ex post facto law

Cultural  

1. A law that makes illegal an act that was legal when committed, increases the penalties for an infraction after it has been committed, or changes the rules of evidence to make conviction easier. The Constitution prohibits the making of ex post facto law. (See ex post facto (see also ex post facto).)

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Example Sentences

Because genocide became an official crime only after the Nuremberg trials, Germany decided in 1949 that charging former Nazis with this crime would amount to ex post facto law.

From Washington Post • Oct. 6, 2021

Constitution bars convicting someone under an ex post facto law, meaning one adopted after the alleged crime.

From Reuters • Apr. 30, 2019

An ex post facto law is a law applied to an act committed before the passage of that law.

From Textbooks • Jan. 1, 2016

What has been done at N�rnberg . . . is a new judicial process but it is not ex post facto law.

From Time Magazine Archive

Then my honourable friend says that this is an ex post facto law.

From Miscellaneous Writings and Speeches — Volume 4 by Macaulay, Thomas Babington Macaulay, Baron