Portugal has decriminalized more than marijuana. They decriminalized "hard drugs" too like cocaine and heroin for example. Yet, in a few years, backed by some additional health policies related to drugs, they saw all metrics used to monitor drug usage improving a lot.

Here is a small article from Time about this counterintuitive, yet very interesting, "experiment" : http://www.time.com/time/health/article/0,8599,1893946,00.ht...