Two recent studies should be the final nails in the coffin of the lie that has propelled some of this nation’s most misguided policies: the claim that smoking marijuana somehow causes people to use hard drugs, often called the “gateway theory.”

Such claims have been a staple of the White House Office of National Drug Control Policy under Drug Czar John Walters. Typical is a 2004 speech in which, according to the Albuquerque Journal, “Walters emphasized that marijuana is a ‘gateway drug’ that can lead to other chemical dependencies.”   

The theory presents drug use as a tidy progression in which users move from legal drugs like alcohol and tobacco to cannabis, and on to hard drugs like cocaine, heroin and methamphetamine. Thus, zealots like to warn, herb is bad because it leads to things that are worse than it.   

It’s a neat theory, easy to sell. The problem is, scientists keep poking holes in it — the two new studies being just the most recent examples.   

In one National Institute on Drug Abuse-funded study, researchers from the University of Pittsburgh tracked the drug use patterns of 224 boys, starting at age 10 to 12 and ending at age 22. Right from the beginning these kids confounded expectations. Some followed the traditional gateway paradigm, starting with tobacco or alcohol and moving on to cannabis, but some reversed the pattern, starting with cannabis first. Some never progressed from one substance to another at all. When they looked at the detailed data on these kids, the researchers found that the gateway theory simply didn’t hold; environmental factors such as neighborhood characteristics played a much larger role than which drug the boys happened to use first. “Abusable drugs,” they wrote, “occupy neither a specific place in a hierarchy nor a discrete position in a temporal sequence.”

Lead researcher Dr. Ralph E. Tarter told the Pittsburgh Post-Gazette, “It runs counter to about six decades of current drug policy in the country, where we believe that if we can’t stop kids from using marijuana, then they’re going to go on and become addicts to hard drugs.”   

Researchers in Brisbane, Australia, and St. Louis reached much the same conclusion in a larger, more complex study involving more than 4,000 Australian twins whose use of cannabis and other drugs was followed in detail from adolescence into adulthood. Then they matched real-world data from the twins to mathematical models based on 13 different explanations of how use of cannabis and other drugs might be related. These models ranged from pure chance, assuming that any overlap between use of cannabis and other drugs is random, to models in which genetic or underlying environmental factors lead to illicit drug use or those in which cannabis use causes use of other drugs, or vice versa.   

Their conclusion: “Cannabis and other illicit drug use and misuse co-occur in the population due to common risk factors (correlated vulnerabilities) or a liability that is in part shared.” Translated to plain English, the data doesn’t show that cannabis causes use of other drugs, but rather that the same factors that make people likely to try cannabis also make them likely to try other substances.   

In a final blow to the theory, researchers added that any gateway that does exist is “more likely to be social than pharmacological” because cannabis “introduces users to a provider (peer or black marketeer) who eventually becomes the source for other illicit drugs.” So, the gateway isn’t herb; it’s laws that put it into the same criminal market with speed and heroin.

The lie that marijuana somehow turns people into junkies is dead. Officials who insist on repeating it as a way of squelching discussion about common-sense reforms should be laughed off the stage.

* Mirken is director of communications for the Washington DC-based Marijuana Policy Project, online at mpp.org.