By Jeffrey A. Fagan and Amanda B. Geller

Following Soto v. State (1999), New Jersey was the first state to enter into a Consent Decree with the U.S. Department of Justice to end racially selective enforcement on the state’s highways. The Consent Decree led to extensive reforms in the training and supervision of state police troopers, and the design of information technology to monitor the activities of the State Police. Compliance was assessed in part on the State’s progress toward the elimination of racial disparities in the patterns of highway stops and searches. We assess compliance by analyzing data on 257,000 vehicle stops on the New Jersey Turnpike by the state police from 2005– 2007, the final months of the Consent Decree. Specifically, we exploit heterogeneity of officer and driver race to identify disparities in the probability that stops lead to a search. We assume a crime-minimizing or welfarist rationale for stops, under which race-neutral factors are equally likely to motivate stops, regardless of driver or passenger race. We also test a Fairness Presumption by comparing search patterns between driver-officer pairs where the driver and officer are different races, and a set of race-neutral benchmarks where the driver and officer are the same race. Results of fixed effects logistic regressions show that Black and Hispanic drivers, when stopped, are more than twice as likely as White drivers to be searched, regardless of officer race. The results also suggest that search patterns vary significantly by officer race: Black officers are less likely to conduct a search in the course of a stop than are White drivers. We also see significant interactions between the race of officers and that of the drivers they stop: Black drivers are significantly more likely to be searched by White officers than they are by Black officers; on the other hand, Hispanic drivers are significantly less likely to be searched by either Black or White officers than they are by Hispanic officers. Racial disparities in the selection of stopped drivers for search and in the rates of seizure of contraband suggest that despite institutional reforms under the Consent Decree in management and professionalization of patrol officers, there were no tangible gains in distributional equity. We review the design of the Consent Decree and the accompanying oversight mechanisms to identify structural weaknesses in external monitoring and institutional design in the oversight of the State Police that compromised the pursuit of equality goals.

J. SOC. POL'Y & L. 16 (2020). Available at:

By New York University School of Law, Policing Project

In response to the Gideon’s Army report indicating racial disparities in traffic stops, and the shooting of Jocques Clemmons, the Nashville Mayor’s Office asked the Policing Project to help develop strategies to address the disparities and improve community-police relations in Nashville. The Policing Project is an organization devoted to front-end democratic accountability to assure just and effective policing. The Policing Project talked with dozens of Nashville residents about their experiences with policing. Based on those conversations, we proposed to conduct a thorough assessment of the costs and benefits of using traffic stops to address crime. And we suggested that the City create a Steering Committee to guide work around community-police engagement and policing in Nashville. We conducted the traffic stop data work in collaboration with the Stanford Computational Policy Lab (SCPL), whose researchers performed the analysis. (The SCPL team’s more detailed report is included here as Appendix B.) The Metropolitan Nashville Police Department (MNPD) provided the necessary data, and has from the beginning shown a strong commitment to re-evaluating its traffic stop strategies and developing alternatives that can achieve public safety with fewer social costs. As the SCPL report shows, and as we summarize below, there are indeed notable racial disparities in traffic stops in Nashville. These disparities are higher for traffic stops around non-moving violations, such as broken taillights or expired tags. Disparity, however, is not necessarily evidence of discrimination. Any number of neutral factors, including officer deployment patterns or differences in rates of offending, may explain these and other disparities in the criminal justice system. MNPD explains these racial disparities in traffic stops on the ground that officers go where the crime is, and that in Nashville, high-crime neighborhoods tend to have larger minority populations. The SCPL analysis bears this out. However, even controlling for crime, unexplained racial disparity still remains. More importantly, the SCPL report shows that traffic stops are not an effective strategy for reducing crime. In particular, MNPD’s practice of making large numbers of stops in high crime neighborhoods does not appear to have any effect on crime. We make a number of recommendations, including that MNPD: • reduce the number of traffic stops • acknowledge black residents have been disproportionately affected by MNPD’s stop practices • monitor racial disparities on an ongoing basis • redeploy officer resources toward more effective crime-fighting tools • consider adopting a Neighborhood Policing strategy • post its department policies online • conduct a review of certain key policies such as use of force • conduct a review of training around use of force, traffic stops, and procedural justice • adopt a body camera policy with attention to transparency regarding the release of body camera footage In addition, we suggest that Nashville engage in a public process of strategic planning around public safety, bringing together the voices of the community and MNPD officials in doing so.

