Also known as: ex post facto
Written by attorneys · grounded in primary & secondary sources — see below
A subsequent act or event. Any act performed after the principal conduct or occurrence has already taken place.
Parker Phillips raised rents on his Franklin apartments four years ago when no criminal penalty attached to the practice. The state later enacted a statute making such increases felonies and authorizing prosecution based solely on old lease records. Prosecutors charged Phillips under the new law for his completed conduct. The court invalidated the charges because the statute operated as a postfactum criminal prohibition.
Pearl Porter completed a financial transaction that became time-barred under the original statute of limitations. Congress later passed a law extending the limitations period and reviving the expired claim for criminal prosecution. Prosecutors indicted Porter solely on the basis of the revived period. The court dismissed the indictment because the extension functioned as a postfactum alteration of the quantum of evidence needed for conviction.
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Pamela Phillips acquired cultural artifacts for a museum fifty years ago in full compliance with then-existing export rules. Congress subsequently enacted a statute criminalizing such acquisitions retroactively and directed federal prosecutors to indict based on the historical records. Prosecutors brought charges against Phillips for the decades-old conduct. The court dismissed the indictment because the statute constituted a postfactum criminalization of previously lawful acts.
Philip Powell sold counterfeit goods last year under a statute carrying a particular penalty range. Congress later increased the mandatory minimum terms and directed that the new penalties apply to all prior offenses. The sentencing court applied the harsher terms to Powell. The court of appeals reversed because the increased punishment operated as a postfactum enhancement.
Preston Pratt disposed of waste in full compliance with State Green environmental rules in effect at the time. The state later enacted a statute reclassifying those same methods as felonies and authorizing charges based on archived compliance reports. Prosecutors indicted Pratt solely for the prior conduct. The court dismissed the charges because the statute imposed postfactum criminal liability on previously lawful acts.
Priscilla Parks entered a patent settlement fifteen years ago that fully complied with then-existing antitrust law. Congress later enacted a statute retroactively declaring such settlements unlawful and requiring treble damages into a compensation fund. The government sued Parks to enforce the payments. The court dismissed the action because the retroactive treble obligation functioned as a postfactum punitive measure.
A statute is an ex post facto law when it retroactively makes conduct criminal that was lawful when performed, increases punishment for past conduct, or alters the rules of evidence to make conviction easier. The prohibition appears in Article I Sections 9 and 10 and applies to both Congress and the states. Courts invalidate such statutes because they deny fair notice and allow legislative punishment after the fact.
The prohibition applies to criminal laws and to civil measures that function as punishment rather than remediation. Courts examine factors such as whether the sanction imposes an affirmative disability, has historically been viewed as punishment, requires scienter, advances retribution or deterrence, and appears excessive relative to any nonpunitive purpose. Purely remedial civil schemes do not violate the clause.
No. A statute that retroactively revives a time-barred criminal prosecution by extending the statute of limitations after it has expired violates the Ex Post Facto Clause. The extension alters the quantum of evidence deemed sufficient to convict and reopens the possibility of punishment for past conduct that was previously insulated.
Yes. When a legislature increases the maximum or mandatory minimum prison terms for past offenses and directs that the new penalties apply retroactively, the statute violates the Ex Post Facto Clause. The clause forbids any retroactive increase in punishment for conduct completed before the change.
…a measure was "necessary and proper" to the discharge of its substantive legislative authority, pass a bill of attainder or ex post facto law contrary to the prohibitions contained in § 9 of Art. I. No more may it vest in itself, or in its officers, the authority to appoint officers of the United States when the Appointments…