A man is bound to his neighbor in two ways: justice and charity. Justice is concerned with giving what is right to whom it is owed (S.T. II-II q57 a1). Charity is the action whereby a man wills the good of another for the sake of God. St. Thomas says the charity we give to our neighbor is the same action as loving God, since a man cannot love God and hate his brother (S.T. II-II q25 a1, cf. I Jn. 4:20).
Therefore, under the aspect of justice, our neighbor is owed some share in the material goods that are superfluous to us by the virtue of distributive justice, as I have discussed elsewhere. Our neighbor has a right to sufficient material goods for himself and his family. Therefore, the virtue of justice compels a man to give what he can for the sake of his neighbor.
On the other hand, the virtue of charity causes a man to act for the good of his neighbor without concern for rights. In this sense, charity may cause a man to give to his neighbor beyond what is his right, solely for the reason that his needs can be met by an act of charity.
Justice is concerned that a neighbor receive what is his right, whereas charity is concerned with our own will toward our neighbor (S.T. II-II q57 a1).
Justice and Charity Regarding the Sacraments
Since the soul is more excellent than the body, those things which regard the soul of our neighbor bind us more gravely than those of his corporeal needs (S.T. II-II q32 a3) . This holds true especially for the priest, who is the ordinary minister of the sacraments.
The obligation to administer the sacraments arises from justice and charity.
Principle 1: Those who have the office of the care of souls are bound out of justice to administer the Sacraments to those under their care who reasonably ask for them.
The reason is because by receiving their office they act as pastors contracted especially to procure the spiritual salvation of those under their charge. The Sacraments are the ordinary means — most excellent and necessary — for spiritual salvation[.] … Reasonably request, if a certainly grave harm is caused to the pastor of souls by administering the sacrament which is equal to the grave harm caused to him who requests by denying the sacrament, there is in that case no obligation (at least not grave) of acceding to the request of the faithful. Otherwise, it is an obligation to administer the Sacraments — the obligation is more grave in proportion to how grave the loss would be for a denial of the Sacraments. 
Moral theology understands that by his appointment as pastor of souls, a priest has been contracted to administer the sacraments to the faithful. In this spiritual contract, as it were, the faithful have a right to the ordinary means of salvation, which the priest must provide. This holds according to justice proviso the request of the faithful does not become unreasonable. Here the principle about “grave harm” is applied by Prümmer in the example of a priest denying confession to a scrupulous soul every day. But he also says a priest sins if he fails to make confession readily available. He also discusses the time of plague, which we will return to below. These obligations hold according to justice.
Prümmer also states that even a priest who has not been appointed a pastor of souls (i.e., a university professor or retired priest) is still bound gravely to administer the sacraments to those who reasonably ask for them. This is because charity binds under pain of mortal sin, as St. Thomas says concerning almsdeeds, when we fail to aid our neighbor who would not be helped otherwise (II-II q32 a5). This is especially true for priests concerning a soul who is in mortal sin, since the priest alone holds the power to absolve him (we will discuss the act of perfect contrition below).
Furthermore, since “[b]aptism is necessary as a necessary means to eternal salvation,” the parent is also bound according to charity to see that their child is baptized . Parents are bound under pain of mortal sin to provide baptism to their infant “within a few weeks” . The Roman Catechism emphasizes this:
The faithful are earnestly to be exhorted to take care that their children be brought to the church, as soon as it can be done with safety, to receive solemn Baptism. Since infant children have no other means of salvation except Baptism, we may easily understand how grievously those persons sin who permit them to remain without the grace of the Sacrament longer than necessity may require, particularly at an age so tender as to be exposed to numberless dangers of death.
It would seem, then, that in our present case of necessity, the layman must perform a valid lay baptism if a priest is unable to administer it within this time, and this is a grave obligation of charity.
We see, therefore, given all the above, that any authority sins who forbids baptism or penance from being celebrated, since such a law would be contrary to justice and charity. Would not St. Thomas’s words on unjust laws apply in such a case?
[L]aws may be unjust in two ways: first, by being contrary to human good … in respect of the end, as when an authority imposes on his subjects burdensome laws, conducive, not to the common good, but rather to his own cupidity or vainglory — or in respect of the author, as when a man makes a law that goes beyond the power committed to him[.] … The like are acts of violence rather than laws; because, as Augustine says (De Lib. Arb. i, 5), “a law that is not just, seems to be no law at all.” Wherefore such laws do not bind in conscience[.] …
Secondly, laws may be unjust through being opposed to the Divine good: such are the laws of tyrants inducing to idolatry, or to anything else contrary to the Divine law: and laws of this kind must nowise be observed, because, as stated in Acts 5:29, we ought to obey God rather than man (I-II q96 a4).
