This month marks 14 years since Portugal decriminalized the purchase, possession and use of all drugs – even cocaine and heroin. As Californians consider joining Alaska, Colorado, Oregon, Washington state and Washington, D.C., in legalizing the recreational use of marijuana, Portugal’s experience is instructive in setting realistic expectations and assuaging fears surrounding legalization.

Portugal saw a significant increase in drug use and abuse following the 1974 overthrow of its nearly 50-year authoritarian military dictatorship, as Portuguese returned from the country’s overseas colonies.

The epidemic reached its peak during the mid-1990s, and the country turned to decriminalization in 2000 (with the law going into effect in July 2001) largely out of desperation since law enforcement approaches had proven to be failures.

While drug smuggling and dealing remain serious offenses, drug use and the possession of a small amount of drugs are treated as administrative infractions, not subject to criminal law procedures...