As Jack Shafer says, everyone should read Ben Wallace-Wells's 15,000-word Rolling Stone cover story on how "the United States has spent an estimated $500 billion to fight drugs—with very little to show for it."
One key tidbit here is that Bill Clinton's first drug czar, Lee Brown, actually had non-crazy ideas about drug policy—even endorsing a RAND study showing that treatment was a better way to tackle the drug problem than throwing millions of black men in prison and gunning down traffickers overseas. But Brown was a poor spokesman, and soon Newt Gingrich came to power in Congress, at which point Clinton, worried about appearing "soft" on drugs, appointed Gen. Barry McCaffrey, who gave us pointless anti-marijuana ads and Plan Colombia.
It's a sobering reminder that, even though Barack Obama and John Edwards are criticizing the "war on drugs" now, the pressures to stay the course once in office are fairly overwhelming. As for Hillary Clinton... well, as Marc Ambinder notes, she's recently come out against applying the new guidelines on crack sentencing to current prisoners. It's a modest proposal—affecting about 20,000 crack offenders who were punished under the old, stricter guidelines—but utterly sensible, and the fact that Clinton's against even that is a decent indication that she isn't really planning to challenge the drug-war status quo. (The same goes for all the Republicans, save, perhaps, Huckabee.)
P.S. Curiously enough, Wallace-Wells suggests that Chris Dodd—who now has one of the more liberal drug-war stances around and supports marijuana decriminalization—might've been partly to blame for Plan Colombia. Rumor has it that Dodd originally pushed the plan so as to benefit the Blackhawk helicopter manufacturer in his home state. Rand Beers offers Rolling Stone only this cryptic comment: "Much has been made of the notion that this was Dodd looking to sell Blackhawks to Colombia. ... [pause] I am not in a position to tell you it didn't happen."