EX POST FACTO CLAUSE

Ex Post Facto Clause. One of two clauses in the U.S. Constitution forbidding the enactment of ex post facto laws. U.S. Const. art. I, § 9, cl. 3; art. I, § 10, cl. 1. [Cases: Constitutional Law 197–203. C.J.S. Constitutional Law §§ 409–428.]