I think the argument against is pretty obvious, however, the argument for is pretty interesting.
Should a governing body be allowed to tell people what it can and cannot do with their bodies?
Surely, it would save a lot of police money by allowing drugs to be filtered in legally.
It is fair to say that anyone who wants to take heroin for example is already doing so, but is committing crimes to fund it. Should the Government then give heroin away for free? So they know that its pure and can conduct a needle exchange etc. Heroin is fairly cheap to produce anyway.
Its an interesting topic. My standpoint is that they should not be legalised as the simple ecomonics say that as soon as it is legalised (or given away for free), then the supply and the demand for all drugs, but most worringly, Class A drugs will go up. Surely one thing that sets the civilised world apart from the developing world is the funds and ability to keeps things such as guns and drugs illegal.