Halakhah for Shevuot 59:12

And from the laws of the commandment is that which they, may their memory be blessed, said (Shevuot 30a) that it not be that one stand and one sit, but rather both of them stand. As in that they are in front of the court, it is fitting for them to stand as if they were in front of the Divine Presence; since the spirit of God dwells among the congregation of the judges of Israel, as it is stated (Psalms 82a), "God stands in the congregation of God." And nonetheless, they, may their memory be blessed, said (Shevuot 30b) that if they wanted to seat the litigants, the option is in their hand. And about what are these words speaking? At the time of give and take. But at the time of the final judgement, there is an obligation to stand, as it is stated (Exodus 18:13), "and the people stood over Moshe." Except that all of the courts of Israel after the Talmud have become accustomed to seat them [in order to avoid] controversy. And even [regarding] the witnesses about whom it is written (Deuteronomy 19:17), "and the two men stand," they have also become accustomed today to seat them (Mishneh Torah, Laws of The Sanhedrin and the Penalties within their Jurisdiction 21:5). [This] and the rest of its details are elucidated in [various] places in Sanhedrin and Shevuot (see Tur, Choshen Mishpat 17).