Vaughan Lowe is Chichele Professor of Public International Law, and a Fellow of All Souls College, in the University of Oxford. He also practices in the field of international law as a barrister from Essex Court Chambers, London and has appeared in cases before English and International courts, and sits on international tribunals. Sir Adam Roberts is now President of the British Academy. Previous to this (from 1986 to 2007) he was Montague Burton Professor of International Relations at Oxford University, and a Fellow of Balliol College. His books include (ed. with Benedict Kingsbury), United Nations, Divided World: The UN s Roles in International Relations, 2nd edn. (Oxford University Press, 1993), and (ed. with Richard Guelff), Documents on the Laws of War, 3rd edn. (Oxforddn. University Press, 2000). Jennifer Welsh is Professor in International Relations at the University of Oxford and a Fellow of Somerville College. She is the author, most recently, of At Home In The World: Canada's Global Vision For The 21st Century (HarperCollins, 2004), and editor of Humanitarian Intervention and International Relations (Oxford Univeristy Press, 2003). She was recently named a Trudeau Fellow, and is currently on a Leverhulme research grant working on a project on 'sovereignty as responsibility'. Dominik Zaum is Lecturer in International Relations at the University of Reading, and author of The Sovereignty Paradox: The Norms and Politics of International Statebuilding (Oxford: Oxford University Press, 2007).