JUSTIFIER
apologist, vindicator, justifier
(noun) a person who argues to defend or justify some policy or institution; “an apologist for capital punishment”
Source: WordNet® 3.1
Etymology
Noun
justifier (plural justifiers)
(chiefly, philosophy) One who, or that which, justifies some belief or action.
One who pardons and absolves from guilt and punishment.
(computing, typography) A machine, program or algorithm that justifies text by aligning it.
Source: Wiktionary
Jus"ti*fi`er, n.
Definition: One who justifies; one who vindicates, supports, defends, or
absolves.
Justifiers of themselves and hypocrites. Strype.
That he might be just, and the justifier of him which believeth in
Jesus. Rom. iii. 26.
Source: Webster’s Unabridged Dictionary 1913 Edition