The challenge of an arbitral award does not constitute an ordinary appeal. In the rescinding phase, the court is limited to ascertaining the grounds of nullity provided for by Article 829 of the Code of Civil Procedure.
The defect of reasoning in the award, pursuant to Article 829(1)(5) of the Code of Civil Procedure, may be invoked only when the reasoning is entirely lacking, not when it is merely insufficient.
The rejection of evidentiary requests in arbitral proceedings may constitute a ground of nullity for violation of the adversarial principle under Article 816 bis of the Code of Civil Procedure only where a party has been prevented from putting forward evidence without justification derived from the legitimate rules of the arbitral process.