The fate of same-sex marriage in California will be decided Tuesday, when the state Supreme Court issues its ruling on legal challenges to Proposition 8, which eliminated the right of same-sex couples to wed.

The state's highest court heard oral arguments in March from attorneys supporting the measure and from those representing plaintiffs who claim the measure is unconstitutional.

Voters approved Proposition 8, an amendment to the state constitution, in November. The ban sparked outrage from gay rights advocates and prompted mass protests across the state.

In the days after the passage of Proposition 8, three lawsuits were filed directly with the state Supreme Court challenging the validity of the measure. A host of organizations filed petitions with the court in support of the challenges.

Eight years ago, California voters approved Proposition 22, which specified in state law that only marriages between a man and a woman are valid in California. But in May 2008, the state Supreme Court ruled the law was unconstitutional because it discriminated against gays, and an estimated 18,000 same-sex couples got married in the ensuing months.

Opponents of same-sex marriage quickly got Proposition 8 on the November ballot, and it was approved by a margin of 52.5 percent to 47.5 percent.

State Attorney General Jerry Brown has also petitioned the state Supreme Court to overturn Proposition 8. Brown noted that in the ruling overturning Proposition 22, the state Supreme Court found that the constitution guarantees that the right to marry cannot be denied to same-sex couples.

In their court papers, proponents of the measure attacked the view of opponents that Proposition 8 represents a radical change of the constitution that should have been required a two-thirds vote of the Legislature.

"But that portrayal is wildly wrong," proponents state in their court papers. "Proposition 8 is limited in nature and effect. It does nothing more than restore the definition of marriage to what it was and always had been under California law before June 16, 2008 -- and to what the people had
repeatedly willed that it be throughout California's history."

They argue that the measure is not vague, but is written in clear, plain language and should invalidate any same-sex marriages that have been performed in the last several months. Brown has argued that the same-sex marriages that have been performed should remain valid.

During oral arguments in March, the state Supreme Court reviewed three specific issues:

-- Is Prop 8 invalid because it constitutes a revision of, rather than an amendment to, the state constitution?

-- Does Prop 8 violate the separation of powers doctrine under the state constitution?

-- And if Prop 8 is not unconstitutional, what affect -- if any -- would it have on the marriages of same-sex couples performed between the legalization of gay marriage in June and the passage of the amendment in November?