This Article draws on Black American intellectual history to offer an approach to fundamental questions of constitutional theory from the standpoint of the politically excluded. Democratic constitutional theory is vexed by a series of well-known challenges rooted in the inability to justify law without democracy (“the countermajoritarian difficulty”) and the inability to justify any particular composition of the popular demos without law (“the problem of constituent power”). Under conditions of genuine egalitarian political inclusion, a constitutional conception of popular sovereignty derived primarily from the civic republican constitutional patriotism associated with Jürgen Habermas and others can resolve these challenges by providing a conceptual basis for understanding the constitutional demos as a corporate body extending across time and capable of ongoing political legitimation. Unfortunately, the constitutional conception cannot justify states, such as the United States, characterized by the persistent exclusion of some legitimate members of the demos from political institutions. The resolution to this problem can be found in an important tradition in Black American constitutional thought, beginning with Frederick Douglass, which represents American constitutional institutions as conditionally worthy of attachment in virtue of their latent normative potential. The correct conception of constitutional legitimacy for the United States combines Douglass’s insights, and those of his intellectual heirs, with those working in the tradition which Habermas represents.