Contractual arbitration (arbitrato irrituale) constitutes an instrument for the contractual resolution of disputes which have arisen or may arise between the parties in relation to certain legal relationships, based on entrusting third parties with the task of seeking an amicable, conciliatory or settlement-based composition. Since the parties undertake to consider the arbitrators' decision as an expression of their will, the contractual arbitral award has a contractual nature and may be challenged exclusively on the grounds for annulment exhaustively provided for by Article 808-ter of the Code of Civil Procedure.
The grounds for annulment of the contractual arbitral award provided for by Article 808-ter of the Code of Civil Procedure are exhaustive and consist of: invalidity of the arbitration agreement and decisions rendered beyond or outside the scope of the claims (extra or ultra petita); appointment of arbitrators outside the forms and methods established by the arbitration agreement; incapacity of the appointed arbitrator; breach of the procedural rules imposed by the parties as a condition of validity of the award; breach of the principle of adversarial proceedings.
In opposition proceedings to an order for payment based on a contractual arbitral award, the mere re-submission of matters of substance already dealt with and determined in the arbitration proceedings does not constitute valid grounds for challenge, as any contestation of the findings contained in the award is precluded outside the grounds for annulment provided for by Article 808-ter of the Code of Civil Procedure.
In the event of annulment of the contractual arbitral award, the ordinary court is precluded from deciding the substance of the dispute, with the consequence that, once every legal effect of the award has been eliminated, the parties must initiate new arbitration proceedings.