by Kathleen Scalise
Dutch cannabis use and other case studies suggest that criminal penalties for smoking marijuana can be reduced without increasing levels of use, but that commercial access might substantially increase consumption, according to a new study by a Berkeley psychologist and a University of Maryland economist.
The study, which appeared in the Oct. 3 issue of Science, compares the Netherlands, which relaxed enforcement of marijuana laws in 1976, with the United States and other countries.
"For years we've heard arguments for and against drug legalization," said Robert MacCoun, professor of public policy. "There are lots of claims about the effects of the liberal Dutch cannabis policy, but the two sides disagree completely on what actually happened there."
He and co-author Peter Reuter, a public policy professor at the University of Maryland, found that Dutch rates of marijuana use are comparable to the United States despite radically different drug policies.
However, this statistic masks two important trends in the Netherlands: use remained constant and well below U.S. levels for years after marijuana was depenalized, but rose sharply when cannabis become broadly available at coffee shops in the '80s.
According to Dutch law, cannabis is illegal. But in 1976 the Dutch adopted a policy of non-enforcement for possession or sale of up to 30 grams of cannabis, slightly more than one ounce. (Few marijuana users consume more than 10 grams, or a third of an ounce a month.)
The Dutch also allowed sales at coffee shops, which can maintain inventories of up to 500 grams. During the early years, these shops were scarce and kept a low profile. MacCoun and Reuter argue that this initial "depenalization era" had little if any detectable effect on levels of use.
But in the 1980s, coffee shops grew in number-by at least 10-fold in Amsterdam, for instance-and became more accessible.
"You now find them in the central business districts, right next to bakeries and department stores," said MacCoun. "They do sell coffee, but if you ask, they'll show you a menu with samples of hash and different strains of marijuana."
Customers are predominantly young adults, including tourists, and prices are similar to the United States. The cumulative effect, said Reuter, "was to make cannabis readily available at minimal legal risk to interested Dutch adults."
During this latter "de facto legalization" era, the report found that "the prevalence of cannabis in Holland increased consistently and sharply." For example among 18-year-olds, those who admitted having used the drug climbed from 15 percent in 1984 to 44 percent in 1996.
While use in the United States and other nations also climbed sharply in the last four years, the jump in Dutch sales from 1984 to 1992 occurred in an era of flat or declining use elsewhere. This, said Reuter, seems to implicate the coffee shops as culprits in the increase.
"While correlation can't prove causation, it is striking that the expansion of the coffee shops was followed by a growth in use," he said.
The authors caution, however, that the upward trend may reverse itself. The Dutch recently reduced the limit from 30 grams to 5 grams and began aggressively enforcing regulations against promotion, closing the most problematic coffee shops.
Though the steep increase in use among the Dutch raises troubling questions about legalization, other aspects of the Dutch experience look promising.
"During the depenalization era, the Dutch stopped punishing low-level marijuana transactions without any detectable increase in use, much like the experience in states that decriminalized marijuana possession during the 1970s," MacCoun said. "So depenalizing drugs and allowing legal commercial sales should be considered two very different interventions."
The Dutch adopted their tolerant policy in part to separate the soft and hard drug markets, theorizing that this might weaken the so-called "gateway" link-the concept that marijuana users are more likely than non-users to move on to hard drugs.
This study suggests the Dutch may have had some success in this regard.
The probability of trying cocaine among marijuana users is 22 percent in Amsterdam, but 33 percent in the United States.
The work was funded by an Alfred P. Sloan grant to the RAND Drug Policy and Research Center.