An introductory chronological, conceptual and juridical foreword dealing with the problem of the heresies in the Roman-Christian law is needed as this law had a great influence upon both Canon and Roman medieval law. The medieval Canon law of the 11th century is expounded, as it is here that the problem of heresies reappears both before and after the Vergentis decree in order to see the amendments that this decree resulted in. The juristic education of its author Pope Innocent III and his relationship with Uguccione da Pisa, the most important and influential canonist not only of this century, is then outlined. The research about the
juridical status of the heretics in the Ordinary Gloss to the Decree of Gratian and in that of Accursio to Codex Iustiniani presents not only the related sentences and legal incapacities which concerned the heretics but also the relationship between Canon and Roman law in the Middle Ages.


Keywords: Heretic; roman christian law; Innocent III; Vergentis; Ordinary Gloss; Decree Gratian; Accursius;  Gloss; Codex Iustiniani.