SAN FRANCISCO (Reuters) - California’s gay marriage ban could open the door to legal discrimination against unpopular groups if the state Supreme Court allows the voter-approved measure to stand, blacks, Latinos, Asians and other minorities said.

Rich Joludow wears a T-shirt at the No on 8 proposition headquarters in West Hollywood, October 29, 2008. REUTERS/Fred Prouser

The November 4 vote, supporting an end to legal same-sex marriage in the most populous U.S. state, has caused a nationwide furor as opponents of the measure decry what they consider a civil rights violation.

California’s highest court agreed on November 19 to hear a challenge, based on whether the state constitution requires support from the legislature -- as well as a majority vote of the people -- to strip rights from any group.

The court had recognized such marriages in May, and about 20,000 same-sex couples wed before the November vote. Those marriages may now hang in the balance. Connecticut and Massachusetts are the only states that allow gay marriage.

Legal scholars say the measure, which defines marriage as between a man and a woman, breaks new ground by limiting the courts’ ability to protect minorities.

“They could take away any right from any group,” said University of Southern California Law Professor David Cruz, who filed a brief in favor of gay marriage in an earlier case.

EQUAL PROTECTION ‘SUBVERSION’

The ban, California Proposition 8, amended the constitution with 52 percent support -- less than is required to approve some state bond measures.

“The entire purpose behind the constitutional principle of equal protection would be subverted if the constitutional protection of unpopular minorities were subject to simple majority rule,” read a brief by black, Asian and Hispanic groups challenging the ban. “This case is not simply about gay and lesbian equality.”

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It is unlikely that relatively liberal California would approve restrictions on racial and religious minorities, especially ones that clash with the protections guaranteed by the U.S. Constitution, Cruz and others say.

“We are past that as a realistic matter. We just elected an African-American president, for Christ’s sake,” said University of California, Berkeley, law professor Jesse Choper, who also filed on behalf of gay advocates in the original gay marriage case.

Other groups -- from prisoners to undocumented workers -- might not have public opinion on their side.

“The history of California demonstrates with sobering clarity the potential for disfavored minorities to be subjected to oppression by hostile majorities,” the minority groups say in their brief, pointing to segregation laws and one excluding Asian-Americans from land ownership as examples.

‘TRACK RECORD’

“It is not hypothetical. It’s a track record,” said Stanford University law professor Jane Schacter, who has not filed briefs in the case.

Indeed, a central argument in support of the gay marriage ban is that majority-vote constitutional amendments can change rights.

“That power is broad and deep and, by nature, populist. It has often been used to be make significant changes in state government and to override judicial interpretations of the Constitution with which the people disagree -- including interpretations involving basic constitutional rights,” lawyer Andrew Pugno argued in court papers.

He also argued that defining marriage as between a man and a woman simply re-established the situation before the court recognized gay marriage in May.

The California high court could hear arguments in March. Berkeley’s Choper says it will be an uphill battle to persuade the judges that the measure requires legislative action.

Choper said he understands why the groups are fighting the ban and he is sympathetic, “but that’s not the way the system works.”