The topic of discussion on this Constitution Monday comes from Article I.9.3: "No … ex post facto law shall be passed [by Congress]. This provision in the Constitution gave every American the guarantee that there would be no law passed by Congress after an act had occurred.
"The term ex post facto simply means `after the deed or fact.' There are five situations which this provision prohibits:
1) Charging someone with an offense or crime which was not illegal at the time it occurred….
2) Charging someone with a crime under a law which has made the offense more serious than when it was committed….
3) Subjecting someone to a greater punishment than was prescribed by the law at the time the offense was perpetrated….
4) Allowing evidence to be introduced under new rules which were not in effect at the time the offense occurred….
5) Passing a law which deprives the accused of some protection to which he was entitled at the time the act occurred….
"Many injustices have been prevented under this provision…." (See W. Cleon Skousen, The Making of America - The Substance and Meaning of the Constitution, p 476.)
"As generally understood, a law that is ex post facto - literally, after the fact - is one that criminally punishes conduct that was lawful when it was done. It is an aspect of the fundamental maxim, nulla poena sine lege: there can be no punishment without law - in this case, without pre-existing law. Despite the fact that the prohibition against such laws had worked its way into English law (as celebrated by Sir William Blackstone), Parliament had, nonetheless, claimed the right to enact ex post facto laws in the form of bills of attainder against unpopular groups and persons. In addition, prior to the Constitutional Convention, some states themselves had passed ex post facto laws. (The prohibition of ex post facto state laws is found in Article I, Section 10, Clause 1).
"Nevertheless, opposition to ex post facto laws was a bedrock principle among the Framers….
, the Framers debated the issue vigorously…. The delegates then approved the clause…. Philadelphia
"While the Supreme Court has hewn to the position that the Ex Post Facto Clause prohibits criminal penalties only, it has also applied the clause in civil cases where criminal penalties are disguised as civil disabilities. As the Court has said, `it is the effect, not the form, of the law that determines whether it is ex post facto.' Weaver v. Graham (1980)." (See Daniel Troy, The Heritage Guide to the Constitution, pp 156-157.)