Challenge of an award for nullity has the character of limited challenge, since it is admitted only to assert errores in iudicando and errores in procedendo within the confines laid down by Article 829 of the Code of Civil Procedure, and does not give rise to proceedings that enable the court hearing the challenge to re-examine the merits of the arbitrators' decision, but permits exclusively the so-called iudicium rescindens.
Nullity of an award for contradiction under Article 829, N. 11, of the Code of Civil Procedure does not subsist for every case of mere contradiction between various points of the reasoning, but only when there subsists contradiction between the various rulings of the operative part, or a contradiction between reasoning and operative part that translates into impossibility of understanding the ratio decidendi of the decision, equivalent to substantial absolute lack of reasoning.
Internal contradiction between different parts of the reasoning of an award may assume relevance as a defect of the award only insofar as it renders absolutely impossible the reconstruction of the logical and legal reasoning underlying the decision due to total absence of reasoning referable to its functional model.
Defective reasoning in an award, as a defect referable to Article 829, N. 5, of the Code of Civil Procedure, may be found only in the case where the reasoning of the award is entirely absent or is so deficient as not to permit identification of the ratio of the decision adopted or to denote an argumentative process absolutely unacceptable on the dialectical plane.