and would have resulted in enhanced punishment in violation of Ex Post Facto Clause, U.S. Const. art. I, § 9, cl. 3. United States v Stinson (2007, SD W lea) 507 F Supp 2d 560. No ex post facto violation arose from retroactive application of 42 USCS § 16913(b),(c) part of Sex Offender Registration and N