JUDY WOODRUFF: It was a historic day at the Supreme Court, at stake, the definition of marriage.

Justices split the issue into two questions: Must every state permit same-sex marriage? And, if not, do states have to recognize same-sex marriages performed elsewhere?

Protesters from both sides of the debate crowded outside the court building in Washington this morning.

Marcia Coyle of The National Law Journal was there and she joins us now.

MARCIA COYLE, The National Law Journal: Hi, Judy.

JUDY WOODRUFF: So, Marcia, big day at the court. Knowing that, what is it, 36 of the states…

MARCIA COYLE: Plus the District of Columbia.

JUDY WOODRUFF: … already declare same-sex marriage legal, what were the petitioners today asking the court to decide?

MARCIA COYLE: Well, basically, they're laying claim to the 14th Amendment's guarantees of equal protection and due process of law.

They're saying that the court has recognized that there is a fundamental right to marry, and under the 14th Amendment, they have been — they deserve to be part and to participate in that fundamental right.

The states that still do ban same-sex marriage, they claim, are excluding them from that fundamental right to marry. It was a packed courtroom, Judy, and the arguments were fast-paced and intense. And I hope anybody who is interested will listen to the full audio and read the transcript.

JUDY WOODRUFF: And, in fact, we're going to listen to some of them in just a minute.

But how did the arguments initially unfold?

MARCIA COYLE: Well, the first argument was on the marriage question, whether the 14th Amendment requires states to license these marriages.

And the arguments focused on several key issues. The justices probed, who should be deciding this? Should it be the court itself, or should it be the states through their electorate? Also, has enough time passed for us to gauge whether there's any impact, good or bad, on the family unit and children in particular of same-sex marriages?

And then also what is the states' real interest here in banning these marriages, when it recognizes other types of marriages, and even though they still stick with the traditional definition?

JUDY WOODRUFF: Now, we picked out — as you said, this is one rare cases where they do allow an audio recording.

MARCIA COYLE: Yes.

JUDY WOODRUFF: And you — we have worked with you today to pick out three different clips.

The first one, Marcia, is an exchange initiated by the chief justice with the attorney representing the same-sex couple.

MARCIA COYLE: Right. Almost off the bat, the chief justice probed her about the definition of marriage.

JUDY WOODRUFF: And let's listen to that.

JOHN ROBERTS, Chief Justice of the U.S. Supreme Court: My question is you're not seeking to join the institution. You're seeking to change what the institution is.

The fundamental core of the institution is the opposite-sex relationship and you want to introduce into it a same-sex relationship.

MARY BONAUTO, Special Counsel, Gay and Lesbian Advocates and Defenders: Two points on that, Your Honor. To the extent that if you're talking about the fundamental right to marry as a core male-female institution, I think, when we look at the 14th Amendment, we know that it provides enduring guarantees, in that what we once viewed as the role of women, or even the role of gay people, is something that has changed in our society.

JUDY WOODRUFF: What do we learn from that exchange?

MARCIA COYLE: Well, I think the justices are being very cautious here. They're pointing out how long we have had this definition of marriage as between a man and a woman.

But what Ms. Bonauto was saying — and I think she got a real boost from Justice Ginsburg. Justin Ginsburg noted that the institution of marriage has changed over the years. There was a time when a woman was obligated to follow her husband. But the Supreme Court in a decision ended that, so marriage does evolve and change and this is just another instance of how it can change.

JUDY WOODRUFF: All right. Now, the second clip we're going to listen to, this was initiated by Justice Anthony Kennedy, widely seen as a swing vote on the court.

MARCIA COYLE: Yes.

JUDY WOODRUFF: So, let's listen to that one.

ANTHONY KENNEDY, Associate Justice, U.S. Supreme Court: This definition has been with us for millennia. And it — it's very difficult for the court to say, oh, well, we — we know better.

MARY BONAUTO: Well, I don't think this is a question of the court knowing better.

When we think about the debate, the place of gay people in our civic society is something that has been contested for more than a century.

