Due process does not require the prosecution to disprove a defendant’s withdrawal from a conspiracy within the statute of limitations. Smith was convicted of federal drug trafficking and other charges. On appeal he challenged his conspiracy conviction as barred by the applicable federal statute of limitations (18 U.S.C. § 3282), as well as the court’s instruction to the jury that once the prosecution proved that Smith was part of a conspiracy, Smith bore the burden of proving withdrawal from the conspiracy. Held: Affirmed. The Court noted the circuits are divided regarding the burden of proving withdrawal from a conspiracy. It held that placing the burden of proving withdrawal on the defendant does not violate the due process clause. While a state may not shift to a defendant the burden of proving an affirmative defense when it would negate the element of a crime, here, the defense would have excused conduct otherwise criminal. Withdrawal prior to the limitation period would not controvert any element of the conspiracy crimes charged, for it presupposes that Smith committed the offense. As for Smith’s statutory challenge, had the Legislature chosen to allocate to the prosecution the burden of proving the nonexistence of a withdrawal, it could have done so.