Unintended reductions in assaults near sobriety checkpoints: A longitudinal spatial analysis

Background: Sobriety checkpoints are a form of proactive policing in which law enforcement officers concentrate at a point on the roadway to systematically perform sobriety tests for all passing drivers. We investigated whether sobriety checkpoints unintentionally reduce assaults in surrounding areas. Methods: Exposures of interest were sobriety checkpoints conducted by the Los Angeles Police Department between 2012 and 2017. Comparison units were matched 1:2 to sobriety checkpoints, selected as the same point location temporally lagged by exactly ±168 hours. The outcome was the density of police-reported assaults around the checkpoint location. Results: In mixed effects regression analyses, assault incidence was lower when sobriety checkpoints were in operation compared to the same location ±168 hours [b= -0.0108, 95% CI: (-0.0203, -0.0012)]. Conclusions: Sobriety checkpoints were associated with decreased assault incidence, but estimated effect sizes were small and effects did not endure long after checkpoints ended.