The Ação Popular is a peculiar mechanism to control State administration in Brazil, due to the possibility of erga omnes effects of an individual pleading. These effects put the plaintiff in the position of controller over the Administration and, therefore, of defender of collective interests, reason why the filling and the procedure of an Ação Popular reveal social and political-institutional elements of the environment where the plaintiff is situated. Recent statistics show that this mechanism of control is less used by plaintiffs than other mechanisms of control, as well as that there has been an increase of fillings of Ações Populares in the last years. Analyzing Brazil’s society and legal system, especially in comparison to Germany’s society and legal system, it’s possible to conclude that there are social and institutional factors which justify these empirical findings.