Chapter I. On the Killing of an Innocent Person in General

I. Direct killing of an innocent person is a grave sin from its whole genus. This is clear both from Sacred Scripture,¹ and from the fact that the murderer: 1. destroys what is not his, but God's; 2. deprives his neighbor of the use of life and of the faculties, to which the neighbor has a right from divine ordination; 3. cuts off a member of the commonwealth (St. Thomas, II-II, q. 64, a. 6; St. Alphonsus, III, 393).

Corollary I. It is illicit to kill those lethally wounded, the dying, so that they may not suffer longer, and so forth.

Corollary II. Puncture of the heart or artery is illicit when done for this end, that one who seems to be dead may certainly be deprived of life, lest, namely, he be buried alive (euthanasia). But if it is certainly established that life has passed away, it is indeed per se lawful for a physician to puncture the heart or artery; yet since by acting thus a practice to be disapproved is promoted, that manner of acting is illicit unless both the physician signifies that he does not approve the wicked intention of those requesting it, and a grave cause is present.

II. Nor is it ever lawful for public authority directly to kill an innocent person; both because public authority does not have a right over the life of innocent subjects, and because the common good itself, for which public authority must provide, is promoted above all by the protection of the life of the innocent.

"The killing of a sinner," says St. Thomas, "becomes lawful, namely for public authority, by comparison to something else: considering man indeed according to himself, it is lawful to kill no one, because in any man, even a sinner, we ought to love the nature which God made, and which is corrupted by killing; but, as was said above (art. 2 of this question), the killing of a sinner is by comparison to the common good, which is corrupted by sin; but the life of the just is preservative and promotive of the common good, because they are the more principal part of the multitude; and therefore in no way is it lawful to kill an innocent person" (II-II, q. 64, a. 6; St. Alphonsus, loc. cit.).

Hence neither "is it lawful to kill hostages, even if those who sent them do not keep faith, because they are innocent" (St. Alphonsus, loc. cit.); nor can an innocent person be killed even if, for example, a tyrant besieging a city threatens that, unless he is killed, he will overturn the city. Nevertheless an innocent subject, when the besieging tyrant demands it, can be sent and handed over to the enemies, especially because the innocent person, if he is not a stranger, seems bound to expose his life for his own commonwealth (St. Alphonsus, III, 393).

Corollary. The killing of an innocent person can become lawful by the authority of God. "For God has dominion of death and life: by His ordination both sinners and the just die; and therefore he who kills an innocent person by the command of God does not sin in such a case, just as neither does God, whose executor he is; and he is shown to fear God, obeying His commands" (St. Thomas, II-II, q. 64, a. 6, ad 1).

III. Indirect killing of an innocent person likewise is per se illicit; it becomes lawful if a proportionate cause is present. It is said:

1. Indirect killing of one's neighbor is per se illicit, because charity per se demands that I avert damage from my neighbor, much less does it permit that I create it for him.

2. It becomes lawful if a proportionate cause is present; this follows from what was said about an act with a double effect (St. Alphonsus, III, 393).

Corollary I. Homicide is not imputed if someone places a work, even an illicit one, that is little dangerous, so that death rarely comes from it, provided, if it can be done, due diligence is used for forestalling death; as if someone rings a bell, and by chance the little bell, falling, crushes a traveler; if someone, giving attention to hunting wild beasts, by chance kills a man; if someone fornicates, and the woman dies from childbirth (St. Alphonsus, III, 398).

Corollary II. "For taking a city and winning victory, if it is necessary, it is lawful to direct cannons at that place where there are many innocent persons, because their death follows outside the intention" (St. Alphonsus, III, 393); in other words, because the aforesaid act is not assumed as a means insofar as it is killing of an innocent person.

¹ Gen. 4:10; Exod. 20:13.