The challenge to an arbitral award under article 829 of the Code of Civil Procedure is limited in scope and does not permit a review on the merits of the arbitrators' decision, exclusively allowing for the determination of the existence of grounds for nullity exhaustively provided by the provision.
The nullity of an arbitral award for contradictory reasoning under article 829, No. 11, of the Code of Civil Procedure exists when the arbitrators' arguments do not allow identification of the logical-legal process that led to the decision or make it impossible to identify the ratio decidendi adopted.
The ground for challenging an arbitral award concerning reasoning is solely that provided by article 829, No. 5, of the Code of Civil Procedure, which provides for the nullity of an award that lacks a summary statement of reasons as an essential element under article 823 of the Code of Civil Procedure.
In proceedings challenging an arbitral award, criticisms that introduce merit-based evaluations of the arbitral decision are not admissible, as only review of procedural defects and violations of law within the limits exhaustively provided by article 829 of the Code of Civil Procedure is permitted.
The production of new documents in proceedings challenging an arbitral award is inadmissible when the documents were available to the party already at the time of the arbitral procedure, except where they concern judicial authority measures made public and accessible for consultation.