What sins are opposed to commutative justice?
These sins are divided into two groups (LXIV.-LXXVIII.).
What are those of the first group?
They are those which touch our neighbour in which his own will has no part (LXIV.-LXXVI.).
What is the first of these sins?
It is homicide, which affects our neighbour by deed, as regards his greatest good, viz., by taking his life (LXIV.).
Is this a great sin?
It is the greatest sin against our neighbour.
Is it ever permitted to attempt our neighbour's life?
Is it never permitted to take away a man's life?
It is never permitted to take away a man's life, unless through some crime, he has merited death (LXIV. 2, 6).
When a man through crime merits to lose his life, who alone has the right to deprive him of life?
Only the public authority has the right to do this (LXIV. 2).
Whence does the public authority derive this right?
It derives this right from the duty incumbent upon it of guarding over the common good of the society (ibid.).
Does the common good of the society sometimes demand that a man be put to death?
Yes, because there may be no other efficient way of putting a stop to the crimes committed within the society; or because the public feeling demands such satisfaction for the expiation of certain crimes that are hateful and revolting (LXIV. 2).
Is it only for crime that a man can be put to death by the public authority?
Yes, for this reason only (LXIV. 6).
May public interest sometimes justify the putting to death of an innocent person?
No, never, because the supreme good in a society is always the good of virtue (LXIV. 6).
Next - The Catechism of the Summa - SECOND SECTION - A DETAILED SURVEY OF MAN'S RETURN TO GOD - XXI. OF THE SINS OPPOSED TO DISTRIBUTIVE JUSTICE: OF THE RESPECT OF PERSONS; OF THE SINS OPPOSED TO COMMUTATIVE JUSTICE; OF HOMICIDE; OF CAPITAL PUNISHMENT; OF MUTILATION; OF FLOGGING; AND OF IMPRISONMENT (C)