Justinian I. (Flavius Anicius Justinianus), Roman Emperor, was born in Illyricum about the year 483. His original name was Uprauda. He was educated in Constantinople, and adopted by his uncle, Justin I., who in the year of his death (527) associated him with himself in the empire. The great work of his reign was the so-called codification of the laws. By the Codex Constitutionum issued in 529, the statute law, consisting of the decrees, edicts, rescripts, etc., of the emperors were reduced and brought into order; and in 533 the Digest or Pandects gave a selection of extracts from Ulpian, Paulus, and some thirty of the other great jurists, no less than two thousand treatises having been consulted. By these all former statutes and legal opinions were abrogated. An elementary manual containing an outline of the laws based upon the Commentarii of Gaius, and known as the Institutes of Justinian, was also prepared; and in 534 a revised Codex was issued, this being the one now in use. In this work Tribonian had been the chief adviser of the emperor, and by him much of the work itself was done. The Novellae Constitutiones, or "Novels," embodying the decrees made in Justinian's own reign, completed the immense legal work, which is known in its entirety as the Corpus Juris Civilis. All but the "Novels" were published in Greek.
Foreign wars and theological strifes occupied the rest of Justinian's attention. As a theologian the emperor was orthodox, and was active in his suppression both of heathens and heretics. Under the influence ofj his wife, Theodora, however, he ultimately became involved in a species of Monophysitism, for holding which heresy he had deprived several bishops. He summoned Pope Vigilius to Constantinople in order to induce him to condemn certain writers of the orthodox party who were tinged with Nestorianism, and ejected Eutychius, the Patriarch of Constantinople, for resisting bis views. He became involved in wars on account of his persecutions of the Montanists in Phrygia and the Samaritans; and by closing the schools at Athens drove the professors to the Persian Court. War with Chosroes, King of Persia, continued for twenty-two years, at the end of which the empire was weakened, and had to pay a tribute in exchange for the possession of Lazica. On the other hand, by the generalship of Belisarius (q.v.), northern Africa and southern Spain were reconquered from the Vandals, and the kingdom of the Ostrogoths in Italy was overthrown. In 536 Rome was taken, and when a revival of the Ostrogoths under Totila had shaken the imperial administration, Narses was despatched in 552 with a fresh army, by which the barbarian was defeated and slain at Taginae. Italy was reunited to the empire. Notwithstanding bhese successes on the borders of the empire, the barbarians of the north were allowed to make frequent incursions, and sometimes to appear even under the walls of Constantinople.
In his administration Justinian had an eye to men of ability, but was not scrupulous as to their character and proceedings, so long as they served him well. Heavy taxes were imposed not only for the wars, but for the purpose of building, of which the emperor was very fond. The Church of St. Sophia (now a mosque) and that of Little St. Sophia (originally Saints Sergius and Bacchus) are memorials of his magnificence in this direction. During this reign the dignity of the consulship was abolished; and since the large expenses which its bearer was expected to support were defrayed by the state, a great economy was effected. Justinian himself was a man of great activity and talent, but fell short of being a great man, though he approached nearer to it than any other Eastern emperor. He had a great passion for theology; but it is unknown to what extent he took part in the great legal work of his reign. He was much under the influence of his wife. He died in 565, after a reign of thirty-eight years, and having no children, was succeeded by his nephew, Justin II.