Ex Post Facto


Latin for "from a thing done afterward."


Ex post facto is most typically used to refer to a criminal statute that punishes actions retroactively, thereby criminalizing conduct that was legal when originally performed. Two clauses in the United States Constitution prohibit ex post facto laws:

  1. Art 1, § 9
    1. This prohibits Congress from passing any laws which apply ex post facto.
  2. Art. 1 § 10
    1. This prohibits the states from passing any laws which apply ex post facto.


What Constitutes Punishment

In the often-cited case of Beazell v. Ohio, 269 U.S. 167 (1925), the Supreme Court defined the scope of the constitutional ex post facto restrictions:

  • "It is settled, by decisions of this Court so well known that their citation may be dispensed with, that any statute which punishes as a crime an act previously committed, which was innocent when done, which makes more burdensome the punishment for a crime, after its commission, or which deprives one charged with crime of any defense available according to law at the time when the act was committed, is prohibited as ex post facto."

Courts have applied this standard to different parts of the criminal process. California Dep't of Corrections v. Morales, 514 US 499 (1995) takes the Beazell standard and applies it to the parole process. In Morales, California amended a law to state that the California Board of Prison Terms may defer parole hearings for up to three years for a prisoner convicted of more than one homicide offense. Respondent-defendant Morales was imprisoned before the law was amended, and he was subsequently affected by it when he applied for a parole hearing. In his lawsuit, he claimed that the amendment violated the ex post facto prohibition. The Supreme Court, in applying Beazell, held that an amendment which impacts someone currently imprisoned to a law does not violate ex post facto if the amendment does not increase the punishment attached to the respondent's crime. The Court held that here, the amendment did not impact Morales's sentence nor did it impact any substantive attempt to be granted parole. The Court found that a simple alteration of a prisoner's process of attaining parole does not violate ex post facto prohibitions. 

Retroactive Judicial Decisions 

At a minimum, ex post facto prohibits legislatures from passing laws which retroactively criminalize behavior. However, this prohibition does not attach as strictly to judicial decisions. Appellate courts sometimes announce a new rule of law, but will not apply it to the case in front of it, in order to attempt to comply with ex post facto prohibitions. 

Year and a Day Rule

The Year and a Day Rule is a common law doctrine which states that a person cannot be convicted of homicide for a death that occurs more than a year and a day after his or her act(s) that allegedly caused the death. Rogers v. Tennessee, 532 U.S. 451 (2000) dealt with the doctrine. Defendant-petitioner Rogers had stabbed Bowdery, who died 15 months later.  The trial court found Rogers guilty of murder. When Rogers appealed to the Tennessee Court of Criminal Appeals under the Year and a Day Rule, the appellate court upheld the conviction and abolished the Year and a Day Rule for Tennessee. Rogers ultimately appealed to the Supreme Court, claiming that the appellate court's action violated the ex post facto prohibition. The Supreme Court in Rogers found that ex post facto was not present here, as the appellate "court's decision was a routine exercise of common law decisionmaking that brought the law into conformity with reason and common sense." The Rogers court also referenced a previous Supreme Court decision, Bouie v. City of Columbia, 378 U.S. 347 (1964), which held that "due process prohibits retroactive application of any judicial construction of a criminal statute that is unexpected and indefensible by reference to the law which has been expressed prior to the conduct in issue." Rogers, considering the holding in Bouie, held that the ex post facto prohibition applies only to legislative decisions, and that even if it were to apply to judicial decisions, the retroactive judicial repeal of the Year and a Day Rule is neither unexpected nor indefensible. 

Further Reading

For more on ex post facto, see this University of Chicago Law Review article, this Berkley Law Review article, and this University of North Carolina Law Review article.