The project explores the view that the political and legal appraisal of international organizations has passed through different stages : A functional stage of IOs’ rise in the mid-nineteenth century (which denotes a view of organizations as vehicles for the activities of states); institutional in the mid-twentieth century predominantly (which refers to a vision of organizations as systems, with a coherent body of rules and a degree of autonomy vis-à-vis the member states, the external aspect of which is traditionally discussed in terms of ‘international legal personality’); and constitutional, especially since the turn of the Millennium (which presents IOs as a system not only because of the coherence of internal rules and component elements, but also because of the incorporation of substantive norms, notably ‘fundamental values’ linked to human rights or theories of justice).