There's a problem though. If you legalize marijuana and get rid of the cartels, then what? Are you just going to make that giant industry aroudn drug enforcement go away?
The point is, there is organizational inertia regarding lobbying etc which more or less guarantees that Congress cannot act on this.
The best thing is to force a Constitutional crisis by states refusing to cooperate with federal drug enforcement. Given the recent health care reform case, the federal government has far fewer options than they did before the ruling on the Medicaid expansion issue there. They certainly cannot cut off all funding, and certainly cannot even cut off a large amount of funding.
No, you just take the people who used to enforce prohibition and make them collectors of taxes on the newly-legal substance.
This would not be a new concept. For most of the period alcohol prohibition in the US, for instance, Federal enforcement of the prohibition laws was the responsibility of the IRS and the Treasury Department (http://en.wikipedia.org/wiki/Bureau_of_Prohibition), because of those agencies' long experience as collectors of alcohol taxes. (When you hear hillbillies in old movies complain about "revenuers," they're complaining about Treasury agents who shut down their untaxed backwoods stills.) And the Prohibition Bureau's successor agency, the Bureau of Alcohol, Tobacco and Firearms, was part of the Treasury from the repeal of Prohibition until the big reorganization after September 11.
