Learning About Police Bias: Prosecutors and Police Before and After Body-Worn Cameras

Two behaviors could lead prosecutors to perpetuate police bias. First, prosecutors may accept information in police reports at face value. Second, they may misinterpret police reports due to inaccurate beliefs about the extent of police bias. Repeated exposure to biased information may further distort these beliefs; for example, a prosecutor who consistently reads reports that associate black people with criminality may internalize this association.

Our research investigates these behaviors by studying the staggered rollout of police body-worn cameras (BWCs) across North Carolina between 2014 and 2019. BWCs are designed to record police interactions with the public and are typically mounted to officers’ chests or belts. Footage is routinely shared with prosecutors and defense attorneys, occasionally with judges, and rarely with the public. Although BWC footage is sometimes blurry or incomplete, it may provide more objective accounts of arrests than police reports.

Our findings reveal that BWCs reduced incarceration rates for black people by 10.5 percent. Our findings also suggest that BWCs increased incarceration rates for white people by 2.0 percent, but this effect is not precise enough to rule out the possibility that there was no effect. Similar reductions in disparities occurred for other outcomes, including conviction rates and jail time. Furthermore, the reduction in incarceration for black people was driven primarily by changes in post-arrest decisions rather than by fewer arrests. While arrest disparities did fall, this change was concentrated in low-level offenses that almost never lead to incarceration. These findings suggest that prosecutors had previously misinterpreted information from police, either because they held biased beliefs or treated police reports as definitive accounts.

Additionally, we surveyed 203 North Carolina prosecutors in 2020 and linked their responses to the half-million cases they handled between 1995 and 2019. First, our survey investigates prosecutors’ tendency to uncritically accept police reports. Our findings show that prosecutors who expressed greater certainty in the accuracy of police reports increased incarceration disparities relative to other prosecutors in their office who worked on the same types of cases at the same time. Thus, prosecutors who put more weight on police reports increased disparities. However, once BWCs were introduced, all prosecutors—regardless of their degree of skepticism toward police reports—reduced racial disparities to the level of the most skeptical prosecutors without access to BWC footage. One interpretation of this pattern is that BWCs enabled prosecutors to cross-check police reports, making their baseline trust in police reports less consequential. Another interpretation is that BWCs deterred police from writing biased reports.

Furthermore, our survey examines how implementing BWCs changed prosecutors’ beliefs about racial differences in crime. We measured each prosecutor’s level of exposure to BWCs based on when they were hired and when their county adopted BWCs. Our findings show that prosecutors with more exposure to BWCs believed that disparities in the criminal justice system were driven more by racial bias and less by racial differences in crime. In addition, prosecutors with greater BWC exposure tended to reduce incarceration disparities relative to other prosecutors in their office. This shift in beliefs likely does not reflect changes in prosecutor composition: Turnover rates did not change when BWCs were adopted, and prosecutors with more BWC exposure were not significantly more likely to be black or politically liberal. Nor does this finding reflect a broader shift toward progressivism: BWC exposure does not correlate with prosecutors’ opinions on the extent of labor market discrimination or support for affirmative action in hiring.

Our research suggests that BWCs provide prosecutors with more accurate information about arrests, which reduces racial disparities in incarceration and changes prosecutors’ beliefs about the sources of racial disparities in the criminal justice system. This implies that reforms such as implementing BWCs—which target the quality and objectivity of information flowing through the system—may be as important as reforms targeting the actors within it.

The broader lesson extends well beyond prosecutors. In hiring, lending, college admissions, and many other high-stakes settings, downstream decisionmakers rely on information produced by earlier actors whose judgments may be biased. Without an independent check on that information, even experienced and well-intentioned professionals may absorb and perpetuate the biases embedded in what they read. Changing the information environment may be an effective way to reduce the resulting disparities.

Note
This research brief is based on Emma Harrington and Hannah Shaffer, “Learning About Police Bias: Prosecutors and Police Before and After Body-Worn Cameras,” Social Science Research Network, February 20, 2026.