It is a momentous day for the couples that are the plaintiffs behind the first federal lawsuit challenging the state's ban on same-sex marriage. All four say they want to marry.
"We believe in our Constitution and that the courts will lead the way to equality like they've done so many times in the past," plaintiff Jeff Zarillo said.
Inside the San Francisco courtroom, they were the star witnesses Monday. Zarillo and his partner Paul Katami are from Southern California. Zarillo talked, often emotionally, about how special he believes marriage is and said that the domestic partnerships the state offers to gays and lesbians "would relegate me to a level of second class citizenship...it's giving me part of the pie but not the whole thing."
Kris Perry, 45, and Sandy Steir live in Berkeley. They have been together a decade and are raising four children. Steir testified the Prop 8 campaign ads, especially the ones labeled "Protect the Children," sickened her. She says the ads made it seem there was "a great evil to be feared and the evil must be stopped."
The couple's supporters gathered early outside the courtroom. They also accuse the Prop 8 backers of fostering negative attitudes that led voters to take away the right to marry that the California Supreme Court had given.
But Prop 8 proponents say their efforts were not based on hatred. In his opening statement, attorney Charles Cooper said, "There are millions of Americans who believe in rights for same-sex couples, but draw the line at the right to marriage."
Protect Marriage lead counsel Andrew Pugno says the evidence they plan to present will back that up.
"The claims that the people, the majority of voters in California who approved Prop 8, had malicious intent and are guilty of fostering hate crimes and so on in California, those are outrageous claims," he said.
But Perry says the passage of Prop 8 made her feel, "like I'm not good enough." When asked why she agreed to be a plaintiff in the case, she said, "I want the discrimination we are feeling with Prop 8 to end."
ABC7 legal analyst Dean Johnson says emotions will matter in this case.
"The first thing you hear and the last thing you hear is what you remember and what persuades and today this judge heard testimony, very emotional testimony, that certainly has got to touch his heart," he said.
After proceedings for the day concluded, attorneys from both sides spoke to the media.
"I think anyone who was in court today could not help but be impressed with how important marriage is and how harmful it is, how discriminatory it is, to deprive people of the right to marry the one they love simply because of their sexual orientation," attorney for the plaintiffs David Boies said.
"We are in a lot of trouble if we start invalidating the vote of the people because we can put on four witnesses who say that their feelings are harmed by a ballot measure," Pugno said.
The testimony ended Monday with a Harvard professor who has written a book on the history of marriage. She will be back on the stand Tuesday.
California fluctuates on gay marriage
California has gone back and forth over same-sex marriage for the past six years.
In 2004, San Francisco began issuing same-sex marriage licenses; 4,000 gay couples got married. But in August of that year, the state Supreme Court declared those marriages "invalid," saying the city lacked the authority to bypass state law.
Four years later, the same court legalized same-sex marriage, giving gay couples a constitutional right to wed in California.
Then came Prop 8, a constitutional amendment which overturned that ruling and again declared same-sex marriage illegal.
Whatever happens this time, any appeal will head to the U.S. Supreme Court.
High court delays trail from being posted online
Hours before Monday's hearing got underway, the nation's high court blocked the proceedings from being posted on YouTube.
The judge last week agreed to allow cameras in the hearing, but Prop 8 supporters argued it might allow their witnesses to be intimidated.
Monday morning, the U.S. Supreme Court said it needed a couple of days to decide the issue -- cameras are not usually allowed in federal courts.
The proceedings are being taped, but the ban on allowing it to go on YouTube will remain in place at least until Wednesday.
Live streaming to other federal courthouses was denied as well.