By Matthew B. Ross

 1. Introduction In November 2021, the New Jersey Attorney General’s Office of Public Integrity and Accountability (NJOPIA) engaged the author of this study for the purpose of conducting an independent analysis of traffic stops made by the New Jersey State Police (NJ-SP). Based on the author’s extensive experience working with state and local policymakers to develop early warning systems for identifying police disparities, the NJ OPIA requested that the analysis focus on the central question of whether there was disparate treatment on the part of NJ-SP towards racial and ethnic minorities.2 After cleaning and linking all of the raw data provided by the New Jersey Office of Law Enforcement Professional Standards (NJ-OLEPS), the analytical sample used in this analysis consisted of 6,177,109 traffic stops made by NJ-SP from 2009 to 2021. In the full analytical sample, 60.52 percent of traffic stops were made of White non-Hispanic motorists while 18.8 percent were Black/African-American and 13.44 percent were Hispanic/Latinx. The overall volume of minority motorists stopped by NJ-SP increased from 35.34 percent in 2009 to 46.28 percent in 2021. The overarching finding from the analysis of the NJ-SP data from 2009-21 is that there was extremely strong evidence of a large and persistent disparity both is the decision to stop as well as the decision to engage in post-stop enforcement like search, vehicular exits, use of force, and arrest. In general, the results were estimated with a very high degree of statistical confidence, survived multiple robustness tests, and were found across most years and troops/stations. In the opinion of this study’s author, these disparities represent strong empirical evidence that NJ-SP is engaged in enforcement practices that result in adverse treatment towards minority motorists. Following best practices, this study applies an ensemble of the most reliable statistical tests available in the scientific literature. The intuition of this approach is that the shortcomings of any individual test are overcome by the totality of the evidence produced by a multitude of tests examining a broad set of enforcement outcomes.

Boston: Northeastern University, 2023. 44p.