Source : Webster's Revised Unabridged Dictionary (1913)

Justificative \Jus*tif"i*ca*tive\ (?; 277), a. [Cf. F.
   justificatif.]
   Having power to justify; justificatory.

Source : WordNet®

justificative
     adj 1: attempting to justify or defend in speech or writing [syn: {defensive},
             {justificatory}]
     2: providing justification [syn: {justificatory}, {vindicatory}]