28 U.S.C.§ 1746(2) (for execution within the United States). For execution outside the United States, see 28 U.S.C.§ 1746(1) ("I declare (or certify, verify, or state) under penalty of perjury under the laws of the United States that the foregoing is true and correct. Executed on (date).").
28 U.S.C.§ 1746: Unsworn declarations under penalty of perjury
