Banning doesn't reduce use. Banning just gives criminals control of drugs. Ever heard of the prohibition of alcohol? That didn't work and neither are the prohibition of other drugs. Why aren't we trying a different approach?
15,000,000 people in the USA have been imprisoned because of marijuana use. Marijuana is a gateway drug to what drugs?... It is a proven gateway drug to tobacco, which is serious killing 400,000 people a year. Marijuana is not a proven gateway to harder drugs like cocaine or heroin. It even has not been proven to impair people's driving ability. Thousands of years of use and there are no reported deaths due to marijuana consumption.
Prescription drugs, cigaretts and alcohol are the only drugs killing people left and right. Two thirds of prisoners are there for drug related activities. A huge amount of police work is devoted to these offenders instead of fighting what I would consider real crime.
Some drugs definitely need to be controlled. Things like heroin, PCP, MDMA, Crystal Meth cause long term psychological and physiological damage and need to be heavily warned against. Things like Marijuana, Mushrooms, salvia divinorum, catha edulis, peyote, these drugs have long been a part of peoples' cultures and have shamanic religious roots. To completely ban them with threat of a prison sentance when there is little or no evidence for long term consequences is non-sensical and a breach of our civil liberties. Do we really have the money to be snooping around to see what shamanic plants are growing in people's gardens?
I don't smoke cigaretts because of what I learned in middle school and high school about what damage they do to people's lungs. That's all you need to know about successful drug policy. Let facts fight the drug war, not police. Treat addicts in clinics not prisons. Compassion can solve are problems much better than fear and disinformantion.