You're assumptions and extrapolations about American culture are on par with picking the "very strong" version of a stereotype...maybe go for the weak to medium level yourself.
How would anyone control it? That's more than kinda Big Brother. And the inverse issue with legalization, or even just legalization for medical use, is that it drives down the price, thus increasing the accessibility of the product still being sold illegally...you know, the totally unregulated stuff.
Where are you from?