When did the Church permit deacons to baptize?
Later in Church history, deacons were classified as extraordinary ministers of this sacrament, whereas priests and bishops continued on as ordinary ministers. In recent decades, deacons have again been deputed as ordinary ministers of baptism in the Latin rite, as parish baptismal practice in the United States illustrates (CCC 1256). In the case of necessity, anyone—even a heretic—can baptize, provided he uses proper sacramental form and matter and intends to perform what the Church intends to perform in baptizing (see CCC 1256).
By Tom Nash