The National Association for Citizen Oversight of Law Enforcement (NACOLE) released two reports on the current status of citizen oversight of the police in the U.S. today. The two reports are the most thorough assessments of citizen oversight available. Funded by the Office of Justice Programs of the U.S. Justice Department, the two reports cover the history of citizen oversight, the nature of the different forms of oversight, and issues related to the effectiveness of oversight. Among other things, the reports provide a precise estimate of the number of oversight agencies as of 2016: 144 agencies.
Read the first report, Joseph De Angelis, Richard Rosenthal and Brian Buchner, Civilian Oversight of Law Enforcement” A Review of the Strengths and Weaknesses of Various Models (2016) here.
Read the second report, Joseph De Angelis, Richard Rosenthal and Brian Buchner, Civilian Oversight of Law Enforcement: Assessing the Evidence (2016) here.