Summa Theologiae Moralis, vol. I: De Principiis

S. Th. I-II, q. 90, a. 1, 2, 3.

221. Notion of law. — Law, according to some, is named from ligando (q. 90, a. 1), because it is a rule that binds and necessitates to acting; according to others from legendo, because it is wont to be written on public tablets and read, and this is the custom because it is a rule of things to be read (Cicero, de Leg. I, 19). Hence

a) in the broadest sense it is the rule and measure according to which something ought to be done, i.e. according to which something is inclined to some end and is led to act or is drawn back from it; in this sense a law is also set before all irrational beings (physical law: Job XXVIII, 26; Prov. VIII, 27; Rom. VIII, 23);

b) in a less broad sense, law, because it is an ordinance of reason, regards the rational creature alone which alone shares in it rationally; and therefore it is the rule and measure of whatever acts are done in dependence on reason, even of arts, sciences, etc., prescribing either good or evil (Is. X, 1; — S. Th. q. 92, a. 1);

c) in a stricter sense it is the norm of human or moral acts, that they may be right, remote and material, and so every precept is called law (e. g. the precept of a father, of a syndicate, of a master);

d) in the strictest sense it is the rule of human acts given to a community, prescribing to it what is right (Rom. II, 12 sq.; Prov. VIII, 15).

Now in each sense it can be considered, both subjectively: 1° according as it is essentially in the legislator as in one who regulates, and so it is taken altogether properly; 2° according as it is participatively in subjects as in those regulated (Rom. VI, 23; II, 14); and 3° according as it is in the external sign (word, writing, book) expressing it (Lk. X, 26; John XV, 25; I Cor. XIV, 21); — and objectively for the object of the law and the very thing prescribed (e. g. the condition of a contract; John VII, 19; Rom. II, 13). In these latter ways it is taken in a less proper sense and derived from the first.

222. Definition of law. — Law, taken in the strictest and most proper sense, is usually defined as: an ordinance of reason for the common good, promulgated by him who has the care of the community (q. 90, a. 4).

In which definition is indicated:

1° The genus: ordinance or disposition to an end through proportionate means, i.e. not so much the very act of ordering as its term or the dictate constituted by it; but the ordinance is to be understood strictly so called and perfect, i.e. a) not merely directive but imperative and efficacious for obligation, and so it differs from counsel, permission, prayer, etc.; b) in itself firm, stable and perpetual.

2° The subject in which law essentially and originally resides: reason, both because it is the office of reason to order or dispose and direct to an end, and to command; and because law is the rule of human acts, but the rule and measure of these is reason, because they are human and proceed from it, and they are good insofar as they are conformed to it¹; therefore law is something constituted by reason, and therefore in Scripture it is called lamp, light, precept enlightening, judgment, word, discourse (Prov. VI, 23; Ps. XVIII, 9; CXVIII, 105; CXLVI, 20).

Since, however, it is an act of practical reason, it supposes the will regulated by it, which it intimates and expresses, and therefore it is everywhere in Scripture called the will of God (Ps. XXIX, 6, 8; XXXIX, 9; CII, 7; CXLII, 10; II Macc. I, 3; Mt. VII, 21).

Hence a) the essence of law can be conceived without knowing the legislator's will, as we shall see must be said of natural law; on the contrary b) the will of a superior, to be able to be law, must be regulated by reason or conformed to reason, otherwise it would be rather iniquity than law, as happens in a positive law commanding evil².

3° The object or end, by which it is distinguished from every other ordinance:

a) for the good, because law is the rule and measure of human acts, but human acts must tend to the last end, which is the happiness of human life and beatitude;

b) for the common good: for man is a part of a perfect community, by which he can arrive at happiness; but every part is ordered to the whole, as the imperfect to the perfect. Therefore law regards order to the common happiness, or to the last end as a good to be obtained in common.

Thus it is distinguished from the precept of a tyrant who commands solely for his own advantage, or from a simple precept and command which can also be given for the good of one or of some: for by law man is ordered as a part to a perfect community; but it would be disorder to order the good of the whole to the good of a part, since the part is for the whole and not conversely (III Kings XIII; Ezek. XXXIV, 8; Conc. Tol. VIII, can. 10).

Hence a law holds:

a) which was made from a depraved end (of the agent), provided it really tends to the common good (the end of the work);

b) which is harmful to some (e.g. to one province), as long as it tends to the good of the community, because the part is subordinated to the whole and the common good is to be preferred to the private, if they cannot both be obtained together;

c) which immediately fosters the good of one class of citizens, as of orphans, clerics, soldiers, etc., but is ultimately ordered to the common good, inasmuch as this requires that such persons be defended with special care and favor or be held in their duty.

4° The author and at the same time the subject to whom the law is imposed: by him who has the care of the community.

Thus it is distinguished from a mere precept which can be imposed on one person or even by a private person: for to order and procure the common good and to command a community cannot be done except by the community itself or by him who presides over it. But the community is understood as perfect, i.e. a society complete in itself which has an end complete in its own order and sufficient means to attain it (the whole human race under God, the Church or the State as regards the faithful or the citizens). Hence laws are made by those who have public and political power of jurisdiction to govern subjects (by declaring right, making laws, even punishing transgressors with grave penalties), whether supreme over the whole community, or derived or only over a part of the community (e.g. the Roman Pontiff and bishops); — but not by those who have only private dominative power or oeconomic power over an imperfect society, such as a father, husband, master, superior of a religious house, parish priest.

5° An essential condition: promulgated, i.e. announced to the community.

223. Law differs from precept. — Every law is a precept, but not conversely; hence as species differs from genus, so law differs from precept, and indeed

a) in end: law is directed immediately and primarily to the common good; precept can also be ordered uniquely to the private good alone of the one commanding or of the one commanded;

b) in author: the legislator is a public person enjoying public power of jurisdiction; the one commanding can be a private person having only private power;

c) in subject to whom it is imposed: law is imposed on a community as such (whether the whole community, or a certain group, i.e. determinate persons taken collectively, e.g. all minors, by reason of the common good); precept can also be imposed on private persons taken singly;

d) in stability or duration: for although law can also be made for a time and be abrogated, nevertheless by its own nature, like the community itself, it is perpetual, and indeed in threefold manner: on the part of the law because it lasts until it is abrogated; on the part of the legislator because it lasts even after his death or removal; on the part of the subjects because it binds not only those present but also those to come; — but precept can by its own nature be transitory, e.g. given for one or another day or act, and bind only those present, and, unless otherwise noted, expires by the death or departure of the one commanding;

e) in extension or place: for law, since it is made for a community, if this is local, does not bind outside its territory; precept can also be given to a person and then accompanies her everywhere.

With moralists, however, precept is often taken in a restricted sense and opposed to law, for that which is a mere precept and not law, i.e. for a particular or temporary obliging rule.

224. Causes of law. — There are four causes of law: 1° final: the common good; 2° efficient: the legislator himself; 3° material, i.e. the object or matter about which it deals and of which it prescribes; 4° formal (essence), i.e. the very ordinance or prescription and the manner in which it is made, in which can be considered its formation, promulgation, acceptance, and interpretation.

225. Remark. — Since laws are the rule of justice or of the just in general, and ought to establish what is just, it has been received by use that their complex should be called Right (Ius); hence we speak of natural, divine, human right, etc.