A Massachusetts Superior Court Judge ordered Cambridge on Thursday to stop paying insurance benefits to domestic partners of city workers, in a decision that opponents of gay marriage claim as another victory in their Massachusetts campaign.

Middlesex Superior Court Judge James F. McHugh ordered Cambridge, the first city in Massachusetts to offer benefits to couples in domestic partnerships, to stop paying the benefits by the end of next January.

According to the ruling, 71 people will lose health insurance benefits worth about $2,790 a year. While anyone can apply for domestic partnership benefits, all but two of those who are currently registered to receive them are gay, according to Cambridge officials.

The American Center for Law and Justice (ACLJ) filed the suit against Cambridge last March, after a similar suit shut down Boston's domestic partnership program last July. The ACLJ is a conservative Virginia group that opposes abortion and gay marriage and champions school prayer.

Vincent McCarthy, who argued the case and is the ACLJ's senior northeast counsel, said the ruling foiled an unconstitutional and illegal ordinance.

"The Cambridge ordinance is simply an attempt to circumvent state marriage laws," he said. "It's clearly just trying to set up a gay parallel marriage."

The ordinance, passed unanimously in 1992, let unmarried couples of any sexual orientation register with the city to gain hospital visitation rights, access to their partner's children's school records, as well as municipal health insurance benefits for partners of city workers or teachers.

The ruling surprised few on either side of the issue, since the Massachusetts Supreme Judicial Court overturned Boston's domestic partnerships benefits program, saying they conflicted with a 1955 state law that limits benefits to worker's spouses and children.

McHugh found Cambridge's ordinance unconstitutional because it conflicted with the state law, but discarded McCarthy's claims that the ordinance was an attempt to legitimize homosexual marriage.

"Although the action the city took was improper, it took that action in an effort to provide a better life for those who daily serve its citizens," McHugh wrote in his decision. "It says nothing about marriage."

Because only the insurance benefits provision of the ordinance conflict with the 1955 law, Cambridge domestic partners will retain hospital visitation rights and access to the school records of each other's dependents under the terms of the ruling.

Cambridge Mayor Anthony D. Galluccio said he and the council were deeply disappointed by the decision.

"The city council has unanimously supported this ordinance," Galluccio said. "We feel very strongly that municipalities should have the right to provide insurance to employees in a manner they see appropriate. We feel all families should be treated equally."

Gallucio said he would use any legal recourse he could to maintain the benefits, but acknowledged that progress would have to come on the state level, by amending or replacing the 1955 law that limits benefits to spouses.

"The real push needs to be in the legislature to allow communities like Cambridge to make their own decisions," he said.

State Rep. Alice K. Wolf, who proposed the 1992 Cambridge ordinance as a city councilor, has authored a bill to replace the 1955 law and allow state workers domestic partnership benefits and municipalities the option of such benefits.

The bill passed the state senate last November, but has since stalled in the House Ways and Means Committee.

"We've been trying at least to protect the people who've had benefits in Cambridge for the past eight years, but we couldn't get [the bill] passed in the last session," Wolf said.

"Unless we can pull some rabbits out of our hats during this informal session and get it passed, we'll have to keep fighting," she said.

Wolf's bill would allow municipalities to reinstate the programs that the ACLJ's litigation has overturned, according to partisans on both sides of the issue.

"A new bill would definitely take care of the state law conflict," McCarthy said. "It would close down a lot of the avenues we have to fight gay marriage."

The ACLJ has waged a city to city battle against domestic partnerships over the past two years, with their first victory against Boston last July. After the Cambridge ruling, Northampton and Brookline voluntarily ended their benefits in response to requests from the ACLJ to comply with the state law.

McCarthy has already drafted a suit against Springfield's domestic partnerships program.

"We're just trying to find some time to file it," he said.