ex post facto

[Latin ex postfactō : ex, from + postfactō, ablative of postfactum, that which is done afterward.]

After the fact, especially a law that makes punishable as a crime an act that was done before the passing of the law and that was innocent when done. Such laws violate the Constitution of the United States.

Lat: after the fact; "every law that makes an action done before the passing of the law and which was innocent when done to become criminal and punishable as such [a crime]; every law that aggravates a crime or makes it greater than when it was committed; every law that changes and inflicts a greater punishment; and every law that alters the legal rules of evidence, and receives less, or different, testimony than the law required at the time of the commission of the offense, in order to convict the offender." 171 S.W. 2d 880. Such a law violates Art. I, Secs. 9 (Cl. 3) & 10 of the Constitution of the United States which provide that neither Congress nor any state shall pass an ex post facto law; these provisions have been held applicable only to criminal statutes. 3 U.S. (3 Dall.) 386, 390. Compare bill of attainder.

resulting after the fact

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.”