BERKELEY, Calif. -- Big change is coming to the lives of the lesbian couple at the center of the fight for same-sex marriage in California no matter how the Supreme Court decides their case.

After 13 years of raising four boys together, Kris Perry and Sandy Stier are about to be empty nesters. Their youngest two children, 18-year-old twins, will graduate from high school in June and head off to college a couple of months later.

"We'll see all the movies, get theater season tickets because you can actually go," Stier said in the living room of their bungalow in Berkeley. Life will not revolve quite so much around food, and the challenge of putting enough of it on the table to feed teenagers.

They might also get married, if the high court case goes their way.

Perry, 48, and Stier, 50, set aside their lunch hour on a recent busy Friday to talk to The Associated Press about their Supreme Court case, the evolution of their activism for gay rights and family life.

On Tuesday, they plan to be in the courtroom when their lawyer, Theodore Olson, tries to persuade the justices to strike down California's voter-approved ban on same-sex marriages and to declare that gay couples can marry nationwide. Supporters of California's Proposition 8, represented by lawyer Charles Cooper, argue that the court should not override the democratic process and impose a judicial solution that would redefine marriage in the 40 states that do not allow same-sex couples to wed.

A second case, set for Wednesday, involves the part of the federal Defense of Marriage Act that prevents same-sex couples who are legally married from receiving a range of federal tax, pension and other benefits that otherwise are available to married people.

The Supreme Court hearing is the moment Perry and Stier, along with Paul Katami and Jeff Zarrillo of Burbank, have been waiting for since they agreed four years ago to be the named plaintiffs and public faces of a well-funded, high-profile effort to challenge Proposition 8 in the courts.

"For the past four years, we've lived our lives in this hurry-up-and-wait, pins-and-needles way," Perry said, recalling the crush of court deadlines and the seemingly endless wait for rulings from a federal district judge, the 9th U.S. Circuit Court of Appeals, also based there, and the California Supreme Court.

Stier said Olson told them the case could take several years to resolve. "I thought, years?" she said.

But the couple has been riding a marriage rollercoaster since 2003, when Perry first asked Stier to marry her. They were planning a symbolic, but not legally recognized, wedding when San Francisco Mayor Gavin Newsom ordered city officials to issue marriage licenses to same-sex couples in 2004. So they were married, but only briefly. Six months later, the state Supreme Court invalidated the same-sex unions.

They went ahead with their plans anyway, but "it was one of the sadder points of our wedding," Perry said.

Less than four years later, however, the same state court overturned California's prohibition on same-sex unions. Then, on the same day Perry and Stier rejoiced in President Barack Obama's election, voters approved Proposition 8, undoing the court ruling and defining marriage as the union of a man and a woman. Their lawsuit was filed six months later, after they went to the Alameda County courthouse for a marriage license and were predictably refused.

"It's such a weird road we've been on," Perry said.

All the more so because neither woman defined herself as a gay rights activist before the marriage fight.

Perry, a native Californian from Bakersfield, and Stier, who grew up in rural Iowa, moved in together in 2000, with Stier's two children from a heterosexual marriage and Perry's from a previous relationship. Utterly conventional school meetings, soccer games and band practice - not the court case - have defined their lives together.

As if to highlight this point, their son, Elliott, briefly interrupted the interview to ask for a pair of headphones. Perry said the boys find her useful for two basic reasons these days. "Do I have any headphones and do I have any money?" she said with a smile.

Perry has spent her professional life advocating on behalf of early childhood education. Stier works for the county government's public health department.

"When you've been out as long as I have been, 30 years, in order to feel OK every day and be optimistic and productive, you can't dwell as much on what's not working as maybe people think you do," Perry said.

Even with Proposition 8's passage, Perry and Stier said they were more focused on Obama's election.

"I was all about health care reform and Kris is all about education reform and that was everything. Gay rights, that would be great, but it's a way off," Stier said.

They don't take the issue so lightly anymore. Of course, they could not imagine a U.S. president would endorse gay marriage along with voters in three states just last November.

When Obama talked about equal rights for gay Americans in his inaugural speech in January, Perry said she felt as if "we've arrived at the adults' table. We're no longer at the kids' table."

They will watch the argument in their case and then return home to wait for the decision, worried that it could come the same day as the boys' high school graduations in mid-June.

They know the court could uphold Proposition 8, which would almost certainly lead to an effort to repeal it by California voters. Recent polls show support for repeal.

Any other outcome will allow them to get married. But Perry said they are hoping the court strikes "a tone of more inclusion" and issues the broadest possible ruling.

They will get married quickly, in a small, private ceremony. "We did the big celebration a long time ago," Perry said. "I hope this will be something a lot bigger than the two of us."

• Read more articles by MARK SHERMAN

Order Reprint