Republican presidential candidate Jeb Bush caught the attention of cannabis activists late last week when he said he supported decriminalization.
"It's one thing to say we should have decriminalization of marijuana. I support that," Bush said during an interview with Joe Mathieu of Boston's WBZ NewsRadio. "Non-violent offenders should not be crowding out our jails and our prisons."
That comment got Bush an improved grade from the Marijuana Policy Project, who bumped him up from a "D" to a "C-" on their candidate rankings.
But don't expect Bush to follow Bernie Sanders' lead. In the same interview, he said, "Marijuana is a gateway drug just as opiates are a gateway drug. Of course it is - every study shows that."
George W. Bush's brother isn't the only 2016 hopeful preaching the "gateway drug" theory. During an interview on FOX News in 2014, Ben Carson spoke out against recreational cannabis use:
"I think medical use of marijuana in compassionate cases certainly has been proven to be useful. But recognize that marijuana is what's known as a gateway drug. It tends to be a starter drug for people who move onto heavier duty drugs – sometimes legal, sometimes illegal – and I don't think this is something that we really want for our society."
His stance hasn't changed since the beginning of the presidential campaign. In October, Carson told Glenn Beck that he would maintain cannabis prohibition and intensify the War on Drugs if he were elected.
New Jersey Governor and GOP presidential candidate Chris Christie also shares the same view. In an interview with Hugh Hewitt in April, Christie said, "Marijuana is a gateway drug. We have an enormous addiction problem in this country."
Republicans aren't the only ones using this anti-legalization theory. During an interview on the Mark Steiner Radio Show in January 2014, Democrat Martin O'Malley said, "I'm not much in favor of it [legalization]. We've seen what drug addiction has done to the people of our state, to the people of our city. This drug, its use and its abuse can be a gateway."
Later that year, Hillary Clinton also preached caution about cannabis during an interview with KPCC:
"I think the feds should be attuned to the way marijuana is still used as a gateway drug...but what I want to see, and I think we should be much more focused on this, is really doing good research so we know what it is we're approving."
So Bush is not alone - many Republicans and Democrats believe the same thing. But that doesn't make it true.
In October, 2015, Dr. Kevin Hill - an assistant professor of psychology at Harvard Medical School - hosted a Marijuana AMA on Reddit. Here's what he said about the "gateway drug" theory:
So people who become addicted to hard drugs often begin experimenting with cannabis, but using cannabis doesn't necessarily lead a person to abusing hard drugs.
Indeed, some scientists wonder if cannabis could help people get off hard drugs. In September, Canadian researchers at the University of Victoria and the University of British Columbia (UBC) released an article suggesting that cannabis could be an exit drug, helping people overcome addictions to alcohol, opiates and prescription drugs.
In a press release, researcher Philippe Lucas noted, "While cannabis is not benign, most research suggests that it's safer and less addictive than many substances, particularly prescription opiates. So research suggesting that cannabis substitution could reduce harms and lessen the public health and safety impact of alcohol and other drugs has significant policy implications."
In March, Michelle Taylor - a cannabis researcher at the University of Bristol - wrote a feature for The Guardian in which she noted that "research generally supports the notion that cannabis use is a risk factor for subsequent use of 'harder' illicit drugs." However, she questions the validity of those findings:
It is important to remember that current research has only provided evidence of association, and not causation, meaning that there is no evidence that cannabis use actually causes the use of later drug use, merely that the two behaviors are linked, a link which could be due to factors which commonly influence both behaviors.
Scientists haven't concluded whether cannabis leads to harder drugs, or whether it can actually wean people off substance abuse. But recent studies do suggest that the gateway drug theory is close to being debunked.
But as for Bush's remark that "every study shows that" cannabis is a gateway drug, that statement's clearly wrong.