ex post facto

[eks pohst fak-toh] /ˈɛks ˌpoʊst ˈfæk toʊ/
noun
1.
from or by subsequent action; subsequently; retrospectively; retroactively.
2.
having retroactive force; made or done subsequently:
an ex post facto law.
Origin
1625-35; < Latin: from a thing done afterward, from what is done afterward
Can be confused
ad hoc, a posteriori, a priori, ex post facto, prima facie.
British Dictionary definitions for ex post facto

ex post facto

/ɛks pəʊst ˈfæktəʊ/
adjective
1.
having retrospective effect: an ex post facto law
Word Origin
C17: from Latin ex from + post afterwards + factus done, from facere to do
Word Origin and History for ex post facto

from Medieval Latin ex postfacto, "from what is done afterwards."

ex post facto in Culture
ex post facto [(eks pohst fak-toh)]

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.”

ex post facto [(eks pohst fak-toh)]

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.”