The Political Safeguards of Horizontal Federalism

For decades, we have debated whether “political safeguards” preserve healthy relations between the states and the federal government and thus reduce or eliminate the need for judges to referee state–federal tussles. No one has made such an argument about relations among the states, however, and the few scholars to have considered the question insist that such safeguards don’t exist. This Article takes the opposite view and lays down the intellectual foundations for the political safeguards of horizontal federalism. If you want to know what unites the burgeoning work on horizontal federalism and illuminates the hidden logic of its doctrine, you need know only one fact: lawyers hate spillovers. Whether it is a state’s decision to license same-sex marriage or set high emissions standards or maintain lax gun-ownership rules, we worry when one state’s regulations affect residents in another state. And just as most scholars aspire to prevent spillovers, most look to the courts to fix the problem. The current state of the law and literature makes clear why no one has thought to develop a safeguards account of horizontal federalism to match the one that dominates debates over vertical federalism. Why bother with political safeguards if politics is the problem and the judiciary is the solution? In this Article, we don’t just question the consensus against spillovers but offer an affirmative account as to why much interstate conflict can or should be left to the free play of politics. Our argument emphasizes the democratic possibilities associated with spillovers and looks to vertical federalism as a model for thinking about how the states ought to interact with each other. Spillovers, after all, occur just as routinely between the state and federal government as they do between the states. State–federal friction, however, is understood to be both a problem and a valuable part of a well-functioning democracy. The same should be true of horizontal federalism. Our goal should not be to suppress friction but to harness it—to shut down damaging spillovers while allowing productive ones to run their course.