This article makes three arguments to contribute to this thematic issue’s intention of examining the role of public spheres in global politics. To begin with, it attempts to develop the concept of “strong” public spheres to include plenary organs of international institutions. It believes in the potential of this concept as a heuristic fiction. The study then examines the role of international law in shaping global public spheres and their role in global politics. International law’s characteristics have contributed to the current incomplete manifestations of global publics. Not only has international law constructed the institutional frameworks of the “strong” public sphere within international institutions, but it has also integrated civil society actors into the deliberative processes of will formation of these institutions. Finally, this research turns to international climate change law as a case study. The institutional structures created by international climate change law have not only created one “strong” public sphere in the form of the conference of the parties but rely on a second “strong” global public, the Intergovernmental Panel on Climate Change, which aims to institutionalise the global climate science community without abandoning an intergovernmental structure. What is more, the paradigm shift accompanying the Paris Agreement has made global climate change governance increasingly reliant on an active transnational global public sphere.