Calder v. Bull, 3 Dallas (3 U.S.) 386; 1 L. Ed. 648 (1798)

Facts—A dispute arose between Calder and his wife on one side and Bull and his wife on the other side concerning a right to property left by N. Morrison, a physician, in his will of March 1793. The Probate Court of Hartford rejected the will in question, and decided in favor of Calder and his wife. As a result of a law enacted in 1795 by the state legislature, a new hearing of the case, which was not allowed according to the old law, took place. This time the will involved in this case was approved, thus transferring the right of the property from Calder to Bull.

Question—Was this Connecticut statute permitting reconsideration of a will, a reconsideration previously not allowed by law, an ex post facto law?

Decision—No.

Reasons—J. Chase (4–0). Chase defined the term ex post facto law as contained in Article I, Section 10 of the Constitution as:

1. Every law that makes criminal an action done before the passing of the law and which was innocent when done, and punishes such an action.
2. Every law that aggravates a crime, or makes it greater than it was, when committed.
3. Every law that changes punishment, and inflicts a greater punishment, than the law annexed to the crime when committed.
4. 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 offense, in order to convict the offender.

Thus a distinction must be made between retrospective laws and ex post facto laws. Likewise, ex post facto laws do not affect contracts, but only criminal or penal statutes.