The Corpus Juris Civilis ("Body of Civil Law") is the modern name for a collection of fundamental works in jurisprudence, issued from 529 to 534 by order of the Byzantine Emperor Justinian I (r. 527–565).
This code compiled all of the existing imperial constitutiones (imperial pronouncements having the force of law), back to the time of Hadrian (r. 117–138). It used both the Codex Theodosianus and the fourth-century collections embodied in the Codex Gregorianus and Codex Hermogenianus, which provided the model for division into books that were divided into titles. These codices had developed authoritative standing.
Justinian gave orders to collect legal materials of various kinds into several new codes which became the basis of the revival of Roman law in the Middle Ages. This revived Roman law, in turn, became the foundation of law in all civil law jurisdictions. The provisions of the Corpus Juris Civilis also influenced the Canon Law of the church since it was said that ecclesia vivit lege romana — the church lives under Roman law.
The work was directed by Tribonian, an official in Justinian's court, and distributed in three parts: Digesta (or Pandectae), Institutiones, and the Codex Constitutionum. A fourth part, the Novels (or Novellae Constitutiones), was added later.