I'm firmly on the "legalize drugs" side if only to get rid of the crime since that's more relevant to me.
That said, one of the "keep drugs illegal" guys from this debate (http://www.intelligencesquared.com/events/versus-drugs/) basically claimed legal drugs kill people. Tobacco is used by 1/3 of humanity and kills 5 million people a year. Alcohol is used by 1/4 of humanity and kills 2.5 million people. 1/20th of humanity uses illegal drugs, that includes people who claim to only use it once a year, and the drugs kill 0.5 million people a year. In other words legal drugs kill 10x the people of illegal drugs. So he extrapolates that if we legalize drugs real deaths by them will go up by as much as 10x.
He also believes after you legalize it the full force of big pharma and VCs and banks and big tobacco will be unleashed on promoting and marketing it. He claims you can google these plans and you can google the lobbyists talking to politicians about all the tax revenue that will come in by making it as big as alcohol etc.
I'm not saying I agree. I have no idea. The idea of it being promoted can be argued away by saying only the government will sell it. Maybe? Here in California there are plenty of shady stores offering instant consultation with a doctor to get your medical approval so you can then buy from them. The point being businesses are popping up. I have no idea what it would take for a giant company to decide to run this stuff.
Others claimed the crime deaths offset the drug deaths although if you check the stats they arguably won't be close. Even a doubling of drug deaths will be far more than drug related crime deaths.
You can also just claim you're more interested in a reduction in crime and even if more people die from drug related accidents. Of course if it's a reduction in theft related crime that's great but of course more intoxicated people could mean more unintentional deaths like drunk drivers?
Anyway, like I said I'm still firmly on the "legalize" side. This was just one of the first arguments against that made me pause.