Tosefta for Horayot 1:4
הוֹרוּ בֵית דִּין, וְיָדַע אֶחָד מֵהֶן שֶׁטָּעוּ, וְאָמַר לָהֶן טוֹעִין אַתֶּם, אוֹ שֶׁלֹּא הָיָה מֻפְלָא שֶׁל בֵּית דִּין שָׁם, אוֹ שֶׁהָיָה אַחַד מֵהֶן גֵּר אוֹ מַמְזֵר אוֹ נָתִין אוֹ זָקֵן שֶׁלֹּא רָאָה לוֹ בָנִים, הֲרֵי אֵלּוּ פְטוּרִין, שֶׁנֶּאֱמַר כָּאן עֵדָה (ויקרא ד) וְנֶאֱמַר לְהַלָּן (במדבר לה) עֵדָה, מָה עֵדָה הָאֲמוּר לְהַלָּן עַד שֶׁיִּהְיוּ כֻלָּם רְאוּיִין לְהוֹרָאָה, אַף עֵדָה הָאֲמוּרָה כָאן עַד שֶׁיִּהְיוּ כֻלָּם רְאוּיִים לְהוֹרָאָה. הוֹרוּ בֵית דִּין שׁוֹגְגִים וְעָשׂוּ כָל הַקָּהָל שׁוֹגְגִין, מְבִיאִין פָּר. מְזִידִין וְעָשׂוּ שׁוֹגְגִין, מְבִיאִין כִּשְׂבָּה וּשְׂעִירָה. שׁוֹגְגִין וְעָשׂוּ מְזִידִין, הֲרֵי אֵלּוּ פְטוּרִין:
If beth-din ruled, and one of them knew that they had erred, and he said to them "You are mistaken," or if the mufla of beth-din [the chief justice, the Rosh Yeshiva] were not there, or if one of them were a proselyte, or a mamzer (a bastard), or a Nathin (viz. Joshua 9:27), or an old man who had not seen children [(and who is not fit to judge capital cases, in all likelihood being a stranger to compassion)], they are exempt (from an offering), it being written here "congregation," viz. (Leviticus 4:13): "And if the whole congregation of Israel (the Sanhedrin) err," and, elsewhere, "congregation," viz. (Numbers 35:24): "Then the congregation shall judge." Just as with "congregation" written there, all of them must be fit to rule, [viz. (Ibid. 11:16): "And they (the judges) shall stand there with you (Moses)" ("with you":) — they must be like you), excluding a proselyte, a Nathin, and a mamzer, who are not fit to be appointed to the Sanhedrin], here, too, all of them must be fit to rule. If beth-din ruled unwittingly and all the congregation transgressed unwittingly, they bring a bullock. If deliberately, [i.e., if beth-din knew that it were forbidden] and they (the people) transgressed unwittingly, they (the people) bring a she-lamb and a she-goat. If (beth-din ruled) unwittingly, and they (the people) transgressed wittingly, both are exempt: beth-din, because the people did not transgress because of their ruling, not relying upon beth-din, knowing that they had erred; and the people who transgressed are exempt because they are witting, and all who are witting are not subject to an offering.]