it's bad enough you have drunk idiots running people over, legalise drugs and they become social habits even more, now you will have a new group of incapacitated people out there causing more havoc.
As it is, on a daily basis you see people having more than the legal limit of booze and driving, saying " it doesn't affect me".. that's just going to happen with marijuana if it's legalized. taxing it is no excuse.. that's just the gov't profiting off letting its citizens kill themselves.