Definition of Ex Post Facto
After the fact; by an act or fact occurring after some previous act or fact, and relating thereto; by subsequent matter; the opposite of ab initio. Thus, a deed may be good ab initio, or, if invalid at its inception, may be confirmed by matter ex post facto.
That's the definition of Ex Post Facto in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.
