ex post facto

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Formulated, enacted, or operating retroactively.

from The Century Dictionary.

• From a subsequent state of facts; from a later point of view; with reference to a former state of facts; retrospectively: as, the transaction was made void by matter ex post facto; a lease made by a life tenant to run beyond his own life may be confirmed ex post facto by the rever-sioner.

from the GNU version of the Collaborative International Dictionary of English.

• (Law) From or by an after act, or thing done afterward; in consequence of a subsequent act; retrospective.
• a law which operates by after enactment. The phrase is popularly applied to any law, civil or criminal, which is enacted with a retrospective effect, and with intention to produce that effect; but in its true application, as employed in American law, it relates only to crimes, and signifies a law which retroacts, by way of criminal punishment, upon that which was not a crime before its passage, or which raises the grade of an offense, or renders an act punishable in a more severe manner that it was when committed. Ex post facto laws are held to be contrary to the fundamental principles of a free government, and the States are prohibited from passing such laws by the Constitution of the United States.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Retroactive
• adjective law Formulated or enacted after some event, and then retroactively applied to it.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective affecting things past