It was one of the largest rallies Castro Street has seen in years. A fight for marriage equality.
Alan and Marcus live in San Francisco but recently got married in New York, "We love each other," Alan said. "We want to get married in the city where we fell in love. I love this guy, I want to be able to walk around and say 'this is my husband,' and have it become legal here."
On the eve of the Supreme Court hearing on California's Proposition 8, Cindy Frank sent a clear message to the woman she wants to marry, "This is the real deal," she said. "Traditions are not just for straight people, I want to get married. And this is my proposal to my lover, so I hope she says yes, and I hope the Supreme Court says yes, we'll be there."
Eventually the group took its message to the streets, marching from Harvey Milk Plaza to City Hall. Several thousand people joined in the march, escorted by police.
"It's important for the world to see that these are real people's lives who just want the same equality as everybody else," San Francisco resident Lori Bilella said.
Once the group arrived at City Hall, the rallying cry got louder.
"Nine years ago we made history in this building by leading the way for marriage equality," shouted San Francisco Supervisor Scott Wiener. "And we're gonna do it again tomorrow when the Supreme Court takes Prop 8 and DOMA and puts them where they belong, on the garbage heap of history!"
Two women from Berkeley and two men from Burbank are the couples bringing the case against Prop 8. Enacted by 52 percent of state voters in November 2008, Prop 8 banned same-sex marriage by providing that "only marriage between a man and a woman is valid or recognized in California."
"This case for us is about how we as Americans just want to be treated equally by our government," plaintiff Sandy Stier said.
Tuesday, one of their lawyers, Theodore Olson, will have 20 minutes to argue the case against Prop 8. He'll likely face questions from the court on why the 2008 vote of the people should be overturned.
U.S. Solicitor General Donald Verrilli will have 10 minutes representing President Barack Obama's opposition to a ban on same-sex marriage.
Supporters of the Prop 8 will be represented by Charles Cooper, one of the attorneys who argued the case in San Francisco's federal court. Cooper will have 30 minutes and will likely face questions on whether Prop 8 supporters have legal standing in the case since California's attorney general won't defend the law.
"When we talk about fundamental rights as it relates to the Constitution, we are talking about those rights that we as a nation designated as being some of the most sacred of all the rights we can have," California Attorney General Kamala Harris said.
And, Harris adds, the Supreme Court has described marriage as fundamental right more than a dozen times.
Supporters of the marriage ban say California voters have already made the call.
"We should not allow the federal judiciary to destroy the vote of the people, especially on something as old and good as marriage," Prop 8 supporter Randy Thomasson said.
Many court observers say Justice Anthony Kennedy will be the swing vote in a 5-4 decision. The Sacramento native has stuck down anti-gay laws in Texas and Colorado, but he's also a strong advocate for state's rights and in 2008 Californians voted for the ban.
NOTE: ABC7 News Reporter Carolyn Tyler will be sitting in the Supreme Court when it considers the constitutionality of Prop 8. Watch her live reports tomorrow on ABC7 News and follow her on Twitter.