As I mentioned previously, I come at this issue from a standpoint of principles rather than pragmatics. I do not suggest that decriminalization would eliminate all drug related problems. But it will quite certainly curtail the opportunity for criminals to profit from its trade, just as there are virtually no social ills related to bootlegging of legalized drugs such as alcohol and tobacco. furthermore, if prohibition were a successful way of limiting drug abuse as you seem to believe, then come to the Downtown East-side some time and see for yourself how successful that strategy has been.
People advocate the solution to legalize it, saying it's as simple as that.
Well if it is a simple solution, then analyzing that solution should be simple too. The reasoning goes something like this: if it is legal, you take away the context of other illegal activity that makes the trade of it dangerous and at the same time profiting from its regulation and sale. The analysis of the reasoning? I contend that those advocating the solution barely analyze that reasoning. Instead they go ad-hominem saying that opponents are backward, not open minded, biased, prejudiced, etc.
What is missing in the reasoning behind legality is the nature of the contraband itself. It is NOT like alcohol or tobacco. It has extreme consequences to mental and physical health, and those consequences are immediate. They are extremely addictive, much more so than alcohol or tobacco. Comparisons such as, "viagra has more side-effects than marijuana" are silly.
These highly dangerous to health, mental health, and highly addictive substances could destroy society if use becomes more widespread. There is a limit to liberalization of rights to hurt oneself as one chooses. A significant number of citizens are incapable of responsible action in the face of vices. These people need to be controlled, and the way to control them vis-a-vis drugs is to keep them from ever having it. You forget that citizens also includes minors. Exposure to these substances at an early age, due to their widespread access, is disastrous.
Indonesia virtually puts to death everyone trafficking in drugs, including marijuana. While this is far extreme, the reason is that they cite the proximity of the availability of drug plants in South-East Asia, the push by some Australian citizens to profit from selling drugs, and that European societies lose entire generations to drugs. Indonesians do not want a waste-land of its citizens lost to drug addiction. As a consequence, their country is cleaner and more peaceful than vice-ridden Thailand, freer of sex and drug exploitation by foreigners. They hope to be an economic powerhouse like Singapore and Malaysia, whose drug laws are nearly as extreme.