Commissary, in general, is any one to whom the power and authority of another is committed. An ecclesiastical commissary is an officer of the bishop, who exercises spiritual jurisdiction in distant parts of the diocese. A military commissary is an officer charged with furnishing provisions and clothes to an army.
When the papal authority was abolished in Scotland, a supreme commissary court was established in Edinburgh in 1563, by a grant of Queen Mary. This court had jurisdiction in actions of divorce, declarators of marriage, nullity of marriage, and all actions which originally belonged to the bishops' ecclesiastical courts. Its powers were gradually conjoined with those of the Court of Session, and it was finally abolished in 1836, the small remains of its once important jurisdiction being united in the sheriff of Edinburgh. See Alexander on Practice of the Commissary Courts in Scotland (1858), and Fraser on Husband and Wife.