We are forgetting some cultural history here, as well. There was a very excellent two-part series in the Atlantic Monthly, I believe sometime in '96, that delved into the whole thing.
Basically, marijuana was first criminalized because the first people smoking it regularly were Mexican migrant workers, Black jazz musicians, and sailors who brought it from foreign ports. Criminalizing their preferred intoxicant was an excuse to keep them under the thumb.
As this sentiment prevailed, newspapers even started running headlines like, “Reefer Crop Expected, Thousands of Youth in Danger.” Texas police even claimed marijuana incited a thirst for blood in criminals. We all know about the Reefer Madness movie.
Then, in the '60s, when white hippie kids started smoking marijuana and getting busted, their parents began lobbying for decriminalization. Laws were relaxed through the '70s.
Along comes the '80s, and a group of parents get pissed off when they find roaches all over the lawn of their suburban home following a party thrown by their kids. The MADD movement is getting underway, so these parents use it to help their campaign against marijuana, which they throw into the whole DRUGS category. Just Say No is born, and we begin to see criminalization back en vogue.
In the '90s we started to see “three strikes” come about, and drug laws jump on board. The War on Drugs received unprecedented cash flow. The U.S. government even used profits from the sale of crack cocaine to finance the arms supply in the Iran-Contra affair (from the now-infamous San Jose Mercury-News investigative series on the subject). Here we are today.
The Atlantic Monthly article also analyzed all of the U.S. government drug czars, and how one in particular had a morphine habit. Sen. McCarthy is even implicated as having his own habit. This is all rather consistent, if you think about it, with the U.S. attitude toward drugs. Pharmaceuticals and similar drugs preferred by a mostly upper-class population are not only legal, but supported in Congress. Intoxicants preferred by middle and lower classes are heavily criminalized. I can go to jail for smoking pot, but a pharmaceutical company that produces a pill that kills thousands of people five years down the road gets support for further research.
Perhaps a way to start the legalization effort is to form a well-funded PAC with plenty of lobbyists. As this election has well illustrated, though, real issues never matter. The important ones are often demonized and kept at a safe distance from most politicians.