Codex Justinianeus a code composed by order of the Emperor Justinian, and intended to embrace all that was still available of former collections of imperial manuscripts and edicts, as well as of edicts then recent. The previous collections were,
1. The Codex Gregorianus, compiled by Gregorianus, who lived about the middle of the fourth century. It contained the "Constitutions" (the collective name for the "Rescripta," or replies to particular inquiries and requests, and the '"Edicta," or orders on general questions) of the emperors up to the time of Constantine;
2. The Codex Hermogenianus, compiled by Hermogenes, likewise about the middle of the fourth century, and containing the "Constitutions" of Diocletian and Maximinian;
3. The Codex Theodosianus, compiled in the first half of the fifth century by order of the Emperor Theodosius II, by a committee of sixteen jurists, and containing the Constitutions of the emperors from Constantine to Theodosius. It was promulgated by Theodosius in 438 in the Eastern empire, and in the same year by Valentinian in the Western. It was divided into sixteen books, of which the first five and the former part of the sixth are lost. All these three codes are found in the Corpus Juris Antejustinianei, published by Hanel. In Feb. 528 the Emperor Justinianus ordered the preparation of a new code, which was to embrace all that was still of practical value of the three previous collections, and, in addition, all the constitutions issued since the publication of the Theodosian Code. This new collection was published in April, 529. After the publication of the Pandects (a compilation of the writings of former Roman jurists) and the Institutiones (an introduction to the study of the Roman law), another revision was made in 534 by Tribonianus. This new revision (Codae repetito prcelectionis) still forms an important portion of the Corpus Juris Civilis, while the first revision (Codex vetus) is lost. In its last revision, the Codex Justinianeus consists of twelve books, each book containing a number of titles in chronological order. Up to the time of Constantine nearly all the constitutions are rescripta (rescripts); after that we meet with numerous edicta (edicts). The code of Justinian is of great importance for Church history and Church law, as a great many edicts of the Christian emperors concerned religious questions. In quoting the code of Justinian, first the number of the constitution is given, next the special code (Greg., Herm., Th., Just.) from which it is taken; and finally the title; thus, c. 45. C. Just. 1, 3, de episc. et cler., which means constitution 45 of the Justinianean code (that is, the entirely new portion of it), book 1, title 3, which treats de episcopis et clericis. Wetzer u. Welte, Kirchen-Lexikon, 2, 650.