Justinian Code, collection of early Roman civil laws, known as Corpus Juris Civilis (Latin, Body of Civil Law). Compiled by legal scholars at the behest of the Byzantine emperor Justinian I (r. A.D. 527–565), the code formed the basis of the legal systems of many Western nations for centuries afterward. Justinian had his scholars determine which Roman laws should remain in force, be modified, or be repealed. The code also proposed new laws. The 4 parts of the code are the Institutes, the Digest, the Codex, and the Novels.