Ex post facto law

Ex post facto law is a legal term that refers to laws that retroactively change the legal consequences of actions committed before the enactment of the law. The term is derived from the Latin expression meaning "from after the fact".

Ex post facto laws are expressly prohibited by the United States Constitution in Article 1, Section 9, Clause 3 (with respect to federal laws) and Article 1, Section 10 (with respect to state laws). This prohibition protects individuals from unfair legislative acts.

Definition

An ex post facto law is a law that retroactively changes the legal consequences or status of actions that were committed, or relationships that existed, before the enactment of the law. In criminal law, it may criminalize actions that were legal when committed; it may aggravate a crime by bringing it into a more severe category than it was in when it was committed; it may change the punishment prescribed for a crime, as by adding new penalties or extending sentences; or it may alter the rules of evidence in order to make conviction for a crime likelier than it would have been when the deed was committed.

Historical Background

The prohibition on ex post facto laws was influenced by a similar provision in the English Bill of Rights of 1689, which was a response to the abusive practices of the Stuart kings. The prohibition is also found in many constitutions around the world, including the Constitution of India, the Constitution of Canada, and the Constitution of Australia.

Controversies

The prohibition on ex post facto laws has been the subject of significant legal debate and litigation, particularly in the United States. The U.S. Supreme Court has ruled on numerous occasions that laws retroactively changing the legal consequences of actions are unconstitutional, but there are exceptions. For example, the Court has held that retroactive civil laws do not violate the ex post facto prohibition.

See Also

• Bill of Attainder
• Habeas Corpus
• Due Process
• Retroactive law