim is unpatentable³. A showing that the petition raises a novel or unsettled legal question important to other patents or applications may also satisfy the requirement³. The decision is due within 3 months after the preliminary response, or after the last date it could have been filed, and is final and nonappealable³.
4. TrialThe Patent Trial and Appeal Board conducts each instituted review⁷. The petitioner has the burden of proving unpatentability by a preponderance of the evidence⁷. The patent owner may file 1 motion to amend, to cancel claims or propose a reasonable number of substitute claims, and the amendment may not enlarge the scope of the claims or introduce new matter⁷.
5. Final written decisionThe final determination must be issued not later than 1 year after the Director notices the institution, and the Director may extend that period by not more than 6 months for good cause shown⁷. If the review is instituted and not dismissed, the Board issues a final written decision on the patentability of each challenged claim and any new claim added by amendment⁸.
6. Appeal and certificateA party dissatisfied with the final written decision may appeal under 35 U.S.C. 141 to 144, and any party to the review has the right to be a party to the appeal⁹. When the time for appeal has expired or any appeal has terminated, the Director issues a certificate canceling claims finally determined to be unpatentable, confirming those found patentable and incorporating any patentable new or amended claims⁸.

• Grounds. The petitioner may request cancellation of claims on any ground that could be raised under paragraph (2) or (3) of 35 U.S.C. 282(b)¹. Those paragraphs cover invalidity on any ground specified in part II of title 35 as a condition for patentability, and failure to comply with section 112 (except that failure to disclose the best mode is not a basis for invalidity) or section 251¹⁰.
• Deadline and reissues. A petition may be filed only up to 9 months after grant or reissue¹. A review may not be instituted if the petition challenges a reissue claim that is identical to or narrower than a claim in the original patent and the 9-month limit would bar a petition against the original patent (35 U.S.C. 325(f))¹¹.
• Which patents. The USPTO says PGR generally applies to patents issuing from applications subject to the first-inventor-to-file provisions of the AIA².
• Earlier validity suit. A review may not be instituted if, before the petition was filed, the petitioner or a real party in interest filed a civil action challenging the validity of a claim. A counterclaim challenging validity does not count as such a civil action (35 U.S.C. 325(a))¹¹.
• Civil action filed after the petition. A civil action challenging validity that the petitioner or a real party in interest files on or after the petition date is automatically stayed until the patent owner moves to lift the stay, the patent owner files an infringement action or counterclaim, or the petitioner moves to dismiss (35 U.S.C. 325(a)(2))¹¹.
• Early infringement suits. If an infringement action is filed within 3 months after the patent is granted, the court may not stay its consideration of a preliminary injunction motion on the basis that a PGR petition has been filed or a review instituted (35 U.S.C. 325(b))¹¹.
• Estoppel. After a final written decision, the petitioner, a real party in interest or a privy may not request or maintain a USPTO proceeding on that claim on any ground that was raised or reasonably could have been raised in the review. The same persons may not assert in a civil action or an ITC proceeding that the claim is invalid on any such ground (35 U.S.C. 325(e))¹¹.

The statute states the minimum for institution, not a right to review³. Since March 2025 the USPTO has set out how it handles institution for IPR and PGR in memoranda and on its Interim Director Discretionary Process page^12,13. The October 17, 2025 memorandum leaves the briefing process on the Interim Director Discretionary Process page unchanged^12,13. What follows is limited to what the USPTO's own pages and notices state.

• Who decides. By a memorandum of October 17, 2025, the USPTO announced that effective October 20, 2025 the Director will determine whether to institute trial in IPR and PGR proceedings, in consultation with at least three PTAB judges. Institution or denial is ordinarily communicated by summary notice, and an instituted proceeding is referred to a three-member panel of the PTAB. The memorandum supersedes the earlier interim processes to the extent that routine institution decisions are limited to summary notices and merit-based decisions are not referred to a three-member panel, and the briefing process stays the same¹².
• Interim process. The interim process begun by a memorandum of March 26, 2025 divides the institution analysis between discretionary considerations and the merits and other non-discretionary considerations. For PGR the merits include whether the patent is eligible for PGR, and whether it is more likely than not that at least one challenged claim is unpatentable or the petition raises a novel or unsettled legal question¹³.
• Discretionary considerations. The USPTO's page says the Director has broad authority to decide whether to exercise discretion to institute, based on a holistic review of the facts. Its non-exhaustive list includes whether the PTAB or another forum has already adjudicated validity of the claims, changes in the law since the claims issued, the strength of the unpatentability challenge, settled expectations of the parties such as the length of time the claims have been in force, and compelling economic, public health or national security interests¹³.
• Briefing. Where the deadline for the patent owner's preliminary response is after March 26, 2025, the patent owner may file a discretionary denial brief within two months of the Notice of Filing Date Accorded, and the petitioner's opposition is due within three months. The page says discretionary issues should not be presented in the petition itself¹³.
• Further considerations (2026). A memorandum of March 11, 2026 says that, when determining whether to institute IPR and PGR proceedings, the Director will consider the extent to which products accused of infringement in a parallel proceeding are made in the United States or tied to US manufacturing investment, the extent to which the patent owner's competing products are made in the United States, and whether the petitioner is a small business that has been sued for infringement of the patent¹⁴.
• Search disclosure declaration. A memorandum of November 17, 2025 allows a petitioner to submit a voluntary declaration describing how the prior art was found. It is treated as a non-exclusive, non-dispositive favorable discretionary factor supporting institution, and a petitioner who does not provide one will not be disadvantaged¹⁵.
• Rulemaking. On October 17, 2025 the USPTO published a proposed rule modifying the rules of practice for instituting inter partes review (90 FR 48335)¹⁶. It concerns IPR, not PGR. As of the review date no final rule had been published in the Federal Register, so check the PTAB pages for what applies on the date you file.

Both are trials conducted at the Patent Trial and Appeal Board^2,4. For the other post-issuance route, see Reexamination.