I think it would depend how the government went about it. I imagine you would have to get a special permit to grow it. Prices would have to be able to compete with the black market, if they can't sell it for the same price or cheaper or if the quality weren't as good, people would continue to go to their dealers.

I will take what I can get on this matter. So long as I'm not considered a criminal anymore.

Oh and the age to use it would be 21 in the states and equivelant to the drinking age in other coutries.