Can there be any law that binds man’s conscience against charity and justice? If the sacraments of baptism and penance are necessary for the salvation of one single soul, can any law prevent their administration for the eternal happiness of this soul? Can any grave evil to the body be worse than the loss of eternal salvation for any soul?
In Time of Plague
From centuries of experience and wisdom, the Church has assessed the morality of the time of plague regarding the necessary sacraments aforementioned. Prümmer summarizes that the moralists argue whether the priest is bound to administer the Viaticum in time of plague, but there is no such dispute regarding penance and baptism:
The pastor of souls is bound to administer the Sacraments to the faithful when they stand in extreme spiritual necessity [i.e., about to die with no hope of recovery] even at the risk of his life or other great temporal harm. They are bound in time of plague or infectious disease to administer the Sacrament of baptism and penance even at the risk of their life, according to this Scripture: the good shepherd lays down his life for his sheep (Jn. 10:11). The same applies concerning the administering of extreme unction, provided there is a certainty that the sick man is not able to receive the Sacrament of penance. 
Prümmer confirms that the priest can and should take all necessary precautions for last rites, but nevertheless, his office binds him to administer the sacraments when there is grave or extreme spiritual necessity, even at the risk of his own life. The plagues of old killed large swaths of the population, and still the Church considered such heroic acts within the duty of a priest.
But if an emergency can necessitate a lay baptism, why is the priest bound to hear confessions in this necessity? Cannot the lay person perform a perfect act of contrition to substitute for the priest’s celebration of penance? It is true that an act of perfect contrition can absolve even mortal sins. The reason why the priest is still bound to celebrate penance is that perfect contrition is difficult for sinners. Thus, Prümmer states:
A priest ought to administer the necessary Sacraments in places where infectious disease has spread, even at the risk of his life. For a man is able to be saved through the act of contrition, but not all who are sick are able to summon up the perfect act of contrition. Indeed, at death one’s necessity is extreme, and he who has lived in the habit of sin and wild living will not be able to summon the act of contrition. 
The perfect act of contrition can be done by a pious soul who loves God, but, as St. Alphonsus says (Serm. 21 for Easter), this is a gift of God’s grace. If a man has lived in sin his whole life, he may not be able to arouse perfect contrition in his soul, but merely imperfect contrition — the fear of Hell. This imperfect contrition is not sufficient for the absolution of his mortal sin, and anyone who dies in mortal sin suffers eternal punishment .
Therefore, the sacrament of penance applies the merits of Christ to make up for imperfect contrition, in order that mortal sins may be absolved and the soul restored to the state of grace. Thus, the priest is still bound to administer the sacrament of penance because many dying souls stand in need of such mercy, since they are not able to perform an act of perfect contrition. This is the reason why our Lord instituted this sacrament — because of our weakness. Thus, from the priest flows the abundance of God’s mercy and charity for sinners.
Nevertheless, we must always have hope in the mercy of God, that all sinners who are truly penitent will receive mercy, as it is written, every one that shall call upon the name of the Lord shall be saved (Joel 2:32). In this time of uncertainty and crisis, let each of us hold fast to his obligations of charity and justice, for the salvation of souls and the greater glory of God.
 Cf. Prümmer, Manuale Theologiae Moralis, Vol. I, no. 579ff
 Ibid., Vol. III, no. 114
 Cf. Can. 867 §1; John Paul II “Instruction on Holy Baptism,” October 20, 1980.
 Prümmer, Vol III, no. 72ff
 Ibid., Vol I, no. 583
Timothy Flanders is the editor of OnePeterFive. He is the author of City of God versus City of Man: The Battles of the Church from Antiquity to the Present and Introduction to the Holy Bible for Traditional Catholics. His writings have appeared at OnePeterFive and Crisis, as well as in Catholic Family News. In 2019 he founded The Meaning of Catholic, a lay apostolate dedicated to uniting Catholics against the enemies of Holy Church. He holds a degree in classical languages from Grand Valley State University and has done graduate work with the Catholic University of Ukraine. He lives in Michigan with his wife and five children.