I've heard this argument, and it makes sense -- medical morphine costs basically nothing compared to street heroin or oxycontin, so it seems like switching to legal supply of drugs could basically delete the profitability of the trade. Instead of a criminal gang making ~$75 from the sale of an oxy pill, some pharmacy makes $1-2 and society makes some taxes we can use to fund rehabilitation programs.

Question, though -- why does legal pot cost the same as illegal pot used to in places like WA? It seems there is still a large amount of profit to be made from growing and selling pot, although I guess (pretty much by definition) that money is no longer going towards criminal enterprise. Is it just high taxes?