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 U.S. cities, homicide and assault rates from 2011 to 2019 were analyzed 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 ≤ .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 15.2 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.

这项研究调查了在抗议警察参与的死亡后凶杀案是否增加，重点关注迈克尔·布朗于 2014 年 8 月在弗格森去世后的时期。它还通过比较凶杀和严重攻击的影响来测试法律犬儒主义的影响，假设报告的假设是后者是自由裁量的，警察滥用职权可能使社区不愿意通知警察。使用来自美国 44 个城市的 FBI 数据，使用中断的时间序列设计分析了 2011 年至 2019 年的凶杀和袭击率，并在荟萃分析中结合以计算汇总效应。元回归测试了影响调节因素，包括外部调查和市/县社会人口学特征。保守阈值为p≤ .01，44个城市中有21个显着增加，1个显着减少。综合效应是凶杀案增加了 26.1%（99% CI：15.3% 至 36.8%）。严重袭击事件增加至高于基线，但其影响比凶杀案的影响小 15.2 个百分点（99% CI：–26.7 至 –3.6）。当结果以百分比变化来衡量时，没有显着的影响调节因子，但当以绝对变化衡量时，当死亡受到外部调查以及在黑人人口、贫困率和基线凶杀案较高的城市中，凶杀案的增加幅度更大率。调查结果表明，由于警察本应保护的社区内部产生了不信任，抗议警察参与的死亡导致凶杀和其他暴力事件增加。