And the American people have been debating and discussing this. It has been exhaustively aired, and the bottom line is that gay and lesbian families live in communities as neighbors throughout this whole country.

JUDY WOODRUFF: Now, what about that? We know that Justice Kennedy had other questions at other times that were more sympathetic to the…

MARCIA COYLE: Yes.

Later, in the arguments, there were things he said that did indicate he was sympathetic to the marriage claim. But Ms. Bonauto is again, in a way, is reassuring the justices that this is not something that's terribly new.

As she pointed out, first same-sex marriage case came to the Supreme Court in 1972, over 40 years ago. And the Hawaii Supreme Court, I think it was back in the early 1990s, indicated that it might rule in favor of same-sex marriage.

So she is saying that this is something that's been around and has been talked about. And it's time basically for the court to decide this.

JUDY WOODRUFF: But, just very quickly, when Justice Kennedy weighed in sounding sympathetic to the other side, what was that about?

MARCIA COYLE: Justice Kennedy has written the three prior decisions of the court dealing with gay rights, basically.

And if you read those decisions, as they come to the most recent one, U.S. vs. Windsor, involving the Defense of Marriage Act, he's spoken about the dignity of the individual. And he's also talked about the importance of marriage and dignity to gay couples and their children.

So, in the questioning, he did bring that forward about how marriage does bestow dignity on those who participate in it.

JUDY WOODRUFF: All right, now, the third clip, Marcia, is from an exchange between the attorney representing the states that bans same-sex marriage — his name is John Bursch — and Justice Sotomayor.

Here's that one.

JOHN BURSCH, Former Michigan Solicitor General: This case isn't about how to define marriage. It's about who gets to decide that question. Is it the people acting through the democratic process, or is it the federal courts?

And we're asking you to affirm every individual's fundamental liberty interest in deciding the meaning of marriage. And I think this whole case really turns on the questions that Justice Scalia asked.

SONIA SOTOMAYOR, Associate Justice, U.S. Supreme Court: I'm sorry. Nobody is taking that away from anybody. Every single individual in this society chooses, if they can, their sexual orientation or who to marry or not marry.

I suspect, even with us giving gays rights to marry, that there's some gay people who will choose not to, just as there's some heterosexual couples who choose not to marry. So we're not taking anybody's liberty away.

JUDY WOODRUFF: So, what does that tell us?

MARCIA COYLE: Well, the justices are trying to get from Mr. Bursch, what is the states' real interest here? And not so much who has to decide it, as he was making that argument. That is one of the state's argument, but what is the state's interest in banning these marriages?

And Mr. Bursch will tell them, and he will be repeatedly asked what this is, that basically the state's interest is in promoting the stability of the family unit and the bonding of children with their biological parents, an interest in procreation as well.

And that's developed as the arguments go along, as justices ask him if repeatedly also, what is the harm to children or the family unit if there are gay marriages?

JUDY WOODRUFF: And just finally, Marcia, there was a second question, as you mentioned earlier, that the justices were discussing. It was part of the argument, and that is whether states should recognize marriages performed in other states if that state itself bans same-sex marriage.

MARCIA COYLE: Yes.

This question will become critical if those who are in favor of gay marriage lose on that first question. Then it does become a recognition issue. And, today, the lawyer for already married gay couples, Mr. Hallward-Driemeier, told the court there's not only a fundamental right to marry, but there is a right to remain married.

And these states that don't recognize those marriages are basically destroying that family unit in their state. And he pointed to the historical practice of states to recognize marriages conducted in other states, so why not these?

In reply, Tennessee's lawyer said basically that that was the historical practice when all the states had the same definition of marriage. The landscape is different today, and the state can decide not to recognize a marriage that doesn't comport with its own policies.

JUDY WOODRUFF: Marcia Coyle, the decision is coming in June.

MARCIA COYLE: Yes, it is. It's going to be a big June, Judy.

JUDY WOODRUFF: We thank you.

MARCIA COYLE: My pleasure.