Usually overlooked in discussions of the effects of the war on drugs is that the illegality of drugs stunts the development of ways to help drug addicts, such as the drug equivalent of nicotine patches. Thus, though the war on drugs may well have induced lower drug use through higher prices, it has likely also increased the rate of addiction. The illegality of drugs makes it harder for addicts to get help in breaking their addictions. It leads them to associate more with other addicts and less with people who might help them quit.Source: WSJ
Some evidence is available on the effects of Portugal's decriminalization of drugs, which began in 2001. A study published in 2010 in the British Journal of Criminology found that in Portugal since decriminalization, imprisonment on drug-related charges has gone down; drug use among young persons appears to have increased only modestly, if at all; visits to clinics that help with drug addictions and diseases from drug use have increased; and opiate-related deaths have fallen.He concludes:
The decriminalization of both drug use and the drug market won't be attained easily, as there is powerful opposition to each of them. The disastrous effects of the American war on drugs are becoming more apparent, however, not only in the U.S. but beyond its borders. Former Mexican President Felipe Calderon has suggested "market solutions" as one alternative to the problem. Perhaps the combined efforts of leaders in different countries can succeed in making a big enough push toward finally ending this long, enormously destructive policy experiment.