Law

I answer that, Law is a rule and measure of acts, whereby man is induced to act or is restrained from acting: for "lex" [law] is derived from "ligare" [to bind], because it binds one to act. Now the rule and measure of human acts is the reason, which is the first principle of human acts, as is evident from what has been stated above (Q[1], A[1], ad 3); since it belongs to the reason to direct to the end, which is the first principle in all matters of action, according to the Philosopher (Phys. ii). Now that which is the principle in any genus, is the rule and measure of that genus: for instance, unity in the genus of numbers, and the first movement in the genus of movements. Consequently it follows that law is something pertaining to reason.

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.

Reply to Objection 1: The natural law is promulgated by the very fact that God instilled it into man's mind so as to be known by him naturally.

Reply to Objection 2: Those who are not present when a law is promulgated, are bound to observe the law, in so far as it is notified or can be notified to them by others, after it has been promulgated.

Reply to Objection 3: The promulgation that takes place now, extends to future time by reason of the durability of written characters, by which means it is continually promulgated. Hence Isidore says (Etym. v, 3; ii, 10) that "lex [law] is derived from legere [to read] because it is written."

And first it manifest, that Law in generall, is not Counsell, but Command; nor a Command of any man to any man; but only of him, whose Command is addressed to one formerly obliged to obey him. And as for Civill Law, it addeth only the name of the person Commanding, which is Persona Civitatis, the Person of the Common-wealth.

Which considered, I define Civill Law in this Manner. “CIVILL LAW, Is to every Subject, those Rules, which the Common-wealth hath Commanded him, by Word, Writing, or other sufficient Sign of the Will, to make use of, for the Distinction of Right, and Wrong; that is to say, of what is contrary, and what is not contrary to the Rule.”