The national gay marriage debate shifted to California on Tuesday, as the state's highest court heard more than 3½ hours of arguments on the constitutionality of a voter-approved law banning same-sex marriage.

Gay rights advocates sued to overturn the ban four years ago after the court halted a months-long same-sex wedding spree that saw thousands of couples marry at San Francisco's City Hall.

''I think I speak for everybody when I say that this has been a long time coming and a day that has been eagerly anticipated,'' said San Francisco city attorney Dennis Herrera, who is representing the city in a lawsuit supporting gay marriage.

The court heard arguments in six cases that were filed after the court stopped the same-sex marriages in the winter of 2004. More than 4,000 couples exchanged vows at the direction of Mayor Gavin Newsom months before same-sex marriage became legal in Massachusetts, although the California high court ultimately voided the unions.

The seven justices asked whether California already protects the civil rights of gay and lesbian couples through domestic partnerships. They also wanted to know if a ruling 60 years ago legalizing interracial marriages in the state gave them a precedent for striking down the same-sex marriage ban.

In briefs submitted to the court, same-sex marriage supporters argued that California's constitution leaves no room for denying gays and lesbians the right to wed.

They say that while the state is one of a handful where gay couples are entitled to most of the same legal rights as married spouses, the institution of marriage is too important to allow for alternatives that are by definition inferior.

''We're very hopeful that California history will stay true today and [that] we'll see the constitution vindicated for the thousands of families in California who depend on our equal place under law,'' said Jennifer Pizer, a Lambda Legal lawyer who is representing gay couples.

The state and same-sex marriage opponents, however, maintain that limiting marriage to members of the opposite sex is reasonable -- not only to uphold tradition but because California voters approved a ballot initiative eight years ago bolstering the gay-marriage ban that was in place at the time. To overturn that law, they say, would abrogate the rights of all Californians.

''A day may come when the people decide to legalize same-sex marriage. But such a social change should appropriately come from the people rather than the judiciary so long as constitutional rights are protected,'' Deputy Atty. Gen. Christopher Krueger wrote in a court brief.

A trial court judge in San Francisco agreed with gay rights advocates and voided the state's marriage laws in April 2005. An appeals court overturned his decision in October 2006.

Since these California cases were filed, the top courts in six other states have been asked to legalize same-sex marriage. New Jersey's top court gave lawmakers the option of adopting civil unions as an alternative, and a ruling is pending in Connecticut, but none of the other courts were persuaded.

Del Martin, 87, and Phyllis Lyon, 84, were the first pair to get married in San Francisco when Newsom directed his staff to issue marriage licenses to same-sex couples on February 12, 2004. At the time they had been together for 51 years. They are one of 23 couples suing the state, but poor health will keep them at home on Tuesday, they said.

''If they would go ahead and throw [the marriage ban] out, we could stagger up to the altar,'' Lyon said with a grin.

The California supreme court has 90 days in which to rule following the hearing. (Lisa Leff, AP)