While I agree 100% that "bad cops" should be punished harsher than they are now (like MUCH harsher....people in positions of power should be held to a MUCH higher standard than regular Joe...and if they commit a crime while abusing that position of power, they should certainly never have any authority again, should probably spend their life in prison and maybe they need to die), I don't see the cops having too much power.
What power(s) would you be taking away from them?
Stop and frisk. The most obvious. Only an issue in one city, but that's also the largest in the country, so not moot.
And the protections against entrapment in the US are far weaker than in most countries.