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Ex Post Facto


In the federalist #84 alexander hamilton argued that "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" has been "in all ages" one of "the favorite and most formidable instruments of tyranny." Indeed, ex post facto legislation has generally been regarded as a violation of the fundamental due process requirement that there must be fair warning of the conduct which gives rise to criminal penalties. The Framers of the Constitution believed so strongly that ex post facto laws were contrary to the principles of republican government that they proscribed their use in two different provisions of the Constitution: Article I, section 9, as a specific exception to the powers of the United States Congress, and Article I, section 10, as a specific prohibition on the powers of state legislatures.

Justice samuel chase in calder v. bull (1798) provided what has since come to be regarded as the authoritative delineation of the kinds of legislation that fall within the Constitution's prohibition against ex post facto enactments:

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, or 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 received less, or different, testimony, than the law required at the time of the commission of the offence, in order to convict the offender.

Although there is some question about the Framers' intent, the Supreme Court has consistently followed Chase's lead in restricting the ex post facto rule to criminal laws. Thus the Court has held that the deportation of aliens, the loss of a passport, and the denial of certain benefits do not fall within the ex post facto exception because they are not punishments in a criminal sense even though they may be "burdensome and severe." In the test oath cases (1867), however, the Court held that oaths that disqualified people from holding certain offices or practicing certain professions constituted ex post facto laws.

The essential ingredient of an ex post facto law is its retrospective character; but not all retrospective laws are ex post facto in the technical meaning of the term. An ex post facto law not only is retrospective but also injures those to whom it is directed by imposing or increasing criminal penalties. For example, Weaver v. Graham (1981) invalidated retroactive application to a prisoner of a law reducing "good time" credits against a sentence. Retrospective laws that ameliorate penalties, however, are not ex post facto.

The rights affected by retrospective legislation must be substantial. As the Court held in Beazell v. Ohio (1925), statutory changes in trial procedures or rules of evidence "which do not deprive the accused of a defense and which operate only in a limited and unsubstantial manner to his disadvantage, are not prohibited." Thus, the ex post facto prohibition secures "substantial personal rights against arbitrary and oppressive legislation without limiting legislative control of remedies and procedures that do not affect matters of substance." Of its own weight, the ex post facto prohibition applies only to legislative acts, and not to changes in the law effected by judicial decisions. But where an unforeseeable statutory construction by a court is applied retrospectively in a manner that is tantamount to ex post facto legislation, that construction is barred by the due process clause. Although the particular application of the ex post facto clause has generated much controversy and debate, and involves, on occasion, the most intricate and detailed considerations, there seems to be almost universal agreement that the Constitution's prohibition against ex post facto legislation remains one of the mainstays of constitutional government.

Edward J. Erler


Field, Oliver P. 1922 Ex Post Facto in the Constitution. Michigan Law Review 20:315–331.

Note 1975 Ex Post Facto Limitations on Legislative Power. Michigan Law Review 73:1491–1516.

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