Doctrine 38

38. Where actions which were formerly considered to be just under former circumstances are seen not to accord with the general concept of mutual advantage, then they are seen not to have been just. But actions which were in fact of mutual advantage and therefore just at one time under former circumstances, but cease being of mutual advantage under new circumstances, cease also being just.

Alternate Translations: Bailey: Where, provided the circumstances have not been altered, actions which were considered just have been shown not to accord with the general concept in actual practice, then they are not just. But where, when circumstances have changed, the same actions which were sanctioned as just no longer lead to advantage, there they were just at the time when they were of advantage for the dealings of fellow-citizens with one another, but subsequently they are no longer just, when no longer of advantage. Strodach: In cases where the surrounding conditions are not new and where laws regarded as just have been shown to be inconsistent with the conception of justice in their actual workings, such laws are unjust. Again, in cases where the circumstances are new and where the same laws, once deemed to be just, are no longer serviceable, the laws in this case were just as long as they were useful to the community of citizens, but later when they were no longer useful they became unjust.