How Is the Composition of  a Court Determined? 

איך מוגדרת ההרכב של בית משפט?

The Talmud clarifies the meaning of the statement that opens the mishna. 

Gemara: At the beginning of the discussion, the Gemara assumes that “one” means an entire tribunal, composed of three judges. It therefore asks: What is the meaning of: This litigant chooses<footnote data-num="22"/> one for himself and that litigant chooses one for himself? Isn’t it sufficient to adjudicate the case with three judges? There is no need to select two entire courts, a total of six judges, to choose three other judges.