International economic relations have always been seen as the field in which the law has developed norms and methods of regulation which combine both flexibility and operators’ autonomy of will. Despite these assets, the failure or inefficiency of law and its authors, the State in particular, is obvious in the financial sector. During the G20 summits, the debate focused on the revalorization of the State as a supervisory authority for the regulation and the control of markets. One of the pioneering measures was the reinforcement of the regulation and the supervision of the financial architecture on the world scale. The emergence of such a regulation is thus conceivable only if actors conform to a principle of common sense: “For transnational or international actor, international law must apply”.