Arbitrators have the power to regulate the conduct of proceedings in the manner they deem most appropriate when the parties have not established in the arbitration agreement or by separate act prior to commencement of the proceedings the procedural rules to be observed, but must in any case implement the principle of adversarial proceedings by granting the parties reasonable and equivalent opportunities for defence.
Arbitrators may set time limits and preclusive rules within the scope of the proceedings entrusted to them, but only within parameters previously and specifically indicated to the parties, it being precluded for the arbitrator to declare inadmissible an act, application or documentary production for non-observance of a time limit or rule of conduct when the corresponding constitutive activity has not been previously provided for as necessary on pain of inadmissibility and made known to the parties.
Breach of the principle of adversarial proceedings constitutes grounds for nullity of the arbitral award arising from the declaration of inadmissibility of procedural acts for non-observance of peremptory time limits when there is no proof of prior communication to the parties of the peremptory nature of such time limits.