STUDIES:
652/
“Whites… rate the police somewhat less favorably in terms of job performance, trustworthiness, and fairness when the force includes mostly black officers… [A] diverse police force is likely to suffer a loss of… legitimacy among whites as compared with black citizens."

Representative Bureaucracy, Race, and Policing: A Survey Experiment
Journal of Public Administration Research and Theory
Vol. 28 Issue 4, pp. 506–518,
2018
Comment on this study on its Twitter thread.