There are lots of issues around legalising drugs.
When you take an objective look at the cost of prohibition of drugs, the cost beggars belief- it soars into the trillions of dollars globally, both in terms of cost of policing, the cost of crimes, both social and in revenue terms, associated with feeding the habit, and the health costs commensurate with treating addicts buying, for instance, heroin adulterated with,say, cement.
And I am not sure that anyone, looking at the current pattern of drug use around the globe, could say the war has been won. So we are faced with more of the same; Vicious gangfights between those criminals seeking to control drug territories; lost revenue because non of this commerce is taxable, tremendous drain on policing resources, a drain of health resources, and an ongoing cost to the public.
The look at those drugs considered legal - Alcohol and Nicotine. Both addictive, both poisonous, both damaging to health, either directly or indirectly. So compare and contrast. For me, legalising all the recreational drugs except say Crack and Heroin would help in many ways.
It would mean the products could be manufactured and produced under licence, guaranteeing quality. It could be sold at prices that would drive criminals out the marketplace, reducing the need for as much crime to feed your habit and contributing money to the exchequer, which in turn could support better care and treatment for drug addiction.
International normalisation of things like cocaine, for instance, could turn that into a cash crop for some very poor countries, again raising living standards in those countries.
I know people are worried that legalising drugs would result in a huge surge in users, but I am not sure about the logic of that; Even were drugs legally available tomorrow, for instance, I would not take them - nor would most of the people I have spoken to about this. And the fact that they are currently illegal does not seem to deter those wishing to take drugs anyway.
So, pragmatically speaking, I think legalising the whole thing would offer more benefits that harm overall.
It would be at odds with a Government and a Health policy geared towards reducing consumption of nicotine and alcohol though,I accept that.
Portugal are trying something along these lines, as a kind of social experiment, and the last I had heard was that drug-associated crime was down, but I have not seen anything recently about the results they have seen.