A contractual arbitral award may be challenged exclusively on grounds pertaining to the expression of contractual intent, such as mistake, duress, fraud or incapacity, and any challenge on the basis of errors of law, whether in the evaluation of the evidence or in the decision, is precluded.
In contractual arbitration (arbitrato irrituale), the award may be challenged for fundamental mistake only where the formation of the arbitrators' intent was deflected by a distorted perception or a false representation of reality (error of fact), and not where the deflection relates to the assessment of a reality whose elements have been correctly perceived (error of judgment).