According to canon law and catholic theology, individual consent was required in a series of acts such as baptism, priestly ordination, marriage, religious vows, oaths and contracts. This article highlights the existence, in the sixteenth and seventeenth century, of two different regimes of consent which would be brought closer only with the increasing secularization of societies. It first explains the legal standards concerning the validity of baptisms conferred under duress, emphasizing the importance of notions inherited from medieval common law (“absolute” and “conditional” constraint, “justified fear”). Then, it shows that these notions were applied differently so as to secure the irreversibility of baptism on one hand, and, on the other hand, to allow Inquisitions and Church courts resolve cases of extortion of consent which could have huge social implications, such as forced apostasy, marriage, and religious vows. The Portuguese canonist Agostinho Barbosa (1590–1649) is our guide in this matter.