Today we go back in time to Cicero’s Laws 1.42-5. There he elucidates the necessary foundation for positive law, which is justice. Without it, there is merely opinion and power. Laws are not ultimately “established” by will and the decisions of the powerful. If they were, one could say that there is a “right” to theft, adultery, and so on, which, for Cicero, is absurd and would serve as an indication that words have lost all meaning.
The just, then, is not determined by what the powerful say is just, as though justice arises immanently and ipso facto in the legislative or judicial process. Rather, justice, if it is actually to be justice, comes from outside, from above, any given political order.
It is meaningless, then, to talk of the “rule of law” if this basic obligation of positive law to natural justice is ignored. Without it, talk of the “rule of law” is just the debt naked power pays to virtue.
 But truly the most foolish thing is to think that everything is just that has been approved in the institutions or laws of peoples. And if those laws are from tyrants? If the Thirty at Athens had wanted to impose laws, or if all the Athenians delighted in tyrannous laws, surely those laws should not be held to be just for that reason? No more, I suppose, than the one that our interim ruler provided, that the dictator could kill whatever citizens he wanted with impunity, even without a hearing. Right is uniform; human fellowship has been bound by it, and one law has established it; that law is correct reason in commanding and prohibiting. He who is ignorant of it is unjust, whether it has been written somewhere or nowhere. Now if justice is compliance with the written laws and institutions of peoples, and if (as the same men say) everything ought to be measured by advantage, he who thinks that it will be enjoyable for himself will neglect and break through those laws if he can. So it happens that there is no justice at all if not by nature, and what is established for the sake of advantage is undermined by that advantage.
 And if right has not been confirmed by nature, they may be eliminated [missing portion of the text] In fact where will liberality be able to exist, where affection for the fatherland, where piety, where the will either to deserve well of another or to return a service? These things originate in this, that we are inclined by nature to cherish human beings; that is the foundation of right. And not only allegiances toward human beings but also ceremonies and religious observances for the gods are eliminated, which I think ought to be preserved not by fear but by the connection that exists between human being and god. But if rights were established by peoples’ orders, if by leading men’s decrees, if by judges’ verdicts, there would be a right to rob, a right to commit adultery, a right to substitute false wills, if those things were approved by the votes or resolutions of a multitude.  But if there is such power in the opinions and orders of the foolish that the nature of things is changed by their votes, why don’t they establish that bad and ruinous things should be held to be good and salutary things? Or if law can make right out of wrong, can’t the same law make good out of bad? But we can divide good law from bad by no other standard than that of nature.
Not only right and wrong are distinguished by nature, but also in general all honorable and disgraceful things. Nature makes common conceptions for us and starts forming them in our minds so that honorable things are based on virtue, disgraceful things on vices.  To think that these things have been based on opinion, not on nature, is for a madman.