Question One: On the Requisites for the Capacity of Valid Reception

648. The use of reason and intention are required for the capacity of receiving the sacrament of Penance. - In order that a man be capable of validly receiving this sacrament, it is not sufficient that he be a wayfarer, and that he has been baptized and is a sinner, but in addition there is required the intention of receiving the sacrament, and therefore the use of reason. Moreover a habitual and implicit intention does not suffice, but an actual or virtual intention is also required at the moment at which the penitent places his part of the sacramental sign, i.e., elicits contrition and makes accusation; and since these are human actions, they cannot be done without the use of reason and due intention (n. 93). Therefore the use of reason is required in the penitent at the moment at which he forms the intention, elicits contrition, and makes accusation.

These things are indeed clear, but in practice they can present difficulty in certain penitents, for example in children, the insane, deaf-mutes, or the dying. Concerning these we shall speak individually.