This chapter considers the idea of an international civil association, constituted by a set of non-instrumental rules, in the light of realist, universalist, and constitutive theories of International Relations. It highlights the similarities between Oakeshott and realism by exploring Oakeshott's arguments against theories of universal moral order, as well as his defence of a phronetic conception of political activity. However, on the basis of textual evidence from Oakeshott's essay "The Rule of Law," the chapter ultimately argues that, in Oakeshott's theory, law reflects evolving moral practices, and that this illuminates the source of international legal obligation. As such, the chapter contributes to debates in constructivist literature on the source of international authority and on the relation between moral values and international law.