We've long been in favour of drug legalisation around here. One obvious reason is that it's your body, you decide what you'd like to put into it, food, other people's (yes, even other peoples') body parts or interesting chemicals. A second is that legalisation cannot be worse than the current disastrous situation of gross coruption of the body politic and society.
But there is always that worry: won't legalisation increase consumption? At which point there's an interesting economic argument that no, probably, it won't:
Many people, on both the pro and con side, recognize that inelastic demand is the core problem with most drugs. Inelastic means not very sensitive to outside influences: illegal drug abusers can’t/won’t quit because their demand isn’t responsive to the usual laundry list of things that cause people to modify their other demands: price, income, and externalities like danger.
One of the prime tenets of economics is that demand is either elastic or inelastic, but it isn’t both (other than when we assume demand as a straight line because it allows us to use algebra). Demand can adjust, and become more elastic with the passage of time, but it’s still unlikely to go from inelastic to elastic.
The very problem we perceive with drugs is that people will do near anything to keep getting them. Which is simply another way of saying that demand is inelastic. If demand is inelastic then legalisation is unlikely to increase consumption very much.
Even I'm not sure that this is perfectly true but I do think it is generally so.