Mishnayos Sanhedrin Perek 3 Mishnah 1

זה בורר לו אחד – One of the litigants selects for himself one judge for adjudicate for him and change his verdict to innocence. And similarly, the second [litigant] chooses for himself a judge, and two of the litigants together choose another third judge, and through this, a faithful and truthful judgment will result, for both litigants will listen the judgment and they will say that truth was adjudicated for us. For the guilty party will hold: “Behold, on my own, I chose the one, and if he is able to change the verdict to innocence, he would change it. And the third judge on his own is willing to change the verdict to innocence for both of them , because both of them (i.e., the litigants) chose him.

וחכמים אומרים: שני הדיינים בוררים להם אחד – without the knowledge of the litigants, in order that the heart of the third judge would not lean towards one of them. And the Halakha is according to the Sages.

זה פוסל דיינו של זה – He can say, I will not judge before the Jewish court that you have selected

בזמן שהביא עליהן ראיה – for this one brings evidence on one judge that he selected to invalidate him.

אבל אם הם כשרים ומומחים – This is how it should be understood: But if they were worthy in that they are neither relatives nor invalid, even though they sit on street corners, they became like specialists and he cannot invalidate them. The Halakhic decision on this is that when the litigants accepted who would judge them, whether for an individual or for the public, and he made a legal decision for them, his judgment is law and they cannot reverse his judgment even though he is not a specialist recognized by the public, and if it is known that he erred, if it is something from the Mishnah that he erred in or something explicitly written in the Gemara, they revoke the matter and re-judge it according to Halakha. But if it is impossible to revoke the matter such as the case that the person who took the money illegally went abroad, the judge is exempt form payment after they had accepted him [as judge] over them, for even though he caused for damage [to be done], he did not intend to cause damage. And if he had erred in his weighing between opposing views, and this is a matter that the Tannaim or Amoraim or Gaonim disputed about, but the general practice is like one off them, and the judge adjudicated like according to the words of that Gaon whose opinion was not like the general practice, if he did not engage in give and take by hand, he should retract the judgment, but if it is impossible to retract, he should pay from his own estate, and if he engaged in give-and-take by hand , what is done is done and he should pay from his own estate. But a judge whom the litigants did not accept but stood up on his own [to be a judge] or a king appointed him or some of the elders of the community appointed him, if he is not a specialist recognized by the public, even though he received permission from the Exilarch his judgments are not law, whether he erred or whether he did not err. And he is not amongst the judges but rather amongst those who act by force, and each one of the litigants if he wants, he reverses the decision and the judgment returns before the Jewish court. And if he erred and did not engage in give-and-take by hand, the judgment should be reversed, and if it is impossible to reverse it, he should pay from his estate according to the law of all who cause damage, and if he engaged in give-and-take by hand he should pay from his estate and return from what the litigant gave him which was not according to Halakha. But specialist recognized by the public whom the litigants accepted or that he received permission [to judge] from the Exilarch even though the litigants did not accept him, for such he is a specialist, if he erred in a matter whether from the Mishnah or from making a decision after weighing between opposing views, and it is impossible to reverse the decision, he is exempt from making payment. And a specialist who received permission from the Exilarch must force the litigants before him that they will adjudicate before him, whether they wanted to or did not want to, whether in the land of Israel or outside the land of Israel. And whomever received permission from the Nasi in the land of Israel cannot force the litigants other than only in the land of Israel. And he who is a specialist, is one who learned the Written Torah and the Oral Torah and knows how to think, to make analogies and to understand a thing from the midst of another thing (and he is called a specialist). And when he is recognized and known and his character/substance has gone out [and become known] among the men of his generation, he is called an expert recognized by the public, and he may judge singularly (i.e., alone) and even if he did not receive permission from the Exilarch.

זה פוסל עדיו של זה – This is a dispute between Rabbi Meir and the Rabbis which is maintained in the Gemara, for when a litigant said: “I have two sets of witnesses in the manner” and he brings the first set and the opposing litigant stands with one another [person] and says, they are invalid, Rabbi Meir states he and another [person] may invalidate them, and he is not an interested witness, for he said that he has another set [of witnesses], but if he requested and did not find [them] he loses. And the Rabbis think that even though he said at first: “I have two sets of witnesses,” he can retract and say “I do not have ought of these, and the person who comes to invalidate them is an interested witness but they are not invalidated by his mouth. And the Halakha is according to the Sages.