Nullity of an arbitral award for lack of reasoning within the meaning of Article 829(1)(5) of the Code of Civil Procedure arises exclusively where the reasoning is entirely absent or so deficient as not to permit an understanding of the course of the reasoning followed by the arbitrators and identification of the ratio decidendi of the decision adopted.
Contradictoriness in the reasoning of an arbitral award, for the purposes of nullity under Article 829(1)(11) of the Code of Civil Procedure, must emerge between the different components of the operative part (dispositivo), or between the reasoning and the operative part, whereas an internal contradiction between different parts of the reasoning is not in itself a relevant defect, unless it prevents the reconstruction of the logical and legal reasoning underlying the decision on account of the total absence of reasoning referable to its functional model.
The proceedings for the setting aside of an arbitral award concern solely the review of the lawfulness of the decision rendered by the arbitrators, and not the re-examination of the merits of the issues submitted to them, so that findings of fact made by the arbitrators, such as those concerning the interpretation of the contract at issue, are not open to challenge in proceedings for the setting aside of the award, unless the reasoning on that point is entirely absent or wholly deficient.