Over the past two decades Jürgen Habermas has produced a body of writings on international law and politics which represent a major contribution to cosmopolitan political thought at the beginning of the twenty-first century. These writings are highly diverse both in terms of the issues they address – ranging from the impacts of globalization on the welfare state, through developments in international law in the post-war period and European political integration, to reforms of the United Nations and a system of global governance for an emerging world society – and in terms of their style and intended audiences. Theoretically speaking, they involve the extension of the theories of modernization and of deliberative democracy that Habermas developed with reference to the nation-state to international and global relations. Drawing on a universalistic conception of human rights and a corresponding interpretation of the development of international law, Habermas argues that a regime of “global governance without a world government” is both normatively required in response to the political challenges confronting the international community and that it could be realized through a constitutionalization of international law based on reforms of existing international institutions and regimes. The model of global governance he envisages would combine a supranational regime with responsibility for global peace and human rights policy with a transnational regime in which a global domestic policy would be negotiated and implemented. Nevertheless, Habermas insists that this multilayered system is not a blueprint for a world state: rather than superseding existing sovereign nation-states, it would instead integrate them into a new global constitutional framework.