Imagine a local police department confronted with the issue of immigration. With a growing immigrant population in the community and increasing federal emphasis on local involvement in immigration enforcement, the police chief realizes that it is no longer possible to ignore the immigration consequences of even the most ordinary of police activity. At the same time, concerned about the deleterious effects of immigration enforcement on local policing priorities, and the potential abuse that might arise from giving unbridled discretion to line-level officers under his charge, the police chief feels it is important to promulgate an official policy on how immigration issues will be addressed as a departmental matter. On the one hand, the policy he arrives at prohibits any local police officer from inquiring about or otherwise contacting federal authorities in regards to an individual's immigration status if that person is not under arrest on suspicions of having committed a felony offense. On the other hand, for those who are arrested for a felony violation, it requires the arresting officer to take steps to determine their immigration status and alert federal authorities if any are identified as being unlawfully present in the United States. This essay begins with the proposition that irrespective of the disagreements that we may have about the particularities of such a policy, broad agreement may nevertheless be reached on the merits of having departmental directives to guide the conduct of line-level officers. Yet, as this essay argues, recent legal developments are calling such local policymaking into serious doubt, both with respect to limitations on immigration enforcement and mandate to participate.

Immigration responsibilities in the United States are formally charged to a broad range of federal agencies, from the overseas screening of the State Department to the border patrols of the Department of Homeland Security. Yet in recent years, no department seems to have received more attention than that of the local police. A robust public debate now rages over the wisdom of involving local law enforcement officials in the enforcement federal immigration laws.'At