No matter what they decide, though, it will be controversial.
The legal question of same-sex marriage has been working its way through the state courts for five years now. On Tuesday, the State Supreme Court will issue its decision not only on Proposition 8, but also on the validity of 18,000 marriages issued while they were legal.
Molly McKay picked up t-shirts for supporters of same-sex marriage, also known as marriage equality. She's helping get ready for a series of events planned around the Supreme Court decision coming Tuesday, where has a lot at stake.
The court is also deciding if her marriage is legal.
"This has just been an absolutely gut wrenching time for all of us. We've all been waiting for this decision, we feel like our lives are on hold. People who wanted to get married are waiting to see if they can start getting married again, and all of us who got married are holding on to our marriage licenses and nothing happens to them," said McKay.
In November, 52 percent of voters passed Proposition 8, which amended the state constitution to define marriage as between a man and a woman.
Passage of Prop 8 effectively banned same-sex marriage in California, even though the State Supreme Court had already ruled that denying it was discrimination.
Now that same court has to decide if voters have the right to change the constitution.
"Equal protection under the law, there are no exceptions to that rule and it would be unconstitutional to rule otherwise, or certainly a revision to the way our constitution has always been for everybody before," said McKay.
"I think the Supreme Court should honor the will of the people," said Bill Tam from Traditional Family Coalition.
Tam is executive director of Traditional Family Coalition, a group of Bay Area Asian and Hispanic churches. He says his group is worried that legalizing same-sex marriage would open the door to all kinds of marriages.
"What about three people, why can't that be legalized. What about intergenerational marriages, why that cannot be legalized. Aren't they discriminating those then?" said Tam.
Police barricades are staged in the Castro District in anticipation of the court decision. They may or may not be needed after the ruling is announced.
Same-sex marriage supporters have a series of organized events planned beginning with a prayer vigil at Grace Cathedral on Monday night, the night before the decision. Both sides say no matter which way the decision goes, they plan to continue fighting hard for their beliefs.