For arbitral proceedings commenced after the 2006 reform but relating to an agreement concluded beforehand, absent any stipulation by the parties, the previous regime applies, which allows the award to be challenged for breach of the rules governing the merits, unless the parties authorised a decision ex aequo et bono or declared the award not open to challenge. A ground of challenge which entails a finding of fact or an assessment of the merits cannot constitute a breach of the rules of law capable of being raised in setting-aside proceedings. A complaint that the award is void for non-observance of the rules of law in adjudicating is admissible only within the same boundaries as a breach of law capable of being raised on appeal to the Court of Cassation, must be anchored to the facts found by the arbitrators and presupposes an express allegation that the legal rule applied was erroneous; it cannot be advanced in connection with the mere assertion of gaps in the enquiry or in the reasoning, or of an incorrect appraisal of the evidence. The review by the court hearing the challenge of the arbitrators’ allocation of costs is limited to compliance with the principle that costs may not be imposed on the wholly successful party, the assessment of the appropriateness of apportioning costs remaining a matter for the arbitral proceedings. No contradictoriness relevant under art. 829, co. 1, no. 11, cod. proc. civ. can be found where there is full consistency between the operative part as stated and the reasoning and rulings preceding it.