Updated

The Supreme Court has a range of options when it comes time to rule on California's Proposition 8 ban on gay marriage.

The justices heard arguments in the landmark case Tuesday morning, and are expected to rule by June. Here are the options for how they could decide:

Proposition 8 violates the Equal Protection Clause of the Constitution, gay marriage is a protected right 

This is the most sweeping decision the court could make. Under this scenario, the court decides that limits on gay marriage violate the 14th Amendment under the Constitution. This would eventually lead to limits on same-sex marriage across the country being invalidated -- from civil union laws to outright prohibitions on gay marriage. Gay marriage would effectively be legalized everywhere.

Proposition 8 does not violate the Equal Protection Clause, states can limit gay marriage 

This would be the ruling Prop 8 supporters want from the Supreme Court. Under this scenario, Prop 8 stands and the court determines that states can legally limit marriage to opposite-sex couples.

Case dismissed 

This scenario would still leave the issue quite unsettled. The court would determine that Prop 8 supporters lack the standing to appeal a lower-court ruling, because they are not government officials. This move could result in the 9th Circuit Court of Appeals decision that struck down the ban being thrown out -- but a lower-court decision against Prop 8 could still stand. It's unclear, then, whether that would mean all same-sex couples in California can wed -- or only the plaintiffs in this particular case.

States with civil unions must allow gay marriage 

Under this ruling, the court decides that once a state allows civil unions or domestic partnerships, there's no justification for not allowing marriage. Such a decision would affect California as well as eight other states that have such laws -- Colorado, Delaware, Hawaii, Illinois, Nevada, New Jersey, Oregon and Rhode Island. In California, Prop 8 would be overturned.

Gay marriage allowed in California 

Under this narrow ruling, the court would affirm the 9th Circuit ruling and in doing so invalidate Prop 8. This would only affect California.