CUM EX APOSTOLATUS OFFICIO
This law forms the basis of the Code of Canon Law on matters of heresy.
Canon 188: All offices shall be vacant ipso fact by tacit resignation in the following cases: 4. is a cleric has publicly lapsed from the Catholic faith; (3,6)
Paragraph 6: We add moreover that if at any time it shall appear that any Bishop even if he assert for himself the rank of Archbishop, Patriarch, Primate, or Cardinal of the aforesaid Roman Church, or legate, or even Roman Pontiff before his promotion or assumption into the Cardinalate or Pontificate, shall have deviated from the Catholic faith or have fallen into any heresy, or incurred, excited or committed any schism, his promotion or assumption even made in full concord and with the unanimous consent of all the Cardinals, shall be null, abrogated, and void, nor shall be called or become valid even by the reception of the grace of consecration nor the subsequent possession of government and administration, nor even by the enthronization or adoration of the elected person as Roman Pontiff or the universal obedience rendered to him for how long a period soever. Nor shall he be held legitimate in any form, nor be deemed capable of giving or be held to have given any authority of administration in things spiritual or temporal to any person promoted to bishoprics, &c., or assumed to the Cardinalate or to the Roman Pontificate.
