Objection 1. It would seem that a priest can use the key which he has, on any man. For the power of the keys was bestowed on priests by Divine authority in the words: "Receive ye the Holy Ghost; whose sins you shall forgive, they are forgiven them" (John 20:22-23). But this was said without any restriction. Therefore he that has the key, can use it on any without restriction.
Objection 2. Further, a material key that opens one lock, opens all locks of the same pattern. Now every sin of every man is the same kind of obstacle against entering into heaven. Therefore if a priest can, by means of the key which he has, absolve one man, he can do the same for all others.
Objection 3. Further, the priesthood of the New Testament is more perfect than that of the Old Testament. But the priest of the Old Testament could use the power which he had of discerning between different kinds of leprosy, with regard to all indiscriminately. Much more therefore can the priest of the Gospel use his power with regard to all.
On the contrary, It is written in the Appendix of Gratian: "It is not lawful for every priest to loose or bind another priest's parishioner." Therefore a priest cannot absolve everybody.
Further, judgment in spiritual matters should be better regulated than in temporal matters. But in temporal matters a judge cannot judge everybody. Therefore, since the use of the keys is a kind of judgment, it is not within the competency of a priest to use his key with regard to everyone.
I answer that, That which has to do with singular matters is not equally in the power of all. Thus, even as besides the general principles of medicine, it is necessary to have physicians, who adapt those general principles to individual patients or diseases, according to their various requirements, so in every kingdom, besides that one who proclaims the universal precepts of law, there is need for others to adapt those precepts to individual cases, according as each case demands. For this reason, in the heavenly hierarchy also, under the Powers who rule indiscriminately, a place is given to the Principalities, who are appointed to individual kingdoms, and to the Angels who are given charge over individual men, as we have explained above (I, 113, 1,2). Consequently there should be a like order of authority in the Church Militant, so that an indiscriminate authority over all should be vested in one individual, and that there should be others under him, having distinct authority over various people. Now the use of the keys implies a certain power to exercise authority, whereby the one on whom the keys are used, becomes the proper matter of that act. Therefore he that has power over all indiscriminately, can use the keys on all, whereas those who have received authority over distinct persons, cannot use the keys on everyone, but only on those over whom they are appointed, except in cases of necessity, when the sacraments should be refused to no one.
Reply to Objection 1. A twofold power is required in order to absolve from sins, namely, power of order and power of jurisdiction. The former power is equally in all priests, but not the latter. And therefore, when our Lord (John 20:23) gave all the apostles in general, the power of forgiving sins, this is to be understood of the power which results from receiving orders, wherefore these words are addressed to priests when they are ordained. But to Peter in particular He gave the power of forgiving sins (Matthew 16:19), that we may understand that he has the power of jurisdiction before the others. But the power of orders, considered in itself, extends to all who can be absolved: wherefore our Lord said indeterminately, "Whose sins you shall forgive, they are forgiven them," on the understanding that this power should be used in dependence on the power given to Peter, according to His appointment.
Reply to Objection 2. A material key can open only its own lock. nor can any active force act save on its own matter. Now a man becomes the matter of the power of order by jurisdiction: and consequently no one can use the key in respect of another over whom he has not jurisdiction.
Reply to Objection 3. The people of Israel were one people, and had but one temple, so that there was no need for a distinction in priestly jurisdiction, as there is now in the Church which comprises various peoples and nations.
Source: Summa Theologica (New Advent)