Police, Judiciary & Law Enforcement
Therein lies your problem: once you allow the Police ,FBI etc. to take on the role of Law Enforcement, which belongs with the judiciary, rather than the law of deterrence, detection and apprehension of criminals, then the 'Judge Dredd' syndrome will take over, as can be seen.
The system whereby senior law officials are elected is deeply flawed and open to politicisation and corruption, with areas of criminality becoming 'pet projects' for DA's/Judges in the run-up to election time.
I am also continually amazed by the apparent reluctance of large sections of the US populace resistant to change in the 'Holy of Holies', the Constitution, given the regular reference to the various Amendments...
Before you ask, no, I don't have an answer to your problems, apart from suggest that you rein your police forces back in, de-militarise them, and remind them who's who in the 'Protect & Serve' relationship.