In contractual arbitration (arbitrato irrituale), the violation of the principle of due process does not take the form of a procedural defect but of a breach of the mandate agreement, and may be relied upon exclusively for the purposes of a challenge pursuant to Article 1429 of the Civil Code, namely as an error on the part of the arbitrators which has vitiated the contractual intent they expressed.
It is permissible to submit to contractual arbitration (arbitrato irrituale) for the partial resolution of the dispute.
The failure to address one of the issues referred to in the submission agreement does not render the award invalid on grounds of incompleteness, where the parties contemplated in advance the distinction between the issues and accepted that the arbitrator would deal with only some of them.