The provision of Article 817(2), second paragraph, of the Code of Civil Procedure does not merely preclude ex officio detection of non-arbitrability when the dispute concerns non-waivable rights or where an express prohibitive provision exists; there also applies the general principle that a party who has given cause to grounds for nullity cannot challenge an award on such grounds.
The sanction of nullity provided by Article 829(1)(4) of the Code of Civil Procedure for awards containing contradictory provisions must be understood in the sense that the contradiction must emerge between different components of the operative part, or between the reasoning and the operative part. Internal contradiction between different parts of the reasoning may assume relevance as a defect of the award only when it renders absolutely impossible the reconstruction of the logical and legal reasoning underlying the decision by reason of total absence of reasoning referable to its functional model.