Dear Deacon:

Since you did not list the issue under question, I'll have to answer generically.

There are four kinds of law: Divine Law, Natural Law, Ecclesiastical (Church) Law, and Civil Law.

Natural Law and Ecclesiastical Law derives from Divine Law. Civil Law "should" derive from Divine and Natural Law. Thus we are to obey civil law unless the civil law contradicts Divine or Natural Law (or Ecclesiastical Law) to which we are then duty bound to disobey such a civil law.

We are bound to obey Ecclesiastical Law, even when it is not an infallible proclamation, because God has given Peter the keys of the Kingdom with the authority not only to infallibly define the faith but also to legislate lesser teachings and disciplinary tenets for the good of the Faithful.

Here are the definitions of each of these Laws excerpted and paraphrased from Father Hardon's Pocket Catholic Dictionary as a source:

Divine Law: The eternal law of God, or the divine reason as governing the whole universe. God conceived as the Ruler of the universe. The plan of government that he has in his mind bears the character of law, and because it is conceived in eternity and not in time, it is said to be eternal law.

This eternal law embraces both the physical and moral laws. Both have in common the idea of some norm to be fulfilled. In physical laws, this norm is filled necessarily, as happens with gravity or the expansion of matter by heat. In moral laws, the norm may or may not be fulfilled depending on the free decision of human beings.

The eternal moral law has been manifested to the human race in two ways, naturally and supernaturally. In the first case, human beings come to know the eternal law from created nature through the light of native reason; this is natural law in the full scope of its meaning. In the second case, human beings come to know the eternal law from divine revelation to which they can respond with the help of God's grace/ This is the revealed law that spans the whole ambit of God's special communication of his will "through the prophets" in times past and in our own time "through His Son" (Hebrews 1:1).

Natural Law: As distinct from revealed law, it is "nothing else than the rational creature's participation in the eternal law" (Summa Theologica, 1a, 2ae, quest. 91, art. 2). As coming from God, the natural law is what God has produced in the world of creation; as coming to human beings, it is what they know (or can know) of what God has created.

It is therefore called natural law because everyone is subject to it from birth (natio), because it contains only those duties which are derivable from human nature itself, and because, absolutely speaking, its essentials can be grasped by the unaided light of human reason.

Ecclesiastical Law: An ordinance issued by legitimate authority in the Catholic Church. The legislators for the entire Church are the Roman Pontiff alone, or the Pope through the Roman Curia, or an ecumenical council together with the Pope; the bishops for their individual dioceses, or conferences of bishops for the territories under their jurisdiction; and the major superiors of institutes of perfection for their members according to the respective constitutions.

The Catholic Church has always professed her right to pass laws that are binding on the consciences of the faithful. This right is of divine origin since received this right "from her Founder, Christ, was endowed with all the qualities suitable to a perfect society. So, too, from her very beginning since she was to obey the Lord's command to teach and govern all nations, she has undertaken to regulate and protect by the laws the discipline of clergy and laity alike" (Benedict XV, Providentissima Mater Ecclesia, May 27, 1917).

Civil Law: Legislation promulgated by the government in a political society. In general, it is morally binding in conscience, as the Church's tradition since biblical times testifies. "For the sake of the Lord," Peter told the first century Christians, "accept the authority of every social institution: the emperor as the supreme authority, and the governors as commissioned by him to punish criminals and praise good citizenship" (1 Peter 2:13).

Civil Law is certainly obligatory insofar as it sanctions or determines higher law, whether natural or revealed. Civil Law is certainly not obligatory when it is unjust, notably contrary to the laws of God and of the Church, when they do not proceed from legitimate authority, when it is not directed to the common welfare, and when it violates distributive justice.

Thus a person is not permitted to obey a law that commands acts against the moral law.

To Your Situation: As mentioned, since you did not mention the issue under question I cannot speak to that. Hopefully these definitions will help you.

I suspect that maybe your parishioner is talking about the difference between, for example, infallible teaching such as the Doctrine of the Justification, and disciplinary law such as abstinence of eating meat on Fridays.  The former is revealed divine law, the latter is Ecclesiastical disciplinary law.

But, even such Church laws as not eating meat on Fridays still derives from eternal truths and thus is still a subset of Divine Law in my understanding.

If I remember correctly it was St. Augustine who said something like, "When the Church speaks, God speaks".

God Bless,
Bro. Ignatius Mary