[In judging] cases of tumah and taharah, they begin from the most eminent; [in] capital cases they begin from the side.  All are eligible to judge civil cases, but not all are eligible to judge capital cases —- only Kohanim, Leviim, and Yisraelim who are eligible to have [their daughters] marry Kohanim.

The Sanhedrin was [seated] in the shape of a semi-circular threshing floor so that they should see one another. Two judicial scribes stand before them, one to the right and one to the left, and they record the words of those who defend and those who convict. R’ Yehudah says: Three: One records the words of those who defend; one records the words of those who convict; and the third records the words [both] of those who defend and those who convict.