By Peter Henderson
SAN FRANCISCO (Reuters) - An appeals court will say on Tuesday whether it will revisit the constitutionality of California's Proposition 8 gay marriage ban or clear the way for the U.S. Supreme Court to take up the issue.
A three-judge panel of the 9th U.S. Circuit Court of Appeals ruled in February that the ban discriminated against gays and lesbians. It rejected the key argument by ban supporters that Proposition 8 furthered "responsible procreation."
Ban proponents appealed the ruling to the full 9th Circuit, which could hear it with a larger panel of judges or decline to review it, opening the way for an appeal to the U.S. Supreme Court in the session that begins in October.
President Barack Obama last month turned gay marriage into a 2012 campaign issue, saying he believed same-sex couples should be able to marry. Republican Mitt Romney disagrees.
The vast majority of U.S. states limit marriage to opposite-sex couples, and popular votes have consistently approved bans on widening those rights.
But polls show growing acceptance of same-sex nuptials, which have been legalized in eight states and the District of Columbia, thanks to votes by legislators and court decisions.
The 1st Circuit Court of Appeals in Boston last week ruled that the federal Defense of Marriage Act unconstitutionally denied benefits to same-sex couples in a state where gay marriage was legal.
The U.S. Supreme Court would set national precedent if it decided to take the case. Appeals courts have so far declined to rule broadly on whether marriage is a fundamental human right for same-sex couples as well as heterosexuals.
The recent Boston ruling focuses on whether the federal government should follow states' definitions of marriage when determining benefits, and the California ruling in February limited itself to Prop 8.
"Proposition 8 serves no purpose, and has no effect, other than to lessen the status and human dignity of gays and lesbians in California," the California ruling read. A 9th Circuit spokesman on Monday said the decision on whether to revisit the case would be published on Tuesday about 10 a.m.(1:00 p.m. EDT/1700 GMT).
The most populous U.S. state is the home of Hollywood and hippies, but it has a socially conservative side as well. That leaning was clear in the 2008 ballot that enacted Prop 8 by 52.24 percent to 47.76 percent, or some 600,000 votes, ending a summer of legal same-sex marriage.
A federal judge struck down Proposition 8 in 2010, although existing same-sex marriages are on hold pending appeals.
(Editing by Eric Walsh)