The lack of subject matter jurisdiction of the ordinary judge exists when the parties have referred the dispute to institutional arbitrators through an arbitration clause, such issue being configured as a problem of jurisdiction and not of competence.
The principle of parallel proceedings excludes the operation of lis pendens between arbitral proceedings and ordinary litigation, not preventing the pendency of the same case before the judge and the arbitrators, save for the prohibition of judicial claims concerning the invalidity or ineffectiveness of the arbitration agreement during the pendency of the arbitral proceedings.