in the number of ER patients who had used marijuana than in states that did not decriminalize the drug.
However, the study also found that by 1978 the proportion of marijuana users among ER patients was about equal in states that did and did not decriminalize marijuana; prior to decriminalization, states in which marijuana continued to remain illegal had higher rates of marijuana use than those that eventually legalized the drug. In contrast to marijuana use, rates of other illicit drug use among ER patients were substantially higher in states that did not decriminalize marijuana. Thus, there is more than one possible explanation for the relatively greater increase in marijuana use in the decriminalized states: on the one hand, decriminalization may have led to an increased use of marijuana; on the other hand, where marijuana remained illegal, people may have been less likely to discriminate between it and other illicit substances, a view that would tend to increase the use of hard drugs.
In 1976 the Netherlands adopted a policy making it legal for individuals to possess up to 30 grams of marijuana. Research indicates that little change in marijuana use occurred for seven years following this change in policy; however, in 1984, when “coffee shops” that sold marijuana began to spread throughout Amsterdam, marijuana use started to increase. During the 1990s, marijuana use continued to increase in the Netherlands at the same rate as in the United States and Norway—two countries that strictly forbid the sale and possession of marijuana. Nearly equal percentages of American and Dutch 18 year olds were found to have used marijuana during this period, while Norwegian 18 year olds were about half as likely to have used marijuana. Although these results offer little evidence that the Dutch decriminalization policy itself led to increased levels of marijuana use, it appears that the commercialization of marijuana sales may have done so.
According to the most recent National Household Survey on Drug Abuse, significantly fewer children between the ages of 12 and 17 reported that they perceived marijuana as a “great risk of harm” in 1997 than in 1996.36 At first glance this might seem to validate the fear that the medical marijuana debate of 1996—prior to passage of the California medical marijuana referendum in November 1997—had caused more teenagers to believe that marijuana use is safe. But a closer analysis of the data show that, de-