Halacha

הלכה א
אֶחָד מִבַּעֲלֵי דִּינִין שֶׁאָמַר אִישׁ פְּלוֹנִי יָדוּן לִי וְאָמַר בַּעַל דִּינוֹ פְּלוֹנִי יָדוּן לִי הֲרֵי אֵלּוּ שְׁנֵי הַדַּיָּנִים שֶׁבֵּרֵר זֶה אֶחָד וְזֶה אֶחָד הֵם בּוֹרְרִים לָהֶן דַּיָּן שְׁלִישִׁי וּשְׁלָשְׁתָּן דָּנִין לִשְׁנֵיהֶן שֶׁמִּתּוֹךְ כָּךְ יֵצֵא הַדִּין לַאֲמִתּוֹ. אֲפִלּוּ הָיָה הָאֶחָד שֶׁבָּרְרוּ בַּעֲלֵי הַדִּין חָכָם גָּדוֹל וְסָמוּךְ אֵינוֹ יָכוֹל לָכוֹף אֶת בַּעַל דִּינוֹ שֶׁיָּדוּן אֵצֶל זֶה אֶלָּא גַּם הוּא בּוֹרֵר מִי שֶׁיִּרְצֶה:
כסף משנה
1.
The following law applies when one of the litigants says: "Let so and so act as a judge for me," and the other litigant says: "Let so and so act as a judge for me." Together the two judges which were chosen by each of the litigants respectively choose a third judge and the three of them adjudicate the case for the two litigants. In this manner, a true judgment will emerge.
Even if the judge chosen by one of the litigants is a great sage who has received semichah, the one litigant cannot compel the other litigant to have him adjudicate the case. Instead, he also chooses a judge he desires.

הלכה ב
מִי שֶׁקִּבֵּל עָלָיו קָרוֹב אוֹ פָּסוּל בֵּין לִהְיוֹתוֹ דַּיָּן בֵּין לִהְיוֹתוֹ עֵד עָלָיו. אֲפִלּוּ קִבֵּל אֶחָד מִן הַפְּסוּלִים בַּעֲבֵרָה כִּשְׁנֵי עֵדִים כְּשֵׁרִים לְהָעִיד עָלָיו אוֹ כִּשְׁלֹשָׁה בֵּית דִּין מֻמְחִין לָדוּן לוֹ. בֵּין שֶׁקִּבֵּל עַל עַצְמוֹ לְאַבֵּד זְכֻיּוֹתָיו וְלִמְחל מַה שֶּׁהָיָה טוֹעֵן עַל פִּיהֶן. בֵּין שֶׁקִּבֵּל שֶׁיִּתֵּן כָּל מַה שֶּׁיִּטְעֹן עָלָיו חֲבֵרוֹ בְּעֵדוּת זוֹ הַפָּסוּל אוֹ בְּדִינוֹ. אִם קָנוּ מִיָּדוֹ עַל זֶה אֵינוֹ יָכוֹל לַחְזֹר בּוֹ. וְאִם לֹא קָנוּ מִיָּדוֹ יָכוֹל לַחְזֹר בּוֹ עַד שֶׁיִּגָּמֵר הַדִּין. נִגְמַר הַדִּין וְהוֹצִיא הַמָּמוֹן בְּדִין זֶה הַפָּסוּל אוֹ בְּעֵדוּתוֹ אֵינוֹ יָכוֹל לַחְזֹר:
כסף משנה
2.
The following rules apply when a litigant accepts his own or an opposing litigant's relative or another person who is unacceptable to serve as a judge or a witness in his case. If he affirms his commitment with a kinyan, he cannot retract his consent. If he did not affirm his commitment with a kinyan, he can retract his consent until the case is concluded. Once the verdict is rendered and the unacceptable judge ruled in his verdict - or a verdict was rendered on the basis of the testimony of an unacceptable witness - that money should be expropriated, the litigant may not retract.
The above laws also apply if a litigant accepted a person who is disqualified because he committed a transgression as two witnesses to testify concerning him or as a court of three judges to rule concerning his interests. Similarly, it applies regardless of whether he gave his consent at the risk of forfeiting rights and waiving a claim that he is pressing or he gave his consent at the risk of having to pay what the plaintiff demands of him because of the testimony of this unacceptable witness or because of the ruling of this unacceptable judge.

