37. Among those actions which the law sanctions as just, that which is determined to be of mutual advantage is in fact just whether or not it is universally regarded to be so. But if a law, once established, is determined not to be mutually advantageous, then it is by nature unjust. As to those laws which were at first just, but later become unjust, such laws were in fact just for the period in which they were of mutual advantage, at least in the eyes of those who do not confound themselves with empty words, but look to the actual facts.

Alternate Translations: Bailey: Among actions which are sanctioned as just by law, that which is proved on examination to be of advantage in the requirements of men’s dealings with one another has the guarantee of justice, whether it is the same for all or not. But if a man makes a law and it does not turn out to lead to advantage in men’s dealings with each other, then it no longer has the essential nature of justice. And if the advantage in the matter of justice shifts from one side to the other, but for a while accords with the general concept, it is none the less just for that period in the eyes of those who do not confound themselves with empty sounds but look to the actual facts. Strodach: In the case of actions that are legally regarded as just, those that are of tested utility in meeting the needs of human society have the hallmark of justice, whether they turn out to be equally just in all cases or not. On the other hand, if somebody lays down a law and it does not prove to be of advantage in human relations, then such a law no longer has the true character of justice. And even if the element of utility should undergo a change after harmonizing for a time with the conception of justice, the law was still just during that period, in the judgment of those who are not confused by meaningless words but who look at the actualities.

Vatican Saying 13: Among the things held to be just by law, whatever is proved to be of advantage in men’s dealings has the stamp of justice, whether or not it be the same for all; but if a man makes a law and it does not prove to be mutually advantageous, then this is no longer just. And if what is mutually advantageous varies and only for a time corresponds to our concept of justice, nevertheless for that time it is just for those who do not trouble themselves about empty words, but look simply at the facts.

NewEpicurean Commentary: Actions that are mutually beneficial are to be considered just whether they are the same for all peoples or not. Laws that are not mutually advantageous are no longer to be considered just. Therefore we see that justice can change over time and is dependent on circumstances, not on some absolute other-dimensional standard.