Halacha

הלכה א
סַנְּהֶדְרִין שֶׁפָּתְחוּ כֻּלָּם בְּדִינֵי נְפָשׁוֹת תְּחִלָּה וְאָמְרוּ כֻּלָּן חַיָּב הֲרֵי זֶה פָּטוּר עַד שֶׁיִּהְיוּ שָׁם מִקְצָת מְזַכִּין שֶׁיְּהַפְּכוּ בִּזְכוּתוֹ וְיִרְבּוּ הַמְחַיְּבִין וְאַחַר כָּךְ יַהֲרֹג:
כסף משנה
1.
When all the judges of a Sanhedrin begin their judgment of a case involving capital punishment and say that the defendant is liable, he is exonerated. There must be some who seek to exonerate him and argue on his behalf, but yet the majority hold him liable. Only then he is executed.

הלכה ב
סַנְהֶדְרִי קְטַנָּה שֶׁנֶּחְלְקוּ בְּדִינֵי נְפָשׁוֹת שְׁנֵים עָשָׂר אוֹמְרִים זַכַּאי וְאַחַד עָשָׂר אוֹמְרִים חַיָּב הֲרֵי זֶה זַכַּאי. שְׁנֵים עָשָׂר אוֹמְרִים חַיָּב וְאַחַד עָשָׂר אוֹמְרִים זַכַּאי אוֹ שֶׁאָמְרוּ אַחַד עָשָׂר זַכַּאי וְאַחַד עָשָׂר חַיָּב וְאֶחָד אוֹמֵר אֵינִי יוֹדֵעַ אֲפִלּוּ עֶשְׂרִים וּשְׁנַיִם מְזַכִּין אוֹ מְחַיְּבִין וְהָאֶחָד אוֹמֵר אֵינִי יוֹדֵעַ יוֹסִיפוּ שְׁנַיִם. זֶה שֶׁאָמַר אֵינִי יוֹדֵעַ הֲרֵי הוּא כְּמִי שֶׁאֵינוֹ שֶׁהֲרֵי אֵינוֹ חוֹזֵר וּמְלַמֵּד חוֹבָה וְנִמְצְאוּ אַחַר הַתּוֹסֶפֶת עֶשְׂרִים וְאַרְבָּעָה חוּץ מִזֶּה הַמִּסְתַּפֵּק. אָמְרוּ שְׁנֵים עָשָׂר זַכַּאי וּשְׁנֵים עָשָׂר חַיָּב הֲרֵי זֶה זַכַּאי. אַחַד עָשָׂר אוֹמְרִים זַכַּאי וּשְׁלֹשָׁה עָשָׂר אוֹמְרִים חַיָּב אַף עַל פִּי שֶׁהָאֶחָד מִן הָרִאשׁוֹנִים אוֹמֵר אֵינִי יוֹדֵעַ הֲרֵי זֶה חַיָּב שֶׁהֲרֵי הַמְחַיְּבִין רַבּוּ בִּשְׁנַיִם. אָמְרוּ שְׁנֵים עָשָׂר זַכַּאי וּשְׁנֵים עָשָׂר חַיָּב וְאֶחָד אוֹמֵר אֵינִי יוֹדֵעַ מוֹסִיפִין שְׁנַיִם אֲחֵרִים. וְכֵן מוֹסִיפִין וְהוֹלְכִין עַד שֶׁיִּרְבּוּ הַמְזַכִּין אֶחָד וִיהֵא זַכַּאי אוֹ יִרְבּוּ הַמְחַיְּבִין שְׁנַיִם אוֹ יוֹתֵר וִיהֵא חַיָּב. הָיוּ אֵלּוּ כְּנֶגֶד אֵלּוּ וְאֶחָד אוֹמֵר אֵינִי יוֹדֵעַ אוֹ שֶׁהָיוּ הַמְחַיְּבִין יוֹתֵר אֶחָד בִּלְבַד מוֹסִיפִין וְהוֹלְכִין עַד שִׁבְעִים וְאֶחָד. הִגִּיעוּ לְשִׁבְעִים וְאֶחָד שְׁלֹשִׁים וְשִׁשָּׁה אוֹמְרִים זַכַּאי וּשְׁלֹשִׁים וַחֲמִשָּׁה אוֹמְרִים חַיָּב הֲרֵי זֶה זַכַּאי. שְׁלֹשִׁים וְשִׁשָּׁה אוֹמְרִים חַיָּב וּשְׁלֹשִׁים וַחֲמִשָּׁה אוֹמְרִים זַכַּאי דָּנִים אֵלּוּ כְּנֶגֶד אֵלּוּ עַד שֶׁיִּרְאֶה אֶחָד מֵהֶן דִּבְרֵי חֲבֵרוֹ וּמְזַכִּין אוֹתוֹ אוֹ מְחַיְּבִין אוֹתוֹ. וְאִם לֹא רָאָה גָּדוֹל שֶׁבַּדַּיָּנִים אוֹמֵר נִזְדַּקֵּן הַדִּין וּפוֹטְרִין אוֹתוֹ. שְׁלֹשִׁים וַחֲמִשָּׁה אוֹמְרִים חַיָּב וּשְׁלֹשִׁים וַחֲמִשָּׁה אוֹמְרִים זַכַּאי וְאֶחָד אוֹמֵר אֵינִי יוֹדֵעַ פּוֹטְרִין אוֹתוֹ. אַרְבָּעָה וּשְׁלֹשִׁים אוֹמְרִים זַכַּאי וְשִׁשָּׁה וּשְׁלֹשִׁים אוֹמְרִים חַיָּב וְאֶחָד אוֹמֵר אֵינִי יוֹדֵעַ חַיָּב שֶׁהֲרֵי רַבּוּ הַמְחַיְּבִין שְׁנַיִם:
כסף משנה
2.
The following rules apply when there is a difference of opinion in a minor Sanhedrin. If twelve judges say that he should be exonerated and eleven say that he should be held liable, he is exonerated. If twelve say that he is liable and eleven say that he should be exonerated or eleven say that he should be exonerated and eleven say that he is liable, and one says: "I don't know," we add two judges. Even if there are twelve who wish to exonerate him and twelve who hold him liable, and one who one says: "I don't know," we add two judges. The rationale is that the judge who says: "I don't know," is considered as if he does not exist, for he cannot change his mind and explain why the defendant should be held liable. Thus after the addition, there are 24 judges aside from the person who says: "I don't know."
If twelve say that he should be exonerated and twelve say that he is liable, he is exonerated. If eleven say that he should be exonerated and thirteen say that he is liable, he is liable. This applies even if one of the original judges says: "I don't know." For there are two more judges who rule that he is liable.
If twelve say that he should be exonerated and twelve say that he is liable, we add two judges. And similarly, if the balance is not broken, we continue to add two judges until there is at least one more judge who rules that he should be exonerated or at least two more judges who rule that he should be held liable. If there are an even number of judges on both sides, and one says: "I don't know," or if the number of judges who rule that he is liable is only one more than those who rule that he should be exonerated, we continue to add judges until we reach 71.
The following rules apply when the court reaches that size. If 36 say that he should be exonerated and 35 say that he is liable, he should be exonerated. If 36 say that he is liable and 35 say that he should be exonerated, they debate back and forth against each other until one of them sees the other's perspective and either exonerates him or holds him liable. If such a change in perspective does not take place, the judge of the greatest stature declares: "This judgment has become aged," and he is released.
If 35 say that he is liable and 35 say that he should be exonerated, and one says "I don't know," we release him. If 34 say that he should be exonerated and 36 say that he is liable, and one says: "I don't know," he is held liable. For there is a majority of two judges who hold him liable.

