U.S. Supreme Court
CALDER v. BULL, 3 U.S. 386 (1798)
3 U.S. 386 (Dall.)
Calder et Wife,
Bull et Wife.
August Term, 1798
This case basically says that the constitutional restriction on passage of ex post facto laws applies ONLY to criminal laws, and NOT to civil laws.
I had been wondering for a while now about tax laws, which are often made retroactive from the enactment date to some previous year (sometimes several years earlier!). This struck me as being quite wrong and blatantly and explicitly unconstitutional. But they do it because of this Calder v. Bull case.
You may be thinking "But wait, that was over 200 years ago! Surely there must be some more recent cases we can look to!" Well, no, there isn't. This Bull case has been cited continuously for 200 years by courts all across the nation. It was even cited in the Kelo v. New London case just last year! It is the definitive court case on ex post facto laws, despite its age.
The most important part of the decision is this:
I will state what laws I consider ex post facto laws, within the words and the intent of the prohibition.
1st. Every law that makes an action , done before the passing of the law, and which was innocent when done, criminal; and punishes such action.
2nd. Every law that aggravates a crime, or makes it greater than it was, when committed.
3rd. Every law that changes the punishment, and inflicts a greater punishment, than the law annexed to the crime, when committed.
4th. Every law that alters the legal rules of evidence, and receives less, or different, testimony, than the law required at the time of the commission of the offence, in order to convict the offender.
All these, and similar laws, are manifestly unjust and oppressive. In my opinion, the true distinction is between ex post facto laws, and retrospective laws. Every ex post facto law must necessarily be retrospective; but every retrospective law is not an ex post facto law: The former, only, are prohibited. Every law that takes away, or impairs, rights vested, agreeably to existing laws, is retrospective, and is generally unjust; and may be oppressive; and it is a good general rule, that a law should have no retrospect: but there are cases in which laws may justly, and for the benefit of the community, and also of individuals, relate to a time antecedent to their commencement; as statutes of oblivion, or of pardon. They are certainly retrospective, and literally both concerning, and after, the facts committed. But I do not consider any law ex post facto, within the prohibition, that mollifies the rigor of the criminal law; but only those that create, or aggravate, the crime; or encrease the punishment, or change the rules of evidence, for the purpose of conviction. Every law that is to have an operation before the making thereof, as to commence at an antecedent time; or to save time from the statute of limitations; or to excuse acts which were unlawful, and before committed, and the like; is retrospective. But such laws may be proper or necessary, as the case may be. There is a great and apparent difference between making an UNLAWFUL act LAWFUL; and the making an innocent action criminal, and punishing it as a CRIME. The expressions 'ex post facto laws,' are technical, they had been in use long before the Revolution, and had acquired an appropriate meaning, by Legislators, Lawyers, and Authors. The celebrated and judicious Sir William Blackstone, in his commentaries, considers an ex post facto law precisely in the same light I have done. His opinion is confirmed by his successor, Mr. Wooddeson; and by the author of the Federalist, who I esteem superior to both, for his extensive and accurate knowledge of the true principles of Government.