This paper provides new evidence on the role of preference-based versus statistical discrimination in racial profiling using a unique data set that includes the race of both the motorist and the officer. We build upon the model presented in Knowles, Persico and Todd (2001) and develop a new test for distinguishing between preference-based and statistical discrimination. In particular, we show that if statistical discrimination alone explains differences in the rate at which the vehicles of drivers of different races are searched, then, all else equal, search decisions should be independent of officer race.We then test this prediction using data from the Boston Police Department. Consistent with preference-based discrimination, our baseline results demonstrate that officers are more likely to conduct a search if the race of the officer differs from the race of the driver. We then investigate and rule out two alternative explanations for our findings:officers are better at searching members of their own racial group and the non-random assignment of officers to neighborhoods. * Respectively, Department of Economics, University of California, San Diego, email: kantonov@ucsd.edu, that it is not easy to empirically distinguish between these two possibilities.Economists have now joined the debate over racial profiling, and a number of recent papers have attempted to determine whether the observed racial disparities in policing patterns are best explained by models of statistical discrimination or by models of preference-based discrimination (see, for example, Knowles, Persico and Todd (2001), Hernández-Murillo andKnowles (2003), Anwar and Fang (2006) and Dharmapala and Ross (2004)).Statistical discrimination arises because law enforcement officials are uncertain about whether a suspect has committed a particular crime. If there are racial differences in the propensity to commit that crime, then the police may rationally treat individuals from different racial groups differently. On the other hand, preference-based discrimination arises because the police have discriminatory preferences against members of a particular group and act as if there is some non-monetary benefit associated with arresting or detaining members of that group. Thus, preference-based discrimination raises the benefit (or, equivalently, lowers the cost) of searching motorists from one group relative to those from some other group.
1This debate among economists over the sources of racial disparities in policing patterns roughly parallels the debate over racial profiling within the court system. That is, statistical discrimination approximately corresponds to the type of behavior that the courts have tended to uphold, while preference-based discrimination approximately corresponds to the type of behavior that the courts have tended to condemn.In this paper, we attempt to understand the reasons for observed racial differences in the rate at which the vehicles of African-American, Hispanic and white motorists are searched during traffic stops. W...