SAN FRANCISCO (AP) – Laws limiting marriage to a man and a woman do not run afoul of California’s constitution, Attorney General Bill Lockyer has declared in a long-awaited legal opinion that sought to avoid offending either side in the contentious same-sex marriage debate.

Meeting a judge’s deadline to answer a pair of lawsuits seeking to put California on par with Massachusetts, Lockyer said it was up to voters or the Legislature to decide whether to change “the common and traditional understanding” of matrimony that “pre-dates the founding of this state or nation.”

“Rights are considered fundamental only if they are deeply rooted and firmly entrenched in our state’s history and tradition,” he said. “There is simply no deeply rooted tradition of same-sex marriage in California or in any other state.”

The lawsuits claim California’s marriage laws violate the state constitution’s anti-discrimination provisions, an argument Lockyer rejected while noting that state lawmakers have taken significant steps toward granting full spousal benefits to same-sex couples who register as domestic partners.

“The state has a strong interest in valuing and maintaining its deeply rooted history and traditions,” Lockyer wrote in the 37-page brief. “California’s effort to find a balance between affording rights and benefits to same-sex couples, while maintaining a common understanding of marriage, does not run up against the Constitution.”

The papers filed in San Francisco Superior Court came in response to lawsuits by the city of San Francisco and gay rights advocates representing a dozen same-sex couples. They sued in March after the California Supreme Court ordered city officials to stop issuing marriage licenses to same-sex couples.

The plaintiffs are relying heavily on the same arguments that persuaded Massachusetts’ highest court to legalize same-sex marriage there this year – namely, that laws limiting marriage to a union between a man and a woman discriminate against same-sex couples, violating their civil rights and several constitutional guarantees.

Both supporters and opponents of same-sex marriage were eager to see how Lockyer, a Democrat who has expressed interest in running for governor in 2006, planned to navigate the politically volatile question.

Jon Davidson, who is helping represent the 12 suing couples as a senior attorney with Lambda Legal Defense and Education Fund, said that in his view, Lockyer “is putting up a vigorous defense.”

“It looks like the attorney general is making the strongest case the state can make to defend the restriction against same-sex couples from marrying given the current state of California law,” Davidson said. “I am disappointed about his view that not allowing same-sex couples to marry is not discrimination against gay people.”

By taking the position that any change in marriage eligibility criteria must come from the Legislature, however, Lockyer essentially advanced the same legal strategy that Massachusetts Attorney General Thomas Reilly, a fellow Democrat, unsuccessfully used to prevent same-sex couples from being able to wed in his state. The attorney general’s office defends state agencies and laws.

In the court papers, Lockyer also took pains to point out that his office rejected many of the arguments that opponents of same-sex marriage have used, such as that “same-sex relationships are less committed or stable than opposite-sex relationships.”

“Committed and loving relationships between two individuals deserve recognition under California law,” Lockyer conceded in a statement. “The obligations and benefits that attend such relationships form the cornerstone of nurturing families and a stable society.”

The parties in the California cases are set to meet in court on Oct. 26 for a schedule setting conference. Meanwhile, Assembly member Mark Leno, D-San Francisco, has announced plans to reintroduce later this year legislation that would allow same-sex couples to wed.

“He’s in a tough position because I believe there is no defense,” Leno said of Lockyer’s duty to argue for the status quo. “He’s got to promote an argument which I believe will be on the losing side of history. It’s not a choice position in which to be.”