post facto
/ˌpəʊs(t) ˈfaktəʊ/adjective
Occurring, made, or enacted after the event; done with hindsight.
adverb
= post factum.
Origin
Late 16th century; earliest use found in George Whetstone (d. 1587), writer. From classical Latin postfacto. With use as adjective compare later post-fact, post factum. With use as adverb compare slightly earlier post factum.