Hold the champagne.

Or at least the California sparkling wine.

This week should be a joyous one for those of us who believe in the right to marry the person you love. A month after the California Supreme Court overturned the state's ban on same-sex marriage, gay couples will be able to walk into county offices here and secure the same marriage license to which heterosexual couples such as my wife and I are entitled.

Partners are hastily arranging nuptials, and the wedding-industrial complex of caterers and consultants is anticipating a summer windfall. In San Francisco, Phyllis Lyon and Del Martin, who are both in their 80s and have been together for more than five decades, have arranged to be married by Mayor Gavin Newsom minutes after the ban is officially lifted at 5 p.m. tomorrow. "It means a great deal that we can get a license like anyone else," Lyon recently told the San Francisco Chronicle.

Gay rights supporters should toast the happy couples, but they might want to wait before raising a glass to the state. The ruling will hardly change California, a place blissfully devoted to its live-and-let-live ethos. But California -- with its dysfunctional politics and government -- may hurt the cause of same-sex marriage.

It's far from clear that California's institutions -- the courts, legislature, governor or ballot process -- possess the credibility or power to bring a lasting resolution to any public debate, especially one as contentious as same-sex marriage. Yes, gay marriage supporters are likely to claim more victories than defeats at all levels of California government. But victories in specific lawsuits or bills don't guarantee the unambiguous legalization of same-sex marriage here. The state's madcap legal and political systems offer too many ways to frustrate or delay a final decision. For gay couples and their supporters, California could become an expensive, time-consuming quagmire -- gay marriage's Vietnam.

How can this be, you ask, after the justices' ringing endorsement of gay marriage rights?

Because California has a powerful ballot-initiative process -- the one that in 2000 allowed voters to outlaw gay marriage in the first place -- and the state Supreme Court doesn't always get the final word. Consider the ballot initiative that Californians will vote on this fall. Sponsored by gay marriage opponents, the measure would define marriage as a union between a man and a woman and put this wording into the state constitution, thus reversing the Supreme Court's ruling.

Or not.

"If people vote yes [on the ban]," said Steve Smith, a political consultant working to defeat the initiative, "I think you're going to have immediate litigation." Lawyers on both sides speculate about all kinds of lawsuits, from technical attacks on the initiative's language to broad federal claims about the nature of republican government. Richard L. Hasen, an election law expert at Loyola Law School in Los Angeles, suggests that even if voters do approve the ban, a court could grant a stay on its enforcement. "That would allow marriages to continue to take place," he said, until judges sort out the initiative's constitutionality -- a process that could take years.

Confusing? Sure. But that's California.

If, on the other hand, the initiative fails, gay marriage opponents wouldn't surrender either. "Would that be the end of the road? Obviously not," said Glen Lavy, a senior counsel with the Alliance Defense Fund, which has provided much of the legal firepower behind the movement to ban same-sex marriage. "This is a fundamental institution of society."

Gay marriage opponents would launch various legal challenges, most on religious grounds. Any institution with a sacred affiliation and a public service mission -- religious schools, health facilities, charities, even summer camps -- could argue that being forced to recognize the marriages of same-sex couples who walk through its doors is a violation of religious freedom. According to Brad Sears, executive director of the Williams Institute on Sexual Orientation Law and Public Policy at UCLA's law school, there could be thousands of such claims.

Even if these legal efforts go nowhere, the political battle will continue. If the ballot initiative is defeated in November, nothing prevents its backers from drawing up another one, to come before voters in 2010, the time of the next regularly scheduled statewide election -- or even earlier if the state holds a special election. "This is one of the problems with the initiative process," said Pamela S. Karlan, a scholar at Stanford Law School. "There isn't any way of saying, 'The voters have spoken, and it's over.' They can be asked to speak on it again and again and again."

Why can't the other branches of California government put a stop to this?

The legislature and the governor could try, but their power is limited, and their record on same-sex marriage doesn't inspire confidence. For at least four years, the Democratic-controlled state legislature has supported marriage rights for gays but has proven too ham-handed to overcome the ban voters enacted in 2000.

