The California-based Ninth Circuit Court of Appeals on Tuesday will decide the fate of Prop 8, the ballot measure to change the state's constitution to ban same-sex marriage.

The traditionally liberal appeals court will rule on the constitutionality of California's 2008 ballot measure that defined marriage as a union between a man and a woman, passed months after the state's Supreme Court opened the door for same-sex couples to wed.  Californians passed Prop 8 in 2008 with 52 percent of the vote.

But before the Ninth Circuit wades into the constitutional question of Prop 8, a three-judge panel will decide if a lower federal judge should have recused himself from the case because he is gay.

Opponents of same-sex marriage say the appeals court should throw out a decision overturning Prop 8 from U.S. District Court Judge Vaughn Walker, a Reagan appointee who publicly acknowledged after his 2011 retirement that he is gay and had a long-time partner.

If the appeals court rejects the argument that Walker should have recused himself from the case because of his sexual orientation, the Ninth Circuit can issue an opinion on Prop 8's constitutionality.

Tuesday's decision could put same-sex marriage before the U.S. Supreme Court, a case that has the potential to effect similar ballot measures that altered state constitutions to limit marriage to heterosexual couples.

The losing party can fast-track the case with a petition to the Supreme Court, or request a review -- called an en banc hearing -- from all 11 judges on the Ninth Circuit.

--