The nullity of an arbitral award for failure to rule on the parties’ claims and defences, pursuant to Article 829, paragraph 1, No. 12, of the Code of Civil Procedure, is only applicable in the case of a failure by the arbitrators to examine questions of substance and not when the arbitral tribunal has comprehensively analysed the claims submitted, rejecting them on the basis of a substantive assessment of the grounds pleaded.
The nullity of an arbitral award for breach of the right to be heard, pursuant to Article 829, paragraph 1, No. 9, of the Code of Civil Procedure, is only applicable where the decision is based on a question raised by the tribunal of its own motion and never submitted for consideration by the parties, and not when the decisive questions have been the subject of adversarial debate and documentary evidence in the course of the arbitral proceedings.
The nullity of an arbitral award for lack of reasoning occurs exclusively when the reasoning is entirely absent or so deficient as to make it impossible to understand the reasoning process followed by the arbitrators and to identify the ratio decidendi of the award, mere inadequacy or gaps in the reasoning not being sufficient.
The challenge to an arbitral award for breach of rules of law relating to the substance of the dispute, in matters of public contracts, is admissible within the same limits as the breach of law that may be alleged by appeal on a point of law pursuant to Article 360, paragraph 1, No. 3, of the Code of Civil Procedure, requiring specific allegation of the incorrectness of the rule of law applied in relation to the facts established by the arbitrators and not being capable of being based on the mere assertion of deficiencies in investigation and reasoning.
The interpretation of contractual clauses by arbitrators may be challenged in nullity proceedings relating to the award exclusively on the ground of breach of the rules of contractual interpretation set out in Articles 1362 et seq. of the Civil Code, and not by the mere submission of an alternative interpretation or assertion of its incorrectness.
The nullity of an arbitral award for being contrary to public policy, pursuant to Article 829, paragraph 2, of the Code of Civil Procedure, requires the breach of fundamental and mandatory rules of the legal order that express essential values, ruling out an attenuated notion of public policy coinciding with the body of mandatory rules. The breach of mandatory rules that do not have the character of fundamental principles of the legal order is not capable of giving rise to the nullity of the award on such ground.