In matters of arbitration, the principle that the jurisdiction of arbitrators is not excluded by the connection between the dispute referred to them and proceedings pending before the ordinary court, enshrined in Article 819-ter, paragraph 1, of the Code of Civil Procedure, entails that, in the presence of a plurality of connected claims, the existence of arbitral jurisdiction must be verified with specific regard to each of them, without the mere connection being able to determine the referral of the entire dispute to the arbitrators or to the ordinary court.
An arbitration clause that refers to institutional arbitrators all disputes relating to a specific contractual agreement extends also to a claim for indemnity based on the same agreement, with the consequence that, not being a case of necessary substantive joinder and being a matter of improper guarantee, the pendency of the main proceedings before the ordinary court cannot entail a derogation from arbitral jurisdiction nor attract the guarantee claim to the cognisance of the state court.