Truth In Tradition
Code of Canon Law, 1983 A.D.
Can. 1323 The following are not subject to a penalty when they have violated a law or precept:. . . 5/ a person who acted with due moderation against an unjust aggressor for the sake of legitimate self defense or defense of another; ...
--- Codex Iuris Canonici. © Copyright, Libreria Editrice Vaticana.
Saint Alphonsus De' Liguori, Theologia Moralis, 1748 A.D.
This work is cited by Pope St. John Paul II as supporting the human right of self-defense. (Evangelium Vitae ¤55, Encyclical of Pope St. John Paul II, 1995 A.D., more here) English translation not yet available, please contact us if you are aware of a translation.
An, et quomodo liceat occidere privata auctoritate iniquum aggressorem?
Whether, and in what manner, is it allowed for a private authority to kill an unjust aggressor?
--- Saint Alphonsus De' Liguori, Theologia Moralis, l. III, tr. 4, c. 1, dub. 3.
Saint Thomas Aquinas, Summa Theologiae, 1274 A.D.
I answer that, Nothing hinders one act from having two effects, only one of which is intended, while the other is beside the intention. Now moral acts take their species according to what is intended, and not according to what is beside the intention, since this is accidental as explained above (II-II:43:3; I-II:12:1). Accordingly the act of self-defense may have two effects, one is the saving of one's life, the other is the slaying of the aggressor. Therefore this act, since one's intention is to save one's own life, is not unlawful, seeing that it is natural to everything to keep itself in "being," as far as possible. And yet, though proceeding from a good intention, an act may be rendered unlawful, if it be out of proportion to the end. Wherefore if a man, in self-defense, uses more than necessary violence, it will be unlawful: whereas if he repel force with moderation his defense will be lawful, because according to the jurists [Cap. Significasti, De Homicid. volunt. vel casual.], "it is lawful to repel force by force, provided one does not exceed the limits of a blameless defense." Nor is it necessary for salvation that a man omit the act of moderate self-defense in order to avoid killing the other man, since one is bound to take more care of one's own life than of another's. But as it is unlawful to take a man's life, except for the public authority acting for the common good, as stated above (Article 3), it is not lawful for a man to intend killing a man in self-defense, except for such as have public authority, who while intending to kill a man in self-defense, refer this to the public good, as in the case of a soldier fighting against the foe, and in the minister of the judge struggling with robbers, although even these sin if they be moved by private animosity.
--- Saint Thomas Aquinas, Summa Theologiae, II-II, q. 64, a. 7
Saint Augustine of Hippo, City of God, 426 A.D.
"Though defensive violence will always be ‘a sad necessity’ in the eyes of men of principle, it would be still more unfortunate if wrongdoers should dominate just men."
--- City of God, Book IV, Ch. 15