467. Why is the legitimate defense of persons and of society not opposed to this norm?

467. Why is the legitimate defense of persons and of society not opposed to this norm?   

(Comp 467) Because in choosing to legitimately defend oneself one is respecting the right to life (either one’s own right to life or that of another) and not choosing to kill. Indeed, for someone responsible for the life of another, legitimate defense can be not only a right but a grave duty, provided only that disproportionate force is not used.

“In brief”

(CCC 2321) The prohibition of murder does not abrogate the right to render an unjust aggressor unable to inflict harm. Legitimate defense is a grave duty for whoever is responsible for the lives of others or the common good. 

To deepen and explain

(CCC 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" (St. Thomas Aquinas, STh II-II, 64, 7,  corp. art.).  (CCC 2265) Legitimate defense can be not only a right but a grave duty for someone responsible for the lives of others. The defense of the common good requires that an unjust aggressor be rendered unable to cause harm. For this reason, those who legitimately hold authority also have the right to use arms to repel aggressors against the civil community entrusted to their responsibility.  

Reflection

(CCC 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 moderation, 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 (St. Thomas Aquinas, STh II-II, 64, 7, corp. art.).

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