Catechism of the Catholic Church

Life in Christ 545 The Old Testament always considered blood a sacred sign of life. 60 This teaching remains necessary for all time. 2261 Scripture specifies the prohibition contained in the fifth commandment: “Do not slay the innocent and the righteous.” 61 The deliberate murder of an innocent person is gravely contrary to the dignity of the human being, to the golden rule, and to the holiness of the Creator. The law forbidding it is universally valid: it obliges each and everyone, always and everywhere. 2262 In the Sermon on the Mount, the Lord recalls the com­ mandment, “You shall not kill,” 62 and adds to it the proscription of anger, hatred, and vengeance. Going further, Christ asks his disciples to turn the other cheek, to love their enemies. 63 He did not defend himself and told Peter to leave his sword in its sheath. 64 Legitimate defense 2263 The legitimate defense of persons and societies is not an exception to the prohibition against the murder of the innocent that constitutes intentional killing. “The act of self-defense can have a double effect: the preservation of one’s own life; and the killing of the aggressor. . . . The one is intended, the other is not.” 65 2264 Love toward oneself remains a fundamental principle of morality. Therefore it is legitimate to insist on respect for one’s own right to life. Someone who defends his life is not guilty of murder even if he is forced to deal his aggressor a lethal blow: If a man in self-defense uses more than necessary violence, it will be unlawful: whereas if he repels force with modera­ tion, his defense will be lawful. . . . Nor is it necessary for salvation that a man omit the act of moderate self-defense to avoid killing the other man, since one is bound to take more care of one’s own life than of another’s. 66 2265 Legitimate defense can be not only a right but a grave duty for one who is responsible for the lives of others. The defense of the common good requires that an unjust aggressor be rendered 60 Cf. Lev 17:14. 61 Ex 23:7. 62 Mt 5:21. 63 Cf. Mt 5:22-39; 5:44. 64 Cf. Mt 26:52. 65 St. Thomas Aquinas, STh II-II, 64, 7, corp. art. 66 St. Thomas Aquinas, STh II-II, 64, 7, corp. art. 1756 1956 2844 1737 2196 2240