a leader of the Bolognese school of jurists and one of the few to write systematic summaries (summae) rather than textual glosses of Roman law as codified under the Byzantine emperor Justinian I (6th century AD). His Summa codicis and Apparatus ad codicem together provided a methodical exposition of Roman law and were very influential on medieval courts. A professor of civil law at Bologna from 1190, he was a pupil of a noted jurist, Joannes Bassianus, and a teacher of another, Franciscus Accursius (Accursius, Franciscus). Much of the Roman material used by the English jurist Henry de Bracton (Bracton, Henry de) in his De legibus et consuetudinibus Angliae (c. 1235; “On the Laws and Customs of England”) was derived from Azzone's summaries. The legal historian Frederic William Maitland (Maitland, Frederic William) edited Select Passages from the Works of Bracton and Azo (1895).