A three-judge panel of the 9th U.S. Circuit Court of Appeals ruled 2-1 that a lower court judge correctly interpreted the U.S. Constitution and Supreme Court precedents when he declared in 2010 that Proposition 8 was a violation of the civil rights of gays and lesbians.
"Although the Constitution permits communities to enact most laws they believe to be desirable, it requires that there be at least a legitimate reason for the passage of a law that treats different classes of people differently. There was no such reason that Proposition 8 could have been enacted," the ruling states.
In 2008, 52 percent of California voters passed Proposition 8, which placed a state ban on same-sex marriage. That started a series of lawsuits and rulings by lower courts.
The most recent was in August 2010. U.S. District Court Judge Vaughn Walker ruled that proposition was discriminatory and illegal. However at the time, Walker failed to disclose his long-term relationship with another man.
The panel said there was no evidence that Walker was biased and should have disclosed that he was gay before he issued his decision.
Tuesday's three-judge panel gave opponents of gay marriage time to appeal the decision before ordering the state to allow same-sex weddings to resume.
The ruling was not only about the legal weight, but also the statement it makes about the place same-sex marriage has in today's society.
"For me it's a beautiful day, not only for the great gay families and great gay couples in California, but it's a great day for the constitution and for the values our country was founded on- equal rights, equal protection for everyone in the state of California," said Billy Bradford from Marriage Equality USA.
Robin Tyler and her partner were the first couple in the gay and lesbian community to obtain a legal California marriage license.
"It's absolutely fantastic," Tyler said. "I was absolutely fantastic that they found it unconstitutional. It's not that we didn't think it was, it's just that now our right to marry has been affirmed by the 9th Circuit, and I couldn't' be happier for all the couples that have waited to get married, and the fact that it might affect, or will affect, all the western states, I think is an enormously huge decision for our community nationally."
Backers of Proposition 8 said they would ask the U.S. Supreme Court to overturn the 9th Circuit ruling.
"This was expected, you've got a Jimmy Carter judge and a Bill Clinton judge and a George W. Bush judge, and it was expected it was going to come down 2-1," said Randy Thomasson of Save California. "The U.S. Constitution states rights must be respected and there should be rule of law in the states. So the California Constitution has to win and marriage has to stay for a man and a woman."
The next question is whether the Supreme Court will consider hearing this argument.
"Even on a fast-track, unless they set something extraordinarily fast, this would not be re-heard in the Supreme Court until next fall sometime, and no decision until about a year from today," said Rory Little from Hastings School of Law.
The court said same-sex marriages cannot resume in the state until the deadline passes for Proposition 8 sponsors to appeal to a larger panel of the 9th Circuit. If such an appeal is filed, same-sex marriages will remain on hold until it's resolved.
"The court has rendered a powerful affirmation of the right of same sex couples to marry," Gov. Jerry Brown said in a statement. "I applaud the wisdom and courage of this decision."
In an exclusive Eyewitness News poll conducted by SurveyUSA, 50 percent of Southern Californians agreed with the federal appeals court ruling that Prop. 8 is unconstitutional, 40 percent disagreed and 10 percent were not sure.
On Tuesday night, supporters of same-sex marriage marched through the streets of West Hollywood. They called the decision a landmark day for civil rights in California.
"For the last 3 1/2 years, we have suffered under Proposition 8, and tonight we have relief at last," said West Hollywood Mayor John Duran.
The Associated Press contributed to this story.