International law faces several structural changes: from the advent of asymmetric wars, the war on terror, the resurrection of targeted killings, piracy to the degradation of the global environment or the challenges posed by the global economic crisis. These challenges escape the constitutive confines of the state system and require new answers. For some, the legal system is in need of a new constitution and a new hierarchy of norms. Proponents of this thesis point to new supranational rules, human rights, transnational judicial cooperation, general principles of law and procedural aspects. Others, however, witness a fragmentation of international law, arguing that the functional differentiation of international law challenges its unity and hierarchy. Yet others have contended that international law has become increasingly politicized since the end of the Cold War - and especially since 9/11. The current literature treats fragmentation, politicization and constitutionalisation as separate or opposite trends in the international legal order. This Action takes as a vantage point that they have to be thought together as dimensions of a more fundamental systemic change. This Action therefore brings together scholars from a variety of disciplines to analyze this complex relationship and assess the changing structure of the legal system.

Memorandum of Understanding


Book Projects
Books in Print
"Deference in international Courts and Tribunals", Oxford University Press
"Experts in International Decision Making", Cambridge University Press

Books underway (in review or all chapters ready in draft):
Assembling the Planet: The Politics of Globality since 1945
Koskenniemi and His Critics, The Politics of International Law Revisited
The Power of Legality

Special Issues
Special issue Leiden Journal of International Law on legal expertise - LJIL symposium 26(4), 2013

Special Issues underway
The Politics of the List: Law, Security, Technology
Comparative Law in International (Quasi-) Adjudication: Comparing the Comparison
Organizing Fragmented Territoriality - Exploring Spaces of Global Legal Practice
Pursuing Global Justice through International Criminal Law

Drone warfare from below
Teaching International Criminal Law