En droit international de l'investissement, le prisme de l'expropriation indirecte couvre une large categorie de mesures - telles que les reglementations - qui n'impliquent pas de transfert de propriete mais aboutissent a une grave interference avec un investissement. La definition des depossessions indemnisables constitue une question extremement sensible, situee a la croisee des chemins entre la protection des droits des investisseurs et la preservation des prerogatives de l'Etat. Cet ouvrage explore, a travers l'exemple de la reglementation environnementale, le droit applicable a cette notion controversee. Il montre que l'approche traditionnelle - reposant sur une dilution du concept d'expropriation - n'est nullement appropriee et il contribue a clarifier l'etendue de la protection de l'investisseur sur le fondement du droit de la responsabilite internationale de l'Etat.In international investment law, the prism of indirect expropriation includes a broad range of measures - such as regulatory measures - which do not involve a transfer of property but result in a serious interference with an investment. The definition of compensable taking is a very sensitive issue situated at the crossroads between the protection of investors' private rights and the safeguarding of the state's sovereign prerogatives. This book explores, through the example of environmental regulation, the law applicable to this controversial topic. It suggests that the traditional approach - based on an extension of the concept of expropriation - is inappropriate and it contributes to clarifying the scope of the international protection of the investor on the ground of the law of state responsibility.