Many commentators have failed to identify the important issues at the heart of the debate between Habermas and Rawls. This is partly because they give undue attention to differences between Rawls’s original position and Habermas’s principle (U), neither of which is germane to the actual dispute. The dispute is at bottom about how best to conceive of democratic legitimacy. Rawls indicates where the dividing issues lie when he objects that Habermas’s account of democratic legitimacy is comprehensive and his is confined to the political. But his argument is vitiated by a threefold ambiguity in what he means by ‘comprehensive doctrine’. Tidying up this ambiguity helps reveal that the dispute turns on the way in which morality relates to political legitimacy. Although Habermas calls his conception of legitimate law ‘morally freestanding’, and as such distinguishes it from Kantian and natural law accounts of legitimacy, it is not as freestanding from morality as he likes to present it. Habermas’s mature theory contains conflicting claims about the relation between morality and democratic legitimacy. So there is at least one important sense in which Rawls’s charge of comprehensiveness is made to stick against Habermas’s conception of democratic legitimacy, and remains unanswered.