DEBORAH AMOS, host:
Now to California, where a federal trial that challenges the state's ban on same-sex marriage wraps up tomorrow with closing arguments. Scott Shafer, from member station KQED in San Francisco, has been following the case that could have implications across the country.
SCOTT SHAFER: When California voters narrowly passed Proposition 8 in November of 2008, it put an immediate end to gay and lesbian weddings here. After the state's Supreme Court refused to strike down the measure last year, two same-sex couples filed a lawsuit in federal court.
To plaintiff Paul Katami, the issue is simple and personal.
Mr. PAUL KATAMI: We want to be married. We have the right to be married. Why can't we be married?
SHAFER: Katami has some high-powered legal help. Republican Theodore Olson and Democrat David Boies were adversaries in the Bush v. Gore U.S. Supreme Court case in 2000. But now, they've teamed up on behalf of gay marriage.
To Olson, the case boils down to a very simple legal principle:
Mr. THEODORE OLSON (Attorney): The Supreme Court of the United States has declared again and again that the right to choose one's life companionship, in the form of marriage, is a fundamental right in this country.
SHAFER: But so far, the high court has only applied that right to heterosexual couples. Does that same right also belong to same-sex couples? That's what this case will help decide.
During 12 days of testimony, Olson and his legal team called a parade of academic witnesses. They testified about the changing nature of marriage, the history of anti-gay discrimination, and the political power of conservative church groups. Olson's co-counsel, David Boies, says Prop 8 was based on stereotypes and anti-gay prejudice.
Mr. DAVID BOIES (Attorney): We've exposed publicly the fact that there simply is no basis for prohibiting gays and lesbians from getting married. It doesn't help anyone.
SHAFER: Boies and Olson hope to convince federal Judge Vaughn Walker that Prop 8 violates the 14th Amendment of the U.S. Constitution: the right to due process, and equal protection under the law.
Defenders of Prop 8 called only two witnesses during two weeks of testimony back in January, focusing mostly on the benefits of limiting marriage to one man and one woman.
Andrew Pugno, an attorney defending the state's ban on gay marriage, says there are plenty of rational arguments for preserving traditional relationships.
Mr. ANDREW PUGNO (Attorney): A same-sex couple can never offer a child both a mother and a father. And that is a reasonable reason for the people to decide to continue to keep marriage as a union between a man and a woman.
SHAFER: During the trial, Pugno and other defense attorneys complained that Judge Walker's decisions have tended to favor gay-marriage supporters. In fact, at times, they seemed to be putting all their chips on an appeal.
Mr. PUGNO: It's not the role of the courts, and it's not proper for judges to substitute their own views on these political questions for the judgment of the people. And that's really what this case boils down to, is who gets to decide.
SHAFER: For years, gay-rights groups fought to keep same-sex marriage cases out of the federal courts for fear they'd ultimately lose if the case went to the U.S. Supreme Court.
If Judge Walker strikes down California's gay-marriage ban, he could do it in a way that sweeps away anti-gay-marriage laws throughout the nation. But he could issue a much narrower ruling, one affecting only states like California and Washington, where same-sex couples already have broad legal rights but can't get married.
In other words, Judge Walker could decide that differentiating same-sex and opposite-sex couples in name only domestic partnership versus marriage - is simply discriminatory.
Tomorrow's closing arguments will be closely watched, but not on television. The judge rejected a request to allow cameras in the courtroom.
For NPR News, I'm Scott Shafer in San Francisco.