Even in the judgment arbitral the omitted compliance of the contradictory not is a formal vice ma of activities; the nullity che n ne n it arises ex art. 829, co. 1, n. 9, cod. Proc. Civ. A concrete sione of the right defense of the part procedural, underlying, in addition, to the rule of the amnesty per achievement of the purpose. therefore, the question of the lesion of the contradictory must be examined Not below the appearance of the violation, on the plane formal, of one prescription preordained at the construction of such principle, ma in the area a search vault to the assessment of a actual denial of the poe Ssitability of deduct and of contradict, waves check if the act has equally reached the purpose of establish a regular contradictory and if, anyway, non -compliance not has caused prejudice to the part.