The aim of this paper is to give a partial answer to the question made in the title. Several works
analyse the evolution of the corruption in dierent societies. Most of such papers show the necessity of
several controls displayed by a central authority to deterrence the expansion of the corruption. However
there is not much literature that addresses the issue of who controls the controller. This article aims to
approach an answer to this question. Indeed, as it is well known. in democratic societies an important
role should be played by citizens. We show that politically active citizens can prevent the spread of
corruption.