Legalisation would not only drive away the gangsters; it would transform drugs from a law-and-order problem into a public-health problem, which is how they ought to be treated. Governments would tax and regulate the drug trade, and use the funds raised (and the billions saved on law-enforcement) to educate the public about the risks of drug-taking and to treat addiction. The sale of drugs to minors should remain banned. Different drugs would command different levels of taxation and regulation. This system would be fiddly and imperfect, requiring constant monitoring and hard-to-measure trade-offs. Post-tax prices should be set at a level that would strike a balance between damping down use on the one hand, and discouraging a black market and the desperate acts of theft and prostitution to which addicts now resort to feed their habits.
The Economist on how to stop the drug wars: the same way we stopped the alcohol prohibition wars.