Control de Constitucionalidad/Convencionalidad en la Unión Europea y el Sistema del Reenvío Perjudicial.

In this manuscript we raise the question of control of constitutionality/conventionality in the European system, which is considered the most effective among the regional systems of control of constitutionality/conventionality due to the relationship between the members' states and the supranational system. In this sense, we start asking if whether there is or not a Constitution in Europe, then we present the basic structure of control of constitutionality/conventionality in Europe, and we finish by presenting two cases of preliminary reference system that challenge part of the effectiveness of this system. [ABSTRACT FROM AUTHOR]