Page "Ex post facto law" Paragraph 0

An ex post facto law ( from the Latin for " from after the action " or " after the fact "), also called a retroactive 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.

Conversely, a form of ex post facto law commonly called an amnesty law may decriminalize certain acts or alleviate possible punishments ( for example by replacing the death sentence with lifelong imprisonment ) retroactively.

Such laws are also known by the Latin term in mitius.