Gregorius, a jurist about whom little is known beyond a possible post as magister libellorum under Carinus and Diocletian, privately compiles imperial rescripts from Hadrian to Diocletian, organized by subject in at least 13-15 books. No complete copy survives; it is known through citations in later works, chiefly the Codex Justinianeus. In 2009, fragments of the codex were identified recycled as binding reinforcement in a medieval book.