The Torah, in giving instructions to the judges, tells them not to accept bribes, KI HASHOCHAD YE’AVER PIKCHIM VISALEF DIVRE TZADIKIM, “…for a bribe will blind those that see and corrupt the words of the righteous.” (Ex.23,8) The words PIKCHIM AND TZADIKIM refer to judges who are honest and just. Why would anyone think that such people would take bribes?
A Rabbi once explained that it means that even after the trial and after a legal decision was given, even then the judge is not to accept a gift from the litigants. What harm could be done once the case has already been decided? The answer is that even after a decision has been made the judge can interpret the decision in a different way if a question arises as to what was really meant.
We often see this in laws that have been passed when at a later date courts and lawyers try to re-interpret the meaning of the law. We see also many politicians will make statements and when they are taken to task or if certain conditions arise and they no longer want to follow their original stand, will re-interpret their pronouncements to mean something else, and at times, even the opposite of what they really said.
That is why judges should not take gifts even after the case is resolved and that is why there are laws prohibiting office holders from taking gifts while in office.