Under art. 819-ter(1) cod. proc. civ., the competence of the arbitrators is not excluded by the connection between the dispute referred to them and a case pending before the ordinary courts, so that, where a plurality of claims has been brought, the existence of arbitral competence must be ascertained with specific regard to each of them, it being impossible to refer the entire dispute to the arbitrators or to the ordinary court by virtue of the mere link of connection.
An award is affected by nullity under art. 829(1)(10) cod. proc. civ. where the arbitrator, seized of claims falling within his competence by virtue of an arbitration clause, has declared his incompetence over the entire dispute by reason of the connection with claims reserved to the ordinary courts, thereby omitting to decide on the merits of the claims referred to him.