הלכה ג
וְכֵן מִי שֶׁנִּתְחַיֵּב לַחֲבֵרוֹ שְׁבוּעָה בְּבֵית דִּין וְאָמַר לוֹ הִשָּׁבַע לִי בְּחַיֵּי רֹאשְׁךָ וְהִפָּטֵר אוֹ הִשָּׁבַע לִי בְּחַיֵּי רֹאשְׁךָ וְאֶתֵּן לְךָ כָּל מַה שֶּׁתִּטְעֹן. אִם קָנוּ מִיָּדוֹ אֵינוֹ יָכוֹל לַחְזֹר בּוֹ וְאִם לֹא קָנוּ מִיָּדוֹ יָכוֹל לַחְזֹר בּוֹ עַד שֶׁיִּגָּמֵר הַדִּין. נִגְמַר הַדִּין וְנִשְׁבַּע כְּמוֹ שֶׁאָמַר לוֹ אֵינוֹ יָכוֹל לַחְזֹר וְחַיָּב לְשַׁלֵּם:
כסף משנה
3.
Similarly, the following rules apply when a person was obligated by a court to take an oath to a colleague and the person to whom the oath must be given state: "Take an oath on your own life, and be freed of liability," or "Take an oath on your own life that your claim is justified and I will give you everything that you claim." If he affirms his commitment with a kinyan, he cannot retract his consent. If he did not affirm his commitment with a kinyan, he can retract his consent until the case is concluded. Once the case is concluded and he took an oath as stipulated, he cannot retract and is obligated to pay.

הלכה ד
וְהוּא הַדִּין לְמִי שֶׁנִּתְחַיֵּב שְׁבוּעַת הֶסֵּת וַהֲפָכָהּ. אִם קָנוּ מִיָּדוֹ אוֹ אִם נִשְׁבַּע זֶה שֶׁנֶּהְפְּכָה עָלָיו אֵינוֹ יָכוֹל לַחְזֹר בּוֹ:
כסף משנה
4.
Similar laws apply when a person was obligated to take a sh'vuat hesset and he reversed it and obligated the plaintiff. If he affirmed his consent with a kinyan or the plaintiff took the oath, the defendant cannot retract.

הלכה ה
וְהוּא הַדִּין בְּמִי שֶׁלֹּא הָיָה חַיָּב שְׁבוּעָה וְאָמַר אֶשָּׁבַע לְךָ שְׁבוּעָה. אִם קָנוּ מִיָּדוֹ אֵינוֹ יָכוֹל לַחְזֹר בּוֹ. וְאִם לֹא קָנוּ מִיָּדוֹ אַף עַל פִּי שֶׁקִּבֵּל בְּבֵית דִּין חוֹזֵר עַד שֶׁיִּגָּמֵר הַדִּין וְיִשָּׁבַע:
כסף משנה
5.
Similarly, when a person was not obligated to take an oath and yet he said: "I will take an oath in response to your claim," if he affirmed his statement with a kinyan, he cannot retract. If he did not affirm his statement with a kinyan, he has the right to retract until the judgment is concluded and he actually takes the oath, even though he made his commitment in court.

הלכה ו
מִי שֶׁנִּתְחַיֵּב בְּבֵית דִּין וְהֵבִיא עֵדִים אוֹ רְאָיָה לִזְכוּתוֹ. סוֹתֵר אֶת הַדִּין וְחוֹזֵר הַדִּין. אַף עַל פִּי שֶׁכְּבָר נִגְמַר הַדִּין כָּל זְמַן שֶׁהוּא מֵבִיא רְאָיָה סוֹתֵר. אָמְרוּ לוֹ הַדַּיָּנִים כָּל רְאָיוֹת שֶׁיֵּשׁ לְךָ הָבֵא מִכָּאן וְעַד שְׁלֹשִׁים יוֹם אַף עַל פִּי שֶׁהֵבִיא רְאָיָה לְאַחַר שְׁלֹשִׁים יוֹם סוֹתֵר אֶת הַדִּין. מַה יַּעֲשֶׂה אִם לֹא מָצָא בְּתוֹךְ שְׁלֹשִׁים וּמָצָא לְאַחַר שְׁלֹשִׁים:
כסף משנה
6.
When a person was obligated by a court, and then brought witnesses or proof to vindicate himself, the judgment is rescinded and the case should be tried again. Although the judgment was already rendered, whenever he brings support for his claim, the judgment is rescinded.
Even if the judges tell him: "Bring all the proofs that you have within 30 days," a litigant may have the judgment rescinded although he brings proof after 30 days. What can he do if he did not discover the proof within 30 days, but found it afterwards?

