What is the burden of proving that the site of the crime was in Indian country?

The structure and wording of 1156 indicate that the prosecution should bear the burden of proof as to the status of the site. Because possession of intoxicants is prohibited by 1156 only in Indian country, the locus of the act of possession constitutes an element of the crime. The statutory definition of "Indian country" excludes fee-patented lands in non-Indian communities. We are therefore persuaded that the Government bears the burden of proving that the site of the offense was not a non-Indian community as part of its proof that the offense occurred in Indian country. Cf. United States v. Vuitch, 402 U.S. 62, 70, 91 S.Ct. 1294, 1298, 28 L.Ed.2d 601 (1971) ("It is a general guide to the interpretation of criminal statutes that when an exception is incorporated in the enacting clause of a statute, the burden is on the prosecution to plead and prove that the defendant is not within the exception").