In contractual arbitration (arbitrato irrituale), the intervention of a third party joined to the proceedings, occurring in compliance with procedural requirements before the first substantive hearing with the agreement of all other parties and the consent of the arbitrators, results in the extension of the original arbitration agreement to include claims made against the intervening third party, who remains bound by all determinations contained in the award, including those relating to costs of defence, where such party has not timely contested the relevant claim during the arbitration proceedings.
The award in contractual arbitration constitutes an expression of the contractual will of all parties who participated in the arbitration proceedings, with the consequence that each of them is obliged to comply with the determinations contained therein and cannot subsequently raise the defence of unenforceability of the award in the absence of timely objection during the proceedings.
Pursuant to Article 808-ter, paragraph 2, no. 1 of the Code of Civil Procedure, the objection relating to a ruling by the arbitrators on claims exceeding the scope of the arbitration agreement must be raised during the arbitration proceedings, with the consequence that failure to raise a timely objection precludes subsequent challenge to the award on such grounds.
In contractual arbitration the principle of adversarial proceedings need not necessarily be structured in strict forms, it being sufficient that the parties' assertive and argumentative activities could be exercised in relation to the elements used by the arbitrator for his or her ruling, giving the parties the opportunity to participate and to be informed of the results of the evidentiary activity conducted.
An award in contractual arbitration is not subject to challenge for errors of law, but exclusively for defects that may vitiate any expression of contractual will, such as essential mistake of fact, duress, fraud or incapacity of the parties who conferred the mandate and of the arbitrator himself or herself, with the consequence that error of judgment, consisting in an erroneous evaluation of correctly perceived elements, does not constitute grounds for annulment.
A settlement agreement concluded after the filing of the award in contractual arbitration between some of the parties to the arbitration proceedings does not produce effects terminating the determinations of the award itself in relation to parties who remained outside such agreement, in application of the principle of relative effect of contracts pursuant to Article 1372 of the Civil Code.