שמע בין אחיכם… לא תכירו פנים במשפט… (דברים א:טז-יז)

Court proceedings shall be based on שמע בין אחיכם – the judge has to listen attentively to the arguments of the litigants and only then give his verdict.  A dayan (judge) should not look at the defendant because if his face turns red, the judge will assume he is guilty.  Indeed, Dayanim of yore were known to be sitting with their Tallis covering their face so as not to look outside their four cubits during court proceedings, as they might become distracted and render a wrong judgment.