Portugal's drug problems PLUMMETED after decriminalizing usage in 2001!
Theorizing that focusing on prevention and treatment rather than in jailing users, Portugal tried decriminalizing the use and possession of heroin, cocaine, marijuana, LSD and other illicit drugs.
Five years later, they found that the number of street drug overdoses had dropped from 400 to 290 annually, and the new number of HIV cases linked to drug use dropped from 1,400 to about 400. Dealing drugs is still illegal; however, the users aren't jailed. Instead they are put in front of a panel that includes at least one lawyer or judge and a health or social services worker. The panel can recommend treatment, a small fine, or no sanction.
On the other hand, studies have shown that lifetime usage of drugs has increased slightly since the introduction of this policy, showing the tradeoff a society must make between penalizing drug usage versus trying to lessen the social problems that they cause.