Finally in order to guarantee the effectiveness of the decrees of this Council, Canon 8 empowered religious superiors to investigate reports of serious irregularities of prelates and clerics. The Canon noted three types of procedure:
I. Accusation (accusatio). An individual enters charges in writing against a prelate or cleric and at the same time binds himself in writing to undergo the same penalty that would have been imposed on the accused if in the course of the investigation or trial his charges should be proved groundless (Lex talionis). This was to prevent malicious or spiteful accusations made to embarrass prelates or clerics.
II. Denunciation (denunciatio). An individual reveals a crime to the religious superior of the accused, but only after repeated admonitions have been ignored. The accuser is not amenable to the law of reprisal.
III. Inquiry, inquest (inquisitio). In this type the religious superior himself undertakes to make an investigation after complaints and evil reports have reached his ears.
The importance of this Canon 8 is not so much its confirmation of long standing Canon Law for the trials of clerics (not heretics), but because it will be the procedure adopted by Pope Gregory IX some fifteen years later for the inauguration of the Inquisition and because of its appropriation by civil criminal law down to the French Revolution!
Albert Shannon, The Medieval Inquisition (1991)