I. Lukashuk, I. Keywords: Participating interest | Law of treaties | Mots clefs: Participation | Droit des traités | ABSTRACT I.I. Lukashuk points out that in the introduction to his course that the peculiarity of subjects of public international law not only possesses rights and duties under international law, but also plays an active role in the development of international law. In the first part, the author presents the different categories of parties to the treaties (States, composite States, international orga…