New York: Policing Project, 2023. 27p.

By Seleeke Flingai, Mona Sahaf, Nicole Battle, and Savannah Castaneda

The murder of George Floyd in May 2020 spurred a national reckoning around how Black people are viewed and treated by law enforcement and the criminal legal system. Some elected officials, prosecutors, and police have acknowledged their moral responsibility to pursue racial justice by examining racial disparities and inequities. This report addresses one such practice—non-traffic-safety stops. These occur when police stop and detain people for minor traffic violations that pose no identifiable risk of harm to people outside of the vehicle. Vera partnered with the Suffolk County (Massachusetts) District Attorney’s Office from July 2020 to March 2022 to study racial disparities in the criminal legal system. Vera’s analysis revealed that non-traffic-safety stops in Suffolk County are worsening racial disparities in traffic enforcement. This report shares findings from Vera’s analysis, along with proposed solutions that prohibit or deter such stops.

New York: Vera Institute of Justice 2022. 37p.

Katie Blum and. Jill Paperno

In recent years our country has faced a racial reckoning. One of the areas of focus has been racial bias in policing. In the following pages we will address the law enforcement practice of pretext stops – stopping individuals for a reason that may not be lawful but using a low-level traffic or other violation to justify the stop. The following report is our working draft of what will later be released as a comprehensive review of pretext stops in New York. In the coming months, Empire Justice Center will be gathering more information and feedback that will be incorporated into later reports. In Section III, the Introduction to this Report, we recognize that of the approximately 1,000 deaths of civilians during police-civilian encounters each year, approximately 10% occur during low-level traffic stops. We explain what pretext stops are, and how they came to be an integral part of modern policing. We preview the harm caused by pretext stops, further discussed in Section VII. In Section IV, Racial Bias and the Data, we review information gleaned from numerous studies, as well as two books – Pulled Over: How Police Stops Define Race and Citizenship, by Charles Epp, Donald Haider and Steven Maynard-Moody, and Suspect Citizens: What 20 Million Traffic Stops Tell Us about Policing and Race, by Frank Baumgartner, Derek Epp and Kelsey Shoub. These sources demonstrate that pretext stops are executed far more frequently on People of Color, with most studies focusing on Black and white drivers. Additionally, once stopped, Black drivers are more likely to be searched than white drivers. In Section V, The Law and Pretext Stops, we explain the cases that have led to the conclusion that absent proof of discriminatory intent on the part of a law enforcement officer, a high bar to reach, pretext stops are lawful. In Section VI, The Community Safety Question, we address findings that pretext stops provide minimal enhancement of community safety, reviewing studies that have addressed the frequency of seizure of contraband, as well as arrests and charges of individuals stopped. In Section VII, The Harms Caused by Pretext Stops, we consider whether these minimal community safety benefits are worth the many harms caused by pretext stops – racial disparities in how policing occurs, civilian deaths, officer deaths, and the resulting lack of trust in law enforcement and the criminal justice system. In Section VIII, Pretext Stops in Rochester, N.Y., we focus on the types of offenses that are the basis for some pretext stops in Rochester, New York, a city that has faced rising tension and civilian opposition to policing in recent years, and the racial disparities as well as geographic disparities in where these stops occur. We also review some of the statements and implicit recognition of racial disparities in policing by community leaders who have considered pretext stops.

Albany, NY: Empire Justice Center, 2023. 71p.

