The challenge to an arbitral award for nullity pursuant to Article 829 of the Code of Civil Procedure has the character of a limited challenge, permitted only for specific procedural defects and, for non-observance of rules of law, exclusively within the limits provided by the cited provision, not giving rise to an appellate judgment that would authorize re-examination of the merits of the arbitral decision.
In the procedural system for challenging arbitral awards, the rescinding judgment for ascertaining nullity is distinct from the subsequent possible *iudicium rescissorium* governed by Article 830 of the Code of Civil Procedure, which permits re-examination of the merits of the arbitral ruling only after ascertainment of the nullity of the award.
Article 829, paragraph 3, of the Code of Civil Procedure, as reformulated by Article 24 of Legislative Decree No. 40/2006, establishes that challenge for violation of rules of law relating to the merits of the dispute is permitted only if expressly provided by the parties or by law, with challenge for contrariety to public policy remaining permitted in all cases.
For arbitral proceedings commenced after the entry into force of Legislative Decree No. 40/2006 but pursuant to an arbitration agreement concluded previously, the admissibility of challenge for violation of rules of law on the merits is determined by the law in force at the time of conclusion of the arbitration agreement.
The silence of the parties in the arbitration agreement regarding the challengeability of the award for violation of rules of law circumscribes the scope of judicial cognition to violation of procedural errors only (*errores in procedendo*), without extending it to violation of substantive rules of law.
Grounds for challenging an award are inadmissible where, though formally brought within the nullity hypotheses of Article 829 of the Code of Civil Procedure, they resolve in substance into criticisms aimed at soliciting review of the merits of the arbitral decision, which is extraneous to proceedings for challenge on grounds of nullity.