In the+procedure+arbitration+the omitted+compliance+of the+principle+of the+contradictory+(sanctioned+by art.+816-bis,+co.+1,+cod.+Proc.+Civ.,+Already+in priority+ri Conducted+in art.+816+of the Italian Civil Code+civ.)+not+is+a+formal vice+mai+ma+activity.+nor+consequent+that,+to the+finical+of the+declaration+of+nullity,+it is necessary+ascert are+the+impairment+of the+right+of+defense,+keeping+account+of the+mode+of the+comparison+between+parts+(having regard+at+respective+claims)+and+of the chances,+per+le+themselves,+of+exercise,+in respect+of the+rule+audiatur+et+altera+pars,+on+a+plane of+equality+.