It's about controlling the dangerous classes. The drug war is the perfect pretext to harass and intimidate whoever the cops feel like harassing and intimidating. I believe it was Nixon who said the drug war was a way to "target the blacks without seeming like we're targeting the blacks". Substitute poor for blacks and you have most of the drug war explained. Occasionally non-poor get caught up in the sweeps but they can almost always buy their way out. The drug war is a pretty good example of the judicial system behaving as a market. It isn't perfect but it works well enough for the wealthy. For the ruling class this is as it should be.
John Thornton