By David S. Abrams, Hanming Fang and Priyanka Goonetilleke

Police “stop-and-frisks” of pedestrians and motorists have become an increasingly controversial tactic, given low average rates of contraband discovery, incidents of abuse, and evidence of racial disparity. Study of the tactic by economists has been much influenced by Knowles, Persico, and Todd (2001; hereafter, KPT) who first suggested the use of a “hit rate” (contraband discovery rate per frisk) test to distinguish racial prejudice from statistical discrimination in highway searches by police officers. Models used by KPT and almost all subsequent literature (e.g., Anwar and Fang 2006) on the subject imply diminishing marginal returns to frisks. That is, if frisks decrease substantially, the rate of contraband discovery should rise, ceteris paribus. This is the first paper to test this assumption empirically using arguably exogenous variations in frisk rates (cf. Feigenberg and Miller 2022). 1 We study the period around the nationwide protests that followed the killing of George Floyd on May 25, 2020, after which police frisks dropped tremendously and rapidly. Using extremely granular data from Chicago, we find that hit rates increased as police frisks plunged, in line with the predictions of KPT.

AEA Papers and Proceedings 2022, 112: 178–183 ,2022. 7p.

By Travis Carter, Jedidiah Knode and Scott Wolfe  

This report presents the results from a racial/ethnic disparity analysis of Michigan State Police (MSP) traffic stops conducted in 2021. The goal of the analysis is to identify the extent of racial/ethnic disparities in MSP traffic stop behavior across MSP worksites (i.e., posts). The analyses are based on a leading empirical approach to assessing racial/ethnic disparities in traffic stop behavior—the veil-of-darkness (VOD). The analyses account for important structural differences across posts and their jurisdictions, such as the rate of violent crime and troopers per capita, as well as temporal factors that may shape traffic patterns and stop behavior (e.g., time of day, day of week) to help ensure the results are as informative as possible. Below, we briefly outline the methodology employed and summarize the main findings. When discussing the results from this report, it is important to recognize the difference between “disparity” and “discrimination.” Disparity in these traffic stop analyses refers to differences in racial/ethnic group representation based on presumed visibility of the driver. Disparity cannot identify intent, whereas discrimination inherently involves intent. Therefore, discrimination in traffic stop behavior refers to police officers intentionally stopping individuals based on their status in a racial/ethnic minority group. Discrimination can generate disparities by way of differential treatment of racial/ethnic groups, but disparities may also be the result of nondiscriminatory (e.g., environmental, situational, etc.) factors such as crime prevalence and driving pattern differences. This report and its findings can speak only to the extent of racial/ethnic disparity in MSP traffic stops. The data cannot ascertain whether racially discriminatory practices are occurring within MSP. Although disentangling disparity from bias is critical towards improving police practices, accurately identifying the existence of such disparity and its magnitude is an important precursor to this process. More information on the data collection process is provided in the body of the report. Next, we highlight the main takeaways from the analyses.   

East Lansing:  Michigan Justice Statistics Center School of Criminal Justice Michigan State University, 2022. 33p.

By Gabrielle T. Isaza, Robin Engel and Jennifer Calnon Cherkauskas 

Sobering centers offer a unique opportunity to reduce arrests for vulnerable populations while removing a person from a potentially dangerous situation. Despite the long and complex history of their use, little is known systematically about the effectiveness of sobering centers as an alternative to arrest. Only a handful of studies have examined the impacts of sobering centers on the criminal justice system, and these studies typically focus on a single site. To build the evidence on sobering centers, Arnold Ventures funded our research study assessing the utility of sobering centers as an alternative to arrest. This report is the first in a series detailing our multi-method and multi-site research study, launched in January 2020. In this research study, examine four primary research questions: 1. What are the patterns of policies and practices for police use of sobering centers as an alternative to arrest? What guides this decision-making? 2. What are the situational factors police use in practice to determine whether or not to use sobering centers as an alternative to arrest? 3. How do police balance and overcome policy and legal inconsistencies guiding the transport to and use of sobering centers? 4. When individuals are sent to sobering centers in lieu of arrest, does it alter their relative risk of recidivism or future contact with police? This report focuses on the quantitative findings of Phase I, disclosing the results of two national surveys—one for law enforcement agencies and one for sobering center facilities. Survey findings shed light on how police use sobering centers and the perceived benefits and barriers to their use. In turn, the survey findings also provide important insights on how to build effective partnerships and enhance the utility of sobering centers as an alternative to arrest.  

