Backers of a Denver ballot initiative that would allow adults to consume marijuana in some bars and other venues say they have collected more than 10,000 signatures in support of the measure -- many more than needed -- and they submitted the petition to the city clerk on Monday.

The city clerk now has 25 days to certify it. If the clerk finds 4,726 valid signatures, the measure will appear on the ballot this November.

The proposal would permit the smoking and vaporizing of marijuana in non-residential spaces that can't be publicly viewed. (Currently, recreational cannabis consumption is restricted to private homes and some hotels that allow it.) Smoking pot would likely be confined to enclosed outdoor areas, since Colorado state law limits indoor smoking.

"While petitioning, we found that most voters agree adults should be able to consume marijuana socially in establishments that choose to allow it," Mason Tvert, proponent of the measure and communications director for the Marijuana Policy Project, said in a statement. "By allowing adults to consume marijuana in private businesses, we can reduce the likelihood that they'll consume it publicly in parks or on the street."

A survey conducted by Democratic-leaning Public Policy Polling in July supports Tvert's observation. PPP found that 56 percent of likely 2015 Denver voters would favor allowing businesses to permit cannabis consumption on the premises. Only 40 percent said they were opposed.

Colorado became the first state -- and the first government in the world -- to legalize and regulate recreational marijuana for adults in 2012, with the first retail shops opening in 2014. State law continues to ban recreational marijuana consumption "openly and publicly," but the law doesn't specifically block pot use in private clubs for those 21 and older. The proposed ballot initiative would help to define private clubs in Denver.

If voters approved the measure, Denver would become the first U.S. city to allow public marijuana use.

Since Colorado's recreational marijuana law passed, a number of underground, fee-based, bring-your-own-pot clubs have sprung up in and around the city. Law enforcement has at times cracked down on those gatherings. A handful of recreational marijuana clubs exist outside the Denver area .

Some Colorado lawmakers questioned whether the ballot measure would be lawful under current state statutes.

"What the proponents of this initiative are trying to do may be pre-empted in a large way by state law," Democratic state Rep. Dan Pabon, who represents Denver, told HuffPost. "It may just be a token statement of allowing use in this manner, rather than actually having a binding effect on how we generally look at this use policy."

But he added, "It invites a much-needed conversation about this issue."

The city government of Denver has not taken a position on the measure. A memo analyzing the proposal and its relationship to existing state law -- prepared by Denver's assistant city attorney, David W. Broadwell, for the city council -- says that the ordinance "will create a serious conflict with state law," which may force the Colorado legislature to address the issue on a statewide basis in its 2016 session.

The city attorney's office still fully expects the measure to find its way onto the ballot. "Based upon the number of signatures reported to be on the petitions, we can anticipate that the Clerk's office will likely determine the petitions to be sufficient, resulting in the measure appearing on the November ballot," the memo begins.

The memo was distributed to the city council on Monday and was provided to HuffPost by the Office of Marijuana Policy.

State Rep. Jonathan Singer (D), a vocal supporter of marijuana policy reform in the state, told HuffPost that people should be able to consume cannabis legally and safely in public venues.

"It's ludicrous that we can't have something similar to the bars, restaurants and private clubs we have for alcohol," Singer said. He told HuffPost that he plans to introduce a bill in the upcoming legislative session to address this exact issue at the state level.

Tvert and Brian Vicente, one of the authors of Amendment 64, which legalized recreational marijuana in the state, gave a press conference in front of the Denver City-County Building on Monday afternoon to announce the collection of the signatures and submission of the petition.

Here's how the proposed ballot question would read, if it makes it onto the November ballot:

Shall the voters of the City and County of Denver adopt a measure permitting the consumption of marijuana by individuals twenty-one years of age or older at certain premises that are not private residential property, provided that individuals under the age of twenty-one are prohibited from entering any space where the consumption of marijuana is allowed, the owner, operator, or individual in control of the premises has authorized the consumption of marijuana, and the individual consuming marijuana neither smokes marijuana indoors in violation of Colorados Clean Indoor Air Act nor consumes marijuana in a location where the consumption of marijuana is visible from a nearby public place; permitting the operation of business and commerce involving the consumption of marijuana; permitting the Denver City Council to adopt ordinances that regulate signage, marketing, and advertising for any business that permits the consumption of marijuana; permitting the Denver City Council to regulate the hours of operation and create distance restrictions for any business that permits the consumption of marijuana that does not also hold a license to sell alcohol for onsite consumption; declaring it unlawful to permit marijuana consumption at a premises that is not private residential property unless certain conditions are met; immunizing businesses and property owners from certain licensing sanctions and public nuisance enforcement actions related to the consumption of marijuana, provided the consumption is in accordance with applicable ordinances; and clarifying that owners and residents of adjacent properties may bring private nuisance actions against any business that permits marijuana consumption and that the City of Denver may enforce air quality standards against these businesses?

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