The RAND Corporation's Drug Policy Research Center released a study Monday that casts grave doubt on the validity of the "gateway theory," the intuitive but unproven notion that the use of marijuana leads to the use of harder drugs. The "gateway theory" has guided US drug policy for a half-century and has been used by prohibitionists to justify imposing tough penalties for even the possession of small amounts of marijuana. In recent months, drug czar John Walters and others of his breed have seized on the "gateway theory" to campaign against relaxing marijuana laws in the states.
While the RAND researchers found links between marijuana use and the subsequent use of harder drugs, they determined that the "gateway theory" was bunk -- or in the more diplomatic terms of the study's lead author, Andrew Morral: "We've shown that the marijuana gateway effect is not the best explanation for the link between marijuana use and the use of harder drugs. An alternative, simpler and more compelling explanation accounts for the pattern of drug use you see in this country, without resort to any gateway effects. While the gateway theory has enjoyed popular acceptance, scientists have always had their doubts. Our study shows that these doubts are justified," he said.
"The people who are predisposed to use drugs and have the opportunity to use drugs are more likely than others to use both marijuana and harder drugs," Morral said. "Marijuana typically comes first because it is more available. Once we incorporated these facts into our mathematical model of adolescent drug use, we could explain all of the drug use associations that have been cited as evidence of marijuana's gateway effect.
"If our model is right, it has significant policy implications," Morral said. "For example, it suggests that policies aimed at reducing or eliminating marijuana availability are unlikely to make any dent in the hard drug problem. When enforcement resources that could have been used against heroin and cocaine are instead used against marijuana, this could have the unintended effect of worsening heroin and cocaine use."
Still, ever-cautious RAND was not willing to call for marijuana legalization or decriminalization. "Even without the effects of a marijuana gateway, relaxing marijuana prohibitions could affect the incidence of hard drug use by diminishing the stigma of drug use generally, thereby increasing adolescents' willingness to try hard drugs," Morral said. "Moreover, marijuana itself can be a serious problem for those who become dependent on it."
The study is getting attention from academic drug specialists. "This is a very important study with broad implications for marijuana control policy," said Charles R. Schuster, a former director of the National Institute on Drug Abuse and now director of the Addiction Research Institute at Wayne State University. "I can only hope that it will be read with objectivity and evaluated on its scientific merits, not reflexively rejected because it violates most policy makers' beliefs." Would that it were so.