37 CFR § 42.201 - Who may petition for a post-grant review.

---
identifier: "/us/cfr/t37/s42.201"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "37 CFR § 42.201 - Who may petition for a post-grant review."
title_number: 37
title_name: "Patents, Trademarks, and Copyrights"
section_number: "42.201"
section_name: "Who may petition for a post-grant review."
chapter_name: "UNITED STATES PATENT AND TRADEMARK OFFICE, DEPARTMENT OF COMMERCE"
subchapter_number: "A"
subchapter_name: "GENERAL"
part_number: "42"
part_name: "TRIAL PRACTICE BEFORE THE PATENT TRIAL AND APPEAL BOARD"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "35 U.S.C. 2(b)(2), 3, 6, 21, 23, 41, 134, 135, 143, 153, 311, 312, 314, 316, 318, 321-326, 328; Pub. L. 112-29, 125 Stat. 284; and Pub. L. 112-274, 126 Stat. 2456."
regulatory_source: "77 FR 48669, Aug. 14, 2012, unless otherwise noted."
cfr_part: "42"
---


# 42.201 Who may petition for a post-grant review.

A person who is not the owner of a patent may file with the Office a petition to institute a post-grant review of the patent unless:

(a) Before the date on which the petition for review is filed, the petitioner or real party-in-interest filed a civil action challenging the validity of a claim of the patent; or

(b) The petitioner, the petitioner's real party-in-interest, or a privy of the petitioner is estopped from challenging the claims on the grounds identified in the petition.