An implied res judicata as to the validity and effectiveness of an arbitration clause for contractual arbitration (arbitrato irrituale) presupposes that the award has determined the merits of the dispute; where the award has merely declined jurisdiction or the power to adjudicate, no implied res judicata can arise as to the existence or validity of the arbitration clause.
Where the very existence of the arbitration clause for contractual arbitration (arbitrato irrituale) is disputed, the ordinary court has the power to construe the clause directly in order to ascertain its existence, without such power being precluded by the prior commencement of arbitral proceedings.
The nullity of a contractual arbitration (arbitrato irrituale) award and its annulment on the ground of a defect of consent are distinct and non-overlapping categories: the former is based on the breach of mandatory rules or on the non-existence of the arbitration agreement, the latter presupposes a defect of consent within the meaning of arts. 1427 ff. cod. civ.