Beyond setting the stage, the Introduction makes three claims about the conceptual triangle of the rule of law, judicial authority and legitimacy. The first is that all three are essentially contested and interpretive concepts in the sense of Walter B. Gallie and Ronald Dworkin. In their expositions, the contested and interpretative nature of such concepts is nothing to be ‘solved’, rather the formulation of different conceptions and contestation about them are central functions of such concepts. The interpretive and essentially contested nature points us to the relevant ‘actors’ and to conflicts and trade-offs between contested competencies. Thus the second point is that arguments about the rule of law and judicial legitimacy are often a means of questioning or securing the authority of a particular actor or institution in relation to other actors and institutions. The final point is that transposing concepts from the domestic to the supranational is a constructive endeavour because it entails creating new conceptions and substituting old ones as well as legitimising new authorities and delegitimising old ones. Thus, this special issue also cautions against discourses that ultimately are more about legitimation than about legitimacy and more about new ways of ruling than the rule of law.