Why do (Some) city police departments enforce federal immigration law? Political, demographic, and organizational influences on local choices

In 1996, Congress created a new way to enforce national immigration laws, inviting state and local law enforcement personnel to become formally involved in the effort. Why have police departments in some communities embraced increased involvement in immigration enforcement, whereas others have shunned this role? Do local elected officials typically determine the contours of police practice in this area or do police departments act with considerable autonomy in deciding how much to become involved in immigration enforcement? We examine these issues by analyzing data from a national survey of police chiefs in municipalities with populations of 65,000 or more. Our analysis takes account of the possibly endogenous relationship between the policies of city government and the practices of police departments. We find that immigrant-supportive city policy commitments and the presence of a Hispanic police chief are associated with less intensive immigration enforcement by local police. Voter partisanship is also related to police practices, but only in cities with an unreformed form of government.