Abstract
This paper is about the concept of legitimacy in Ackerman's theory of constitutional moments. Ackerman's theory of the constitutional moment explains how constitutional change takes place outside of, and even in tension with, established channels of constitutional amendment. The main tool of legitimacy which Ackerman uses is popular sovereignty, to which he gives special features. Ackerman's particular conception of popular sovereignty I name hyperconsensus, and then I explore whether that is sufficient to justify deviations from Article V, as Ackerman claims. I conclude, with many others, that the constitutional moment needs more justificatory work. I offer reciprocity as a corrective procedural requirement as found in Rawls's liberal principle of legitimacy. Doing so enhances the normative attractiveness of dualist democracy.