The challenge of an arbitral award for nullity pursuant to Article 829 of the Code of Civil Procedure has the character of a limited challenge, admitted only for certain procedural defects and for non-observance of rules of law within the limits of the cited provision, not giving rise to an appellate judgment that would authorise a review on the merits of the arbitrators' decision.
Article 829 paragraph 1 No. 11 of the Code of Civil Procedure provides for nullity of the award not for every case of mere contradiction between various points of the reasoning or insufficiency thereof, but only when there exists contradiction between the various rulings in the operative part, or a contradiction between reasoning and operative part which results in the impossibility of understanding the ratio decidendi of the decision, equivalent to a substantial absolute lack of reasoning.
In proceedings challenging an arbitral award for nullity, reassessment of the merits of the dispute through criticism of the reasoning put forward by the arbitrator as foundation of the award is not admissible under the profile of alleged contradictoriness of the reasoning itself.
Violation of the principle of adversarial proceedings in arbitral proceedings, relevant for purposes of nullity of the award pursuant to Article 829 paragraph 1 No. 9 of the Code of Civil Procedure, occurs when the arbitrators' decision is based on an issue raised ex officio and not previously submitted for the parties' evaluation, but not when the decision is limited to a different evaluation of the probatory material already presented and discussed by the parties during the arbitral proceedings.