Trouble is, there's almost no empirical evidence backing the so-called "gateway theory," and a new study pokes another hole in the hoary old argument.
The study, based at the National Drug and Alcohol Research Centre, University of New South Wales, Sydney, Australia, evaluated the gateway theory using cross-national data regarding "consistency and associations of the order of initiation of drug use."
In layman's terms: Is there something about marijuana (or tobacco or alcohol) which leads one inexorably down the path to more addictive substances?
"We compared patterns and order of initiation of alcohol, tobacco, cannabis, and other illicit drug use across 17 countries with a wide range of drug use prevalence," the study's 23 co-authors say.
The results, using data from World Health Organization (WHO) World Mental Health Surveys from 17 countries, "suggest that the 'gateway' pattern at least partially reflects unmeasured common causes rather than causal effects of specific drugs or subsequent use of others."
"This implies that successful efforts to prevent use of specific 'gateway' drugs may not in themselves lead to major reductions in the use of later drugs," the study concludes.
In layman's terms: Marijuana doesn't make you do harder drugs, and stopping the availability of marijuana wouldn't reduce the demand for harder drugs.