La légalité de l’investissement devant l’arbitre international : à la recherche d’un point d’équilibre

The idea that the protection offered to foreign investors under international law is conditioned upon the respect of legality has emerged in the practice of investment arbitration, on the basis of some treaty provisions and on the basis of general principles of international law. The effect of such legality condition is however intricate, because an argument on illegality is raised sometimes as a jurisdictional objection, sometimes as an admissibility issue, and sometimes on the merits. This article argues that arbitral decisions have become more consistent over time, and that different legal characterizations are understandable, taking into account the different legal basis for a legality condition, the timing of proceedings, and the multifaceted aspects of legality. A balanced approach of the legality condition would be to ground it in international as well as national law, and to focus on the moment of the making of the investment; conversely, an expansive approach would create conceptual and practical difficulties