The U.S. 9th Circuit of Appeals in San Francisco Tuesday upheld a lower court decision, which had declared unconstitutional California’s controversial Proposition 8 banning same sex marriage.

The matter is now expected to travel to the U.S. Supreme Court.

The ruling, made by judges Stephen Reinhardt, Michael Daly Hawkins and Randy Smith -- appointed by Jimmy Carter, Bill Clinton and George W. Bush respectively -- ruled on both the constitutionality of Prop 8 and whether the judge who struck down Prop 8 should have recused because he is gay.

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They heard oral arguments on the constitutionality question more than a year ago, and the recusal matter in December.

California voters agreed to Prop 8 — also known as the California Marriage Protection Act — in November 2008 by a 52 to 47 percent margin (approximately 13 million voters took part). That vote inserted language in the state constitution expressly allowing marriage only between a man and a woman.

Two same-sex couples challenged the vote, and in 2010 retired U.S. Federal Court Judge Vaughn Walker declared the proposition unconstitutional because it denied equal protection under the law. However, Prop 8 supporters argue that because Walker later acknowledged that he is gay, it was improper for him to rule on the matter.

The California Supreme Court upheld the validity of the voter initiative, and a stay has been in place on Prop 8 pending appeals.

California Gov. Jerry Brown told CNN when he was attorney general in 2009 that he expected gay marriage to return to the state after the issue was likely decided by the highest court in the land.

It is very hard to say, well, some get it and some don't when there's no real basis for the distinction. I think that's where the law is evolving at this point, said Brown.