International law was born from the impulse to 'civilize' late nineteenth-century attitudes towards race and society, argues Martti Koskenniemi in this extensive study of the rise and fall of modern international law. In a work of wide-ranging intellectual scope, now available for the first time in paperback, Koskenniemi traces the emergence of a liberal sensibility relating to international matters in the late nineteenth century, and its subsequent decline after the Second World War. He combines legal analysis, historical and political critique and semi-biographical studies of key figures (including Hans Kelsen, Hersch Lauterpacht, Carl Schmitt and Hans Morgenthau); he also considers the role of crucial institutions (the Institut de droit international, the League of Nations). His discussion of legal and political realism at American law schools ends in a critique of post-1960 'instrumentalism'. This book provides a unique reflection on the possibility of critical international law today.

Successive ICJ Presidents have expressed concern about the proliferation of international tribunals and substantive fragmentation of international law. This is not a new phenomenon. International law has always lacked a clear normative and institutional hierarchy. The problem is more how new institutions have used international law to further new interests, especially those not predominant in traditional law. The anxiety among ICJ judges should be seen less as a concern for abstract “coherence” than a worry about the demise of traditional principles of diplomatic law and the Court's privileged role as their foremost representative. As jurisdictional conflicts reflect divergent political priorities, it is unclear that administrative co-ordination can eliminate them. This does not, however, warrant excessive worries over fragmentation; it is an institutional expression of political pluralism internationally.

Public international law hovers between cosmopolitan ethos and technical specialization. Recently, it has differentiated into functional regimes such as ‘trade law’, ‘human rights law’, ‘environmental law’ and so on that seek to ‘manage’ global problems efficiently and empower new interests and forms of expertise. Neither of the principal legal responses to regime‐formation – constitutionalism and pluralism – is adequate, however. The emergence of regimes resembles the rise of nation States in the late nineteenth century. But if nations are ‘imagined communities’, so are regimes. Reducing international law to a mechanism to advance functional objectives is vulnerable to the criticisms raised against thinking about it as an instrument for state policy: neither regimes nor states have a fixed nature or self‐evident objectives. They are the stories we tell about them. The task for international lawyers is not to learn new managerial vocabularies but to use the language of international law to articulate the politics of critical universalism.