The York Board of Selectmen will hold a public hearing Monday night on a proposal that would legalize recreational marijuana use by adults in town but which town officials caution runs counter to state and federal law.

The public hearing and board discussion expected to follow will be the first extended conversation in town on the proposed ordinance submitted last month by supporters of the Marijuana Policy Project, which helped pass a ballot initiative last year in Portland that legalized recreational marijuana use in the city by people 21 and older.

York selectmen could vote Monday to put the question on the November ballot, delay action for up to 45 days or do nothing at all, said Town Manager Robert Yandow. If the board refuses to act on the petition within 45 days, the petitioners can collect additional signatures to restart the process of getting it on the ballot, he said.

If selectmen forward the proposal to the ballot, it would be the first of as many as three local referendums on the issue scheduled for November.

Marijuana activists are also working on proposals to legalize marijuana use by adults 21 and older in South Portland and Lewiston. Supporters successfully collected 959 signatures in South Portland, and the City Council there will decide Aug. 4 whether to enact the ordinance or send it to voters in November.

David Boyer, Maine political director of the Marijuana Policy Project, said supporters have until Aug. 8 to submit 859 valid signatures to the Lewiston city clerk. He said the group is “on track to submit enough signatures to make it onto the ballot.”

York, South Portland and Lewiston were chosen as test communities because they represent a wide spectrum of Mainers, according to supporters. After the group began collecting signatures, the South Portland City Council passed a nonbinding resolution opposing the legalization campaign.

Boyer said the long-term plan is to have a statewide vote on the issue in 2016. He said the public hearing in York “is a great place to have a discussion about the relative harms of marijuana and alcohol.”

“Marijuana is objectively safer than alcohol, and arresting adults for possessing it is a waste of time and resources,” Boyer said. “If voters approve these measures, law enforcement officials can use their discretion to stop punishing otherwise law-abiding citizens and saddling them with criminal records that can hurt them for the rest of their lives.”

The York Board of Selectmen voted this month to hold the public hearing July 28 and requested a legal opinion from town attorney Mary Costigan. The short discussion among board members about scheduling the public hearing provided a glimpse of board members’ concerns about the proposal, including questions about whether it is a “lawful” ordinance as required by the town charter.

In her opinion, made public Friday, Costigan cautioned that the ordinance would be inconsistent with state law and that state law would prevail. Marijuana possession remains illegal under both state and federal law.

“Because possession and use of one ounce or less of marijuana is a civil offense under state law, an ordinance that legalizes the possession or use of one ounce or less of marijuana by a person 21 years of age or older would likely be found to frustrate the purpose of state law and would therefore likely be preempted,” she wrote.

Costigan said the lawfulness of a similar ordinance approved last year in Portland has not been challenged, but both the police chief and Maine attorney general have said the Portland ordinance is pre-empted by state law and is viewed as advisory in nature.

If the board decides to submit the proposed ordinance to voters, Costigan said a committee that includes the town manager, town attorney and a petitioner should review the proposed language and make “stylistic changes to comport with the form of an ordinance.” The committee is not allowed to make changes that materially change its meaning and effect, she said.

The proposed ordinance would allow adults 21 and older to possess up to an ounce of marijuana and paraphernalia. The petition also contains language that the town would resolve to support a change in state law to tax and regulate the sale of marijuana in a manner similar to alcohol.

Police Chief Doug Bracy said that if the ordinance passes in York, his officers will continue to enforce state law.

“The vote tends to be more symbolic,” he said. “As I’ve said to the proponents, they should be directing their efforts to the state and federal level.”

Last year, York police cited 96 adults 21 and older for possession of marijuana, down from 139 in 2012.

Scott Gagnon, Maine director of Smart Approaches to Marijuana, said he and others who oppose legalization will be at the meeting Monday to discuss their concerns about the affect legalization would have on the community. He said the “normalization” of marijuana leads youths to think it is OK to use the drug.

“At the end of the day, with federal and state laws pre-empting local laws, it doesn’t really change anything,” he said. “But I’m really concerned what direction this (normalization) will take us in.”