There are a vast wealth of carefully documented instances with video evidence of police misconduct in the US. Often times the departments internally investigate and find no wrongdoing, even when it's on video or issue a slap on the wrist and allow the officer to continue his job with little or no consequence, even as we watch video evidence with lawyers explaining that the police interactions are blatantly illegal. Often the victims sue and win, but the taxpayers cover this consequence rather than the officers.
Even after the nation broke out in massive historic protests of police misconduct, perhaps shining the biggest spotlight on the issue ever likely to occur, seemingly very little has been done to meaningfully address this problem.
It seems like every time I see the topic brought up, the obstacle to reforming the police departments involved is
"The police unions are too powerful."
and
"Police are sheltered from consequence by qualified immunity."
But neither of those things seem to have solutions obvious to a layperson, as both of them have a fairly clear role in allowing police to do their jobs and protect their rights. On the other hand, clearly many police departments and municipal governments can't be reliably counted on to hold officers accountable. So I'd like to ask:
How can police be held accountable for wrongdoing without deterring their ability to enforce the law? To narrow down the scope of this question, I'm looking for political avenues at the state federal level of government.