Trial means a contested case instituted by the Board based upon a petition. A trial begins with a written decision notifying the petitioner and patent owner of the institution of the trial. The term trial specifically includes a derivation proceeding under 35 U.S.C. 135; an inter partes review under Chapter 31 of title 35, United States Code; a post-grant review under Chapter 32 of title 35, United States Code; and a transitional business-method review under section 18 of the Leahy-Smith America Invents Act. Patent interferences are administered under part 41 and not under part 42 of this title, and therefore are not trials.
37 CFR § 42.2
The following definitions apply to this part: