In contractual arbitration (arbitrato irrituale), the resolution of the dispute takes place on a purely contractual basis, as the parties entrust the arbitrators with the task of settling the dispute through amicable composition or an ascertainment agreement, undertaking to consider the arbitral award as an expression of their own will; the content of the contractual award is not limited to the dispositions provided in the operative part, but also includes the determination of the rights and obligations of the parties, which constitutes its logical-legal basis.
The passing into res judicata of the judgment declaring the nullity of the contractual arbitral award causes the contractual ground upon which the order for payment obtained by virtue of the arbitral decision is based to cease to exist, with consequent automatic necessity to revoke the payment order, which has become irremediably devoid of justifying cause.
The party that has submitted a dispute to contractual arbitration is bound by the arbitrators' decision, unless it proceeds to challenge the award in the forms provided by the legal system; the authority of res judicata formed in the proceedings for annulment of the contractual arbitral award establishes the determination of the logical-legal prerequisites of claims based on the same award.
The submission of the dispute to arbitration precludes the party, even in opposition proceedings to an order for payment, from the possibility of founding the claim for credit on a ground different from the contractual one constituted by the arbitral decision.