The challenge of an arbitral award for nullity is a form of review of limited scope, admissible only to assert errors in iudicando and errors in procedendo within the boundaries set by art. 829 of the Code of Civil Procedure, without the reviewing court being permitted to re-examine the merits of the arbitrators' decision.
A defect of reasoning in the arbitral award, as a ground of nullity under art. 829(1)(5) of the Code of Civil Procedure in conjunction with art. 823(5), is found only where the reasoning is entirely absent or so deficient as not to allow identification of the ratio of the decision, thereby amounting to an absence of reasoning.
Where the arbitration clause does not in any way provide for the possibility of challenging the award for violation of the rules of law relating to the merits of the dispute, such challenge is inadmissible under art. 829(3) of the Code of Civil Procedure, as reformulated by Legislative Decree No. 40 of 2006.