Chapter 2 moves from the constitutional foundations of the European legal order to the architecture of fiscal federalism constructed atop them. It investigates where the constitutional principles identified in Chapter 1 inhere in the legal architecture of EMU, and explains the basic principles of economics inscribed for their attainment. The principles of fiscal sovereignty, price stability, and fiscal discipline are shown to penetrate three levels of investigation: The travaux préparatoires and the mandate for EMU (Article 119 TFEU); the allocation of competences in economic policy (Articles 2(3) and 5(1) TFEU); and the technical architecture governing public finance itself (Articles 121-126 TFEU). By those provisions, EU fiscal federalism rests on two principles: (1) Fiscal sovereignty – member state economic/fiscal competences remain outside the EU legal order altogether; and (2) market discipline –member states are exposed to ‘hard budget constraints’ and ‘market discipline’ to ensure fiscal discipline.