ex post facto

1 of 2

adverb

ex post fac·​to ˌeks-ˌpōs(t)-ˈfak-(ˌ)tō 

: after the fact : retroactively

ex post facto

2 of 2

adjective

: done, made, or formulated after the fact : retroactive

ex post facto approval

ex post facto laws

Did you know?

Ex post facto is Latin for "from a thing done afterward". Approval for a project that's given ex post facto—after the project already has been begun or completed—may just have been given in order to save face. An ex post facto law is one that declares someone's action to be criminal only after it was committed--a procedure forbidden by our Constitution.

Examples of ex post facto in a Sentence

Recent Examples on the Web

Adverb

Geragos molded Combs’s relationships with Ventura and Jane into nasty little afternoon soaps: the passionate meeting, the descent into addictive toxicity, infidelity and violence on both sides, the separation, and, ex post facto, the financial revenge. —Doreen St. Félix, New Yorker, 3 July 2025

Problem #1: Ex Post The Constitution forbids states to enact ex post facto laws, those that impose penalties for actions that took place before the laws were enacted. —William Baldwin, Forbes, 11 Jan. 2025

Adjective

Related Stories There was just one problem: This charge violated the Constitution’s ex post facto rule. —Andrew George, The Hollywood Reporter, 3 Mar. 2023

Imposing new and coercive restrictions on existing properties purchased by owners based on a codified set of economic and land-use assumptions isn’t fair under a constitutional system that abhors ex post facto laws. —WSJ, 20 June 2021

Word History

Etymology

Adverb

Late Latin, literally, from a thing done afterward

First Known Use

Adverb

1621, in the meaning defined above

Adjective

1787, in the meaning defined above

Kids Definition

ex post facto

1 of 2 adverb

ex post fac·​to ˌek-ˌspōst-ˈfak-tō 

: after the fact

an explanation given ex post facto

ex post facto

2 of 2 adjective

: made, done, or formulated after the fact

got ex post facto approval

Etymology

Adverb

Latin, literally, "from a thing done afterward"

Legal Definition

ex post facto

1 of 2 adverb

ˈeks-ˌpōst-ˈfak-tō 

: after the fact : retroactively

cannot judge ex post facto

ex post facto

2 of 2 adjective

1

: done, made, or formulated after the fact : retroactive

2

: of or relating to an ex post facto law

the chief concerns of the ex post facto ban

—L. H. Tribe

Etymology

Adverb

Late Latin, literally, from a thing done afterward