37 CFR 42.208 : Patents, Trademarks, And Copyrights (Section 2.11 To Chapter V) — United States Patent And Trademark Office, Department Of Commerce (Parts 1 - 199) (Section 2.11 To Parts 151-199) — Unknown Title (Parts 2 - 90) (Section 2.11 To Section 90.3) — Trial Practice Before The Patent Trial And Appeal Board (Section 42.1 To Section 42.407) — Post-Grant Review (Section 42.200 To Section 42.224) — General (Part 42) (Section 42.200 To Section 42.224) — Institution of post-grant review.

(a) When instituting post-grant review, the Board may authorize the review to proceed on all or some of the challenged claims and on all or some of the grounds of unpatentability asserted for each claim.

(b) At any time prior to institution of post-grant review, the Board may deny some or all grounds for unpatentability for some or all of the challenged claims. Denial of a ground is a Board decision not to institute post-grant review on that ground.

(c) Sufficient grounds. Post-grant review shall not be instituted for a ground of unpatentability, unless the Board decides that the petition supporting the ground would, if unrebutted, demonstrate that it is more likely than not that at least one of the claims challenged in the petition is unpatentable. The Board's decision will take into account a patent owner preliminary response where such a response is filed.

(d) Additional grounds. Sufficient grounds under § 42.208(c) may be a showing that the petition raises a novel or unsettled legal question that is important to other patents or patent applications.