There are far too many laws against non-crimes, and the nature of police as a tax-funded monopoly is already inherently corrupting due to the incentives. Add in racism, quotas, and plain old psychological problems and you have a recipe for disaster.

And unfortunately, this isn't a US-only problem, although we do have the highest per-capita prison population in the world, which doesn't speak well for the government of the "land of the free."