The fundamental question addressed in this essay is that of the conditions under which a legal state can be effectively established between peoples - conditions without which peace, and hence human freedom, is a delusion. To elucidate this concern is to commit oneself resolutely to thinking about the conditions for establishing just relations between states and peoples. Such an issue is not new to philosophy. It runs through modern thought and the work of Kant, where it crystallizes on the question of the law of nations and cosmopolitical law in the Project for Perpetual Peace and the Doctrine of Law. Our interest in starting with Kant is to rediscover in him the path to a much-maligned aporia. Admittedly, the context of our thinking is current. But our interest in Kant on this question lies in the similar effort he made in his own time. To let ourselves be caught up in his effort is to allow ourselves a space for lucidity, to keep an analytical distance from the effort already underway, so as to be aware of its impasses and explore ways of overcoming them.