03/09/2024 | Press release | Distributed by Public on 03/09/2024 22:10
Alternative traffic enforcement is an emerging crime and justice issue prompted by efforts of dozens of jurisdictions throughout the United States. In response to documented dangers and disparities, they seek to change how some traffic violations are handled.[1] Specifically, these strategies try to increase public safety and reduce demands on officers by deprioritizing some traffic offenses and shifting enforcement responsibilities to alternative agencies or technologies. Most of these programs are in their infancy. Few have documented outcomes or formal evaluations to assess their effectiveness. As a result, there is little information about the potential impact of recent initiatives on public and officer safety, disparities, and other important outcomes, which provides a fundamental research opportunity.
This article provides an overview of the current state of alternative traffic enforcement practice and discusses opportunities for future research. By informing the field about this critical but understudied topic, we hope to encourage further examination and promote cutting-edge research as well as evidence-based policies and practices. The article first describes the issue and current state of U.S. alternative traffic enforcement strategies, highlighting challenges in measuring disparities. We then provide a summary of documented alternative traffic enforcement reforms, initiatives, and related research. The article closes with a description of future research opportunities.
Traffic stops are the most common reason people encounter police,[2] and data suggest that officers spend substantial time on traffic enforcement.[3] Several studies show that traffic stops and searches are associated with reduced motor vehicle crashes, injuries, and fatalities.[4] However, traffic stops can pose risks for the public and the police, and specific traffic enforcement strategies may perpetuate criminal justice contact disparities.[5]
Risks like these have caused some researchers to examine traffic stops. Although low-level traffic stops sometimes reveal more serious crimes, such as those involving drugs or weapons, data indicate they infrequently lead to discovered contraband.[6] Some studies find that limiting low-level traffic stops can be associated with fewer traffic crashes and could increase arrests for more serious traffic offenses, such as a DUI.[7] Reducing stops is not associated with increases in serious crime. Policy changes, such as deprioritizing investigative stops, have been linked with reduced assaults on police officers.[8]
Traffic encounters can be dangerous for police. Traffic-related deaths are a leading cause of officer fatalities, although some deaths may not relate to traffic stops. In 2023, five officers were killed in firearm-related incidents during traffic enforcement, and another 37 officers were killed in crashes or vehicle impacts. This accounts for almost a third of the 136 officer fatalities that year.[9]Beyond firearm-related deaths, the data do not distinguish which officer deaths result from traffic stops. Additionally, it is unknown how many motorists and officers are injured during traffic stops each year.
Police conduct more than 20 million traffic stops per year.[10] Although most traffic stops end without incident, recent high-profile deaths of Black motorists following traffic stops have prompted calls for reform.[11] In 2023, a total of 109 people were killed by police after being stopped for traffic violations.[12] Available data indicate that Black people were disproportionately killed by police compared to their share of the population. Although Black people were 12% of the population, 24% of individuals killed by police were Black in 2023. (This data does not indicate how many deaths were related to traffic stops.)
Racial disparities have been documented in traffic stops. This is exemplified by the community-developed terms "driving while Black" and "driving while brown," which describe non-white motorists' personal experiences of racial profiling in traffic stops.[13]
Several studies validate this experience, finding that Black motorists are more likely to be pulled over than white motorists.[14] Research also finds that Black and Hispanic motorists are more likely to be searched compared to their white counterparts.[15] Although non-white motorists are searched more frequently, multiple studies find that the "hit rate"- the odds of finding contraband - is the same or lower than the hit rate for white motorists. Lower hit rates for non-white motorists have been interpreted as evidence of racially biased motivation for traffic stops. Racial bias interpretations are also supported by findings that Black male drivers are more likely to be involved in stop-related searches that do not lead to an arrest.[16]
However, estimating disparities is complex. Studies use different methods to test for bias, making it difficult to discern disparities on a large scale or across studies and jurisdictions.[17] Some data and research studies suggest bias, but findings are mixed.
Recent traffic enforcement research attempts to overcome previous methodological shortcomings in measuring racial disparities. However, few evaluations rigorously measure the impact and effectiveness of alternative traffic enforcement programs, procedures, and policies on safety or disparities.
