By Robert Doar

“Given New York Today, Could Anyone Lead It?” So bemoaned a 1991 New York Times headline after decades of failure and futility.1 Crime was endemic, schools were failing, poverty was pervasive, and the economy had stagnated. From John Lindsay to David Dinkins, mayor after mayor had tried to tackle these problems. They had all failed. After three decades of policy futility, New Yorkers were giving up. In 1991, surveys indicated that more than half of New Yorkers wanted to leave.2 Political leadership had come to regard the city’s ills as intractable pathologies. Daniel Patrick Moynihan, then New York senator, said at one public hearing on juvenile violence in 1993, “There is nothing you’ll do of any consequence, except start the process of change. Don’t expect it to take less than thirty years.”

Washington, DC: American Enterprise Institute, 2023. 10p.

By Jeffrey Fagan and Lila Nojima

Theories of rational behavior assume that actors make decisions where the benefits of their acts exceed their costs or losses. If those expected costs and benefits change over time, the behavior will change accordingly as actors learn and internalize the parameters of success and failure. In the context of proactive policing, police stops that achieve any of several goals—constitutional compliance, stops that lead to “good” arrests or summonses, stops that lead to seizures of weapons, drugs, or other contraband, or stops that produce good will and citizen cooperation—should signal to officers the features of a stop that increase its rewards or benefits. Having formed a subjective estimate of success (i.e., prior beliefs), officers should observe their outcomes in subsequent encounters and form updated probability estimates, with specific features of the event, with a positive weight on those features. Officers should also learn the features of unproductive stops and adjust accordingly. A rational actor would pursue “good” or “productive” stops and avoid “unproductive” stops by updating their knowledge of these features through experience. We analyze data on 4.9 million Terry stops in New York City from 2004–2016 to estimate the extent of updating by officers in the New York Police Department. We compare models using a frequentist analysis of officer behavior with a Bayesian analysis where subsequent events are weighted by the signals from prior events. By comparing productive and unproductive stops, the analysis estimates the weights or values—an experience effect—that officers assign to the signals of each type of stop outcome. We find evidence of updating using both analytic methods, although the “hit rates”—our measure of stop productivity including recovery of firearms or arrests for criminal behavior—remain low. Updating is independent of total officer stop activity each month, suggesting that learning may be selective and specific to certain stop features. However, hit rates decline as officer stop activity increases. Both updating and hit rates improved as stop rates declined following a series of internal memoranda and trial orders beginning in May 2012. There is also evidence of differential updating by officers conditional on a variety of features of prior and current stops, including suspect race and stop legality. Though our analysis is limited to NYPD stops, given the ubiquity of policing regimes of intensive stop and frisk encounters across the United States, the relevance of these findings reaches beyond New York City. These regimes reveal tensions between the Terry jurisprudence of reasonable suspicion and evidence on contemporary police practices across the country.

New York, NY: Columbia Public Law School, 2023, 61p.

By Andrew Bacher-Hicks and Elijah de la Campa

Millions of Americans—particularly young men of color—are stopped on the street by police
each year. This form of proactive policing has been embraced by cities across the country as a
way to maintain order in high-crime neighborhoods and deter more serious crimes before they
occur. However, civilian stops rarely lead to an arrest and little is known about the social
impacts of frequent, unproductive interactions with police. In this paper, we leverage the quasi-
random movement of New York City police commanders across police precincts to estimate the
net impact of stop and frisk policing on students’ long-run educational attainment. We find that
a commander’s predicted effects on stops—based on data from one precinct—is highly predictive of changes in average stops after that commander enters a new precinct. We find that increased exposure to police stops has negative effects on high school graduation, college enrollment, and college persistence. These effects are substantially larger for black students, the racial group overwhelmingly stopped by police. However, we also find increases in overall school safety and evidence of positive spillovers for white and Asian students, who are less likely to interact with the police directly. These results highlight the social effects of criminal justice policy and have important implications for inequality.

Working paper, 2020. 60p.

By Andrew Bacher-Hicks and Elijah de la Campa

In an effort to thwart crimes in progress and deter future incidents, police in the US conduct
millions of civilian street stops each year. Though this practice is commonplace in most large
urban police departments, little is known about the net impact of this strategy on crime. This
paper exploits the naturally-occurring movement of New York Police Department commanders
during the height of New York City’s Stop and Frisk program to estimate commanders’ effects on
civilian stops and their subsequent impact on crime. We generate predictions of commanders’ effects on stops in a precinct, conditional on neighborhood demographics, crime rates, and policing strategies. Commanders’ effects—estimated using data only from tenures in prior precincts—are highly predictive of observed stops in new precincts, which highlights the transferability of commanders’ tactical preference for stops. We find that a high-stop strategy decreases misdemeanor crime within a precinct, but has no effect on more serious felony offenses. Moreover, we find suggestive evidence that the decrease in misdemeanor offenses is partially offset by crime displacement to adjacent neighborhoods. We conclude by demonstrating that commander stop effects are uncorrelated with their effects on other proactive policing strategies, and that commanders trade off their ability to build police legitimacy in the community with their preference for stops. Contrary to broken windows theory, our findings suggest that stop and frisk tactics do not deter more

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  serious criminal behavior, and thus, police should consider alternatives to strategies that emphasize the proactive enforcement of low-level offenses.

Unpublished paper 2020. 71p.