OK, actually my sis and I have been talking about this for years, it seems. We decided 21 and it should have the same type of laws alcohol has. Of course 18 seems reasonable because it's identical to smoking a cig., but a cig doesn't cause the same effects as a joint does. It causes a reaction that impaires your jugement. Must be 21 to purchase, smoke, got to coffee shops, and of course no driving while stoned. Of course many of the laws would be broken, just like drinking, but I think that this is the only type of the thing the Government would go for, if they ever do it at all... too bad we didn't have the same laws as the Netherlands. Legal pot and drinking at 16.