In California -- wouldn't you know -- only the voters can change statutes enacted by ballot initiative. The legislature ignored this inconvenient fact, and on more than one occasion passed bills that were almost certainly unconstitutional. Gov. Arnold Schwarzenegger, a very California-style Republican, vetoed those bills, probably saving gay marriage supporters from potentially disastrous court rulings. California lawmakers, an irresponsible species, were hardly grateful, criticizing the governor for his actions.

But frankly, Schwarzenegger hasn't shown much leadership. He has been trying to have it both ways on the issue. Asked about the subject during his 2003 campaign, he delivered an all-time great malapropism: "I think that gay marriage is something that should be between a man and a woman." At a state Republican convention in 2004, he blasted Newsom, who had married gay couples in San Francisco even though it was against state law. Less than two weeks later, he told Jay Leno that he would have no problem if such marriages were legalized.

Recently, Schwarzenegger has said that he believes that marriage should be between a man and a woman but that he doesn't want to impose his views on Californians. And he opposes the current initiative, aligning himself with same-sex marriage supporters. But no one should count on the Terminator traveling through time to save gay marriage. Schwarzenegger often sounds like a man who just wishes that the issue would go away.

So why do supporters need the governor and the legislature, if the state Supreme Court has already made its ruling?

Because the court's decision is so broad that it raises new political and legal questions that will have to be taken up by the other branches of government. For the first time, the court ruled that gay people are a "suspect classification" -- a group, such as women or African Americans, who face discrimination because of immutable characteristics -- and that any law governing sexual orientation requires "strict scrutiny." In his majority opinion, Chief Justice Ronald M. George cited a new right that appears nowhere in the text of the state constitution: "the right of an individual and a couple to have their own official family relationship accorded respect and dignity equal to that accorded the family relationship of other couples."

In a footnote, George added that such a right doesn't apply to polygamous or incestuous relationships. Good to know. But the court may have opened the door for "other, less deserving, claims of a right to marry," as Justice Marvin R. Baxter noted in a response to the majority opinion. (Please, nobody call the Mansons.)

Even if novel claims to marriage based on the same-sex marriage decision die in the courts, gay marriage opponents could use them as political fodder. And that's hardly the only political problem that might arise. In three separate sections of its 121 pages, the decision raises the possibility that, to achieve equality for same-sex couples, the state might eliminate the term "marriage" altogether. The decision doesn't endorse such a remedy, but it doesn't rule it out, either.

The elimination of "marriage" is unlikely, even in California. But at least some people here seem to think that no marriages are better than same-sex marriages. Clerks in two California counties have announced that they'll stop performing wedding ceremonies this week for any couples, gay or straight. (They'll still have to hand out licenses.) Just imagine the backlash if the push to recognize same-sex couples turned marriage into a merely religious rite (and right).

These tangles will seem academic to gay couples, who have waited years for simple freedoms. It shouldn't matter that California politics and controversial social policy make for, well, a rocky marriage. But it is a strategic problem. And gay rights advocates would be wise to remember that, with all the political and legal risks involved, the practical advantages of legalizing same-sex marriage in California are underwhelming.

Gay couples who upgrade their status from domestic partners to married spouses will win only a handful of new benefits, and many aren't worth all that much. In California, married couples may live apart, while domestic partners have to reside in the same home. Married couples also have a little-known right to "confidential marriage," meaning that the marriage certificate and the date of the marriage aren't part of the public record. (The reasons for this provision are another California story altogether.) Domestic partnerships, on the other hand, are public. When it comes to divorce, though, married spouses are actually at a disadvantage -- they must have a legal residence in the state and must seek a court judgment; divorcing domestic partners don't need either.

Gay couples who get married this week will gain these new rights and responsibilities, but they still won't have all the same freedoms as heterosexual married couples in California. That's because federal law provides legal recognition only to marriages between a man and a woman. So when it comes to spousal benefits related to federal income taxes, Social Security, federal housing, food stamps and military and veterans' programs, same-sex married couples remain unmarried in Uncle Sam's eyes.

If there's ever going to be true marriage equality in California, the fight that counts most won't take place in Sacramento. For that fight, the battleground is Washington.

Joe Mathews, an Irvine senior fellow at the New America Foundation, is the author of "The People's Machine: Arnold Schwarzenegger and the Rise of Blockbuster Democracy."

This article appeared on page B1.