RACIAL DISPARITIES IN LAW ENFORCEMENT TRAFFIC STOPS: MEASUREMENT, INTERPRETATION, & INTERVENTION POSSIBILITIES

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  • Fliss, Michael Dolan
    • Gillings School of Global Public Health, Department of Epidemiology
Abstract
  • Law enforcement traffic stops are one of the most common entryways to the US justice system, with significant downstream impacts for both individuals and communities. Group-specific rates are typically based on jurisdiction resident populations; these rates, like many justice-system indicators, demonstrate race-ethnicity disparities. Residential-based rates implicitly assume race-ethnicity groups have equal vehicle access, equal driving volume, and that all driving occurs in resident’s jurisdictions. In contrast, surveys suggest Black non-Hispanic and Hispanic households have less access and drive less than White non-Hispanic households. Aim 1 reported the direction and degree of change in disparity indices when accounting for these driving factors. Data from over 20 million traffic stops in North Carolina were combined with US Census data and race-ethnicity driving factors from the 2017 National Household Travel Survey to calculate traffic stop rate-ratios (TSRRs) under multiple model assumptions. Spatial simulation models distributed Vehicle Miles Traveled (VMT) across the state and rebuilt rates for 177 law enforcement agencies. Adjusting for three driving factors simultaneously, disparity indices increased 15% on average from 2.02 (1.86, 2.18) to 2.33 (2.07, 2.59) for Black non-Hispanic drivers and were largely unchanged for Hispanic drivers. All models suggested both groups experience disparate traffic stop rates compared to White non-Hispanic drivers. Aim 2 evaluated an intervention from 2013 to 2016 in Fayetteville, North Carolina that prioritized safety stops, intending to reduce both traffic crashes and disparities. Synthetic control methods were used to compare Fayetteville to a counter-factual Fayetteville that did not enact the intervention, built by the weighted combination of eight NC cities matched on pre-intervention measures (2002-2012). These models demonstrated reductions in crashes and disparities and, in contrast to the Ferguson Effect hypothesis, the de-prioritization of investigatory and economic stops was not associated with increases in crime. Supplemental analyses explored the author’s driving, alternate intervention evaluation methods, and within-jurisdiction spatial dynamics. The Public Health Critical Race Praxis (PHRCP) guided framing, results interpretation, and self-evaluation of the dissertation aims. Traffic stops have associated public health outcomes and create disparities of relevance for public health researchers. Interventions guided by critical public health frameworks can save lives and reduce disparities.
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  • Baumgartner, Frank
  • Marshall, Stephen W
  • Poole, Charles
  • Robinson, Whitney
  • Delamater, Paul
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2019
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