הלכה ז
אֲבָל אִם סָתַם אֶת טַעֲנוֹתָיו אֵינוֹ סוֹתֵר. כֵּיצַד. אָמְרוּ לוֹ יֵשׁ לְךָ עֵדִים אָמַר אֵין לִי עֵדִים. יֵשׁ לְךָ רְאָיָה אָמַר אֵין לִי רְאָיָה. וְדָנוּ אוֹתוֹ וְחִיְּבוּהוּ. כֵּיוָן שֶׁרָאָה שֶׁנִּתְחַיֵּב אָמַר קִרְבוּ פְּלוֹנִי וּפְלוֹנִי וְהָעִידוּנִי אוֹ שֶׁהוֹצִיא רְאָיָה מִתּוֹךְ אֲפֻנְדָּתוֹ אֵין זֶה כְּלוּם וְאֵין מַשְׁגִּיחִין עַל עֵדָיו וְעַל רְאָיָתוֹ:
כסף משנה
7.
If, however, the litigant completed stating his claims, he cannot have the judgment rescinded.
What is implied? The judges asked him: "Do you have witnesses supporting your claim?"
He replied: "I do not have witnesses."
"Do you have proof of your position?"
"I do not have proof," he answered.
In such a situation, if the court judged him and held him liable, the judgment is not rescinded. Although when he sees that he was being held liable, he declared: "So-and-so and so-and-so come forward and testify on my behalf" or he produced written proof from his money-belt, it is not significant. We do not pay any attention to his witnesses or his proof.

הלכה ח
בַּמֶּה דְּבָרִים אֲמוּרִים כְּשֶׁהָיְתָה הָרְאָיָה אֶצְלוֹ וְהָעֵדִים עִמּוֹ בַּמְּדִינָה. אֲבָל אִם אָמַר אֵין לִי עֵדִים וְאֵין לִי רְאָיָה וּלְאַחַר מִכָּאן בָּאוּ לוֹ עֵדִים מִמְּדִינַת הַיָּם. אוֹ שֶׁהָיְתָה הַחֵמֶת שֶׁל אָבִיו שֶׁיֵּשׁ שָׁם הַשְּׁטָרוֹת מֻפְקֶדֶת בְּיַד אֲחֵרִים וּבָא זֶה שֶׁהַפִּקָּדוֹן אֶצְלוֹ וְהוֹצִיא לוֹ רְאָיָתוֹ. הֲרֵי זֶה מֵבִיא וְסוֹתֵר. וּמִפְּנֵי מָה סוֹתֵר מִפְּנֵי שֶׁיָּכוֹל לִטְעֹן וְלוֹמַר זֶה שֶׁאָמַרְתִּי אֵין לִי עֵדִים אֵין לִי רְאָיָה מִפְּנֵי שֶׁלֹּא הָיוּ מְצוּיִין אֶצְלִי. וְכָל זְמַן שֶׁיָּכוֹל לִטְעֹן וְלוֹמַר זֶה שֶׁאָמַרְתִּי אֵין לִי עֵדִים אֵין לִי רְאָיָה מִפְּנֵי שֶׁלֹּא הָיוּ מְצוּיִין אֶצְלִי אוֹ מִפְּנֵי כָּךְ וְכָךְ אָמַרְתִּי אֵין לִי עֵדִים וְאֵין לִי רְאָיָה וְהָיָה מַמָּשׁ בִּדְבָרָיו הֲרֵי זֶה לֹא סָתַם טַעֲנוֹתָיו וְסוֹתֵר. לְפִיכָךְ אִם פֵּרֵשׁ וְאָמַר אֵין לִי עֵדִים כְּלָל לֹא הֵנָּה וְלֹא בִּמְדִינַת הַיָּם וְלֹא רְאָיָה כְּלָל לֹא בְּיָדִי וְלֹא בְּיַד אֲחֵרִים אֵינוֹ יָכוֹל לִסְתֹּר:
כסף משנה
8.
When does the above apply? When the proof was in his possession and the witnesses were together with him in the country. If, however, he said: "I have neither witnesses, nor proof," and afterwards, witnesses came from overseas or a leather satchel belonging to his father where legal documents were held had been entrusted to another person and that person came and supplied him with proof, he may call on these witnesses and/or this proof and have the ruling rescinded.
Why may he have the ruling rescinded? Because he could claim: "The reason I said: 'I don't have any witnesses' and 'I don't have any proof is because they were not available to me." Whenever he could make such a claim and there is substance to his words, he is not considered to have completed stating his claims when he originally stated: "I have no witnesses...." He may bring the witnesses and/or proof and have the judgment rescinded.
Accordingly, if he explicitly states: "I have no witnesses at all, neither here or overseas, nor any written proof, neither in my possession or in the possession of others," he cannot have the judgment rescinded.

