Ex Post Facto Laws

An ex post facto law (Latin for “made after the occurrence”) is one promulgated as punishment for acts not punishable at the time they were committed. (It gives new meaning to the warning “Ignorance of the law is no excuse,” because it requires foreknowledge of what will be a law in the future.) Ex post facto laws are generally criminal, not civil (see Criminal Law); they may make a formerly lawful act unlawful as well as increase the punishment for an existing crime.

Such laws are a clear violation of due process and, like bills of attainder, are twice prohibited by the Constitution. Article I, section 9, pertaining to congress, states: “No…ex post facto Law shall be passed.” And section 10 declares: “No state shall…pass any…ex post facto Law….” Many other countries, including India (1950) and Bolivia (1967), prohibit retroactive criminal laws.

Alexander Hamilton in essay 84 of The Federalist (1787–88) (see Federalist Papers) comments on the Constitution’s prohibition against ex post facto laws. “The creation of crimes after the commission of the fact, or, in other words, the subjecting of men to punishment for things which, when they were done, were breaches of no law, and the practice of arbitrary imprisonments, have been, in all ages, the favorite and most formidable instruments of tyranny.”

In the Supreme Court’s decision in Calder v. Bull (1798), Justice Samuel Chase (1741–1811) gave the ultimate definition of ex post facto laws: “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.” As the first definition indicates, the prohibition against ex post facto laws was interpreted as applicable only to criminal law and not to civil law.

The Supreme Court, however, has relaxed the prohibition against ex post facto laws in instances where changes in the rules of evidence had no substantial impact on a defendant’s rights—for example, in Beazell v. Ohio (1925), in which the Court held that changes in trial procedures or rules of evidence that “do not deprive the accused of a defense and [that] operate only in a limited and unsubstantial manner are not prohibited.” It has also exempted judicial decisions that change the law as opposed to statutory changes made by legislation; in Powell v. Nevada (1994), the Court decided that any constitutional rule of procedure that had an impact on criminal prosecutions had to be applied retroactively to all cases that were not yet final when the new rule was announced. Further, in Carlson v. Landon (1952), the Court upheld the deportation of aliens for acts committed before the applicable law was passed.

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