Racial Disparities in Law Enforcement: The Role of In-Group Bias and Electoral Pressures

Racial disparities are widespread throughout the U.S justice system; in arrests and incarceration. These disparities are typically explained by appealing to racial biases among the police and the judiciary. I present a model in which disparities arise between groups in spite of unbiased actions on the part of these authorities. Voters determine the intensity with which legal sanctions are enforced against an offence that creates a negative externality. Individuals discount the harm caused by members of their own group taking the action. A county's population is comprised of two unequally sized groups, with the median voter drawn from the majority. In this model the intensity of law enforcement increases with the size of the minority. In states where counties are heterogenous in the composition of their population, this leads to group disparities at the state level. The intensity of law enforcement depends on both the level of policing and the strictness of the judiciary. In some states, voters can elect their judges and increase the legal sanction through judicial severity, while in other states judges are appointed. We should therefore expect that the relationship between the size of the minority population and the intensity of policing to be stronger in counties where judges are appointed. Using a county-level panel of arrests between 2000-2014 in the United States, I find that in states with appointed judges the level of policing is increasing with the share of the black population. A 1% higher share of black population leads to a 0.58% increase in the clearance rate of property crimes. I do not find a comparable effect in states with elected judges. This agrees with the predictions of the theoretical model