The "double filtering" of the Priority Question of Constitutionality refers to the specificity of the French system of a posteriori constitutionality review, which associates, the Supreme courts – Conseil d’Etat and Cour de cassation - with the transmission of the question of constitutionality to the Constitutional Council. Thus, they play the role of a second filter when that “question” is raised before the courts of First instance. Within that system, the interpreters of the Constitution seem to be in competition with each other. They are caught up in a game of complex constraints in which certain actors of the Priority Question of Constitutionality seem to have an advantage over others. Who and what benefits from the double filtering? To what end is it the means? To answer these questions, several hypotheses are formulated. Two of them are tested in depth. According to the first one, which will prove to be fragile, the Supreme Courts and the Constitutional Council would be in an equal position of strength compared to the courts of first instance. On the other hand, according to the second, more likely, double filtering distorts competition in favor of the supreme courts.