* Lecturer in Law, London School of Economics and Political Science. Parts of this paper were presented at a series of European Union Law Seminars at Columbia Law School in the Spring Term of 2001. I owe many thanks to my students and to George Bermann for their observations and perceptive criticism. I also benefited from discussions at the workshop ‘Cosmopolitan Law: A Good Idea?’ held at the London School of Economics in December 2000 and by the papers presented on that occasion by Daniele Archibugi, Chris Brown, David Held, Mary Kaldor, Gerry Simpson and Jeremy Waldron. I am grateful to Jack Balkin, Chaloka Beyani, Fanny Calder, Christine Chinkin, Hugh Collins, Arabella Duffield, Susanne Jaspars, Frances Jordan, Christos Hadjiemmanuil, Carol Harlow, Dino Kritsiotis, Jenny Kuper, James Penner, Paul Roberts, Peter Strauss and John Tassioulas for their help at various stages of research- ing and writing this paper. Cosmopolitan Law Pavlos Eleftheriadis* Abstract: The European Union need not choose between the two options of a federalist constitution or a loose intergovernmental association of states. There is a third possibility. This is described by Kant as an order of perpetual peace, whereby states undertake to one another to be good republics, to join in a federation of peace, and to respect the rights of each other’s citizens. For Kant this corresponds to a combination of principles of consti- tutional law, international law and, a new category, ‘cosmopolitan law’. If we adopt Kant’s concepts we can see, first, that the international law of human rights has become some kind of cosmopolitan law of the international community and that, second, parts of Euro- pean Community law can also be seen as cosmopolitan law for its member states. The features of cosmopolitan law are that it does not follow a conventional theory of sources of law, it does not respect traditional state sovereignty and does not require a hierarchy of institutions for its interpretation and application. The debate on the European Constitution is often said to present us with the follow- ing dilemma: either the Union endorses a Constitution creating a well-structured legal order of a quasi-federal kind, or it will allow the narrowness of the present Treaties to reduce the Union to a loose intergovernmental organisation of twenty-five Member States. The choice seems forced on us both by the nature of the Union and the nature of constitutions. There seem to be only two available options: either we borrow the idea of the state and build a federalist union and legal order, or we reject the federal ideal and remain within a largely international and intergovernmental model split between domestic and international law. I shall call this argument the federalist dilemma. It is a flawed argument because the theoretical disjunction on which it is based is mistaken. Legal theory and practice do not deliver just these two constitutional models, that of a federal state and that of an international organisation. European Law Journal, Vol. 9, No. 2, April 2003, pp. 241–263. © Blackwell Publishing Ltd. 2003, 9600 Garsington Road, Oxford OX4 2DQ, UK and 350 Main Street, Malden, MA 02148, USA