PD 38 - Where, provided the circumstances have not been altered...

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.