I live in New Zealand - where prostitution is legal (however it hasn't always been legal). Despite this however, STDs and other negative social impacts of prostitution don't seem to be apparent. Surely it's common sense - that is happens anyway. Plus, unlike drugs - supply and demand aren't likely to increase excessively, as (I know from where I live), it's still not something that is socially accepted even though it's legal.

So that's why it shouldn't be illegal .. and why it should be legal is that it would mean that the government can regulate it, and receive revenue from it.

I agree with the point someone said earlier, that if drugs were legalized, that would take away revenue from gangs/criminals that they are able to use for capital (the likes of guns). However, simple economics - if illegal drugs were legalized, then both supply and demand will increase. This then has health risks for more people, which then will become a huge social costs.

I don't know about different places in the world, but I know in NZ we have huge anti-tobacco, pro-smoke free programs/advertising etc. - however there are still too many people here smoking, and this has huge social costs.

So I believe, the social costs would outweigh any other benefits (government revenue, less gang revenue etc),