WASHINGTON - The Supreme Court on Tuesday seemed to be debating how -- not if -- same-sex marriage should become legal in every state in the country.
During oral arguments, the nine justices weighed whether now is the right time to force states to let same-sex couples marry, pointing to how quickly public opinion has shifted on the issue. Thirty-seven states and Washington, D.C., currently recognize same-sex marriage.
Justice Anthony Kennedy, who is considered a swing vote and who was a key figure in striking down the Defense of Marriage Act back in 2013, suggested the court may be moving too quickly to force states to marry same-sex couples.
“This definition has been with us for millennia,” Kennedy said of opposite-sex marriages. "It's very difficult for the court to say, 'Oh, well, we know better.'”
However, Kennedy noted that about 10 years had passed between when the Supreme Court struck down separate-but-equal racial discrimination and laws banning interracial marriage. That's about the same amount of time between when the Supreme Court ended sodomy laws and the present, he said.
The judges are considering two issues during the oral arguments: whether states are required to offer marriage licenses to gay couples, and whether states have to recognize same-sex marriages performed in other states. The court will likely issue one decision in June covering appeals from four states -- Kentucky, Michigan, Ohio and Tennessee.
“You’re seeking to change what the institution is,” Chief Justice John Roberts told Mary Bonauto, the lawyer representing the same-sex couples. "Every definition that I looked up, prior to about a dozen years ago, defined marriage as unity between a man and a woman, as husband and wife. Obviously, if you succeed, that core definition will no longer be operable."
Justice Ruth Bader Ginsburg, meanwhile, said there have been plenty of changes to the institution of marriage, which used to be built on “dominant and subordinate” relationships.
"There was a change in the institution of marriage to make it egalitarian when it wasn't egalitarian," she said. "Same-sex unions wouldn't fit into what marriage was once."
“Did they have same-sex marriage in ancient Greece?” asked Justice Samuel Alito. He also questioned whether four consenting, highly educated adults, two men and two women -- perhaps lawyers, he joked -- could ask a state to be married.
Bonauto responded that there would be issues of coercion, consent and family disruption that would give states an interest in banning such unions.
John Bursch, the special assistant attorney general of Michigan, argued in favor of states restricting marriage to opposite-sex couples. At the crux of his argument was child-rearing, and why it is in a state's interest to "inextricably bind kids to their biological moms and dads."
Changing the meaning of marriage, he argued, has long-term consequences.
"The out-of-wedlock birthrate in this country has gone from 10 percent to 70 percent from 1970 to today," said Bursch. "I think everybody would agree that that's not a good result for children."
"But that wasn't changed because of the recent gay marriages," responded Justice Sonia Sotomayor. "In Massachusetts, we've got data that rates remained constant since they changed their laws."
When Bursch said it's been too short of a time frame to see the effects of Massachusetts' law on birthrates, Kennedy jumped in.
"You're the one that brought the statistic up," he said. "Under your view, it would be very difficult for same-sex couples to adopt some of these children. I think the argument cuts quite against you."
Kennedy continued, "It goes back to the basic point where you began, where you had some premise that only opposite-sex couples can have a bonding with a child. That was very interesting, but it's just a wrong premise.”
Both sides saw reasons for optimism after the arguments.
"I think it went really well," said Marc Solomon, national campaign director for the group Freedom to Marry. "What's so clear to me is how completely bankrupt our opponent's arguments are. Their argument was that if you allow gay people to marry, one might speculate that fewer straight people will marry. It's not based on any facts, on any truth or any evidence."
Rep. Jerry Nadler (D-N.Y.), who has been a leading advocate for lesbian, gay, bisexual and transgender equality in Congress, said he was "cautiously optimistic."
Opponents of same-sex marriage were buoyed because they believed the judges seemed skeptical of "redefining marriage."
Ryan Anderson, a fellow at the Heritage Foundation, told supporters after he came out of the court that they can "fully expect a good decision come June."
Josh Duggar, the executive director of FRC Action, which is part of the Family Research Council, said he also expects the justices to side with them. Duggar is the eldest child on the TLC reality show "19 Kids and Counting."
"I think it was clear for those that were in the court of what the mood of the court was today. And that is to take a very careful look at the effects this decision could have on the American family, and the fact that children, like my own three children, are going to be faced with a very different America," he said. "A place where children are not going to grow up with a mother and a father."
About 30 minutes into the arguments, a man in the audience suddenly jumped up and began shouting, "You will burn in hell! Homosexuality is an abomination!"
He was led out by security and could be heard screaming in the halls for several minutes. Justice Antonin Scalia didn't seem to mind the dust-up.
"It was rather refreshing, actually" he said to laughs.
(Editor's note: This post was originally published on our media partner HuffPost Gay Voices.)