In a unanimous city council vote, Oakland, California, decriminalized psilocybin, or psychedelic mushrooms, on June 4, less than a month after Denver narrowly passed a ballot measure doing the same.

Now other local and state governments are looking to follow the cities' leads: Activists in Oregon and California are pushing for decriminalizing psilocybin, and a lawmaker in Iowa introduced similar measures earlier this year.

In the nation's capital, Rep. Alexandria Ocasio-Cortez, D-N.Y., recently filed legislation that would allow researchers to more easily study the therapeutic and medical benefits of psilocybin and other psychedelic drugs.

Like heroin, LSD and ecstacy, psilocybin is a federal Schedule 1 drug , meaning it currently has no accepted medical use but has a high potential for abuse. Decriminalization is not the same as legalization; Denver and Oakland will no longer use city money to impose criminal penalties on people age 21 and older who use or possess psilocybin (also called "magic mushrooms"), but selling the substance is still illegal.

Proponents say decriminalization of psilocybin opens the door for researchers to explore possible medical benefits; opponents argue it could lead to higher rates of drug abuse. Current use of the drug is low--an annual average of 0.1% of the U.S. population reported using any drug under the "hallucinogen" category (including psilocybin) within the last 30 days between 2002 and 2014, acording to the Drug Policy Alliance , a nonprofit committed to ending the war on drugs.

Oakland City Council Member Noel Gallo sponsored the city's resolution , which also decriminalizes other plants and fungi containing psychoactive substances. He says psilocybin has been used for millennia "for providing healing, knowledge, creativity, and spiritual connection."

Jeremy Daniel, an assistant professor at South Dakota State University College of Pharmacy and Allied Health Professions, who published a literature review of psilocybin studies in 2017, says psilocybin research isn't nearly as robust as that of marijuana, which was first legalized in Colorado and Washington in 2012 and is now legalized for recreational use in 11 states and for medical use in 46 states. Still, he says studies have shown psilocybin could have some medical benefits.

"Overall, based on the evidence that was available at the time (of my review), it appears that (psilocybin) may potentially be a promising agent to help with mental health concerns," Daniel says. Research has shown a possible decrease in depressive mood symptoms, he says, as well as a decrease in suicidality, betterment of anxiety disorders including obsessive-compulsive disorder and a decrease in cravings for alcohol and nicotine.

"Though I would argue that there is very little standardization between studies and between the actual agents that were given to the patients," he says, adding that health concerns relate mainly to high doses, and "more robust studies are needed to know for certain the potential benefits of the drug.

Iowa state Rep. Jeff Shipley, who filed a bill in February to decriminalize psilocybin in the Hawkeye State, brings up another argument: personal freedom.

"Where did government derive authority to regulate substances to begin with?" he asks.

Shipley says people should have the right to experiment with the drug, as long as they accept the possible consequences. He also points to conversations he's had with people who have had what they call life-changing experiences from magic mushrooms.

"Who am I to say this isn't good for them?" Shipley says.

The freshman legislator filed a second bill that would allow the state pharmacy board to reclassify psilocybin, in addition to ibogaine and MDMA (also known as ecstasy or molly), for medicinal purposes. He says he hopes a committee hearing about the legislation will start a conversation about the topic.

Some opponents of these measures worry a decriminalization approach will encourage more people to use magic mushrooms and that drug addiction rates could increase, as the nation is already facing an addiction epidemic.

Others, such as Denver's District Attorney Beth McCann, believe it's important to learn the effects of marijuana legalization before seeing magic mushrooms decriminalized.

"Colorado is still in the early stages of legalizing marijuana and learning about the impact of that decision on a multitude of fronts," McCann told U.S. News in an email statement, adding that she has always supported a provision of Denver's ballot initiative that calls for a policy panel to assess the effects of decriminalizing psilocybin.