The interpretation of an arbitration clause must be conducted according to the criteria of good faith and the common intention of the parties, as provided for in Article 1362 of the Civil Code. Particular regard must be had to the correspondence and negotiations which took place between the parties in the period preceding the stipulation of the arbitration agreement.
Where an arbitration clause entrusts to the arbitrators "the determination of rental payments with possible reduction thereof" without express temporal limitations, such clause confers upon the arbitral tribunal general competence over the subject matter. This competence extends to future relationships arising from the same agreement which forms the object of the dispute.
The nullity of an arbitral award for contradictory provisions, under Article 829, paragraph 1, number 11 of the Code of Civil Procedure, requires contradiction between the different components of the operative part, or between the reasoning and the operative part. By contrast, internal contradiction within the reasoning alone is relevant only when it renders absolutely impossible the reconstruction of the logical-juridical process of the decision, due to a total absence of reasoning referable to its functional model.
The nullity of an arbitral award for failure to decide, under Article 829, paragraph 1, number 12 of the Code of Civil Procedure, arises exclusively when the arbitrator fails to pronounce upon a specific and autonomous claim properly formulated in the final submissions. The mere failure to confute defensive arguments raised incidentally does not constitute such grounds for nullity.