The Catechism of the Summa - SECOND SECTION - A DETAILED SURVEY OF MAN'S RETURN TO GOD - XXIII. OF THE SINS AGAINST JUSTICE BY WORDS; OF THE JUDGMENT PRONOUNCED BY A JUDGE; OF THE SINS ON THE PART OF THE ACCUSED AND OF THE ACCUSER; AND ON THE PART OF THE WITNESS AND OF THE ADVOCATE (C)

(C)  
What is the second sin which may be committed against justice in the solemn act of judgment?

It is the sin of those who are wanting in their duty as accusers, or who accuse unjustly (LXVIII.).
 
What is meant by the duty of accusing?

By this is meant that duty incumbent upon every man living in a society who knows of some evil that assails the society itself; he is thereby bound to bring to the notice of the judge the author of the evil so that justice may be done; he is free from this obligation only if he is unable to establish the truth of the fact juridically (LXVIII. 1).
 
When is an accusation unjust?

Accusation is unjust when from simple malice one falsely imputes crimes to another; or if when one is called upon to give evidence one does not follow up the accusation according as justice demands, either by making overtures to the opposite party or by unreasonably declining to follow up the accusation (LXVIII. 3).

Next - The Catechism of the Summa - SECOND SECTION - A DETAILED SURVEY OF MAN'S RETURN TO GOD - XXIII. OF THE SINS AGAINST JUSTICE BY WORDS; OF THE JUDGMENT PRONOUNCED BY A JUDGE; OF THE SINS ON THE PART OF THE ACCUSED AND OF THE ACCUSER; AND ON THE PART OF THE WITNESS AND OF THE ADVOCATE (D)