Joe Biden is still questioning if marijuana is a gateway drug, even though research doesn't support the idea

• Former Vice President and 2020 Democratic hopeful Joe Biden said his questions over marijuana's reputation as a gateway drug hold him back from supporting legalization.
• Biden claimed at a town hall that "there's not nearly been enough evidence" to confirm if marijuana isn't a gateway drug, which he would need before legalizing it nationwide.
• However, research has repeatedly failed to find solid evidence of marijuana leading people to harder drugs.
• The former vice president's openness to medical marijuana and state-specific policies is a development from his staunch past, but still separates him from other Democratic presidential candidates, with the majority of current candidates openly supporting nationwide legalization.
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Former Vice President and 2020 Democratic hopeful Joe Biden doubled down on his reserved stance over legalizing marijuana and said his questions over its status as a gateway drug hold him back from supporting legalization.

Biden was speaking at a Las Vegas town hall when he claimed that "there's not nearly been enough evidence" to confirm if marijuana isn't a gateway drug, which he would need before legalizing it nationwide.

"The truth of the matter is, there's not nearly been enough evidence that has been acquired as to whether or not it is a gateway drug," Biden said. "It's a debate, and I want a lot more before I legalize it nationally. I want to make sure we know a lot more about the science behind it."

Though he wouldn't overturn federal law right away, Biden said he thinks "states should be able to make a judgment to legalize marijuana."

He added that he also supports medical marijuana and possession of the substance "should not be a crime."

Biden's most recent comments are a much softer approach than how he spent his 40-year career in the Senate, much of which overlapped with the government's war on drugs, specifically in designing harsh criminal penalties for nonviolent drug users.

His campaign has since said in announcing a massive criminal justice reform plan that included decriminalizing marijuana, that he was aiming to cut down on rates of incarceration and fix "the racial, gender, and income-based disparities in the system." He also said in a June campaign speech that he supported expunging past convictions for possession.

Despite his priorities in marijuana-related prosecution and incarceration, Biden again stopped short of backing policy for recreational marijuana but called for increasing the amount of scientific research into the drug.

"It is not irrational to do more scientific investigation to determine, which we have not done significantly enough, whether or not there are any things that relate to whether it's a gateway drug or not," Biden said.

National organizations have not been as suspicious of marijuana as Biden has, and have found no solid evidence to support the claim that using marijuana leads to the use of harder drugs. A 1999 Institute of Medicine report said marijuana "typically precedes rather than follows initiation of other illicit drug use," but it "does not appear to be a gateway drug to the extent that it is the cause or even that it is the most significant predictor of serious drug abuse; that is, care must be taken not to attribute cause to association."

The National Institute on Drug Abuse says that research shows "the majority of people who use marijuana do not go on to use other, 'harder' substances," and drug use can be affected by numerous other biological and environmental factors.

The former vice president's stance appears to be a head-on effort to improve his image as related to marijuana, but it separates him from other Democratic presidential candidates, with the majority of current candidates openly supporting nationwide legalization.