In matters of arbitral proceedings, violation of the adversarial principle can only be established where there is an actual impairment of a party's opportunity to present arguments and counter-arguments, and cannot be considered to include the refusal to admit testimonial evidence, which falls within the discretionary assessment of the arbitrators.
In challenging an arbitral award, the defect of failure to rule on claims and defences pursuant to Article 829 paragraph 1 No. 12 of the Code of Civil Procedure does not exist when the arbitrators have ruled on the issue, albeit to reject it.
The defect of lack of reasoning in an arbitral award pursuant to Article 829 paragraph 1 No. 5 of the Code of Civil Procedure can only be identified when the reasoning is entirely absent or so deficient as to prevent understanding of the logical process of the decision or contains irreconcilable contradictions, it being sufficient to provide the summary statement of reasons required by Article 823 paragraph 1 No. 5 of the Code of Civil Procedure.
The defect of contradiction in the provisions contained in the award pursuant to Article 829 paragraph 1 No. 11 of the Code of Civil Procedure cannot be invoked to censure errors of law in the arbitrators' decision, such use constituting an improper attempt to circumvent the prohibition on challenge for rules of law relating to the merits pursuant to Article 829 paragraph 3 of the Code of Civil Procedure.