The biggest obstacle to legalization, as I see it at any rate, is that the DEA and local LEA's have become just as addicted to drug money as the cartels they're fighting. Take away all the cash, convertible property and toys they confiscate from low and mid-level distributors on a regular basis (notice how they rarely, if ever, seem to catch the really BIG fish? Why do you think that might be, hm?) and they'll start freaking like crazy trying to figure out how they're going to pay for all the new armor and ordinance and helicopters and high-speed cruisers and what-all they've managed to accumulate over the years, thanks to our idiotic, Puritanical need to tell other people what they can or can't put into their own bodies.

And don't even get me started on the effect legalization would have on the for-profit incarceration industry...