Talmud for Sanhedrin 11:2

זָקֵן מַמְרֵא עַל פִּי בֵית דִּין, שֶׁנֶּאֱמַר (שם יז) כִּי יִפָּלֵא מִמְּךָ דָבָר לַמִּשְׁפָּט וְגוֹ'. שְׁלֹשָׁה בָתֵּי דִינִין הָיוּ שָׁם, אֶחָד יוֹשֵׁב עַל פֶּתַח הַר הַבַּיִת, וְאֶחָד יוֹשֵׁב עַל פֶּתַח הָעֲזָרָה, וְאֶחָד יוֹשֵׁב בְּלִשְׁכַּת הַגָּזִית. בָּאִים לָזֶה שֶׁעַל פֶּתַח הַר הַבַּיִת, וְאוֹמֵר, כָּךְ דָּרַשְׁתִּי וְכָךְ דָּרְשׁוּ חֲבֵרָי, כָּךְ לִמַּדְתִּי וְכָךְ לִמְּדוּ חֲבֵרָי. אִם שָׁמְעוּ, אוֹמְרִים לָהֶם. וְאִם לָאו, בָּאִין לָהֶם לְאוֹתָן שֶׁעַל פֶּתַח הָעֲזָרָה, וְאוֹמֵר, כָּךְ דָּרַשְׁתִּי וְכָךְ דָּרְשׁוּ חֲבֵרָי, כָּךְ לִמַּדְתִּי וְכָךְ לִמְּדוּ חֲבֵרָי. אִם שָׁמְעוּ, אוֹמְרִים לָהֶם. וְאִם לָאו, אֵלּוּ וָאֵלּוּ בָּאִים לְבֵית דִּין הַגָּדוֹל שֶׁבְּלִשְׁכַּת הַגָּזִית, שֶׁמִּמֶּנּוּ יוֹצֵאת תּוֹרָה לְכָל יִשְׂרָאֵל, שֶׁנֶּאֱמַר (שם) מִן הַמָּקוֹם הַהוּא אֲשֶׁר יִבְחַר ה'. חָזַר לְעִירוֹ וְשָׁנָה וְלִמֵּד כְּדֶרֶךְ שֶׁהָיָה לָמֵד, פָּטוּר. וְאִם הוֹרָה לַעֲשׂוֹת, חַיָּב, שֶׁנֶּאֱמַר (שם) וְהָאִישׁ אֲשֶׁר יַעֲשֶׂה בְזָדוֹן, אֵינוֹ חַיָּב עַד שֶׁיּוֹרֶה לַעֲשׂוֹת. תַּלְמִיד שֶׁהוֹרָה לַעֲשׂוֹת, פָּטוּר, נִמְצָא חֻמְרוֹ קֻלּוֹ:

An elder who rebels against beth-din (is put to death by strangulation), viz. (Deuteronomy 17:8): "If there be hidden from you a thing of judgment, etc." There were three batei-din there [in Jerusalem, concerning which it is written (Ibid.): "Then you shall arise and go up."], one at the entrance to the Temple mount, [the eastern gate, inside the Chel (a place within the fortification of the Temple), before the ezrath nashim (the women's compartment)], one at the entrance of the azarah (the Temple court) [above it, as they crossed the ezrath nashim and came to the entrance of the ezrath Yisrael], and one in the chamber of hewn stone, [built in the midst of the azarah, part in sanctified ground, part in non-sanctified.] They come to the one at the entrance to the Temple mount, [(this elder who ruled in his city and with whom the beth-din in his city differed, Scripture requiring them to come up to Jerusalem.) He and the beth-din of his city come up to this beth-din at the entrance to the Temple mount, arriving there first.], and he says: "Thus did I expound. Thus and thus did my colleagues expound. Thus did I teach. Thus and thus did my colleagues teach." If they (that beth-din) had heard it (the halachah in that matter), they tell them, and if not they come to those at the entrance of the azarah. He says: "Thus did I expound, and thus did my colleagues expound. Thus did I teach, and thus did my colleagues teach." If they had heard, they tell them. And if not, these and the others come to the great beth-din in the chamber of hewn stone, whence Torah goes out to all of Israel, viz. (Deuteronomy 17:10): "…from that place which the L rd chooses." If he returned to his city and he ruled again as he had ruled before, he is not liable. And if he ruled "to do," he is liable, it being written (Ibid. 12): "And the man who shall do willfully" — he is not liable until he rules to do. A disciple who rules to do is not liable. [A disciple who had not attained to (expertise in) ruling and the beth-din in his city differed with him — If they came to the great beth-din and inquired, and he returned to his city and ruled as at first, he is not liable, for they should not have relied upon his ruling. The Torah made liable only an expert of beth-din, as is derived from (Ibid. 8): "If there be hidden (ki yipalei) from you." Scripture speaks of an expert (muflah) of beth-din.] His severity, then, is found to be his lenity! [The severity of his transgression — ruling though he is not qualified to rule, compounded with his rebelling against beth-din — becomes his lenity, exempting him from the death penalty. For if he were an elder qualified to rule and he rebelled against beth-din, he would be put to death.]

Jerusalem Talmud Bava Kamma