I'm sitting here waiting on the dryer to finish up reading through Understanding Power: The Indispensable Chomsky when I come across a perspective on the reason for keeping marijuana illegal that I hadn't considered before:
... ask yourself a simple question: how come marijuana is illegal but tobacco legal? It can't be because of the health impact, because that's exactly the other way around - there has never been a fatality from marijuana use among 60 million reported users in the United States, whereas tobacco kills hundreds of thousands of people every year 32. My strong suspicion, though I don't know how to prove it, is that the reason is that marijuana's a weed, you can grow it in your backyard, so there's nobody who would make any money off it if it were legal. Tobacco requires extensive capital inputs and technology, and it can be monopolized, so there are people who can make a ton of money off it. I don't really see any other difference between the two of them, frankly - except that tobacco's far more lethal and far more addictive.
That would help explain all of the institutional resistance to medical marijuana. Drug companies don't want you growing your own treatments, they want you lining up with at the pharmacies for their "cures" - I mean treatments since there's more money treating than there is curing.
Leave it to Chomsky to state the obvious in a way you've never thought of before.