It's cop culture that has to change.
There's no two ways about it. The institutional racism and blue wall of silence is the problem. The only people who can fix this are the members of law enforcement themselves. It's all on them. Until they expunge racist and trigger happy cops from their ranks the notion of a few bad apples is meaningless.
I'll be the first to admit that police work is dangerous and many cops will demonstrate exceptional bravery under extraordinary circumstances. But same cop who will rush into a bank, guns a blazing, to resolve a hostage crisis is the same cop will also stand and watch another cop beat, brutalize, and murder you and will happily lie to cover up the crime.
Sorry Obama. That's not most cops are good. The bar is set pretty for low when "good cop" is defined by "he didn't actually pull the trigger" he just falsifies reports and lies in court as a matter of standard operating procedure.
At some point the institution itself has to take responsibility. Just like the Catholic Church with their pedophile priest issues you cannot ignore the complete corruption of your culture and expect anyone to take you seriously.