On 8 April 2026, the Rio Course on Regional and International Dispute Settlement (Rio CRIDS) was honored to welcome Prof. Frédéric Megret Professor of Law and the holder of the Hans & Tamar Oppenheimer Chair in Public International Law at McGill University. The course is held by the FGV Jean Monnet Centre of Excellence, co-funded by the European Union under the Erasmus+ programme and directed by Prof. Paula Wojcikiewicz Almeida.

In the lecture “’Tous pour un, et un pour tous’? Third State Dispute Settlement in the Age of Erga Omnes Obligations and its Limits”, moderated by Prof. Paula Wojcikiewicz Almeida, Prof. Mégret challenged the assumption that international law is moving from sovereignty to community interests. He began by presenting the main differences between these two systems: traditionally, the superstructure of international law consisted of obligations, mostly bilateral, based on consent, with the enforcement of norms through countermeasures. This horizontal system of enforcement was proven not efficient for communal norms and shared values: if the obligations are erga omnes, all states are required to implement them. However, international procedure has not fully translated to reflect a more vertical and communal structure. 

In the second part of the class, Prof. Mégret questioned whether there has been a judicial turn to erga omnes. He analyzed the evolving jurisprudence of the International Court of Justice, under which advisory proceedings and interventions have gained more relevance in the name of community interests, transcending institutional limitations. Nonetheless, he argued that it is too simplistic to view this trend as the realization of an idea in history. He presented three theses about third party involvement, indicating that experts do not agree on the role of erga omnes in the development of international law. Prof. Mégret invited students to complexify the narrative and the interests behind the increasing multilateral judicialism. While this shift is possible because of a hyperfocus on community interests, it is also invoking polarizing litigation, like the case of South Africa v. Israel. 

We warmly thank Prof. Mégret for this enriching session. We look forward to further collaboration.