.028. The moral law is eternal and universal and unchanging. The moral law applies to all persons, at all times, in all circumstances, without any exception. The moral law is eternal and universal and unchanging, because God is eternal and universal and unchanging. God is all-knowing, and present everywhere, and eternal, and unchanging. The moral law did not change when the Old Testament covenant was established. The moral law did not change when the New Testament covenant was established. The moral law did not change when one Ecumenical Council or another issued its teachings. The moral law will not change when Christ Returns. The moral law will not change when God takes away heaven and earth, and makes a new heaven and a new earth. The moral law is unchanging because God is unchanging. The moral law is eternal because God is eternal.

The moral law is universal, applying to all persons, at all times, in all places, in all situations. There is no context in which the moral law changes, or in which the principles of morality are different, or in which nothing is immoral, or in which the moral law does not apply, or in which the moral law applies only in a limited way, or only to a limited extent. All the principles of the moral law are universal, applying to all persons, at all times, in all places, in all situations.

The moral law is a type of law. The moral law is the archetype of all law. The moral law is the one law above all other laws, from which all particular just laws are derived. The moral law is ultimately the law of justice itself. God is Justice. God is the eternal moral law.

All that applies to just laws in general also applies to the moral law, with the provision that the moral law exceeds all other laws by being the eternal Justice of God. No law has any legitimate authority, and no law is recognized as a law in the eyes of God, unless it is based upon the eternal moral law. And all human persons are subject to the moral law equally.

Pope John Paul II: “It makes no difference whether one is the master of the world or the ‘poorest of the poor’ on the face of the earth. Before the demands of morality we are all absolutely equal.”

.029. An unjust law is not a law.

All unjust laws are contrary to the eternal moral law, and therefore contrary to God, who is Justice, who is the eternal moral law. Whoever obeys the moral law, obeys God. Whoever disobeys the moral law, disobeys God. Whoever obeys justice, obeys God. Whoever disobeys justice, disobeys God.

Saint Augustine: “For it seems to me that an unjust law is no law at all.”

Pope Leo XIII: “For laws are to be obeyed only insofar as they conform with right reason and thus with the eternal law of God.”

Saint Thomas Aquinas: “Human law is law only in virtue of its accordance with right reason: and thus it is manifest that it flows from the eternal law. And in so far as it deviates from right reason it is called an unjust law; in such case it is no law at all, but rather a species of violence.”

An unjust law is not a law.

All just laws are (1) reasonable, (2) of proper authority, (3) for the common good, (4) promulgated, and (5) enforced.

Saint Thomas Aquinas: “Thus from the four preceding articles, the definition of law may be gathered; and it is nothing else than an ordinance of reason, for the common good, made by him who has care of the community, and promulgated.”

But elsewhere Saint Thomas also states that violations of law (human or Divine) are punished. Therefore, the definition of just law includes enforcement, by means of the punishment (and threat of that punishment) of those who offend against the law.

Saint Thomas Aquinas: “for the sinner acts against his reason, and against human and Divine law. Wherefore he incurs a threefold punishment; one, inflicted by himself, viz. remorse of conscience; another, inflicted by man; and a third, inflicted by God.”

[The above text was quoted from my book: The Catechism of Catholic Ethics, n. 028 and 029.]