CASE STUDY
Assessing the Legality of Police Stops
LOCATION
New York, NY
ACTIVE
2019-2025
This research initiative assessed the legal and constitutional compliance of the New York Police Department’s (NYPD) street encounters and the accuracy of officers’ documentation of those encounters. CUNY ISLG convened a team of experts to analyze and determine the legality of encounters recorded on body-worn cameras (BWC) to better understand how frequently stops conducted by police are unlawful and to identify the characteristics of unlawful stops.
Challenge:
In 2013, the United States District Court in Manhattan found that the NYPD’s policies and practices related to “stop, question, and frisk” were unconstitutional. The Court ruled that the NYPD was violating the Fourth and Fourteenth Amendments of the US Constitution, because police were making stops without reasonable suspicion and because the stops were based on individuals’ race or ethnicity—and thus discriminatory. The Court formulated remedies, including the appointment of a Monitor, to oversee reforms designed to ensure that NYPD encounters with citizens met Constitutional and other legal requirements. This included the proper recording and reporting of stops, so they can be adequately evaluated.
To evaluate the NYPD’s progress and ensure implementation of those reforms, the Monitor required information on the full range of stops conducted by the NYPD. But many stops are not reported. This is particularly problematic because reported stops may differ in key ways from unreported stops.
Approach:
In 2021, the Monitor selected CUNY ISLG to conduct a study addressing fundamental questions about the constitutionality of stops, searches, and frisks conducted by the NYPD, including assessing racial disparities and the appropriate documentation of stops. To address these questions, the study examined over 2,200 selected encounters recorded on body-worn cameras (BWCs), involving more than 5,000 individuals, from over 1.5 million unique BWC recordings. This broad range of encounters included both stops reported by police and encounters that officers did not report as a stop.
Working with a team of retired New York state judges, we generated first-of-its-kind data about the nature of police-citizen encounters, including information about the legality of encounters and the reasons certain encounters are unlawful. This enabled quantitative analysis of the constitutionality of stops, including insight into differences by race and context on who initiated the stop and why, among other details. This data-intensive analysis followed a series of complex steps—from gathering BWC footage to selecting encounters and coding for features, to then coordinating with legal experts to classify and analyze encounters—to provide the Monitor and the Court with a comprehensive evaluation of the documentation practices of the NYPD and constitutional compliance.
Working with a team of retired New York state judges, we generated first-of-its-kind data about the nature of police-citizen encounters, including information about the legality of encounters and the reasons certain encounters are unlawful.
In short, the study found approximately 72 percent of stops were constitutional, 19 percent were not, and 9 percent had no consensus among the reviewers; 21 and 19 percent of stops involving Black or Hispanic people were found to be unconstitutional, compared to 11 percent of stops of all other races. For more findings related to the constitutionality and documentation of self-initiated stops, stops by Neighborhood Safety Teams, and other findings, see the full report.
Progress:
In spring 2025, we submitted our study to the Monitor. Our findings provided the Monitor and the Court with critical information on both underreporting and NYPD compliance with the Fourth and Fourteenth Amendments, as well as a more nuanced portrait of police-citizen encounters—and their compliance with citizens’ rights—than has been previously available. Besides data for the Monitor, the findings have informed a number of subsequent studies, including a Stanford study on using AI to analyze BWC recordings. We have also supported the Office of the Attorney General for New York State in two pattern and practice investigations related to stop practices and use of force.
For more information on the NYPD Monitor project, please contact Kathleen Doherty at kathleen.doherty@islg.cuny.edu.
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