Calder v. Bull

Calder v. Bull, 3 U.S. 386 (1798), is a United States Supreme Court case in which the Court decided four important points of constitutional law.

First that the ex post facto clause of the United States Constitution only applies to criminal acts, and then only if the law does one of four things: "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. 2d. Every law that aggravates a crime, makes it greater than it was, when committed. 3d. 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." The decision restates this later as laws "that create, or aggregate, the crime; or encrease(sic) the punishment, or change the rules of evidence, for the purpose of conviction." (italics in original)