The essay examines the condition of foreigners in an old regime society by focusing on judicial practices and jurisdictional conflicts. For the Bourbon monarchy the juridical definition of foreigners and their subordination under the kingdom's laws represented an important moment in the implementation of its territorial sovereignty against the extensive privileges acquired by the foreign nations during the Spanish period. By refusing to recognize any jurisdictional power of the consuls and by abolishing the particularistic judge-delegates, the foreigners were put under the unifying jurisdiction of the Supreme Magistracy of Commerce. Nevertheless, by mobilizing the consuls' protection and taking advantage of international power disparities, the foreigners adapted themselves to these institutional changes and managed even to influence them. Finally, discussing the social actors' manipulating capacities, the author stresses the instability of belongings and the corresponding categories of classification.