Police-involved deaths and the impact on homicide rates in the post-Ferguson era: a study of 44 US cities

This study investigated whether homicides increased after protested police-involved deaths, focusing on the period after Michael Brown’s death in Ferguson in August 2014. It also tests for effects of legal cynicism by comparing effects in homicide and aggravated assault on the assumption that reporting of the latter is discretionary and police abuses may make communities reluctant to notify police. Using FBI data from 44 US cities, homicide and assault rates from 2011 to 2019 were analysed using an interrupted time series design and combined in a meta-analysis to calculate pooled effects. A meta-regression tested effect moderators including external investigations and city/county sociodemographic characteristics. With a conservative threshold of p ≤ 0.01, 21 of the 44 cities experienced a significant increase and one had a significant decrease. The pooled effect was a 26.1% increase in the homicide (99% CI: 15.3% to 36.8%). Aggravated assaults increased above baseline, though the effect was 15.1 percentage points smaller (99% CI: -26.7 to -3.6) than the effect in homicides. When outcomes were measured as percent change, there were no significant effect moderators, but when measured as absolute change, homicides increased to a greater extent when the death was subject to external investigation and in cities with higher black populations, poverty rates, and baseline homicide rates. The findings suggest that protested police-involved deaths led to an increase in homicides and other violence due to the distrust fomented within the very communities whom police are meant to protect.