The Code of Justinian (Codex Iustinianus) forms part of the Corpus Iuris Civilis. It collects the constitutiones of the Roman Emperors. The earliest statute preserved in the code was enacted by Emperor Hadrian ; the latest come from Justinian himself. The compilers of the code were able to draw on earlier works like the official Codex Theodosianus and private collections such as the Codex Gregorianus and the Codex Hermogenianus. Due to legal reforms by Justinian himself, this work later needed to be updated, so a second edition of the Codex was issued in 534, after the Digest.