The light outside fades as Shirley Traiman mills about the century-old Victorian in Alameda, doing her 83-year-old best to sidestep her grandkids' toys.

Her son Leland, who runs a gay sperm bank from an office downstairs, ponders a jigsaw puzzle on the floor with Rosalinda, his 2-year-old curly blonde sprite. Julian, 8, glides over the hardwood in white socks. Mushrooms and onions sizzle on the stove. Stewart Blandón, just home from work, settles on the sofa. It's family time.

Leland Traiman, 55, and Blandón, 41, sought the Golden State seal of approval back in 2004, joining thousands of same-sex duos who formed a festive rainbow lei around City Hall. The couple wed on the marble steps below its gilded dome. Proof hangs in the hallway: their marriage license, voided by a court order six months later, is a quaint souvenir.

Now, with the California Supreme Court set for a hearing Tuesday on whether a ban on same-sex marriage violates the state Constitution, Traiman and Blandón say they hope it remains just that: a memento, nothing more.

Their big fear: More backlash. If the court rules for same-sex marriage, they worry California voters will join dozens of other states in passing a constitutional amendment to ban it, possibly rolling back benefits that domestic partners have won -- now virtually identical to those of marriage. Any hope of federal civil unions, they say, would also dim.

Their views seem to run against the gay grain, making them strange Advertisement bedfellows with defenders of traditional marriage in a bellwether court case being watched across the country. But they also reflect a significant shift in legal and political ground since San Francisco Mayor Gavin Newsom unleashed a monthlong gay wed-fest during his own political honeymoon.

That shift, legal experts say, has altered the stakes and the legal strategy on both sides.

"We really don't need to fight for the word marriage. It's something I don't need. It's something my family doesn't need. Marriage is what we have," said Blandón, a doctor.

"At the time, there was a certain amount of euphoria. We got caught up in that," said Traiman. "Things have changed."

Over time, the state has granted domestic partners the full range of benefits that spouses get, including the ability of partners to make medical decisions for each other, receive employee benefits through a partner, hold parental rights with a partner's child. Most recently, in 2006, it gave registered domestic partners the right to file joint state tax returns.

Domestic partners still cannot file federal tax returns or file jointly for bankruptcy, get spousal benefits such as social security, federal pensions or spousal veterans benefits, or receive special consideration for partners when it comes to immigration, among other rights for married couples.

The federal government will not recognize same-sex marriage, under a law that President Bill Clinton signed in 1996. States need not recognize same-sex marriages forged in other states.

Among the few remaining differences in California: Couples must live together to become domestic partners; those partnerships are easier to dissolve; and prisoners can marry, but can't enter into domestic partnerships.

Legal scholars say the leveling of benefits has helped isolate central questions in the marriage debate: What, beyond a collection of benefits and rights, is marriage? And who gets to decide how it's defined?

"The battle is really over the label itself," said Vikram Amar, a law professor at UC Davis. "Ironically, that may make it harder for the plaintiffs to prevail. There's not as clear a sign of disrespect toward same-sex couples that existed then, or that exists in other states."

The state's high court will hold a three-hour hearing in a case consolidating a half-dozen challenges to the state's statutory ban -- established in 1977 and reinforced in 2000 with Prop. 22, which defined marriage as being only between a man and woman.

The plaintiffs, including 15 same-sex couples, have challenged the ban largely on equal protection and due process grounds.

In 2005, San Francisco Superior Court Judge Richard Kramer found it violated both. He saw it as gender-based discrimination and akin to a long-rejected ban on inter-racial marriage. The state has a compelling reason for denying marriage to, say, a pet or a child, but Kramer found none to deny same-sex couples what he called "a fundamental right: the right to marry."

The state Appeals Court rejected Kramer's view a year later. In a 2-1 ruling, the appeals court found that the state's ban did not discriminate based on gender because anyone can get married and that allowing same-sex marriage would be granting those couples a new right.

The state's interest in upholding the will of voters -- Gov. Arnold Schwarzenegger's central argument -- is enough, the court found.

"In the final analysis, the court is not in the business of defining marriage," the majority found.

Some gay advocates say that a high court ruling in their favor could help couples in other states or countries that recognize same-sex marriage, or that it may help in a later fight for federal marriage benefits. Legal experts say the Supreme Court is not likely to heed those arguments.

With virtual parity now in state benefits and obligations for spouses and domestic partners, legal scholars say the court can face head-on the issue of what, or who, makes marriage special.

"It's the purest case in the country, totally different than anywhere else," said Michael Wald, a Stanford law professor emeritus who is among several family law professors opposing the ban.

"It can go either way," said Jennifer Rothman of Loyola Law School. "For opponents of same-sex marriage, it's hard to come up with justifications for denying same-sex couples marital rights when the state has already said they should be treated identically, including in the realm of parenting."

