Has an individual, in order to defend himself, or his belongings, the right to take the life of the one who attacks him?
No, an individual has never the right to do this unless there be question of losing his own life or the life of those in his charge, and there be absolutely no defence other than that which entails the death of his assailant; further, in thus defending himself he must in no way whatever intend the death of his assailant, but only intend to defend his life or that of others in his charge (LXIV. 7).
What are the other sins against our neighbour that touch his person?
They are mutilation, which attacks the integrity of his person; flogging, which inflicts pain on his body; and imprisonment, which deprives him of the freedom of his person (LXV. 1-3).
When are these acts sinful?
Whenever they are done by those who have no authority, or who, having authority, exceed the just bounds (ibid.).
Next - The Catechism of the Summa - SECOND SECTION - A DETAILED SURVEY OF MAN'S RETURN TO GOD - XXII. OF THE RIGHT OF PROPERTY, AND OF THE DUTIES IT ENTAILS -- OF THE VIOLATION OF THIS RIGHT, VIZ., OF THEFT AND ROBBERY (A)