[n] a person who argues to defend or justify some policy or institution; "an apologist for capital punishment"
\Jus"ti*fi`er\, n. 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.