Miami Beach voters could cast ballots for Mary Jane come November should a budding effort to decriminalize marijuana possession in the city gain traction.

In front of City Hall Wednesday evening, the Committee for Sensible Marijuana Policy announced a drive to gather signatures in support of a proposed amendment that would make ``personal'' possession of marijuana in Miami Beach a civil code violation punishable by a mere fine.

``We're empowering local government to deal with this differently,'' said Ford Banister, the group's chairman.

Banister hopes to put the proposal before the city's voters in November.

But already questions have been raised about the legality of the initiative, given state and federal authority over drug laws.

Florida law says possession of less than 20 grams of pot is a misdemeanor punishable by up to a year in jail and a $1,000 fine.

Activists like Banister argue that criminal charges for personal marijuana possession are excessive and a burden on police, prosecutors and jails. Banister's proposal would punish possession of less than 20 grams with a city-levied fine of $100.

Norman Kent, the attorney who drafted the proposal, said police would have the choice to issue a city code citation or charge a subject under state law.

Not surprisingly, the movement has its critics.

Miami Beach Mayor Matti Herrera Bower said she would not support such a change in the city's code, and questioned whether marijuana laws could be changed in Miami Beach alone.

And Bob Jarvis, a constitutional law professor who teaches at Nova Southeastern University, said he was ``stunned'' and doubted the viability of the proposal.

``Even if it got enough votes to pass, I would assume at some point in that timeline federal officials would say, `What the heck are you doing here?' '' he said.

Banister scoffed at any skepticism, and said ``we are prepared to defend the amendment without question.''

Prosecutors and voters have weakened laws against personal marijuana possession in cities and towns such as Seattle and Breckenridge, Colo., and the Committee for Sensible Marijuana Policy was successful with a similar 2008 ballot initiative in Massachusetts.

However, decriminalization proposals have never made it to a vote in Florida. Banister's group has spent months gathering petitions in Orlando, Jacksonville Beach and Atlantic Beach without success.

Miami Beach's charter states that 10 percent of its 42,527 registered voters must support a ballot initiative for it to reach a vote. That would have to happen before Aug. 20 for the amendment to go before voters in the Nov. 2 election, according to a spokeswoman with the Miami-Dade Elections Department.

Banister said the group had about 80 signatures since starting Friday.

The group may have better luck in Miami Beach than in other Florida cities. The film studio rakontur, which created the Cocaine Cowboys documentaries, has backed the effort financially. Wednesday's press conference was advertised on rakontur.com, which once offered visitors fake Miami Beach parking passes.

Cocaine Cowboys director Billy Corben said he reached out to Banister to bring the decriminalization initiative to Miami Beach in part because of its reputation as a progressive city.

``Are the people of Miami Beach ready for a sensible marijuana policy?'' Corben said. ``We're just saying let's find out.''