35 U.S.C. 316
From Conservapedia
In 35 U.S.C. § 316 establishes the procedure for inter partes review of patents under the America Invents Act. Most notably, it establishes a lower preponderance of the evidence standard for a petitioner to prove the invalidity of a patent for unpatentability:
“ | In an inter partes review instituted under this chapter [35 USCS §§ 311 et seq.], the petitioner shall have the burden of proving a proposition of unpatentability by a preponderance of the evidence. | ” |
35 U.S.C.S. § 316(e).