Sovereignty’s lingering commitment to voluntarism and the limitations of the voluntarist approach are exposed by the crisis of authority represented by contradictory claims to ultimate authority on the part of the Court of Justice and national courts. Whilst it is uncontroversial to assert that both pluralism and subsidiarity pose significant challenges to state sovereignty, this chapter argues that pluralism and subsidiarity not only threaten sovereignty because they allow for the re-allocation of authority to institutions other than those of the nation state but also because they call into question sovereignty’s fundamental assumption that authority is dominated by will to the neglect of countervailing considerations. They offer solutions to this crisis of authority which finally tackle the problem of voluntarism, by deflecting focus away from the will and towards the good (higher moral principles), towards reasoned dialogue and towards a spirit of co-operation.