A lesbian couple from Berkeley and a gay couple from Burbank are challenging Prop 8, the constitutional amendment passed by California voters which is preventing them from getting married.
Their prominent attorneys, Ted Olson and David Boies were on opposite sides of the disputed 2000 presidential election, but have joined forces for this case.
"This is not a matter of being a conservative or liberal, or Republican or Democrat. This is a matter of fundamental human rights and human decency," said Olson.
Gay rights organizations that wanted to join these attorneys efforts were turned down.
At the hearing in U.S. District Court, Chief Judge Vaughn Walker said those groups would not add to the case and would only delay the proceedings. He also denied a request by opponents of same-sex marriage to intervene.
The Campaign for California Families argued their perspective, including the question of whether gay couples can form lasting committed relationships, is not being adequately addressed by those defending the marriage ban. But those Prop 8 attorneys say they are focusing on one issue -- the will of the voters.
"The people have already made their decision. What's on trial is whether the people can validly make that decision," said Andy Pugno from Protect Marriage.
The only party the judge is allowing to get in on the case is the city of San Francisco citing a distinct, governmental interest. The mayor says that's an appropriate ruling.
"So much of the origins of national movement, and actions by other states initiated from San Francisco's efforts," said San Francisco Mayor Gavin Newsom.
ABC7 Legal analyst Dean Johnson says this will be one of the most important trials of the century.
"This case will take this issue to the U.S. Supreme Court and most people believe as the court is currently made up, it'll be a 5-4 decision against the right to same-sex marriage, and that precedent will be cemented for at least a generation," said Johnson.
The trial is scheduled to start January 11th.