Implementing Jewish law, the manifestation of the Almighty's Will in this world, is a daunting task.  Luckily, חז"ל gave us a formula through which success is guaranteed:  כל מחלוקת שהיא לשם שמים סופה להתקים - Any debate which has pure intentions, its goal will be achieved [רע"ב אבות ה-יז].  The intention of those involved in a dispute must be genuine and pure - to find the truth.  If that is their only objective, the truth will be revealed.  It's a guarantee.  Litigants in a dispute are inherently biased.  With the assistance of a neutral third party, however, like a mediator or a Bais Din, the truth will prevail.  But even a small bias can divert one's attention from the primary goal, which is why, at Machon Mishpat Tzedek, we are particularly stringent to ensure even an indirect bias does not exist when choosing a mediator or a Dayan.  The job also requires a basic level of humility.  If I articulate an argument during a case, human nature compels me to promote and maintain my argument. It is a natural bias which I must be prepared to reject if presented with a counter argument from another Dayan, or even a litigant.  And it goes without saying that monetary or political biases have no place in a Din Torah.  The truth is all that matters.