Those who warned of slippery slopes can start crowing: The city of Denver, one of the first places in the US to legalize recreational marijuana, will vote on whether to decriminalize magic mushrooms in May. The city’s election division announced last week that a petition from the Denver Psilocybin Mushroom Decriminalization Initiative had 5,559 valid signatures—well above the 4,726 signatures (5% of the total votes from the most recent mayoral election) required to mandate a city-wide vote.

Denver citizens will have the chance to vote on whether to make possession and growth (but not sales) of psilocybin mushrooms legal. The city will not be the first in the US to decriminalize psychedelic mushroom. It has been legal to grow and consume fresh magic mushrooms (but not dried mushrooms) in New Mexico since 2005, following a ruling by the state’s court of appeals. Meanwhile, the secretary of state in Oregon has approved language for a 2020 ballot measure on magic mushrooms; if the proposal gets 117,578 signatures, then the state’s citizens will also vote on whether to decriminalize the drug.

The campaign director for Decriminalize Denver, Kevin Matthews, told Reuters that magic mushrooms helped treat his depression. Though Matthews’ claims haven’t been independently verified, they aren’t implausible. There’s a growing body of research on using psychedelic drugs to treat mental health conditions including post-traumatic stress and obsessive-compulsive disorders. In October 2018, a trial on using psilocybin, the key ingredient in magic mushrooms, to treat depression was given “breakthrough therapy designation” by the US Food and Drug Administration (FDA), meaning it will be fast-tracked through the drug-development process.

Decriminalizing magic mushrooms could have a major impact on how the drug is used for medical purposes. In November, a Quartz investigation showed that Compass Pathways, the company behind the FDA-approved research into psilocybin as a treatment for depression, had taken steps to create a monopoly on medicinal applications of the chemical. If the fungi that produce the drug were legal to grow and use, it would be far more difficult for any one organization to raise prices and restrict patient access to psilocybin as treatment.

But, though studies suggest magic mushrooms can have beneficial uses, the very scientists behind this research are wary of decriminalizing the drug outright. Matthew Johnson, psychiatry and behavioral sciences professor at Johns Hopkins University, told NBC in June that he was concerned about the risk of bad trips and how magic mushrooms could affect people with psychotic disorders. Charles Grob, psychiatry professor at the University of California-Los Angeles, agreed that magic mushrooms “should not be treated in a trivial manner,” and said that, if they ever were widely available, citizens should be educated on the drugs’ effects.

Instead of decriminalizing recreational use of magic mushrooms, John Hopkins scientists including Johnson argued in a review of the research published in the November issue of Neuropharmacology that the drug should be reclassified from its current status as schedule 1 drug (a dangerous substance with high potential for abuse and no known medical potential), to a schedule IV drug (a prescription medication with low potential for abuse or dependency, such as Valium and Xanax).

Magic mushrooms were made illegal in the US under president Richard Nixon’s 1970 Controlled Substances Act; since then, Nixon’s domestic policy advisor John Ehrlichman has openly admitted that the criminalization of various narcotics, stimulants, depressants, and hallucinogens, under the act were an overt attempt to vilify hippies and black people. “Did we know we were lying about the drugs? “Of course we did,” said Ehrlichman in a 1994 interview. Nearly 50 years on, then, it makes sense that these policies are increasingly up for review.