The original Codex Justinianus was promulgated in April of 529 by the C. "Summa". This made it the only source of imperial law, and repealed all earlier codifications.[2] However, it permitted reference to ancient jurists whose writings had been regarded as authoritative.[3] Under Theodosus II's Law of Citations, the writings of Papinian, Paulus, Ulpian, Modestinus, and Gaius were made the primary juristic authorities who could be cited in court.