35 U.S.C. § 324: Institution of post-grant review

The Director may not authorize a post-grant review to be instituted unless the Director determines that the information presented in the petition filed under section 321, if such information is not rebutted, would demonstrate that it is more likely than not that at least 1 of the claims challenged in the petition is unpatentable. The determination required under subsection (a) may also be satisfied by a showing that the petition raises a novel or unsettled legal question that is important to other patents or patent applications. receiving a preliminary response to the petition under section 323; or if no such preliminary response is filed, the last date on which such response may be filed. The Director shall notify the petitioner and patent owner, in writing, of the Director’s determination under subsection (a) or (b), and shall make such notice available to the public as soon as is practicable. Such notice shall include the date on which the review shall commence. The determination by the Director whether to institute a post-grant review under this section shall be final and nonappealable.