Correct: In a legal context, ex post facto is most typically used to refer to a criminal statute that punishes actions retroactively, thereby criminalizing con

Correct: In a legal context, ex post facto is most typically used to refer to a criminal statute that punishes actions retroactively, thereby criminalizing conduct that was legal when originally performed. Two clauses in the United States Constitution prohibit ex post facto laws: Article 1, § 9 --- This prohibits Congress from passing any laws which apply ex post facto. Article 1 § 10. --- This prohibits the states from passing any laws which apply ex post facto. <https://www.law.cornell.edu/wex/ex_post_facto https://www.law.cornell.edu/wex/ex_post_facto>