Sustainable decentralization: Power, extraconstitutional influence, and subnational symmetry in the United States and Spain

In the Madisonian tradition of constitutional design, the foundation of a sustainable federalism is thought to be a scientifically precise balancing of national and subnational power. Experience shows, however, that national and subnational actors in highly diverse systems are capable of developing a rich array of extraconstitutional methods of mutual influence, so that the formal, constitutionalized balance of power rarely settles the question of the actual balance of power between levels of government. A more important factor in ensuring the long-term sustainability of a meaningfully federal system is the degree of symmetry across subnational units in their relation to the central state. A comparison of the United States and Spain suggests that federalism is most directly threatened when subnational units compete not collectively with the central state, thereby checking its power, but with each other, a condition that furnishes the central state with opportunities to exploit subnational rivalries in ways that risk genuine, long-term destabilization.