Chapter — Sabetti-Barrett, Compendium of Moral Theology
Chapter III. On Dueling
Dueling, properly so called, is a dangerous fight of two persons according to a previous agreement concerning place, time, and weapons.
I say. Dueling undertaken by private authority can never be licit; because not only is it repugnant to natural right, since God has given to none of men dominion over his own life or that of another, nor over members, outside the case of defense against an actual aggressor; but also to canon law, as is clear from Trent, sess. 25, cap. 19, where dueling is called: "A detestable usage, introduced by the devising of the devil." - I said private, because if it is undertaken by public authority for the common good, e.g., so that war may be settled, it will certainly be licit no otherwise than war. - Cf. St. Alphonsus, nn. 399 and 400.
You Will Resolve. - 1st. Certainly, practically speaking, there can be dispute concerning the conditions of a duel, all of which are required for the whole malice of the act and the incurring of penalties; but never concerning a cause which could legitimate the provocation or acceptance of it, since it is something intrinsically evil. Wherefore, once the existence of a duel has been proved in some particular case, no reason, however grave, will ever excuse.
2nd. It is not licit to undertake a duel by this rule, that when one person has been wounded, or a certain number of blows has been completed, the fight should cease; both because Clement VIII prohibited even non-fatal duels, and because those acting thus implicitly admit any outcome whatsoever of the fight and consequently contract the whole malice of dueling.
3rd. But it is licit to fight for mere defense, even by accepting weapons from the adversary, if death is threatened by him unless the fight is accepted, and there is not another way of escaping this danger; but it is not licit to betake oneself to another place, or to appoint another determined time for defense; because then a duel properly so called would be had.
4th. Those who, on account of an injury, suddenly growing hot with anger, and provoking one another to a fight, immediately come together, do not enter into a duel properly so called; because it is more truly a brawl than a duel, which must be done from an agreement concerning place and time. - Sacred Congregation, Oct. 5, 1744. - Cf. St. Alphonsus, n. 401.
It is useful here to report the five propositions concerning dueling condemned by Benedict XIV in the year 1752, in the Const. Detestabilem. They are the following:
1st. "A military man who, unless he offers or accepts a duel, would be held as fearful, timid, abject, and unfit for military duties, and thence would be deprived of the office by which he sustains himself and his own, or would have to be perpetually without hope of promotion otherwise due and merited by him, would be free from guilt and penalty, whether he offers or accepts the duel."
2nd. "Those accepting a duel, or provoking to it, can be excused, even for the sake of protecting honor or avoiding human contempt, when they know certainly that the fight will not follow, since it is to be impeded by others."
3rd. "A leader or officer of the military accepting a duel from grave fear of loss of reputation or office does not incur the ecclesiastical penalties laid against duelists."
4th. "It is licit in the state of nature of man to accept and offer a duel for preserving fortunes with honor, when the loss of them cannot be repelled by another remedy."
5th. "The asserted license for the natural state can also be applied to the state of a badly ordered commonwealth, in which, namely, either by negligence or by the malice of the magistrate, justice is openly denied."