The Codex Justinianus, or Code of Justinian, was a legal code. It consisted of the various sets of laws and legal interpretations collected and codified by scholars under the direction of Byzantine Emperor Justinian I. The code synthesized collections of past laws and extracts of the opinions of the great Roman jurists. It also included an elementary outline of the law and a collection of Justinian’s own new laws. The four-book code was completed in stages. Work on the first book, the Codex Constitutionum, began shortly after Justinian’s elevation in 527. The second book, the Digesta, was drawn up between 530 and 533. The third book, Institutiones, was compiled and published in 533, and the fourth book, Novellae Constitutiones Post Codicem, was completed upon Justinian’s death in 565.