הלכה ג
בֵּית דִּין הַגָּדוֹל שֶׁבָּא לָהֶם מַחְלֹקֶת בֵּין בְּדִינֵי נְפָשׁוֹת בֵּין בְּדִינֵי מָמוֹנוֹת בֵּין בְּדִינֵי תּוֹרָה. אֵין מוֹסִיפִין עֲלֵיהֶן אֶלָּא דָּנִין אֵלּוּ כְּנֶגֶד אֵלּוּ וְהוֹלְכִין אַחַר הָרֹב שֶׁלָּהֶן. וְאִם בְּדִין אֶחָד מִן הַנֶּהֱרָגִין נֶחְלְקוּ דָּנִין אֵלּוּ כְּנֶגֶד אֵלּוּ עַד שֶׁיִּפְטְרוּהוּ אוֹ יִתְחַיֵּב:
כסף משנה
3.
When there is a difference of opinion in the Supreme Sanhedrin, whether with regard to a law involving capital punishment, monetary law, or other matters of Torah law, we do not add judges. Instead, they debate against each other and the ruling follows the majority. If their difference of opinion involves whether a person will be executed, they should debate against each other until they either exonerate him or hold him liable.

שופטים הלכות סנהדרין והעונשין המסורין להם פרק ט
Shoftim Sanhedrin Chapter 9