The Supreme Court will hear arguments today on Arizona Senate Bill SB 1070, widely considered the toughest immigration law in the country. Among its provisions, the statute requires state and local police to check the immigration status of people they have stopped if there is a "reasonable suspicion" they are in the country illegally. While the oral arguments will likely involve a complicated dissection of the preemption doctrine, we wanted to highlight our research on the enforcement of immigration in different localities around the country. Here are some op-eds and research from our scholars, many supported by our immigration program:

Missing from this important legal debate, however, is the larger question of why states and localities are getting involved in immigration enforcement in the first place. The conventional wisdom on these policies is that federal inaction, combined with demographic pressures from immigration, have left these states and cities little choice but to act. According to this logic, new immigrants, especially illegal immigrants, are causing cultural and economic upheavals in places unaccustomed to such transformations. Consequently, laws like Arizona's SB 1070 and Alabama's HB 56 are seen as natural and inevitable responses.

These reasons, however, do not stand up to empirical investigation. In our new systematic study of these state and local immigration laws, the data show that commonly assumed factors — e.g., the growth of immigrant populations, immigrant-caused economic stress, prevalence of Spanish speakers and overcrowded housing — make no significant difference in the proposal or passage of these restrictive immigration laws.

By contrast, political partisanship consistently predicts when and where states and localities will introduce restrictive immigration laws, with Republican-heavy areas especially likely to do so. For instance, restrictive ordinances are 93% more likely to pass in Republican counties than in Democratic ones. At the state level, there is a 47% difference between Republican-heavy states and Democrat-heavy states.

Abstract: Arizona’s unauthorized immigrant population shrank after employers were required to verify workers' legal status with the federal E-Verify system. The 2007 law also pushed a substantial number of unauthorized immigrants into self-employment. The study estimates that from 2008 to 2009 Arizona’s population of unauthorized immigrants of working age fell by about 17 percent, or about 92,000 people, as a result of the Legal Arizona Workers Act (LAWA).

Passage of Utah State Senate Bill 81 (SB 81) in 2008 calling for the deputization of police officers as immigration officers thrust Utah onto the national stage as the first state to pass such legislation. Due to law enforcement’s resistance to the policy, cross-deputization has not yet gone into effect. Though there are strong feelings on both sides of the issue, there has been limited empirical data to support the claims of either the bill’s opponents or advocates. Thus, in 2009, at the request of the Salt Lake City Police Department (SLCPD), the Consortium for Police Leadership in Equity, (CPLE) began a program of research in Salt Lake City, Utah. Surveys were conducted with SLCPD police officers as well as White and Latino residents, and crime data from the last five years were analyzed.