ex post facto

American  

[eks pohst fak-toh] / ˈɛks ˌpoʊst ˈfæk toʊ /

adverb

1. from or by subsequent action; retroactively; subsequently; retrospectively.

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adjective

1. having retroactive force; made or done subsequently.

   an ex post facto law.

ex post facto British  

/ ɛks pəʊst ˈfæktəʊ /

adjective

1. having retrospective effect

   an ex post facto law

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ex post facto ¹ Cultural  

1. An explanation or regulation concocted after the event, sometimes misleading or unjust: “Your ex post facto defense won't stand up in court.” (See ex post facto law.) From Latin, meaning “after the deed.”

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ex post facto ² Cultural  

1. A descriptive term for an explanation or a law that is made up after an event and then applied to it: “The chairman's description of his plan sounds like an ex post facto attempt to justify an impulsive action.” Ex post facto is Latin for “from after the deed.”

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Etymology

Origin of ex post facto

First recorded in 1625–35; from Latin: “from a thing done afterward, from what is done afterward”

Example Sentences

The issue is not just to admit, ex post facto, that we were wrong, but to think more deeply about why we were wrong.

From Salon • Dec. 20, 2025

“This is a violation of the ex post facto clause of the constitution,” said Neama Rahmani, president of West Coast Trial Lawyers.

From Washington Times • Feb. 10, 2023

The ban on ex post facto laws, the court said, prohibits increasing the punishment for a crime after the crime was committed, and that it does not apply in the inmates’ cases.

From Seattle Times • Nov. 13, 2021

So many shows rely on studio interviews or guests recapping their adventures ex post facto — the equivalent of Aunt Jane prattling on about her trip to Tuscany over the phone.

From Washington Post • Dec. 10, 2020

There is reason to believe that recollection was an ex post facto elaboration; those on the scene recall a sensation more suggestive of relief and euphoria in the air.

From "Big Science" by Michael Hiltzik