Art 4 (3) of the SSM Regulation allows, under certain conditions, the European Central Bank to directly apply national law in the exercise of its prerogatives. This article recaps the general framework of application of the SSM Regulation by looking in particular to the question of national law transposing relevant directives in the area and discusses the role of the ECB when interpreting and applying national law in the exercise of its prudential tasks and powers. Finally, it attempts to place the scope of application, the limitations and legislative instruments related to the application of national law by the ECB in a wider EU constitutional fram-ework.