PORTLAND — Proponents of legalizing the recreational use of marijuana in Maine’s largest city evoked the controversial George Zimmerman verdict during a Monday news conference in Portland and said laws against pot are used to unfairly target blacks.

“Our justice system is failing us,” said Regina Phillips, an executive board member of the Maine NAACP, during the event. “It does not treat people equally.”

The news conference was held to rally support for a proposed ordinance change that would decriminalize possession of the drug in Portland just hours before the city council effectively voted to place the ordinance amendment on the Nov. 5 citywide ballot.

Zimmerman, a neighborhood watch coordinator, was found not guilty of murder last week in the Feb. 26, 2012, shooting death of black teenager Trayvon Martin in Florida. The high-profile case has been been protested by many civil rights groups as an example of racial inequality, first because Zimmerman was not initially charged in the shooting, and subsequently after a jury found him not guilty.

Zimmerman claimed self-defense in the case, but critics have pointed to the fact that Martin was unarmed and that police subsequently reported that there was no indication the teen was involved in criminal activity at the time of the shooting.

On Monday, legalization advocates recalled the flashpoint case and said the enforcement of anti-marijuana laws is another illustration of the criminal justice system targeting blacks.

“I strongly believe the outcome [in the George Zimmerman trial] wouldn’t be the same if the roles were reversed — if the shooter was black and the victim was white,” Phillips said during the Monday afternoon news conference, later adding, “We know that white people and black people use marijuana at roughly the same rate. Yet black people in Maine are twice as likely be arrested for marijuana-related charges as white people.”

A coalition of groups calling itself Citizens for a Safer Portland — including the Portland Green Independent Committee, the American Civil Liberties Union of Maine, the Libertarian Party of Maine and the national Marijuana Policy Project — collected 2,508 certified signatures of registered Portland voters on a petition seeking to legalize possession of small amounts of pot and marijuana paraphernalia in the city.

Those who attended the Monday afternoon news conference said that, according to 2010 figures, blacks are 2.1 times more likely to be arrested for marijuana possession in Maine than whites — with 461 such arrests per 100,000 black people compared to 216 arrests on the charge per the same number of whites.

The contrast is most glaring in York County, where the ratio was 1,399 blacks against 282 whites to face the marijuana possession charge — meaning blacks in Maine’s southernmost county were five times more likely to be arrested on the pot charge than their white counterparts.

In the aftermath of the Zimmerman verdict, Portland Green Independent Committee Secretary Adam Marletta said, that disparity takes on renewed significance.

“There is certainly a racial component, but considering the events of recent days, I feel more strongly [about it],” Marletta, who said he plans to run for a seat on the council, said during the afternoon news conference.

On Monday evening, the city council voted not to accept the rule changes sought by the coalition’s petition, a procedural move that instead places the ordinance proposal on a citywide ballot to be decided by voters in the fall, a step which many in the advocacy groups said they preferred.

The vote not to accept the petition changes was 5-1, with Councilor David Marshall in favor of the ordinance change and councilors John Anton, Cheryl Leeman and Jill Duson absent.

The coalition needed about 1,500 signatures from registered Portland voters to push the legalization issue to a citywide or council vote.

The legalization ordinance proposed by the coalition would allow adults age 21 and older to possess up to 2.5 ounces of marijuana as well as pot paraphernalia within city limits, while prohibiting recreational use of the drug in public spaces, including school grounds and on public transportation.

Bob Talbot, representing the ACLU of Maine during the Monday afternoon event, referenced a statistic claiming Maine spent $8.9 million during the most recent U.S. census year of 2010 enforcing marijuana laws, and that 47.9 percent of all drug arrests in the state that year were for pot charges.

“In Maine alone, nearly $9 million is spent on enforcing marijuana laws [annually],” he said. “Those are taxpayers’ dollars that could be spent on hospitals or schools or finding solutions to more serious problems.”

The pot legalization effort was dealt a blow at the statewide level during the recently completed legislative session, during which a bill that would have legalized recreational use of the drug statewide attracted 35 co-sponsors but did not gain the endorsement of the Legislature’s Criminal Justice and Public Safety Committee. The House and Senate subsequently voted down a follow-up proposal that would have put the legalization issue before voters on statewide ballots in the fall.

Proponents of the legalization measure, including councilor Marshall, have said the prohibition of the drug is ineffective and drives use of the substance underground. They say pot use should be allowed, regulated and taxed the same way as alcohol, which was prohibited in the 1920s in what is largely considered a failed initiative.

Opponents of the move, including the Maine Chiefs of Police Association, argue that the step would exacerbate substance abuse problems that feed other crimes, and that overseeing regulation and distribution of pot would be an expensive and time-consuming task for overburdened state agencies.

The Maine Office of Substance Abuse and Mental Health Services has argued that marijuana today has more than double the mind-altering chemical THC that the pot on the market in 1983 had, making it more potent and addictive, and that teenagers may be more likely to experiment with the drug after hearing legalization advocates downplay the danger.

Jo Morrissey of the substance abuse prevention group 21 Reasons distributed cards to attendees of the council meeting Monday night stating that Portland high schoolers became less likely to believe marijuana is harmful and more likely to use the drug after medicinal use of pot was legalized in the state in 2009.

Efforts to defang enforcement of marijuana laws in Portland in the past have fallen short. In 2011, activists gathered signatures on a petition seeking to make pot possession offenses the lowest enforcement priority for Portland police. But despite getting more than 2,100 signatures on the petition — 600 more than necessary to gain a spot on the local ballot — the city clerk’s office found the document was invalid because only about 1,400 of the names were from verified Portland residents.

In 2005, voters in Denver passed a law making it legal to possess a small amount of marijuana. It was the first major U.S. city to do so. In 2012, Colorado joined Washington as the first states to legalize recreational marijuana use.

Maine is one of 18 states in which marijuana can be legally used for medical reasons, prescribed to patients to fight chronic pain, among other ailments.