Implicit bias training for police: Evaluating impacts on enforcement disparities.

Objective: The purpose of this study was to estimate the behavioral impacts of training police officers in implicit bias awareness and management.

Hypotheses: Training police in implicit bias reduces racial and ethnic disparities in stops, arrests, summonses, frisks, searches, and/or use of force.

Method: A cluster randomized controlled trial using the stepped wedge design was applied to 14,471 officers in the New York City Police Department, with a 1-day training delivered to clusters of police commands between May 2018 and April 2019 and outcomes measured with police records of individual events from April 2018 to May 2019.