Some past research has documented disparities in traffic enforcement, but methodological and sample variations, coupled with limitations in estimation techniques, offer an incomplete understanding of systematic bias.[18]
One of the missing pieces is how traffic stop disparities are measured. Commonly used estimation methods involving population benchmarks or hit rates may fail to consider relevant factors in police contact and officer decision-making.[19]For example, methodologists note that using underlying population statistics (e.g., determining racial distributions based on inhabitants' residential addresses) does not accurately reflect who is at risk of being stopped and distorts risk estimations across groups. This impacts the accuracy of conclusions concerning officer bias. Additionally, behavior such as a motorist's demeanor is not captured in data but can influence officer search decisions, further distorting bias estimations. In practice, inaccurate or incomplete statistics and data can generate inaccurate disparity estimations[20] Further, prior research fails to adequately examine why identified disparities exist.[21]
Recent research to address previous methodological concerns has sparked further debate. For example, Grogger and Ridgeway's "veil of darkness" (VOD) hypothesis argues that bias can be detected if drivers' race distribution is different after sunset than during the day, which is when a motorist's race is easier for officers to discern.[22] Comparing the racial distribution of daytime stops to nighttime stops may avoid population benchmark problems. Using variations of the VOD hypothesis, two single-site studies report little evidence of traffic stop racial bias,[23] while one large-scale study (with data from nearly 100 million traffic stops in 21 states) finds the opposite.[24] Differences in sampling strategies may account for the mixed findings.[25] Recently, researchers funded by the Bureau of Justice Statistics developed a new quantitative method to test the VOD hypothesis that incorporates several considerations including providing a weighting method to account for seasonal driving patterns. When applying this method to an analysis of 50,000 traffic stops conducted by Michigan State Police in 2021, results suggests that stops conducted in daylight were more likely to involve Black drivers.[26]
Several U.S. localities have instituted alternative traffic enforcement strategies to reduce police resource burdens while also addressing racial disparities and negative public safety outcomes. We describe several of these efforts below.
Common alternative traffic enforcement strategies include deprioritizing minor traffic violation enforcement, shifting enforcement responsibilities to unarmed civilians, and using technology like red light cameras in lieu of in-person enforcement. New policies are often implemented with little to no research evidence to support changes; they may face challenges legislatively and with implementation. We reviewed policies and programs around the country and highlight examples below.[1] See Table 1 for all reviewed policies and programs. (Policy searches were conducted in summer 2023 and updated as of spring 2024. The results do not constitute a formal evaluation of all policies.)
In addition, scholars and advocates argue for programs and policies that do not directly involve the police. They believe these changes can improve traffic safety while decreasing police interaction. These strategies may be used alone or in conjunction with other alternative traffic programs, but racial equity has been identified as a primary concern.[34] These include:
Formal evaluations of alternative traffic enforcement strategies are still emerging, but some research on existing programs and technologies is available. We summarize these studies below.
This paper shows how research demonstrates the potential dangers present in traffic stops, but few evaluations measure the impact of alternative traffic strategies on public safety or disparities. Such rigorous evaluations are needed to understand whether these programs achieve their objectives or generate unintended consequences.
The need to measure the racial disparities in traffic stops has grown particularly urgent. Many recently implemented reforms were prompted by calls to reduce racial disparities among those stopped, searched, and arrested. Rigorous evaluations should include all alternative programs, including red light and speed cameras.
The research community also needs new, innovative, and more accurate ways to measure traffic enforcement disparities as well as greater consensus about how to best account for different levels of risk or exposure to police stops by age, race, ethnicity, and sex. Current research includes a variety of ways to measure risk, making it difficult to compare results across studies. Theoretical concepts like the veil of darkness could be further specified to ensure proper testing of hypotheses and comparability across studies.
It is important to also have consistent, comparable studies that examine how new traffic enforcement policies and practices impact officers, particularly officer safety. Researchers have opportunities to further assess the impact of traffic policy changes on police operations, cost, and officer productivity. Although some police departments are shifting traffic enforcement to nonsworn staff, additional research can address the impact of such policies on both the unarmed, nonsworn responders and the public.
Evaluation of policies related to traffic enforcement could expand beyond traditional law enforcement policies. For instance, in July 2023, Maryland passed a bill which prohibits specific types of cannabis-related evidence to be used as the sole basis for establishing reasonable suspicion or probable cause.[51] Clear disparities in statewide traffic stop data led to the passing of the bill, and its goal is to decrease the volume of investigative stops as well as warrantless vehicle searches. However, in early 2024, a new bill was introduced to eliminate these protections for motorists. This type of policy change and its associated debates should also be considered part of the conversation regarding alternative traffic enforcement.
NIJ plays an important role in this research. Since fiscal year (FY) 2018, NIJ has funded over $3 million in research related to traffic stops or traffic safety. Due to the continued need for more rigorous research and evaluation on these policies, NIJ released a solicitation for funding in this area for FY24 (Research and Evaluation on 911, Alternative Hotlines, and Alternative Responder Models).[52] With this solicitation, NIJ sought proposals to assess the impact and benefits of alternative traffic enforcement models. Awards are forthcoming.
Table 1: Alternative Methods of Traffic Enforcement in PracticeNote: The table represents results from review of policy searches conducted in summer 2023 with status updates as of spring 2024. Although it includes data on traffic stops and enforcement for some localities, the results do not constitute a formal evaluation of all policies. NIJ librarians and science staff completed all searches.