So a pretty reasonable question you'd ask in the rest of the world is: Why aren't these cops prosecuted for excessive violence? The use of civil rights lawsuits in the US was a workaround for an already broken legal system that doesn't punish wrong doing by certain people.
The police and prosecutors need to work closely together to function. It's unreasonable to ask the prosecutors to then also prosecute police powers. It's biased and unjust—even when the actors are all doing their best to act in good faith.
- While the (especially Anglo-American) courtroom is adversarial, prosecutors shouldn't be at all compensated (money, promotion, etc.) by who they lock up. Something based on future crime rates would be much better.
- Rather than DA's needing the police, the police should need the DA. Arresting someone that isn't convicted should reflect very poorly on the police.
That side, both groups are badly in need of complete replacement, which makes it hard to talk how they ought to work together when the real "ought" goes so much further
We currently allow PDs to investigate themselves, which is a mockery of justice.
It ends at subpoena and arresting power. The courts would mediate disputes as they already do.
Until the concept of "Internal Affairs" dies and we get an actual independent investigative arm or some other strategy that will continue
The only time an outside investigator is called in, normally is because someone dies AND the public is upset about that death.
In fact, the most effective way for prosecutors to improve their crime rate would be to persecute the high-crime racial demographics until they move out of town.
[1] edit: the non-organized-crime kind
It's not great to rely on intermediate performance, but it is often less worse than the alternative.
What? A prosecutor’s purpose is not to prevent other crime nor to reduce recidivism. It’s strictly to ensure that crimes that do happen meet justice.
“Unsolved crimes” might be closer, but the prosecutors would definitely need to absorb the detective arm of the police branch at that point.
People testify because they feel greater loyalty to society as a whole than to the defendants.
Neither of those things are going to work against cops.