Arlington VA: National Policing Institute, 2022. 78p.

By Robin S. Engel,  Jennifer Calnon Cherkauskas, Nicholas Corsaro, Murat Yildirim

In 2002, the Pennsylvania State Police (PSP) was one of the first state police agencies to initiate traffic stop data collection voluntarily. The current data collection effort is based on foundational work conducted with the same research team for more than a decade, beginning with initial planning in 1999. After discontinuing the data collection program in 2011, the PSP renewed its traffic stop data collection effort in 2021, which now continues in partnership with the National Policing Institute (the Institute). Given the variety of factors involved in police stop and enforcement decisions, it is beneficial for agencies to identify and better understand trends and patterns to enhance their ability to interact with the public safely and fairly. The voluntary collection and analysis of traffic stop data is consistent with recommended best practice, demonstrates dedication to transparency and accountability to the public, and continues the PSP’s commitment to evidence-based policing practices. This report documents the findings from statistical analyses of data collected during all member-initiated traffic stops by the PSP from January 1, 2022 – December 31, 2022. These data are reported by individual troopers after each member-initiated traffic stop, gathered and compiled by the PSP, and transmitted weekly to the Institute’s research team. Throughout each section of this report, information is presented at multiple organizational levels, reflecting the PSP’s organizational structure consisting of four Areas, 16 Troops, and 88 Stations. Presenting information in this manner illustrates differences and similarities across organizational units. It permits the identification of organizational and geographic groups that may appear as outliers, providing opportunities for closer examination and focused attention by PSP officials.  

Arlington, VA: National Policing Institute, 2023. 169p.

By Shelley Hyland, Lynn Langton and Elizabeth Davis

This report presents data on the threat or use of nonfatal force by police against white, black, and Hispanic residents during police contact. This report describes the characteristics of the contact, the type of force threatened or used, and the perceptions that force was excessive or the police behaved properly during the contact. It also examines trends in the threat or use of force and the relationship between officer and driver race and Hispanic origin in traffic stops involving the threat or use of force. Data are from the 2002, 2005, 2008, and 2011 Police- Public Contact Surveys, which were administered as supplements to the National Crime Victimization Survey.

Washington, DC: U.S. Department of Justice Office of Justice Programs Bureau of Justice Statistics, 2015. 17

By Magnus Lofstrom, Joseph Hayes, Brandon Martin, and Deepak Premkumar

Stark racial inequity has long been a deeply troubling aspect of our criminal justice system. In recent years, traffic stops have emerged as a key factor driving some of these inequities and an area of potential reform. Are there opportunities to identify kinds of traffic stops that could be enforced in alternative ways—potentially improving officer and civilian safety, enhancing police efficiency, and reducing racial disparities—without jeopardizing road safety?

To explore this question, in this report we use data on 3.4 million traffic stops made in 2019 by California’s 15 largest law enforcement agencies to examine racial disparities in stop outcomes and experiences across time of the day, type of law enforcement agency, and type of traffic violation.

San Francisco: Public Policy Institute of California, 2022. 29p.

By Frank R. Baumgartner; Derek A. Epp; Kelsey Shoub

Suspect Citizens offers the most comprehensive look to date at the most common form of police-citizen interactions, the routine traffic stop. Throughout the war on crime, police agencies have used traffic stops to search drivers suspected of carrying contraband. From the beginning, police agencies made it clear that very large numbers of police stops would have to occur before an officer might interdict a significant drug shipment. Unstated in that calculation was that many Americans would be subjected to police investigations so that a small number of high-level offenders might be found. The key element in this strategy, which kept it hidden from widespread public scrutiny, was that middle-class white Americans were largely exempt from its consequences. Tracking these police practices down to the officer level, Suspect Citizens documents the extreme rarity of drug busts and reveals sustained and troubling disparities in how racial groups are treated.

