The ‘ne bis in idem’ principle in respect of decisions issued by foreign judicial authorities is not so well-established in general international law that Italian law must conform to it in accordance with Article 10 of the Constitution. In the case, the fact that a Court in Montenegro had issued a final judgment in respect of the same person and for the same facts was not an obstacle for instituting a proceeding in Italy, given that the offense had been committed, in part, on Italian territory. Article 54 of the Convention on the Application of the Schengen Agreement – which enshrines a contrary principle – was not applicable in the case, because the Montenegro Republic is not an EU member State, nor one of the States of the Schengen Area.