ex post facto

• expost facto
• expostfacto

From Latin ex (“from”) + post (“after”) + facto, ablative of factum (“deed”). In Latin, ex takes the ablative case, while post takes the accusative case. (See Wikipedia for a discussion of the grammatical form and usage of this phrase.)

ex post facto (not comparable)

1. Retroactive.
   1. (law) Formulated or enacted after some event, and then retroactively applied to it.
      • 1998, Daniel E. Troy, Retroactive Legislation, page 56:

        Coupled with the Constitution's proscription of ex post facto laws is a similar prohibition against bills of attainder.

      • 2009 March 21, Jim McTague, “Would a Tax on Bonuses Be Constitutional?”, in Barron's:

        That the tax would take effect after some of the payments were made also raises issues. Says former Attorney General Richard Thornburg, also in an e-mail: "Such legislation could well run afoul of constitutional restrictions on bills of attainder, ex post facto laws, laws impairing the obligations of contract, unauthorized takings of property and the like."

• ex post

• Ex post facto law on Wikipedia.Wikipedia