Sanhedrin 36 - Description of the Sanhedrin Trying a Capital Case
A sanhedrin was seated in the shape of half a circular "threshing floor," that is, in a semicircle, so that the judges could see each other. Two judicial scribes stand before them, one to the right and one to the left, and they would record the words of those arguing for conviction and the words of those arguing for acquittal. Both scribes record all words, so that if one errs, he can be corrected from the other scribe's notes.
Three rows of disciples of the sages would sit before them, so that if the presiding judges would be deadlocked, more judges could be added from these disciples. The disciples sit in the order of eminence. If the judges needed to ordain someone, they would ordain one of the disciples from the first row. One disciple from the second row would move to the first, one disciple from the third row would move to the second, and one more person from the scholarly community would be put in the third row.
Art: Archibald Henning - The Judge And Jury Society In The Cider Cellar