Leaving aside the absurdity of telling people how to wear their pants, just contemplate the ironic path that brought us here. The style itself is an artifact of prison culture, where inmates' belts and shoelaces are confiscated and the standard-issue clothes never fit right. The style made its way back onto the streets where it entered popular culture. Now, in 2008, you can go to jail for 93 days to a year just for dressing like an inmate.
In an urban landscape already ravaged by decades of racial profiling and drug war demolition tactics, police have codified their own authority to stop and frisk people whose style of dress is already stigmatized by presumed criminality. The number of things young people in America can't get arrested for approaches zero at an exponential rate.