The fight to keep Boston employees within city limits may resurface this year and could become a campaign issue if a Dorchester activist has her way.

Eileen Boyle, an activist with "Save Our City," a pro-residency group, and a member of a residency compliance commission, is seeking signatures for a petition that charges both the mayor and the city council do not have the authority to change the rules requiring municipal employees to live within the city.

The move comes after Mayor Thomas Menino, through collective bargaining, loosened residency rules last year for several powerful municipal unions in exchange for smaller increases in salary and health care costs. The Boston Teachers Union already has a statewide exemption, and as many as two-thirds of city employees are also exempt.

Menino ran for mayor in support of the residency requirement in 1994, a rule that had been on the books since Kevin White's days in City Hall and the so-called "white flight" to suburban neighborhoods outside of Boston, but infrequently enforced.

"This is just to leave it alone and follow the rules," Boyle said of her petition in a recent interview, noting that strong support remains for the residency requirement.

Menino said last week he is still a "big supporter" of the residency requirement, but a relaxation of the law is appropriate. The issue has also been taken up at the legislative level, he said.

Menino noted city employees must still live in the city for ten years, and the choice to move outside afterwards isn't as appealing as it used to be. "Our taxes are much lower, our schools are improved, our facilities are much better," he said.

Michael Flaherty, at-Large City Councillor, said he always understood the requirement to be part of collective bargaining, but added that he would go back to check the law. He said residency remained an "important issue."

Pro-residency advocates say the requirement is necessary to keep a middle class in the city. But some from their ranks, such as Rosemary Powers, Sen. Jack Hart's chief of staff who left for a job this past fall at the Department of Conservation and Recreation, appear to be absent from the fight this time around.

Undeterred, Boyle said she met with Menino last summer, demanding an explanation for the change. He told her the city was changing, she said. "I said, 'Well, I don't think that's a good enough reason.'"

Boyle said she has gathered several dozen signatures at Dorchester civic associations, including 18 at Ashmont Adams, 30 at Columbia-Savin Hill, and about a dozen at Clam Point. She hopes to hit other civic associations at their regular meetings in the coming months.

Boyle said she also plans on heading into Brighton and Jamaica Plain for signatures as well. "I've only started the campaign," she said.

Boyle said she has also attempted to contact officials in Cincinnati, Philadelphia, Detroit and Milwaukee.

She noted that Detroit, a city with a high crime rate, doesn't have a residency requirement.

"No city workers are working within the city limits of Detroit," she said. "It's crazy."

Boyle also raised the prospect of a lawsuit, if necessary.

The city council, through Councillor John Tobin of West Roxbury, held two hearings on the issue in 2006, and Tobin sought to push through an ordinance that would require all city employees to stay for only five years. He backed off the proposal after it didn't appear to have enough support among his fellow councilors, including District 3 Councilor Maureen Feeney, then-chair of the Government Operations Committee and current Council President.

Residency has also surfaced at the state level, with two bills that were heard in the fall.

The bills, both sponsored by Rep. Demetrius Assails (D-Hyannis), would alter residency requirements for firefighters and police officers, with one exempting them entirely. The other would allow an officer or firefighter to live within 50 miles of the city they serve instead of the current 15, though each community has different standards.