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Could make it 3rd party state level watch dogs. Acceptable use of force requires familiarity with the culutre of the area as well as recent happenings.
The bulletin said the Justice Department as well as the International Association of Chiefs of Police would take part in an "independent, external review" requested by the city to assess the Memphis Police Department's special units and use-of-force policies.

I wish there could be an independent, federal review of all use of force cases. Allowing the police to investigate themselves is not working. Neither is expecting the local DAs, who depend on their cooperation, to hold them accountable. >

I'm assuming you mean use of deadly force cases. Reviewing all use of force cases would require a federal agency with tens of thousands of employees to focus on only that. 
All use of deadly force cases are reviewed by a state agency, the TBI in the Memphis incident, not the agency involved.