Moral Theology / A Complete Course Based on St. Thomas Aquinas and the Best Modern Authorities

by John A. McHugh; Charles J. Callan

(b) According to the effect, interpretation is declarative, if it clears up what was obscure in the law; it is supplementary, if it extends or limits the law, by adding to or subtracting from the cases included under it.

(c) According to the manner in which it is made, interpretation is strict or wide, Strict interpretation gives to a word of law that least inclusive and most proper signification it bears (e.g., it understands “son” to stand for son by birth). Wide interpretation gives to a word a more inclusive and less proper signification (e.g., it understands “son” to stand for son by birth or by adoption).

387. Those Subject to Law.—Only those are morally obliged to observe human law who are subjects of the lawgiver and who have the use of reason. (a) Those who are not subjects in any sense are not bound, for to obligate by law is an act of authority and jurisdiction; (b) those who have not reached the age of reason, or who are habitually insane, are not themselves morally bound, since they are incapable of moral obligation. Of course, they may be restrained as to acts, and their rights may be determined.

388. The lawgiver himself, even though not subject, is held to observe the laws he makes. Thus: (a) if the lawmaking power resides in a legislative assembly, each legislator is subject to the body and hence to its laws; (b) if the lawmaking power is vested in an individual, he is not subject to the coactive force of his own laws, since he cannot punish himself; but he is subject to their directive force, inasmuch as the higher law of nature requires that the superior show good example by observing what he requires of others.

389. Change of Law.—The growth of knowledge and experience, or the change of social circumstances, requires now and then that human laws be improved or adapted to new conditions. But, since laws derive a great part of their influence from custom, they should not be changed unless the break with custom is compensated for by the urgent necessity of the new law, by its manifest advantage, or by the evident iniquity or harmfulness of the old law, In brief, the common good should be the norm by which to decide whether a law should be retained or changed.

390. Constitutional law, as being fundamental and organic, is more immutable than ordinary law. (a) If given to a society established according to the positive ordinance of a superior, it cannot be abrogated or modified by the legislative authority of that society, since this would be contrary to the will of the founder. Hence, the Church has no power to change the fundamental constitution given her by Christ, who prescribed the religious society as established by Him to be necessary. (b) If a constitutional law is given to a society which is perfect and necessary from the law of nature, such constitution can be modified for extraordinary reasons and in the special ways provided (e.g., by amendments approved by the people).

391. The Law of Custom.—Custom (i.e., a long-continued practice that has acquired binding force) is able to establish a new law or to do away with an old law. For the will of the lawgiver is manifested not only by words, as happens in the written law, but also and more clearly by repeated and continued acts, as happens in the case of the unwritten law of custom. In a democracy it is the consent of the people who follow the custom as law that imposes the obligation; in a monarchy it is the consent of the ruler who permits the custom.

392. With reference to their legal effects, there are three kinds of customs: (a) customs according to the law, which are those that confirm by use an existing law; in this way custom interprets law (see 386); (b) customs beside the law, which are those that introduce a new obligation that is not prescribed by any written law; in this way custom establishes law; (c) customs contrary to law, which are those that remove the obligation of a previous law; in this way custom repeals, at least in part, the law to which it is opposed.

393. Custom has not the power to establish or repeal a law, unless it possesses the requisites of law itself (see 285). Hence arise the following conditions:

(a) Since the exercise of the legislative power requires freedom, customs do not possess legal force unless they have been practised freely. Hence, a custom that has been established by force does not suffice;