After the fact
What's the meaning of the phrase 'After the fact'?
'After the fact' means after an action is performed; in legal parlance, after a crime has been committed.
What's the origin of the phrase 'After the fact'?
When referring to something as a fact we now understand the word to mean a truth, something which all reasonable people would accept. That wasn't the meaning of the word in mediaeval England. Not only were they not troubled by the 21st century gobbledegook of 'alternative facts' their understanding of 'fact' was 'a deed or action'.
In the phrases 'after the fact' and the corresponding 'before the fact' the action they were referring to was a deed or action with evil intent.
That meaning is the reason that these two expressions are now used mainly by the legal profession. The 'fact' is the crime itself. Lawyers also extend the phrase to refer to a conspirator in a crime as 'an accessory before/after the fact'.
'After the fact' and 'before the fact' are old expressions and have been in use in English since the 16th century.
Both of them can be found in this citation from the English theologian Thomas Stapleton's translation of the Apology of Staphylus 1565:
Demosthenes the lerned and eloquent oratour saith, wise men deliberat before the facte and fooles after the facte.