הלכה ט
בַּמֶּה דְּבָרִים אֲמוּרִים בְּגָדוֹל שֶׁנִּתְחַיֵּב וְהֵבִיא רְאָיוֹת וְהֵבִיא עֵדִים אַחַר שֶׁסָּתַם טַעֲנוֹתָיו. אֲבָל יוֹרֵשׁ שֶׁהוּא קָטָן כְּשֶׁמֵּת מוֹרִישׁוֹ וּבָאוּ עָלָיו טְעָנוֹת מֵחֲמַת מוֹרִישׁוֹ אַחַר שֶׁהִגְדִּיל וְאָמַר אֵין לִי עֵדִים וְאֵין לִי רְאָיָה וְאַחַר שֶׁיָּצָא מִבֵּית דִּין חַיָּב אָמְרוּ לוֹ אֲחֵרִים אָנוּ יוֹדְעִים לְאָבִיךָ עֵדוּת שֶׁתִּסְתֹּר בָּהּ דִּין זֶה. אוֹ אָמַר לוֹ אֶחָד מוֹרִישְׁךָ הִפְקִיד רְאָיָה זוֹ. הֲרֵי זֶה מֵבִיא מִיָּד וְסוֹתֵר שֶׁאֵין הַיּוֹרֵשׁ קָטָן יוֹדֵעַ כָּל רְאָיוֹת מוֹרִישׁוֹ:
כסף משנה
9.
When does the above apply? With regard to an adult who was held liable and then brought written proof or witnesses after completing the statement of his arguments.
Different concepts apply, however, with regard to an heir who was a minor when the person whose estate he inherited died and a suit was lodged against him because of that person after he came of age. Even though he stated: "I have neither witnesses, nor proof," and after he departed from the court after being held liable, others told him: "We know testimony that favors your father that will cause this judgment to be rescinded," or "The person whose estate you inherited entrusted this written proof to me," he may bring the testimony or the proof immediately and have the judgment rescinded. The rationale is that a minor is not aware of all the proofs possessed by the person whose estate he inherited.

הלכה י
מִי שֶׁקָּנוּ מִיָּדוֹ שֶׁאִם לֹא יָבוֹא בְּיוֹם פְּלוֹנִי וְיִשָּׁבַע יִהְיֶה חֲבֵרוֹ נֶאֱמָן בְּטַעֲנָתוֹ וְיִטּל כָּל מַה שֶּׁטָּעַן בְּלֹא שְׁבוּעָה. אוֹ שֶׁאִם לֹא יָבוֹא בְּיוֹם פְּלוֹנִי וְיִשָּׁבַע וְיִטּל אִבֵּד אֶת זְכוּתוֹ וְאֵין לוֹ כְּלוּם וְיִפָּטֵר חֲבֵרוֹ. וְעָבַר הַיּוֹם וְלֹא בָּא נִתְקַיְּמוּ הַתְּנָאִים וְאִבֵּד אֶת זְכוּתוֹ. וְאִם הֵבִיא רְאָיָה שֶׁהָיָה אָנוּס בְּאוֹתוֹ הַיּוֹם הֲרֵי זֶה פָּטוּר מִקִּנְיָן זֶה וְיִשָּׁבַע כְּשֶׁיִּתְבָּעֶנּוּ חֲבֵרוֹ כְּשֶׁהָיָה מִקֹּדֶם. וְכֵן כָּל כַּיּוֹצֵא בָּזֶה:
כסף משנה
10.
The following rules apply when a person affirmed his consent to the following agreement with a kinyan: If he does not come on this-and-this day and take an oath, his colleague's claim would be accepted and that colleague could take whatever he claims without taking an oath. Alternatively, if he does not come on this-and-this day, take an oath, and collect his due, he forfeits his right to the claim. Nothing is to be granted him and his colleague is released of liability. Should that day pass and he not come, the stipulation is binding and he forfeits his rights.
If, however, he brings proof that he was held back by forces beyond his control on that day, he is not bound by his agreement. He may take an oath against the claim issued by his colleague as before. Similar laws apply in all analogous situations.

שופטים הלכות סנהדרין והעונשין המסורין להם פרק ז
Shoftim Sanhedrin Chapter 7