37 CFR 42.207: Preliminary response to petition.

(a) The patent owner may file a preliminary response to the petition. The response is limited to setting forth the reasons why no post-grant review should be instituted under 35 U.S.C. 324 and can include supporting evidence. The preliminary response is subject to the word count under § 42.24.

(b) Due date. The preliminary response must be filed no later than three months after the date of a notice indicating that the request to institute a post-grant review has been granted a filing date. A patent owner may expedite the proceeding by filing an election to waive the patent owner preliminary response.

(c) [Reserved]

(d) No amendment. The preliminary response shall not include any amendment.

(e) Disclaim Patent Claims. The patent owner may file a statutory disclaimer under 35 U.S.C. 253(a) in compliance with § 1.321(a), disclaiming one or more claims in the patent. No post-grant review will be instituted based on disclaimed claims.