I. Lack of authenticity: deceit or fraud in consent
In the case of simulation, the lack of authenticity in marital self-giving is evident. The person going through the ceremony does not give himself conjugally. There is a constitutional lack of integrity in the marital donation made to the other.
Incapacity for giving valid matrimonial consent, deriving from some notable defect of the person's psychic faculties, is dealt with in c. 1095 of the 1983 Code: "They are incapable of contracting marriage: 1º who lack sufficient use of reason; 2º who suffer from a grave lack of discretion of judgment concerning the essential matrimonial rights and duties which are to be mutually given and accepted; 3º who are not capable of assuming the essential obligations of matrimony due to causes of a psychic nature".
(Opening address to the Canadian Canon Law Society Convention, St. John's, Newfoundland, October, 1997)
If I am glad to have been invited to speak on a topic other than canon 1095, the reason is certainly not any feeling that the last word has been said on consensual incapacity. It is simply because of a personal conviction that there are more null marriages today through simulation of consent, than through incapacity for it.
The 1917 Code of Canon Law described matrimonial consent as that "act of the will by which each party gives and accepts a perpetual and exclusive right over the body, for acts which are of themselves suitable for the generation of children" (1917 Code: canon 1081, # 2.). The 1983 Code describes this consent in apparently very different terms: it is that "act of the will by which a man and a woman, through an irrevocable covenant, mutually give and accept each other in order to establish a marriage" (1983 Code: canon 1057, # 2. ).