Siman 23

As long as the litigants are standing before the judge, he is believed to say, "I have acquitted this one and I have liable this one," and the litigant is not believed to contradict him. Since they appointed him as a judge or a mediator, he is believed like two witnesses. And even if the litigant has a migo, in that he could have said "I did not accept you as a judge or a mediator"—such as when there are no witnesses to the fact that they accepted him—nevertheless, he is not believed to contradict him, for since he is believed like two witnesses, it is like a migo in the place of witnesses [Netivot HaMishpat]. But once they have departed from before him, he is only believed as a single witness, provided he is not a relative or disqualified, and he necessitates an oath for the one who contradicts him and exempts from an oath the one he supports, as I wrote in siman 75. And if the judge is not a witness in the matter—for example, if he died or went away from here—and the litigants contradict one another, such that each one says "He acquitted me," if one is the possessor, the other must bring proof, according to the law of one who seeks to extract from his fellow. And if both are possessors, they shall divide. And if neither is a possessor, "whoever is stronger prevails" or they shall make a compromise [Sma], just as these laws will be explained in siman 133. And it appears to me that one can impose an oath upon his fellow. And if one of the litigants says that he already acquitted him, and the second litigant and the judge say that the judgment has not yet been decided: if there are witnesses that they appointed him as a judge, the judge is believed in this even when they have departed from before him. But if there are no witnesses that they appointed him as a judge and they have departed from before him, the litigant is believed with a migo that he did not accept him as a judge [Netivot HaMishpat]. And it appears to me that regarding this second one, if he wishes to adjure the first one to swear that he already acquitted him and take, he can adjure him with a shevuat hesat and not a Torah oath, even though the judge is a witness who contradicts him, for a Torah oath is only to swear and be exempt, as I wrote in siman 87. And the first one cannot adjure the second, for the judge is a witness who supports him and exempts him from an oath according to the opinion that will be explained there, that even when not regarding a Torah oath, a supporting witness exempts from an oath.

That which we have said, that when they have departed from before him he is not believed like two witnesses, this is specifically regarding a law that depends on the estimation of the judge’s mind, such as in a "shuda de-dayyani" or in a compromise, for it is possible that afterwards the estimation of his mind will change. However, regarding a Torah law, the concept of "believability" does not apply to this at all, for he is able to return and judge them, as a Torah law does not change. However, this is specifically when there is no contradiction between them regarding the claims; but when there is a contradiction between them, where the litigant says "this was my claim" and the judge contradicts him, and it is not relevant that he should return and judge them, even in a Torah law his status returns to being only like one witness. And so too, even when they are standing before him and there is a contradiction between them regarding the claims, the judge is only believed like one witness [Shach and Netivot HaMishpat]. And all this is specifically regarding one judge; but two judges, and all the more so more, are always believed even when the litigants have departed from before them. And even when two witnesses contradict the judges, the judges are believed, for they certainly were more exacting than the witnesses because the judgment is incumbent upon them. But when one judge and one witness say thus, and two witnesses contradict them, they have no advantage against the witnesses, and their law is like two groups of witnesses that contradict one another, which will be explained in siman 31, and they are equal as one without advantage [Sma].

And all this is specifically when there is no verdict, but when there is a verdict, they shall fulfill what is written in the verdict, and the judge is not believed to provide a distant explanation that the wording of the verdict does not tolerate; and perhaps even many judges are not believed in such a case. However, if the wording of the verdict tolerates two explanations, it appears to me that even one judge is believed to say, "This was my intention."

If they accepted an arbitrator for a set time, he is believed within that time regarding everything he says, like a trustee in siman 56. After the time, he is believed only as a single witness. If he gave them the compromise in writing, he may not provide a distant explanation that the language cannot bear, as has been written in section 3.