In the meantime, two groups in California are circulating petitions to place competing constitutional amendments banning same-sex marriage on the ballot. One would also repeal benefits for domestic partners.

The same groups have tried and failed before. Some political scholars, and advocates on either side of the debate, suggest that their success in reaching the ballot hinges on what the court decides. A ruling for same-sex-marriage, they say, could ignite the same sort of clamor that trailed a court ruling for same-sex marriage in Massachusetts and, soon after, Newsom's gambit.

Between the City Hall delirium and Tuesday's hearing at the Supreme Court -- a distance of 200 paces that has taken four years to mark off -- 23 states have approved constitutional amendments banning same-sex marriage, bringing the total to 27. An additional 20, California included, have statutory bans.

Connecticut, New Jersey, New Hampshire and Vermont now allow civil unions -- with equal benefits to marriage -- while others have added benefits for domestic partners. One, Massachusetts, has legalized same-sex marriage.

What rankles and confounds both sides, they say, is Schwarzenegger's stance.

In 2005, the Republican governor vetoed a bill that defined marriage as gender-neutral, while pledging to defend domestic partnership rights.

A social moderate, Schwarzenegger has returned to a favorite tactic when it comes to galvanizing issues. Rather than embrace one side in a debate with scant middle ground, he says he leaves it to the people to decide.

"If the ban of same-sex marriage is unconstitutional, this bill is not necessary," he said of the same-sex marriage bill. "If the ban is constitutional, this bill is ineffective."

In a legal brief, the governor defends the ban. And in a move that riled both sides, his lawyers also argue that there are no constitutionally guaranteed rights of marriage; the state could eliminate all of them, or change the name to something else.

He also argues that marriage is no longer needed "to legitimize the conjugal and family relationships (once) regarded as the exclusive prerogative of married couples -- such as cohabitation, sexual intimacy, mutual lifelong care and support, procreation or child-rearing."

The brief seems to downplay or undermine the argument for a fundamental marriage right that the state must recognize. But opponents of same-sex marriage say the governor has dismissed a strong state interest for the court to consider.

"The state has an interest in responsible procreation," said MatStaver, president and general counsel for Liberty Counsel and one of the lawyers who will argue before the court Tuesday.

His argument: Because childbirth in same-sex relationships is always intentional, but heterosexual couples often conceive accidentally, marriage as an encouragement for stable families is only needed for the latter.

"Granting same-sex marriage would ultimately diminish the marriage institution," Staver argues. "To rename marriage or include marriage with same-sex couples, for which procreation would not naturally occur, ultimately limits the value."

Same-sex marriage backers also insist that marriage is more than a collection of benefits and obligations.

"Distressing" is how Shannon Minter, who represents the same-sex couples in the case, describes the governor's take.

"It's a misguided attempt to justify denying marriage to gay people," said Minter, legal director for the National Center for Lesbian Rights. "No amount of adding additional rights can ever make a domestic partnership equal to marriage. It's about how we value family. It is the way in our culture that we express the deepest level of commitment to another person."

Many gay couples who converged on City Hall in 2004 look back with a mix of nostalgia and pride. Some see it as one of many steps toward recognition. They savored a feeling.

As with all marriage, the taste has faded for some. One pair of former plaintiffs has dropped out of the case. They split up.

Karen Shain and Jody Sokolower, both now 59, arrived at a City Hall scene "so wholesome on some levels, and not -- a combination of gay pride and a line for a rock concert," said Shain.

Marriage wasn't on their radar until Newsom thrust it there. They'd been together for three decades, and were living in Berkeley with a 14-year-old daughter, Ericka. She wanted to see them wed. But with Ericka soon leaving home, a wedding ceremony seems less important.

Still, they remain plaintiffs in the court case, confident of success.

"To me the thing just becomes clearer and clearer. This is just a window to try to articulate that there are all kinds of families," said Shain. "We think so much the same and we can't have this so-simple thing."

Sokolower, a longtime Berkeley High School social studies teacher, said she expects a same-sex marriage ban to "certainly" appear on the ballot if they win in court. But she also remembers how it was back when they met in 1972.

"If people knew, you lost your children. You couldn't hold on to a teaching job. Lesbian moms trying to get custody of kids, lesbian partners not being able to make decisions -- a lot of those thing changed," she said. "I think history is on our side."

In either case, the debate offers a prime example of California in all of its lawmaking glory, said Brad Sears, executive director of the Williams Institute on Sexual Orientation Law at UCLA.

"The Legislature has had a role here. The governor has vetoed. The courts are now having its role. It could be in November that the people have their role," said Sears. "In terms of a civics lesson, it's pretty interesting."

Reach John Simerman at 925-943-8072 or jsimerman@bayareanewsgroup.com.