San Francisco officials went on the attack Thursday in their fight over same-sex weddings, suing the state on the grounds that laws defining marriage as between a man and woman illegally discriminate against gays and lesbians.

In bringing the Superior Court suit, officials also tried to gain an edge over anti-gay marriage forces by naming as defendants the two groups that have sued the city, the Proposition 22 Legal Defense and Education Fund and Campaign for California Families.

The city's suit comes as the same-sex marriage opponents head to court today trying to persuade a judge to halt the stream of gay and lesbian weddings at San Francisco City Hall. So far they've been unsuccessful in getting a judge to issue a stay.

"The city and county of San Francisco is going on the offensive today in protecting the mayor's actions,'' City Attorney Dennis Herrera said in announcing the suit.

He said city officials want to make sure the courts rule on the cornerstone of Mayor Gavin Newsom's defense -- that state laws defining marriage as between a man and woman violate the state constitution's guarantee of equal protection.

The city also charges that the state laws run afoul of the constitution's guarantees of due process and privacy.

Newsom said he backed Herrera's decision to sue the state. "It goes to the core of the question, and our belief that we're in the right from a constitutional perspective,'' he said.

State Attorney General Bill Lockyer issued a statement saying it was his duty to defend state laws that prohibit same-sex marriages.

"As a lifelong defender of civil rights, due process and equal protection for all, I do not personally support policies that give lesser legal rights and responsibilities to committed same-sex couples than those provided to heterosexual couples,'' the Democratic attorney general said.

He said that is why he has supported extending benefits through domestic partnerships and civil union statutes.

"But the people of California have spoken,'' Lockyer said. "State law prohibits the recognition of same-sex marriages.''

Voters banned same-sex marriages under Proposition 22 in 2000. The Alliance Defense Fund, the group representing the Proposition 22 Legal Defense and Education Fund, issued a statement saying that the city's suit was an "implicit concession that the city lacks legal authority. It is trying to retroactively validate its lawsuit activity.''

Richard Ackerman, one of the lawyers for Campaign for California Families, said the city should have filed suit in the first place, before officials began issuing same-sex licenses. He also said Lockyer should recuse himself from the case because, he said, Newsom called the attorney general last week before the city acted.

Former California Supreme Court Justice Joseph Grodin said the city may have filed the suit just in case the anti-gay marriage groups convince a judge that Newsom acted illegally under a section of the constitution barring state agencies from refusing to apply a state law.

"It serves as backup insurance so that the constitutionality of the statute will somehow get litigated,'' said Grodin, who teaches constitutional law at the University of California's Hastings College of the Law in San Francisco.

Both sides are expected to wrestle over several issues in court today. The city is seeking to consolidate the two anti-gay marriage groups' lawsuits and have both heard before Superior Court Judge James Warren. Earlier this week, Warren refused to issue a stay immediately barring city officials from issuing same-sex licenses. He has scheduled a March 29 hearing in the case.

Lawyers for the Proposition 22 Legal Defense and Education Fund said they will make their own request to have both suits combined and heard today before Superior Court Judge Ronald Quidachay.

"If you think this has been a procedural nightmare,'' Ackerman said, "you haven't seen anything at all.''

A total of 3,034 same-sex couples have been issued marriage licenses since Feb. 12, and there were long lines at City Hall again Thursday.

Outside, about a dozen members of an East Coast-based evangelical group, Repent America, spent part of the afternoon on the steps of the building protesting same-sex marriage. Aside from some angry words from the crowd, there was no confrontation.

Earlier in the afternoon, a few members of Repent America tried to block entry to the clerk's office so that people seeking marriage licenses couldn't get in. That lasted about 15 minutes before police arrived to remove them.

One evangelist also attempted a citizen's arrest.

Volunteer officiant Bill Jones said he was marrying a couple on the mayor's balcony when he noticed a stranger looking on. Jones asked the man to take a picture of him with the happy couple, and the man obliged.

The man proceeded to follow Jones down the hall, saying he was performing a citizen's arrest.

"I thought he was kidding," said Jones, of San Rafael. "I was giving him all this campy stuff, saying, 'Yes, arrest me -- I love a man in uniform.' "

When Jones realized the man was serious, he told him that he wouldn't go anywhere with him without a police officer.

The man apparently was unable to round one up, and Jones continued on his fifth day of marrying gay couples.

Chronicle staff writers Suzanne Herel and Rachel Gordon contributed to this report.

©2004 San Francisco Chronicle

###