The nullity of an arbitral award for lack of impartiality of the arbitrator, pursuant to Article 815, paragraph 1, No. 3, of the Code of Civil Procedure, falls within the species regulated by Article 829, paragraph 1, No. 2, of the Code of Civil Procedure, with the consequence that such nullity must be raised in the arbitral proceedings and remains always available as a ground for nullity of the award in the subsequent challenge proceedings, whatever the outcome of the separate recusal procedure may have been.
Where a party has submitted an application for recusal of the arbitrator to the president of the court during the course of the arbitral proceedings, and has moreover produced it before the arbitrators who have been made aware of it, this constitutes a raising of the specific nullity before them, fulfilling the requirements of Article 829, paragraph 1, No. 2, of the Code of Civil Procedure, even if the recusal application is subsequently rejected for being time-barred.
For the purposes of establishing nullity of an arbitral award for lack of reasoning, it is necessary that it should not be possible to proceed to reconstruct the ratio decidendi; such nullity must instead be excluded whenever, through the ordinary canons of interpretation and the rules of legal logic, it is possible to discern it.
The equitable assessment of damages by the arbitral tribunal pursuant to Article 1226 of the Civil Code does not result in nullity of the award when the existence of the damage and the methods of assessment have been the subject of adversarial proceedings between the parties, it remaining within the discretion of the tribunal to choose to proceed to equitable assessment where the conditions provided by law are met.