37 CFR 42.108 : Patents, Trademarks, And Copyrights (§ 1.1 To Chapter V) — (§ 1.1 To Chapter V) — United States Patent And Trademark Office, Department Of Commerce (§ 1.1 To Parts 151-199) — General (§ 1.1 To § 90.3) — Trial Practice Before The Patent Trial And Appeal Board (§ 42.1 To § 42.412) — Inter Partes Review (§ 42.100 To § 42.123) — Instituting Inter Partes Review (§ 42.108) — Institution of inter partes review

(a) When instituting inter partes 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 inter partes 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 inter partes review on that ground.

(c) Sufficient grounds. Inter partes review shall not be instituted for a ground of unpatentability unless the Board decides that the petition supporting the ground would demonstrate that there is a reasonable likelihood 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.