The main purpose of this work is to analyze the issue of democratic legitimacy of regulatory norms produced by independent agencies in Brazil, considering the following question: How to think about legitimating the lawmaking activity of these administrative entities according to Jürgen Habermas´ discourse theory of democracy and the law? The analysis focuses on the challenges that a theory which explains the integration and reproduction processes of modern societies through a concept of rationality situated between the facts and norms of social action must face, when applied to a reality that is different from the one that inspired its development. Thus, I take the work of Paulo Todescan Lessa Mattos, an authority in the topic of regulatory agencies, as a reference of an analytical perspective that sees in Habermas´ discursive model of procedural legitimation a way to find normative parameters to legitimate the norms of these entities. The dialog with Mattos´ argument and his conclusions is constant in this work, and it sets the basis for developing several problematic issues related to identifying, through Habermas´ theory, potentials of democratic legitimation in the institutionalized spaces of public participation within the decision-making processes of Brazilian regulatory agencies.