Several scientific studies have refuted the idea that cannabis consumption would lead to getting hard drugs (e.g., cocaine and heroin). But it is still prevalent in the collective imagination.
Even US President Joe Biden used to think that cannabis is a gateway drug. Still, he has changed his position over time.
However, when discussing cannabis, those who oppose legalization claim the Gateway Drug Theory, a hypothesis in which the use of cannabis would lead to the use of so-called hard drugs, such as cocaine and heroin.
This assumption has also fueled the idea that there is no distinction between soft and hard drugs. Even today, the concept of the absence of difference between soft and hard drugs is one of the main reasons why many governments do not legalize cannabis.
A brief history of the Gateway Drug Theory
The Gateway Drug Theory dates back to the 1930s. Harry Anslinger, head of the Federal Bureau of Narcotics, campaigned against cannabis after actively participating in the campaign against alcohol, which remained illegal in the United States of America from 1920 to 1933. In that period, Anslinger created a campaign against cannabis. He used the media as a propaganda tool to spread the idea that cannabis was a harmful substance that led people to commit criminal acts and violence.
The propaganda against cannabis began mainly with its name: marihuana (or marijuana). This term, probably of Mexican origin, had been popularized by Anslinger during the propaganda against cannabis and connoted with a negative meaning.
From words to deeds
The Federal Bureau of Narcotics collected a series of crime reports claiming that the trigger behind those dramatic events was the use of cannabis. The so-called Gore Files reported stories of violence, rape, and murder by people who had consumed cannabis.
The propaganda against cannabis perpetrated by Anslinger led to enacting the Marihuana Tax Act of 1937. The law did not expressly prohibit the consumption, sale, or cultivation of cannabis plants, but it made creating a business impossible.
La Guardia Report
Fiorello La Guardia, mayor of New York City from 1934 to 1945, opposed the propaganda of Anslinger’s Federal Bureau of Narcotics. In 1938 he created a commission of inquiry made up of doctors, professors, and researchers to understand the real effects of cannabis on health. The study, released in 1944, highlighted the absence of correlation between addiction and cannabis use, no relationship between cannabis consumption and episodes of violence and criminality, and no cannabis-induced switch to hard drugs.
Anslinger’s reaction to La Guardia Report was not long in coming. He called “unscientific” the report and sued Mayor La Guardia, the New York Academy of Medicine, and the members who took part in the study. Moreover, he halted all cannabis researches between 1944 and 1945. He also commissioned the American Medical Association (AMA), which opposed the Marihuana Tax Act of 1937, to publish a study reflecting government positions.
In 1972, former US President Richard Nixon appointed politician Raymond Shafer as President of the National Commission on Marijuana and Drug Abuse (also known as the Shafer Commission). The commission’s goal was to evaluate the real effects of cannabis and a potential reschedule of cannabis within the Controlled Substances Act of 1970, which entered into force in 1971.
The study’s results entitled ‘Marihuana – A Signal of Misunderstanding’ debunked the Gateway Drug Theory. Still, it did not lead to a rescheduling of cannabis. The report also stated that the study commissioned to the AMA by Anslinger had no scientific value.
Finding science-based evidence to support the Gateway Drug Theory
Although La Guardia Report and the Shafer Commission debunked the Gateway Drug Theory, the studies of Kandel and DuPont tried to back up the Theory.
The studies of the American sociologist Denise Kandel had focused on the use of legal and illegal drugs. Through longitudinal studies, Kandel formulated in 1975 the hypothesis that narcotic substances were triggered by legal drugs, such as alcohol and tobacco.
The study observed that alcohol and tobacco were necessary intermediates between nonuse and cannabis. “Whereas 27 percent of high school students who smoke and drink progress to marihuana within a 5- to 6-month follow-up period, only 2 percent of those who have not used any legal substance do so. Marihuana, in turn, is a crucial step on the way to other illicit drugs,” the study read.
In his book Getting Tough on Gateway Drugs: A Guide for the Family (1984), Robert DuPont, an American psychiatrist, laid the socio-psychological foundation for cannabis as a gateway drug. DuPont described cannabis as one of the most dangerous drugs. According to DuPont, anyone taking cannabis will almost certainly switch to hard drugs.
Both Kandel and DuPont relied on statistics that hard-drug users had also had experience with cannabis use. But their theories don’t find causality between cannabis use and hard drug use.
Debunking cannabis as a gateway drug
Most people who use cannabis do not use other so-called hard drugs. The National Institute on Drug Abuse (NIDA) said that most people who use marijuana do not use other, “harder” substances. Instead, the institute supposed that people more vulnerable to drug-taking are more likely to start with readily available substances such as marijuana, tobacco, or alcohol. Their subsequent social interactions with others who use drugs increase their chances of trying other drugs.
According to the US think tank RAND Corporation (Research and Development), what triggers people to use hard drugs is not cannabis but the individual opportunities and the unique inclinations of people.
Another idea that gives a different version of cannabis as a gateway drug is the Theory of Common Responsibility. In a study, Pharmaceutical Science Professor Michael M. Vanyukov stated that many factors contribute to a person’s predisposition to become addicted to drugs. A person can consume cannabis, tobacco, or alcohol without necessarily switching to the intake of harder drugs.
Cannabis as a gateway drug seems to be a hypothesis based on simplistic and fallacious logical processes. If cannabis were a gateway drug, we would expect to see far more hard drug users than there are. According to the World Health Organization (WHO), 2.5% of the world population (about 147 million people) consume cannabis globally, compared to 0.2% of those who consume cocaine and opiates.
But most importantly, recent studies position cannabis as a ‘getaway’ drug. In other words, cannabis is seen as a substance capable of removing people from the use of hard drugs and playing a substitute role for opioids.
For instance, a 2017 Canadian study found that cannabis is perceived as an effective treatment for several conditions, such as treating pain and mental health. The results show high consumption of cannabis as a substitute for prescription drugs (63%), in particular opioids (30%), benzodiazepines (16%), and antidepressants (12%).
Other studies report similar dynamics. Cannabis seems to have a beneficial effect from reducing opioid use. However, further research is needed.
In the meantime, thousands of scientific reports have contributed to debunking the assumption of cannabis as a gateway drug.