In Book 2 of De legibus (“On the Laws”), Cicero gives an account of law’s foundation in divine reason, and discourses on the relation between civil law and divine law, which is the standard for determining the justness of the former (all the passages quoted here the author Cicero puts in his own mouth within the dialogue). In these passages, it is clear that, for Cicero, the simple fact of a magistrate making an enactment does not mean that he has made a “law,” because law does not depend on power but on justice; the sovereign’s say-so doesn’t make it so, for law is not based on will: the magistrate himself is subject to a higher law. How important it is, then, to have magistrates who understand their role and what justice is. The excerpts are long; but they are, I think, worth our attention.
This, then, as it appears to me, has been the decision of the wisest philosophers,–that law was neither a thing contrived by the genius of man, nor established by any decree of the people, but a certain eternal principle, which governs the entire universe, wisely commanding what is right and prohibiting what is wrong. Therefore they called that aboriginal and supreme law the mind of God, enjoining or forbidding each separate thing in accordance with reason. On which account it is, that this law, which the Gods have bestowed on the human race, is so justly applauded. For it is the reason and mind of a wise Being equally able to urge us to good and to deter us from evil.[..]
From out childhood we have learned, my Quintus, to call such phrases as this, “that a man appeals to justice, and goes to law,” and many similar expressions, law; but, nevertheless, we should understand that these, and other similar commandments and prohibitions, have sufficient power to lead us on to virtuous actions and to call us away from vicious ones. Which power is not only far more ancient than any existence of states and peoples, but is coeval with God himself, who beholds and governs both heaven and earth. For it is impossible that the divine mind can exist in a state devoid of reason; and divine reason must necessarily be possessed of a power to determine what is virtuous and what is vicious. Nor, because it was nowhere written, that one man should maintain the pass of a bridge against the enemy’s whole army, and that he should order the bridge behind him to be cut down, are we therefore to imagine that the valiant Cocles did not perform this great exploit agreeably to the laws of nature and the dictates of true bravery. Again, though in the reign of Tarquin there was no written law concerning adultery, it does not therefore follow that Sextus Tarquinius did not offend against the eternal law when he committed a rape on Lucretia, daughter of Tricipitinus. For, even then he had the light of reason deduced from the nature of things, that incites to good actions and dissuades from evil ones; and which does not begin for the first time to be a law when it is drawn up in writing, but from the first moment that it exists. And the existence of moral obligation is coeternal with the divine mind. Therefore, the true and supreme law, whose commands and prohibitions are equally authoritative, is the right reason of Sovereign Jupiter.[…]
Therefore, as that Divine Mind, or reason, is the supreme law, so it exists in the mind of the sage, so far as it can be perfected in man. But with respect to civil laws, which are drawn up in various forms, and framed to meet the occasional requirements of the people, the name of law belongs to them not so much by right as by the favour of the people. For men prove by some such arguments as the following, that every law which deserves the name of a law, ought to be morally good and laudable. It is clear, they say, that laws were originally made for the security of the people, for the preservation of states, for the peace and happiness of society; and that they who first framed enactments of that kind, persuaded the people that they would write and publish such laws only as should conduce to the general morality and happiness, if they would receive and obey them. And then such regulations, being thus settled and sanctioned, they justly entitled Laws. From which we may reasonably conclude, that those who made unjustifiable and pernicious enactments for the people, acted in a manner contrary to their own promises and professions, and established anything rather than laws, properly so called, since it is evident that the very signification of the word law, comprehends the whole essence and energy of justice and equity.[…]
If, then, in the majority of nations, many pernicious and mischievous enactments are made, which have no more right to the name of law than the mutual engagements of robbers, are we bound to call them laws? For as we cannot call the recipes of ignorant and unskilful empirics, who give poisons instead of medicines, the prescriptions of a physician, so likewise we cannot call that the true law of a people, of whatever kind it may be, if it enjoins what is injurious, let the people receive it as they will. For law is the just distinction between right and wrong, made conformable to that most ancient nature of all, the original and principal regulator of all things, by which the laws of men should be measured, whether they punish the guilty or protect and preserve the innocent. (De legibus 2. 4-5, tr. C.D. Yonge)