In the face of a growing number of deaths and cases of HIV linked to drug abuse, the Portuguese government in 2001 tried a new tack to get a handle on the problem—it decriminalized the use and possession of heroin, cocaine, marijuana, LSD and other illicit street drugs. The theory: focusing on treatment and prevention instead of jailing users would decrease the number of deaths and infections and they have been successful.
Edit: Since 2001, possession of any drug for personal use has been decriminalized, though sale and trafficking are still criminal offenses. One can still be arrested and fined for using cannabis in public, or be accused of drug trafficking if in possession of more than 25 grams.