Cambridge, UK; New York: Cambridge University Press, 2018. 294p.

By Greg Ridgeway

In 2002, the Cincinnati Police Department (CPD) joined with other agencies and organizations to improve police-community relations in the city. This report focuses on the analysis of racial disparities in traffic stops in Cincinnati. The authors find no evidence of racial differences between the stops of black and those of similarly situated nonblack drivers, but some issues can exacerbate the perception of racial bias.

Santa Monica, CA: RAND, 2009. 93p.

By Elizabeth Luh

Biased police officers may purposely mis-record, or mask, the race of citizens that they interact with in order to evade detection. Indeed, journalists uncovered widespread evidence of such masking among Texas Highway troopers from 2010 to 2015. I propose a new test of racial bias in the presence of masking that is more powerful than standard tests and is well-suited to explore the rich heterogeneity in bias. Using various data-driven techniques to detect masking, I estimate that 24% of 130,240 searches were masked, with over half being Hispanic drivers being mis-recorded as white when searches failed to turn up contraband. I find that Hispanic and white troopers are biased against non-white motorists, with Hispanic motorists being treated the most unfairly. Using my model, I also find evidence of institutional racial bias and ‘bad apple’ troopers across Texas.

Ann Arbor, MI: Department of Economics; University of Michigan at Ann Arbor2019. 45p.

By Jeremy West

Nonrandom selection into police encounters typically complicates evaluations of law enforcement discrimination. This study overcomes selection concerns by examining automobile crash investigations, for which officer dispatch is demonstrably independent of drivers’ race. I find State Police officers issue significantly more traffic citations to drivers whose race differs from their own. This bias is evident for both moving and nonmoving violations, the latter indicating a preference for discriminatory leniency towards same-race individuals. I show this treatment is unmitigated by socioeconomic factors: officers cite other-race drivers more frequently regardless of their age, gender, vehicle value, or characteristics of the local community.

Santa Cruz, CA: Economics Department, University of California at Santa Cruz, 2018. 37p.

By The U.S. Civil Rights Commission. Oklahoma Advisory Committee

In 1981, the Commission issued a seminal report on police practices in America, Who is Guarding the Guardians? Twenty years later the Commission issued a follow-up report, Revisiting Who is Guarding the Guardians? Both reports raised troubling concerns about insular police practices that undermine equal protection under the law. Now, forty years after the Commission’s first report on police practices, a number of public incidents involving police conduct have returned such concerns to the forefront of national conversation. The Black Lives Matter movement was founded in 2013 in response to the acquittal of George Zimmerman for the death of Trayvon Martin.1 The movement has increasingly gained national attention since its founding through organizing and demonstrations against racial inequality, particularly police use of force against Black people. High profile incidents of deadly force by police include the deaths of Michael Brown in Ferguson, MO, Tamir Rice in Cleveland, OH, Walter Scott in North Charleston, SC, Sandra Bland, in Prairie View, TX, and many others. In June 2020, protests against police use of force, particularly force against Black victims, became one of the largest protest movements in U.S. history, with about 15 million to 26 million people in the United States participating in demonstrations. 2 These protests started in response to the killings of Ahmaud Arbery, George Floyd, and Breonna Taylor. The movement calls for widespread police reform and accountability for allegedly race-motivated violence against people of color, as well as calling for broader race equity in the U.S.3 On June 6, 2020 an estimated half a million people participated in public protests in nearly 550 places across the United States. As of July 3, 2020, there had been an estimated 4,700 demonstrations in all 50 states.

Washington, DC; The Commission, 2021. 26p.

By Lynn Langton and Matthew Durose

Examines the characteristics and experiences of persons age 16 or older who were stopped by police during traffic and street stops, and their perceptions of police behavior and response during these encounters.

