In a compelling interview with Bill Moyers, the producer of The Wire, David Simon outlines how the drug war has destroyed the profession of the policeman. First, he points out how 25 years ago 30-35% of prisoners were incarcerated for violent crimes, and now violent crimes account for only about 7% of prisoners. He then explains how police get promoted by valuing "easy to go after" cases, and drug cases are easy. You find a guy who has drugs on him, and you charge him. Easy. And a cop can make an arrest every few days by just shaking up some guys in the right neighborhoods. So he can make a lot of arrests. Whereas the cop who spends his time investigating murders and rapes has to put in many, many hours to gather enough evidence to make a bust. So the guy who makes the drug collars (which is basically a non-violent crime) gets promoted.
And the guy who tries to solve crimes where citizens were actually hurt? He gets passed over and told to go make more arrests.