In this article we consider certain elements of the normative theory of Jürgen Habermas in the light of the proposals of Bruce Ackerman, with a view to strengthening a concept of deliberative democracy applied to the legitimation of juridical rules. We do not construct a hierarchy of the two positions, but seek to bring together certain elements to achieve a common project. As the starting point for examining the work of the two authors, we take the scheme proposed by Habermas in Faktizität und Geltung. In this connection, through the work of Ackerman, we intend to fill in some of the gaps that Habermas appears to have left in the theory of radical democracy applied to the law. The work of Ackerman can make a significant contribution to deliberative democracy, to the discourse principle that Habermas defines, and to the contractualist theories from a liberal perspective. The study of these contributions makes possible a critical judgment that enables the legitimation of juridical rules carried out by Habermas to acquire greater practicity. In examining the epistemological status of juridical science and law, we attempt to determine the weight and the performance of normative democracy. In Tarr's view, it is a matter for philosophers to examine direct democracy and its desirability.