Such laws are specifically prohibited by the U. S. Constitution, Article I, Section 9. Therefore, if a state legislature or Congress enact new rules of proof or longer sentences, those new rules or sentences do not apply to crimes committed before the new law was adopted” (ex post facto, n.d.).
In simpler terms ex post facto means that once a law was created no penalty could be extended from a crime committed before the law was passed but once in effect the punishment would be more for anyone committing the crime after the passing of the law. Before the ratification of the constitution the ex post facto laws were “not forbidden” (Comparing the Articles and Constitution, n.d.), but after the ratification of the Constitution the ex post facto laws were “forbidden in both states and Congress” (Comparing the Articles and Constitution,