Proposition 8 Before Federal Appeals Court

Photo Courtesy - Getty Images(SAN FRANCISCO) -- A federal appeals court in San Francisco heard oral arguments Monday in the landmark legal battle over Proposition 8, California's voter-approved ban on same-sex marriage.

A three-judge panel of the Ninth Circuit Court of Appeals is weighing two questions: whether supporters of the ban have legal standing to bring an appeal, and whether the ban itself is unconstitutional.

In August, U.S. District Judge Vaughn Walker struck down Prop 8, saying it amounts to unconstitutional discrimination and ordered it lifted immediately. But the Ninth Circuit issued a stay on the injunction while the appeal is pending.

The effort to ban gay marriage in California was first launched in response to a state Supreme Court decision allowing same-sex couples to wed. Voters approved Proposition 8 in a November 2008 ballot with a 52-percent vote.

Despite the popular support, Judge Walker found that the measure was rooted in "unfounded stereotypes and prejudices" and that the plaintiffs in the case -- one lesbian and one gay couple -- demonstrated by "overwhelming evidence" that it violates rights to due process and equal protection under the Constitution.

The case, which will likely reach the U.S. Supreme Court, is one that experts say has the potential to transform social and legal precedent.

A recent California Field poll found that 51 percent support legalizing gay marriage with 42 percent opposed. Nationwide, public views are more narrowly divided, according to the most recent ABC News/Washington Post poll. Forty-seven percent of Americans polled favor gay marriage while 50 percent are opposed.

Five states -- Massachusetts, Iowa, Connecticut, Vermont and New Hampshire -- and the District of Columbia perform same-sex marriages. Four states recognize marriages performed elsewhere and nine states grant civil unions or partnerships.

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