No. 1807, page 444 of the Catechism of the Catholic Church, Libreria Editrice Vaticana: Urbi Et Orbi Communications:
Justice is the moral virtue that consists in the constant and firm will to give their due to God and neighbor. Justice toward God is called the "virtue of religion." Justice toward men disposes one to respect the rights of each and to establish in human relationships the hrmony that promotes equity with regard to persons and to the common good. The just man, often mentioned in the Sacred Scriptures, is distinguished by habitual right thinking and the uprightness of his conduct toward his neighbor. "You shall not be partial to the poor or defer to the great, but in righteousness shall you judge your neighbor." (68) "Masters, treat your slaves justly and fairly, knowing that you also have a Master in heaven." (69).
From the Baltimore Catechism No. 3; Benziger Brothers, Inc and Tan Books and Publishers, Inc. Nos. 1273, 1277, and 1280 Pages 286-288
Q: What are we commanded by the Fifth Commandment?
A: We are commanded by the fifth Commandment to live in peace and union with our neighbor, to respect his rights, to seek his spiritual and bodily welfare, and to take proper care of our own life and health.
Q: What is forbidden by the Fifth Commandment?
A: The Fifth Commandment forbids all wilful murder, fighting, anger, hatred, revenge, and bad example.
Q: Why are fighting, anger, hatred and revenge forbidden by the Fifth Commandment?
A: Fighting, anger, hatred and revenge are forbidden by the fifth commandment because they are sinful in themselves and may lead to murder. The commandments forbid not only whatever violates them, but also whatever may lead to their violation.