This article explores how proposals for democratizing the European Union (EU) according to a supranational, contestational model are likely to disrupt its existing political system. The current EU is characterized by a dual system of representation that combines the representation of member states with that of individual citizens. Democratization typically entails enhancing the representation of individuals at the expense of state prerogatives. It is thus possible to make a pertinent analogy with the antebellum United States, which also featured dual representation, and where a great wave of democratization took place following Andrew Jackson's presidency (1829–1837). As the system of representation there became more majoritarian, John C. Calhoun led the calls for introducing new anti-majoritarian constitutional safeguards. A transatlantic comparison suggests the contestational system born of EU democratization will require institutional innovation in order to prove viable. In this context, Calhoun's theory of nullification, an ex post political mechanism wielded by the units to stymie federal legislation, appears more appropriate as an anti-majoritarian bulwark and better able to engender constitutional debate over competences than is the EU's stillborn judicial principle of subsidiarity. In similarly Calhounian fashion, a bottom-up procedure of constitutional amendment originating in the units is further proposed as a way of establishing unit acquiescence to greater supranationalism.