Nico Krisch, Professor of International Law, Hertie School of Governance; currently Visiting Professor of Law, Harvard Law School.] This post is part of the Leiden Journal of International Law Vol 25-2 symposium. Other posts in this series can be found in the related posts below. Tom de Boer's review of my recent book, Beyond Constitutionalism: The Pluralist Structure of Postnational Law, presents not only a careful analysis, but also a direct challenge to its normative thrust. This gives me an opportunity to defend and clarify my views, and I am grateful to the editors of the Leiden Journal of International Law for allowing me to do so in this Opinio Juris discussion. De Boer's critique is constitutionalist in nature and internationalist in outlook. What he finds most troubling in the book is that the pluralist structure I defend may allow national courts to question international law's authority on dubious – particular rather than universal – grounds. The potential danger of pluralism, he argues, is much broader than what emerges from the relatively benign examples in the book: pluralism may open Pandora's box to all kinds of problematic action by domestic political and judicial bodies and thus undermine the force of international rules. A constitutionalist order, in de Boer's view, would be better able to protect international law and institutions from such unwarranted challenges. This portrayal of the potential consequences of a pluralist order is not implausible. Pluralism as I see it eschews ultimate authority and overarching conflict norms, and it grants different parts of the global legal order the space to distance themselves from the others. It creates an interplay of suborders in which the relationships are defined from within each suborder, both as between different international regimes and between different layers of law in the interaction of national, regional, and international orders. There is no overarching, hierarchical frame that would order their relations, and consequently no external legal constraint that would keep the suborders from getting it wrong.