In contractual arbitration, given its nature aimed at integrating a contractual expression of will substituting that of the parties in conflict, the award may be challenged for defects that can harm such expression of will. Error in arbitral judgment, deducible in challenge proceedings, to be relevant must meet the requirements of essentiality and recognizability under Articles 1429 and 1431 of the Civil Code.
For challenging a contractual arbitral award, the only relevant error is essential error of fact that vitiated the arbitrator's will through false representation of alleged facts. This occurs when the arbitrator did not examine elements of the dispute or supposed others that did not exist, or treated as contested facts that were undisputed and vice versa.
A contractual arbitral award, for its contractual character, is not challengeable for error of judgment regarding evaluation of evidence or appropriateness of determinations taken to resolve the dispute. Error committed by arbitrators regarding determination adopted based on conviction reached after interpreting and examining acquired elements is not relevant.