Gay marriage in California may turn the corner yet.

After an $83 million ballot battle – the costliest in American history – lawyers will resume their fight over gay marriage at the California Supreme Court on Thursday in San Francisco.

Justices are set to hear oral arguments in a lawsuit that argues that Proposition 8, the ballot initiative that yanked back the right of gay and lesbian couples to marry in the state, is an illegal constitutional revision and should be invalidated.

Proposition 8 passed voter approval by a slim majority (52%) on November 4 and overturned a May state Supreme Court ruling granting gay and lesbian couples the right to marry.

At stake is the legality of 18,000 gay marriages performed during the June-to-November “summer of love” when gay marriage was legal.

Opponents of Proposition 8 say it is an illegal revision to the state Constitution and not an amendment at all. Because it takes away previously granted rights – minority rights protected by the Constitution – it fundamentally alters the document. They contend that only the Legislature has the right to place such a question before the voters.

Passage of Proposition 8 sparked huge gay rights protests, heated debates, boycotts and even political retribution for people on both sides of the issue.

Gay rights activists reacted immediately, taking to the streets the day after passage. Thousands demonstrated in front of churches and temples that had supported the gay marriage ban holding signs that read “No More Mr. Nice Gay,” “No on H8” and “I didn't vote against your marriage.”

Businesses that donated to the Yes-on-8 campaign were picketed and boycotted. Donor lists were published on the Internet.

The debate only intensified when conservative leaders took out a full page ad calling the demonstrations mob “intimidation.” A New York Times full-page ad paid for by The Becket Fund for Religious Liberty called the protesters “mobs, seeking not to persuade but to intimidate.”

And some people paid dearly for voting their convictions. Twenty days after the vote, Richard Raddon stepped down as director of the Los Angeles Film Festival after it was revealed that he had given $1500 to the Yes-on-8 campaign. Also out was Scott Eckern, director of the not for profit California Musical Theatre, a Sacramento playhouse that was producing The Color Purple at the time of Eckern's ouster.

As fall gave way to winter, and the state Supreme Court agreed to intervene, the demonstrations died down and the rhetoric was placed on simmer. The gay marriage debate shifted away from California – first to New England, then to New York, Hawaii and New Mexico – but on Thursday the pot is certain to boil over once again.

Will the court side with popular will or, having already tagged marriage as a fundamental right, move to strike the anti-gay measure?  A decision is expected before summer.

Arguing in favor of Proposition 8 will be Kenneth Starr, the former independent counsel who investigated President Bill Clinton in the Whitewater affair, which led to the impeachment of Clinton in the House. The Senate, however, acquitted him.

Proponents of Prop. 8 say they will also seek to nullify the thousands of gay marriages performed.

“Its [Prop. 8] plain language encompasses both pre-existing and late-created same-sex (and polygamous) marriages, whether performed in California or elsewhere,” Prop. 8 backers wrote in a brief. “With crystal clarity, it declares that they are not valid or recognized in California.”

Supporters of repeal have flooded the court with “friend of the court” briefs, including the NAACP, the National Organization for Women, labor groups, local governments and the ACLU. On Monday, the California Legislature passed a resolution expressing support for repeal. And California's top lawyer, Attorney General Jerry Brown, has refused to defend the initiative and called it “unconstitutional.”

But whatever decision is handed down, it will certainly not be the final say. Both sides have hunkered down for the long haul and voters are likely to face a pro- or anti-gay marriage initiative in 2010 – the only question that remains is which.