I don't believe that they are required to recuse themselves[1], but if there was a bias, it probably makes an appeal easier. [1] A good example was when Jack T

I don't believe that they are required to recuse themselves[1], but if there was a bias, it probably makes an appeal easier. [1] A good example was when Jack Thompson (personally) sued one of the judges that was hearing a case he had. The judge was not required to recuse himself, even with the possible conflict of interest, because this would effectively allow someone to 'choose a new judge' by suing the judge they didn't like.