Gay-rights advocates asked the California Supreme Court on Monday to overturn a lower court's decision that the state's ban on same-sex marriage isn't a violation of constitutional rights.

The state's highest court — which all parties always have expected would have the final word on this issue — has up to 90 days in which to accept or decline the case.

San Francisco Superior Court Judge Richard Kramer in March 2005 ruled the statutory same-sex marriage ban serves no rational purpose and unconstitutionally denies same-sex couples equal protection under the law.

But the California Court of Appeal, in a 2-1 ruling issued Oct. 5, concluded that the ban does not violate anyone's constitutional rights, and that marriage's definition is best left to the people and lawmakers rather than courts.

Arguing against same-sex marriage in these six consolidated cases are the state Attorney General's office, which is duty-bound to defend existingstate law; the conservative nonprofit Campaign for California Families; and the Proposition 22 Legal Defense and Education Fund, named for the 2000 ballot measure passed by 61 percent of voters to reinforce an already-existing statutory ban on same-sex marriage.

Arguing for the right to same-sex marriage are the City and County of San Francisco, which fueled the debate by issuing marriage licenses — later voided — to same-sex couples in 2004, and same-sex couples and gay-rights groups that challenged the

ban. The couples and groups are represented by a legal team including the National Center for Lesbian Rights, Lambda Legal and the American Civil Liberties Union.

"Today's petition begins the third round of what we've always known to be a three-round fight," San Francisco City Attorney Dennis Herrera said in a news release. "We are confident of the rightness of our case, the justice of our cause, and the wisdom of our state's highest court."

One of the plaintiff couples, Lancy Woo and Cristy Chung, announced this weekend they're separating after spending 18 years and having a daughter together, and they will no longer take part in the lawsuit.

The state and national context in which this case proceeds continues to ebb and flow. New Jersey's Supreme Court ruled Oct. 25 marriage's legal protections must be extended to same-sex couples; it gave that state's Legislature six months in which to amend its laws to permit same-sex marriage, or to create some other, equivalent system bestowing the same rights.

Here in California, the Assembly and state Senate last year narrowly approved a bill to permit same-sex marriage, but Gov. Arnold Schwarzenegger vetoed it.

Contact Josh Richman at jrichman@angnewspapers.com.