The Effect of Minority Peers on Future Arrest Quantity and Quality

A common proposal to improve US policing is to increase minority representation in police departments. The net effect of such policies depends on the direct effect of the minority officers as well as their peer effect on others. I document the effect of minority peers in the Chicago police academy on officers' future arrests by exploiting the lottery system which provides exogenous variation in the composition of academy cohorts. I find that minority (e.g., Black, Hispanic) peers reduce officers' future propensity to arrest minority civilians through a reduction in low-quality, low-level arrests. For example, a 1 standard deviation increase in Black cohort share decreases future arrests of Black civilians for low-level crimes by about 1 arrest per 100 officer-shifts. Additional results suggest that other peer characteristics, such as age and gender, modify the effect of minority peers, which is consistent with peers' preferences for aggressive policing playing an important role beyond their minority status