certain jurist ("Gregorianus") made an orderly and comprehensive collection of such as early as the close of Diocletian's reign; it was supplemented by the work of another jurist ("Hermogenianus") in the time of Constantine. Each compilation was the work of a private person, who, without authority to restate, could but compile the imperial constitutions. The same method was adopted by the later codifications, which were made and promulgated under imperial decree. There were two which were to be of supreme importance for the legal future of western Europe, the Theodosian Code and the legislation of Justinian. The former was promulgated in 438 by Theodosius II. and Valentinianus. The emperors formally announce that "in imitation (ad similitudinem) of the Code of Gregorianus and Hermogenianus we have decreed that all the Constitutions should be collected" which have been promulgated by Constantine and his successors, including ourselves.[1] So the Theodosian Code contains many laws of the emperors who decreed it.[2] It was thus a compilation of imperial constitutions already in existence, or decreed from year to year while the codification was in process (429-438). Every constitution is given in the words of its original announcement, and with the name of the emperor. Evidently this code was not a revision of the law.
The codification of Justinian began with the promulgation of the Codex in 529. That was intended to be a compilation of the constitutions contained in the previous codes and still in force, as well as those which had been decreed since the time of Theodosius. The compilers received authority to omit, abbreviate, and supplement. The Codex was revised and promulgated anew in 534. The constitutions which were decreed during the remainder of Justinian's long reign were collected after his death and published as Novellae. So far there was nothing radically novel. But, under Justinian, life and art seemed to have revived in the East; and Tribonian, with the others who assisted in these labours, had larger views of legal reform and jurisprudential
