Guilielmus Durantis, Speculum iuris (Basel: 1574) III de inquisitione Vltimo (p. 42):

Abbas non privabit eum defensione, quae excommunicato, et etiam diabolo, si in iudicio adesset, non negaretur [The abbot may not take his defense away from him, which is may not be denied to an excommunicated person or even to the devil].