Art. 808 ter of the Code of Civil Procedure applies only to arbitration agreements entered into after 2 March 2006; accordingly, in relation to awards rendered pursuant to arbitration clauses predating that date, a breach of the right to be heard does not constitute a procedural defect but a breach of the mandate contract, and may be relevant only for the purpose of a challenge based on defects of consent such as mistake, fraud or duress.
In contractual arbitration (arbitrato irrituale), the party challenging the award must demonstrate in concrete terms the error in the assessment of reality allegedly committed by the arbitrators, whereas the mere fact of not having been heard or of not having been able to file a rejoinder does not, in itself, imply a defect of the arbitrators’ will.