BISHOP, TITULAR: According to the old law of the Church, only one bishop was consecrated for a diocese; and none was consecrated at large or without a definite diocese (First Council of Nicæa, canon viii). If, therefore, occasion arose for the designation of a representative to perform episcopal functions in the place of an incapacitated bishop, it was necessary to call upon some neighboring bishop or one who happened to be in those parts (see COADJUTOR). In the ninth and tenth centuries, certain Spanish bishops who had been driven from their sees by the Saracens, and in the tenth some from Prussia and Livonia who were in a similar position, served in this capacity. The same service was rendered in the fourteenth century by the bishops of sees founded in the East during the crusades and afterward occupied by the Mohammedans. So, even after all hope of the recovery of these territories had been abandoned, bishops continued to be consecrated for these dioceses, called episcopi in partibus infidelium ("bishops in the regions of the unbelieving") until 1882, when Leo XIII ordered the use of the designation episcopi titulares. Their functions are various. In the first place, they serve as auxiliary or coadjutor bishops in dioceses where the need exists, when the diocesan makes a request to the pope for such an assignment, naming a suitable person, and giving assurance for his support. The coadjutor of course possesses all the jura ordinis like any other bishop, but exercises them only at the direction of his superior, and he has not, ex officio, the other prerogatives of a diocesan bishop (see BISHOP). Apostolic vicars, who administer missionary districts not formed into dioceses are usually consecrated bishops, and so are certain Roman functionaries who are members of the great congregations, and papal nuncios and other diplomatic representatives. Titular bishops are also consecrated for certain special purposes, such as the administration of holy orders to the Uniat Greeks of Italy, and the spiritual oversight of the military and naval forces of certain countries (see EXEMPTION).
Bibliography: L. Thomassin, Vetus et nova eeclesiæ disciplina, part I, book i, chaps. 27-28, Lucca, 1728; A. H. Andnucci, Tractatus de episcopo titulari, Rome, 1732; J. C. Möller, Geschichte der Weihbischöfe von Osnabrück, Lingen, 1887.