The definition of ex post facto is something that affects things that happened in the past.
(adjective)When a law changes the zoning rules and applies even to zoning decisions that were made in the past, it is an example of an ex post facto change to the zoning laws.
See ex post facto in Webster's New World College Dictionary
Origin: L, from (the thing) done afterward
See ex post facto in American Heritage Dictionary 4
adjective
Origin:
Origin: Latin ex postfactō
Origin: : ex, from
Origin: + postfactō
Origin: , ablative of postfactum, that which is done afterward
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