Gaius

Also spelled  Caius  Roman jurist whose writings became authoritative in the late Roman Empire. The Law of Citations (426), issued by the eastern Roman emperor Theodosius II, named Gaius one of five jurists (the others were Papinian, Ulpian, Modestinus, and Paulus) whose doctrines were to be followed by judges in deciding cases. The Institutiones (“Institutes”) of the Byzantine emperor Justinian