first Roman emperor of his name, and more celebrated for his code of laws than for the military achievements which distinguished his reign, was nephew of Justin I. and succeeded to the imperial purple on the death of his uncle in 527. He began his reign with the character of being a religious prince; and having published severe laws against heretics, and repaired ruined places of worship, he openly declared himself the protector of the church. But whilst thus engaged in re-establishing Christianity at home, he carried his arms against the enemies of the empire abroad, and, through his generals, proved so successful, that he in some measure reinstated it in its ancient glory. By means of Belisarius, the greatest captain of his age, the Persians were conquered, and the Vandals exterminated; Africa was regained; the Goths in Italy were subdued; the Moors were defeated; and the Roman empire was restored almost to its primitive glory. But, in the midst of these successes, the Emperor was endangered by a powerful faction at home; Hypalius, Pompeius, and Probus, nephews of the Emperor Anastasius, the immediate predecessor of Justin, raised an insurrection to dethrone him, and it required all the energy of Belisarius, seconded by Mundus, to put down the rebellion. This, however, was at length effected; the conspiracy was broken, and the ringleaders were capitally punished. The empire being now in the full enjoyment of profound peace and tranquillity, Justinian made the best use of it, by collecting the immense variety and number of the Roman laws into one body. To this end he selected ten of the most able lawyers in the empire, who, having revised the Gregorian, Theodosian, and Hermogenian codes, compiled one body, called Codex Justinianus. This may be called the statute law, as consisting of the rescripts of the emperors. But the reduction of the other part was a much more difficult task. It was made up of the decisions of the judges and other magistrates, together with the authoritative opinions of the most eminent lawyers, all which lay scattered, without any order, in no less than two thousand volumes. These were reduced to the number of fifty books; but ten years were spent in the reduction. The design was completed in the year 553, and the name of Digest or Pandects given to it. Besides these, for the use chiefly of young students in the law, and to facilitate that study, Justinian ordered four books of Institutes to be drawn up, containing an abstract or abridgment of the text of all the laws; and, lastly, the laws of a date posterior to that of the former were, in the year 541, thrown into one volume, called the Novelle, or New Constitutions. See Civil Law.

This transaction has immortalised the name of Justinian, who, in other respects, was neither a great nor a good man, and whose name was held in abhorrence by the people, partly on account of his rash and inconsiderate conduct in ecclesiastical matters, but still more by reason of the heavy burdens which he imposed on them. He died suddenly in 565, after a reign of thirty-nine years, at the advanced age of eighty-three. Justinian built a great number of churches, particularly the famous St Sophia at Constantinople, which is esteemed a masterpiece of architectural design.

Justinian, St Laurence, the first patriarch of Venice, descended of a noble family, was born there in the year 1381. He died in 1485, leaving several religious works, which were printed together at Lyons in 1568, in one volume folio, with his life prefixed by his nephew. He was beatified by Clement VII. in 1524, and canonized by Alexander VIII. in 1690.

Justinian, Augustin, bishop of Nebbio, one of the most learned men of his time, was descended from a branch of the same noble family with the preceding, and born at Genoa in 1480. He assisted at the fifth council of Lateran, where he opposed some articles of the concordat between France and the court of Rome. Francis I. made him his almoner; and he was for five years regius professor of Hebrew at Paris. He returned to Genoa in 1522, where he discharged all the duties of a good prelate; whilst learning and piety flourished in his diocese. He perished at sea in his passage from Genoa to Nebbio, in 1536. He composed several pieces, the most considerable of which is Psalterium Hebraicum, Graecum, Arabicum, et Chaldaicum, cum tribus Latinis interpretationibus et glossis. This was the first psalter of the kind printed. There is also ascribed to this prelate a translation of Maimonides's More Nevochim.