The current debate over Arizona's new immigration statute, S.B. 1070, has largely focused on the extent to which it “empowers” or “allows” state and local law enforcement officials to enforce federal immigration laws. Yet, in doing so, the conversation thus far overlooks the most significant part of the new statute: the extent to which Arizona mandates local immigration enforcement by attacking local control. The fact is the new Arizona law does little to adjust the federalist balance with respect to immigration enforcement. What it does, however, is threaten to radically alter the state-local relationship by eliminating local discretion, undermining the ability of localities to manage their law enforcement and other domestic priorities, and authorizing a new legal cause of action against local communities. Thus, S.B. 1070 not only targets undocumented immigrants and those who may be suspected of being such, but also local law enforcement agencies and the counties, cities, and towns that they serve. This, I argue, is the true significance, and one of the overlooked tragedies, of S.B. 1070.