In A Cosmopolitan Legal Order: Kant, Constitutional Justice and the European Convention on Human Rights, Alec Stone Sweet and Clare Ryan argue that there has been the emergence of, and increasing prospects for, a cosmopolitan legal order based on the Convention. This symposium aims to engage with, and to better explore, the theoretical implications and practical legal ramifications of their argument. In doing so, this first article acts as a general introduction to the symposium, laying out the major arguments of the book as well as arguments presented by the symposium contributors. Moving beyond the summative, this introduction also situates A Cosmopolitan Legal Oder within broader debates in global constitutionalism, while defending its use of Kant’s cosmopolitan theory. Lastly, it explores some of the key implications and challenges that arise from the symposium itself, rooting these insights within the current context of anti-globalism, nationalism, populism and neo-sovereigntism, and the corresponding necessity for a more transitional and pluralistic response as offered in A Cosmopolitan Legal Order.