Examines the characteristics and experiences of persons age 16 or older who were stopped by police during traffic and street stops, and their perceptions of police behavior and response during these encounters. It describes the outcomes of traffic and street stops by the reason for the stop; demographic characteristics of the persons stopped; race or Hispanic origin of the officers; and whether a ticket was issued, a search was conducted, or force was used. It also describes variations in perceptions of the police across characteristics and outcomes of traffic and street stops. Data are from the 2011 Police-Public Contact Survey, a supplement to the National Crime Victimization Survey, which collects information from a nationally representative sample of persons in U.S. households on contact with police during a 12-month period.

Washington, DC: U.S. Bureau of Justice Statistics, 2013. 22p.

By Emma Pierson, et al.

To assess racial disparities in police interactions with the public, we compiled and analyzed a dataset detailing over 60 million state patrol stops conducted in 20 U.S. states between 2011 and 2015. We find that black drivers are stopped more often than white drivers relative to their share of the driving-age population, but that Hispanic drivers are stopped less often than whites. Among stopped drivers—and after controlling for age, gender, time, and location— blacks and Hispanics are more likely to be ticketed, searched, and arrested than white drivers. These disparities may reflect differences in driving behavior, and are not necessarily the result of bias. In the case of search decisions, we explicitly test for discrimination by examining both the rate at which drivers are searched and the likelihood searches turn up contraband. We find evidence that the bar for searching black and Hispanic drivers is lower than for searching whites. Finally, we find that legalizing recreational marijuana in Washington and Colorado reduced the total number of searches and misdemeanors for all race groups, though a race gap still persists. We conclude by o↵ering recommendations for improving data collection, analysis, and reporting by law enforcement agencies.

Palo Alto, CA: Stanford University, 2017. 24p.

By Magnus Lofstrom, Joseph Hayes, Brandon Martin, and Deepak Premkumar, with research support from Alexandria Gumbs

In this report, we analyze data for almost 4 million stops by California’s 15 largest law enforcement agencies in 2019, examining the extent to which people of color experience searches, enforcement, intrusiveness, and use of force differently from white people. While it is important to caution the reader that analysis of these differences is not causal, our analysis—which focuses in particular on differences between Black and white Californians—reveals notable differences.Black Californians are more than twice as likely to be searched as white Californians, at about 20 percent versus 8 percent of all stops. …hese disparities are driven primarily by traffic stops made by the 14 data-contributing police and sheriff departments (as compared with the California Highway Patrol). These findings can provide guidance for discussing which stops can safely be reduced to mitigate racial inequities, which may also reduce risks and injuries to both officers and civilians.

San Francisco, CA Public Policy Institute of California, 2021. 30p.

By Jeremy West

Nonrandom selection into police encounters typically complicates evaluations of law enforcement discrimination. This study overcomes selection concerns by examining automobile crash investigations, for which officer dispatch is demonstrably independent of drivers’ race. I find State Police officers issue significantly more traffic citations to drivers whose race differs from their own. This bias is evident for both moving and nonmoving violations, the latter indicating a preference for discriminatory leniency towards same-race individuals. I show this treatment is unmitigated by socioeconomic factors: officers cite other-race drivers more frequently regardless of their age, gender, vehicle value, or characteristics of the local community.

Santa Cruz, CA: Economics Department, University of California at Santa Cruz , 2018. 37p.

By Roland G. Fryer, Jr

This paper explores racial differences in police use of force. On non-lethal uses of force, blacks and Hispanics are more than fifty percent more likely to experience some form of force in interactions with police. Adding controls that account for important context and civilian behavior reduces, but cannot fully explain, these disparities. On the most extreme use of force – officer-involved shootings – we find no racial differences in either the raw data or when contextual factors are taken into account. We argue that the patterns in the data are consistent with a model in which police officers are utility maximizers, a fraction of which have a preference for discrimination, who incur relatively high expected costs of officer-involved shootings.

Cambridge, MA: National Bureau of Economic Research, 2018. 57p.