The Corpus Juris Civilis (Body of Civil Law) also known as Codex Justinianus is a fundamental work in jurisprudence, issued from 529 to 534 by order of Justinian I, Byzantine Emperor. This code compiled all of the existing imperial constitutiones (imperial pronouncements having the force of law), back to the time of Hadrian. It used both the Codex Theodosianus and private collections such as the Codex Gregorianus and Codex Hermogenianus.