The question concerning the existence or otherwise of an arbitration agreement between the parties constitutes a matter of jurisdiction and not of subject-matter jurisdiction, with the consequence that, on appeal, the court which reverses the order declining jurisdiction in favour of arbitrators is not required to remit the case to the first instance court pursuant to Article 353 of the Code of Civil Procedure, but must retain the case and decide on the merits.
The arbitration clause, as a derogation from the jurisdiction of the ordinary court, requires written form ad substantiam and must be expressly stipulated between the parties to the disputed relationship, and cannot be implicitly inferred from the will of the parties nor derived per relationem from acts or agreements signed by different parties or relating to legal relationships other than that brought before the court.