35 U.S.C. 323, Preliminary response to petition
If a post-grant review petition is filed under section 321, the patent owner shall have the right to file a preliminary response to the petition, within a time period set by the Director, that sets forth reasons why no post-grant review should be instituted based upon the failure of the petition to meet any requirement of this chapter.
Effective Dates for Changes Made to this Section
POST-GRANT REVIEW CHANGES
Section 6 of the America Invents Act
(f) REGULATIONS AND EFFECTIVE DATE.--
(1) REGULATIONS.--The Director shall, not later than the date that is 1 year after the date of the enactment of this Act, issue regulations to carry out chapter 32 of title 35, United States Code, as added by subsection (d) of this section.
(A) IN GENERAL.--The amendments made by subsection (d) shall take effect upon the expiration of the 1–year period beginning on the date of the enactment of this Act and, except as provided in section 18 and in paragraph (3), shall apply only to patents described in section 3(n)(1).
(B) LIMITATION.--The Director may impose a limit on the number of post-grant reviews that may be instituted under chapter 32 of title 35, United States Code, during each of the first 4 1–year periods in which the amendments made by subsection (d) are in effect.