The California Supreme Court on Tuesday upheld a voter-approved ban on same-sex marriages, a decision it said addressed only the narrow question of whether the state's constitution was properly amended.

The justices said their 6-1 ruling was not intended to decide whether gay marriage "is wise or sound as a matter of policy or whether we, as individuals, believe it should be a part of the California Constitution."

The court, however, said the estimated 18,000 same-sex marriages that took place in the state last year will remain legally valid.

At issue was the validity of Proposition 8, a state constitutional amendment banning same-sex couples from marrying. About 52 percent of the state's voters approved the controversial proposition last year.

In a ruling written by Chief Justice Ronald George, the court rejected the argument that the ban so dramatically changed the civil-rights protections in the California Constitution that it needed the Legislature's approval.

In Tuesday's ruling, the justices said their decision was not a matter of policy, but rather one of law. At issue was not same-sex marriage, the majority found, but whether the voter-approved amendment to the California Constitution passed legal muster. The majority found that it did.

Supporters of Prop. 8 hailed the ruling as a victory for the will of the people.

"Any decision overturning Proposition 8 would have been a clear attack on fundamental democratic principles," said attorney Robert Tyler, who fought for Prop. 8 through his Murrieta-based firm Advocates for Faith and Freedom.

Gay rights advocates decried Tuesday's ruling as a failure to protect a minority class from attack by the majority. They vowed to find support from the masses -- and take their fight back to the ballot box, perhaps as soon as next year.

Roughly 125 gay rights supporters gathered in front of Escondido City Hall Tuesday evening to express their disappointment and continue their push for equal rights.

The crowd of gay and some straight couples, children and adults, chanted "Justice won't wait, repeal Prop. 8" and held signs reading "18,000 is not enough. Marriage is for all."

Garry Irvingwhite, 56, said he was incensed to hear the court's decision Tuesday.

"I thought for sure people would come to their right mind and this would get settled," said the Escondido resident, standing next to his partner of 15 years, Jim Weld. The two had planned to wed if the court overturned the proposition.

Same-sex marriage, among the most polarizing social issues in the nation, has gained momentum in the five years since Massachusetts became the first state to recognize such unions as legally valid.

Within the past few months, Iowa, Vermont and Maine legalized marriage between same-sex couples, either through legislation or court rulings. New Hampshire may soon follow suit, and advocates say it may become legal in New York and New Jersey by year's end.

Still, a number of states ban the practice, and it routinely loses at the ballot box.

California, with its reputation as a pioneer in social issues, briefly allowed same-sex marriages last year. That ended with the ballot-box win for Prop. 8.

'Constitutionally bound to uphold it'

The day Prop. 8 passed last November, gay rights advocates filed a legal challenge saying the amendment was flawed. This was a constitutional revision, they argued, and thus required Legislative approval.

On Tuesday, the high court disagreed.

"In a sense, petitioners' and the attorney general's complaint is that it is just too easy to amend the California Constitution through the initiative process. But it is not a proper function of this court to curtail that process; we are constitutionally bound to uphold it," Justice George wrote.

The court upheld the ban on same-sex marriage. But it said Prop. 8 is not retroactive -- and thus it upheld last year's same-sex marriages, which came during a five-month window before the passage of Prop. 8.

The news was bittersweet for Max Disposti. The Oceanside resident said he was happy to learn the state Supreme Court upheld his June marriage to his husband. But he was disheartened -- though not surprised -- to learn the court had OK'd the ban.

"It's not like, 'Whoa, shock me completely,'" said Disposti, who heads up the North County LGBT (Lesbian, Gay, Bisexual, Transgender) coalition. "We heard the hearing; we knew where they were going with it."

Protect Marriage, the organization that backed Prop. 8 last year, issued a statement calling the ruling "a major victory."

Local supporters of the ban on same-sex marriage also cheered the ruling -- though they were not surprised by it.

"This was expected," said Vista resident Terry "Skip" Curtis, a retired Marine colonel who worked in support of Prop. 8. "It really supports the democratic process in the state of California. We have an amendment process, and that process was upheld."

Attorney Tyler's firm, a religious-rights law practice, has played a leading role in the same-sex marriage legal battle for five years, and earlier this year filed briefs with the court asking that it uphold Prop. 8.

"The court had no other choice if it was going to respect our democratic form of government," Tyler said of the ruling.

'Setting aside personal beliefs'

This was the second time the state's highest court has grappled with the issue of allowing same-sex marriage. Last year, the same seven justices voted 4-3 to overturn a simple statute banning the practice.

At that time, the court found that civil rights in the state constitution trumped the law, which at that time was just a simple statute and thus relatively low on the hierarchy of laws.

Then came Prop. 8, a constitutional amendment.

At the top of the ruling it issued Tuesday, the court noted that its role in this case was not to determine whether Prop. 8 was "wise or sound as a matter of policy."

Instead, George wrote, the court was "limited to interpreting and applying the principles and rules embodied in the California Constitution, setting aside our own personal beliefs and values."

"It's a different issue, and that is why the justices flipped sides," said Julie Greenberg, a professor at Thomas Jefferson School of Law in San Diego.

Justice Carlos R. Moreno cast the sole dissenting vote, finding that Prop. 8 should not be valid because it was not a lawful amendment to the California Constitution.

"The rule the majority crafts today not only allows same-sex couples to be stripped of the right to marry … it places at risk the state constitutional rights of all disfavored minorities," Moreno wrote. "It weakens the status of our state Constitution as a bulwark of fundamental rights for minorities protected from the will of the majority."

Moreno, whose name had been floated a few weeks ago as a possible replacement for retiring U.S. Supreme Court Justice David Souter, said the law denying same-sex couples the right to wed "strikes at the core of the promise of equality that underlies our California Constitution" and represents a "drastic and far-reaching change."

'Just a matter of time'

The Supreme Court published the ruling on its Web site at 10 a.m. Tuesday. Interest in reading the opinion was so great, the court's Web site briefly crashed, according to court officials.

Among those experiencing point-and-click frustration was Vista resident Susan Bauer, whose nearly year-old marriage was at stake. The Vista resident finally had to call her wife, Colleen Francis, to learn the news: Their marriage was still valid.

"It is hard to be excited when you see that it is not over," Bauer said. "There is a lot of work to be done now."

Gay-rights advocates such as Disposti and Bauer said they will be foot soldiers in support of a possible ballot measure to overturn the ban on same-sex marriage. And, they say, the shift in societal values is heading in their direction.

In 2000, about 63 percent of the California electorate voted to ban same-sex marriage. Eight years later, in the November 2008 election, that number dropped to 52 percent in favor of the ban.

"It's just a matter of time," Disposti said. "It is."

Holding a sign reading "Straight supporter for Marriage Equality" at the rally in Escondido, Helen Lindner said she felt a need to show up Tuesday evening.

"I was devastated," the Vista resident said of Tuesday's ruling. "I felt a loss for all the people that are continuing to lose their civil rights."

Disposti said supporters of same-sex marriage from across the state will gather in Fresno on Saturday to discuss their planned ballot measure, including just when they should bring it. He said they are eyeing perhaps 2010 and 2012.

The gay rights group Equality California said Tuesday the lion's share of its membership is pushing to put the measure on the ballot next year.

Opponents such as Curtis, who posted "Yes on 8" signs throughout Vista last fall, said they would be willing to hit the streets again to defend the ban on same-sex marriage.

"When you believe strongly in something, you are willing to support it and put your money where your mouth is," Curtis said. "As long as I can walk and talk, I will speak my personal view. The term 'marriage' has personal and religious significance to me."

Contact staff writer Teri Figueroa at 760-740-5442.