 But , in 1948 , Congress amended the Assimilative Crimes Act , 18 U.S.C. § 13 , to incorporate changes in state criminal law , as they occur , up until the commission of the charged conduct . The Supreme Court upheld the constitutionality of the revision in United States v. <unk> ( 1958 ) . <unk> held that : " There is nothing in [ Paul ] to show that the issue was decided as anything more than one of statutory construction falling within the doctrine calling for the narrow construction of a penal statute . So interpreted , the decision did not reach the issue that is before us . " 
