But if it passes, the measure would make the possession, use or cultivation of the mushrooms by people 21 or older the lowest-priority crime for law enforcement in the city of Denver and Denver County.
Psilocybin would remain illegal under both Colorado and federal law. "It's pretty clear" from the FDA granting psilocybin "breakthrough status", Matthews said, "that the federal government knows we need some other solutions as well". The ballot does not differentiate between the medical and recreational use of mushrooms.
The referendum on the ballot in local elections set to produce a result late in the evening would block the city from using its resources to enforce criminal penalties for the use of psilocybin, the psychoactive substance in hallucinogenic mushrooms.
"No one deserves to go to jail and lose their family, their livelihood, their jobs for something that has a therapeutic benefit", said Decriminalize Denver campaign manager Kevin Matthews ahead of the vote.
Voters could make Denver the first US city to decriminalize the use of psilocybin - the psychoactive substance in "magic mushrooms". A number of other states have since broadly allowed marijuana sales and use by adults. The effects also appeal to recreational users.
In 2005, Denver became the first major USA city to legalize possession of small amounts of marijuana for adults aged 21 or older. It would not legalize psilocybin or permit its sale by Denver's cannabis businesses.More news: Facebook cofounder says it's time to break up company
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It took the pro-psilocybin organizers in Denver three tries to develop language approved by city officials for the ballot.
Participants in recent medical studies using psilocybin have described seeing vivid colors and geometric patterns and experiencing powerful spiritual connections and emotions.
Organisers collected more than 8,000 signatures to get on the ballot, the third time they had attempted to put the proposal up for a vote.
The mushroom ordinance also prevents city funds from being used to pursue criminal penalties on possession or use and creates a panel to study the effects of the change. The district attorney McCann's spokesperson said that McCann opposes the initiative partly because the city is still trying to understand the effects of legalizing marijuana.
Denver Mayor Michael Hancock opposes the initiative, along with District Attorney Beth McCann.
Activists in California failed to get a similar initiative on the ballot past year, and supporters in OR are hoping to put the matter to a vote statewide in 2020. "One arrest is too many".