One of the first major studies to debunk the gateway theory was commissioned by New York City Mayor Fiorello La Guardia in 1938. The six year study, conducted by a team of scientists from the New York Academy of Medicine, was the most comprehensive, extensive marijuana fact-finding mission since the Indian Hemp Drug Commission released its monumental app…roximately 50 years earlier. Released in 1944 as “The LaGuardia Report,” the study found that: “The use of marijuana does not lead to morphine or heroin or cocaine addiction. The instances are extremely rare where the habit of marihuana (sic) smoking is associated with addiction to these narcotics.”[2][3]

“In 1972, President Richard Nixon appointed a panel of politicians and leading addiction scholars to examine federal policy regarding marijuana. The commission, headed by former Pennsylvania governor Raymond P. Schafer, contracted a study of 105 middle class California marijuana smokers to investigate marijuana’s alleged gateway potential. According to the commision’s findings, “incidence of other drug use was relatively low, [even among] frequent marihuana users.”

“The issue of marijuana’s purported gateway effect was explored yet again several years later in a federally contracted study for the Center for Studies of Narcotics and Drug Abuse of the National Institute of Mental Health. Directed by Drs. Vera Rubin and Lambros Comitas of the Research Institute for the Study of Man and conducted in Jamaica, the study was hailed as “the first intensive multidiscplinary study of marijuana use to be published.”[5] Summarizing the findings of the study in the July 4, 1975 issue of Science Magazine, Dr. Erich Goode of the State university of New York at Stony Brook wrote: “One of the more interesting findings to emerge from this study relates to the ‘stepping-stone’ hypothesis. Nothing like that occurs among heavy, chronic ganja smokers of Jamaica. No other drugs were used, aside from aspirin, tea, alcohol, and tobacco. The only hard drug use known on the island is indulged by North American tourists.”
“A fourth federally contracted study reaffirmed this conclusion some years later. Conducted by the Institute of Medicine of the National Academy of Sciences (NAS) and released in 1982, the 15-month study analyzed the habits of American marijuana smokers and offered one of the most comprehensive and balanced analyses ever compiled regarding marijuana and its effects. In regards to marijuana’s gateway potential, the study concluded that, “There is no evidence to support the belief that the use of one drug will inevitably lead to the use of any other drug.” “In March 1999, the Institute of Medicine issued a report on various aspects of marijuana, including the so-called, Gateway Theory (the theory that using marijuana leads people to use harder drugs like cocaine and heroin). The IOM stated, “There is no conclusive evidence that the drug effects of marijuana are causally linked to the subsequent abuse of other illicit drugs.”

The Institute of Medicine’s 1999 report on marijuana explained that marijuana has been mistaken for a gateway drug in the past because “Patterns in progression of drug use from adolescence to adulthood are strikingly regular. Because it is the most widely used illicit drug, marijuana is predictably the first illicit drug most people encounter. Not surprisingly, most users of other illicit drugs have used marijuana first. In fact, most drug users begin with alcohol and nicotine before marijuana — usually before they are of legal age.”

Marijuana Not A Gateway To Hard Drug Use, Rand Study Says “While the gateway theory has enjoyed popular acceptance, scientists have always had their doubts,” said lead researcher Andrew Morral, associate director of RAND’s Public Safety and Justice unit. “Our study shows that these doubts are justified.”
“According to a study to be published by the Centre for Economic Policy Research, London, cannabis does not lead to the use of hard drugs”