The work aims to present a justification for the need to democratize the Constitution, within the perspective of weak constitutionalism, developed by Professor Joel Colón-Ríos. The assumption is that the relations between constitutionalism and democracy in modern constitutional democracies are most in favour of the limitations on the exercise of popular sovereignty. The proposal of a weak constitutionalism is presented as a possible way to redefine this balance putting the people to directly deliberate about the fundamental decisions of the Constitution and taking It away from Courts and Parliament. In order to proceed to this theoretical justification, we take separately the institutional and rights themes of the Constitution. Each one deserves a specific explanation about the need of popular participation in its essential definitions. Also, we try to think in constitutional designs that would make this proposal effective, drawing on some Latin American constitutional experiences.