Louisiana Revised Statutes Tit. 14, § 17. Mistake of law

(1) Where the offender reasonably relied on the act of the legislature in repealing an existing criminal provision, or in otherwise purporting to make the offender's conduct lawful; or

(2) Where the offender reasonably relied on a final judgment of a competent court of last resort that a provision making the conduct in question criminal was unconstitutional.