A contractual arbitration award (arbitrato irrituale) whose validity has been confirmed by a final judgment following challenge proceedings pursuant to Article 808-ter of the Code of Civil Procedure cannot be called into question in separate proceedings for opposition to an order for payment based on the same award, as the judge hearing the opposition is precluded from any assessment of the validity of the award by reason of the res judicata effect of the judgment dismissing the challenge.
Where a contractual arbitration award (arbitrato irrituale) orders the payment of “legal interest” without further specification, the judge called upon to enforce the award may not supplement its content by granting entitlement to default interest provided for by the legislation on late payment in commercial transactions under Legislative Decree No. 231/2002, but must instead limit himself to applying the rate of legal interest pursuant to Article 1284, paragraph 1, of the Civil Code, given that a different determination would constitute an inadmissible supplementation of the arbitral decision.