By Chris Johnson

The Supreme Court is set to hear oral arguments on Tuesday in cases seeking the right for same-sex couples to marry across the nation, and the questions asked by key justices could indicate the nature of the ruling expected by the end of June.

For two-and-a-half-hours, the nine members of the court will hear from attorneys on both sides of litigation challenging state marriage bans in Michigan, Ohio, Kentucky and Tennessee in what is arguably the most significant gay rights lawsuit ever heard. The Supreme Court agreed to hear these cases in January after the U.S. Sixth Circuit Court of Appeals upheld prohibitions on same-sex marriage in those states.

The stakes are high: Either the court will rule that same-sex couples have a constitutional right to marry across the country, or that states are allowed to prohibit them from marrying, which could jeopardize the rapid gains made on marriage in the courts in recent years because defendants would be allowed to reopen cases.

One LGBT advocate who’s set to argue before justices is Mary Bonauto, the civil rights director of the New England-based Gay & Lesbian Advocates & Defenders who successfully argued in favor of marriage equality in Massachusetts before the Massachusetts Supreme Court in 2003. The occasion will mark the first time she has argued before the U.S. Supreme Court.

She’ll answer Question 1 justices have posed in the cases: Does the 14th Amendment require a state to license a marriage between two people of the same sex?

In a conference call with reporters on Tuesday, Bonauto said her task now shares an important similarity to when she stood before the Massachusetts Supreme Court more than 10 years ago.

“There is one thing that is for certain that is exactly the same, which is that we’re dealing with real people who truly have committed to one another and feel that the commitment and responsibilities for one another can really best be described by marriage,” Bonauto said. “And yet, they are foreclosed from making that commitment simply because of who they are.”

In terms of what is different, Bonauto said more than 10 years ago there were a fair number of skeptics about marriage equality, but now that a majority of Americans believe that marriage is a right that should be afforded to gay couples, there’s “no reason to tell LGBT families they should be denied legal respect.”

Joining Bonauto in arguing on behalf of same-sex couples is Doug Hallward-Driemeier, an attorney at the global law firm Ropes & Gray LLP. A newcomer in advocating for LGBT rights, he has argued cases in every federal court of appeals and at the Supreme Court.

He’s set to answer Question 2 in the cases: Does the 14th Amendment require a state to recognize an out-of-state same-sex marriage?

In the conference call, Hallward-Driemeier said he thinks the arguments on the two questions are “very much mutually supportive.”

“Of course, we think there is a fundamental right for same-sex couples to marry and we think that pretty much ends the question on Question 2, but we also think that it’s really quite instructive when you see the arguments that the state is making for denying already existing marriages and denying the legal existence of these families that the rationales just disappear as you give them any kind of scrutiny,” Hallward-Driemeier said. “We think that argument actually only further supports the argument that we’re making on Question 1, that there’s just no legitimate state purposes to deny these marriages.”

Also arguing on behalf of same-sex marriage is U.S. Solicitor General Donald Verrilli. After the Justice Department filed a brief before the court arguing against state constitutional bans on same-sex marriage, Verrilli sought time to speak before the court to address Question 1.

In preparations for arguments, Hallward-Driemeier said his legal team has discussed favorably the addition of the Obama administration as part of the arguments.

“We’re talking about this in our legal team, and when one of the members who’s been working on these issues since the ’70s said she was just so excited that we’ve come to the day when the United States legal representative is standing beside gay and lesbian couples to argue that they cannot be denied the right to marry, that is something to celebrate, and we absolutely do,” Hallward-Driemeier said.

The states have two attorneys: John Bursch, a former Michigan solicitor general who is now in private practice, is designated to address the license issue, while Tennessee Associate Solicitor General Joseph Whalen will handle the issue of out-of-state recognition. Ohio and Kentucky won’t have separate counsel.

It wasn’t that long ago the marriage issue was before the Supreme Court. In 2013, the Supreme Court heard challenges to Section 3 of the Defense of Marriage Act, which prohibited federal recognition of same-sex marriage, and California’s Proposition 8. The court overturned DOMA, but determined defendants in the Prop 8 case didn’t have standing, letting stand a lower court decision affecting the marriage ban only in that state.

This time around, standing issues aren’t in play, and LGBT advocates are heading into the arguments with a sense of a optimism that the court will rule favorably for marriage. Although a number of observers have said the court is poised to issue a nationwide ruling in favor of marriage equality, other legal experts have urged caution.

Two justices — U.S. Associate Justice Anthony Kennedy and Chief Justice John Roberts — are expected to face particular scrutiny from observers. Kennedy was in the majority in the DOMA ruling and is considered a swing justice on the court. Roberts was in the dissent, but is still considered in play.

Both Roberts and Kennedy have also indicated they may be ready for a nationwide ruling for marriage equality by joining other justices in denying stays on lower court decisions in favor of gay nuptials.

Judith Schaeffer, vice president of the progressive Constitutional Accountability Center, said in a conference call that Roberts might be gettable for supporters of marriage equality. Among other reasons, he issued a concurring dissent in the DOMA decision as opposed to joining U.S. Associate Justice Antonin Scalia, perhaps in anticipation of the issue returning to the court. 

“What Roberts did by not joining Justice Scalia’s dissent on the merits was to preserve a clean slate for himself when that case ultimately came before the court, as it has now,” Schaeffer said.

Schaeffer also noted without any recorded dissent, the court declined to review decisions in favor of marriage equality from three circuit courts.

“It only takes four votes for the court to agree to hear a case, and certainly the four Windsor dissenters on their own could have stopped marriage equality dead in its track by voting to hear those cases,” Schaeffer said. “But that did not happen; there were not four votes to do it.”

Although opponents of same-sex marriage have been briefing the cases to get Kennedy’s vote, Schaeffer said they face a “huge, uphill battle” in persuading him to rule against gay nuptials because of the decisions he wrote in three major gay rights cases — Romer, Lawrence and Windsor — during his decades on the bench.

“It’s very difficult to read his opinions and conclude Justice Kennedy would now reverse course on the application of those fundamental constitutional principles for gay people,” Schaeffer said.

Kennedy last year in the case of Schuette v. Coalition to Defend Affirmative Action upheld a state constitutional amendment in Michigan prohibiting public universities from using race as a factor in admissions, but Schaeffer noted he wrote in the decision no fundamental rights or invidious discrimination was involved in the case, so the people could make a policy choice.

Adam Romero, senior counsel and Arnold D. Kassoy Scholar of Law at the University of California, Los Angeles, urged caution about reading too much into questions during oral arguments, but said he’s eager to see if Kennedy talks about children of same-sex couples and the Schuette case.

“If Justice Kennedy focuses on Schuette or respecting the will of voters, that may suggest he is uncomfortable overturning voter-enacted same-sex marriage bans,” Romero said.

As for Roberts, raising questions about the political power of LGBT people, as he did two years ago during the DOMA hearing, may indicate where he’s leaning, Schuette said.

“I am keen to see if Justice Roberts again raises questions about political power, which may suggest he is leaning to uphold the bans,” Romero said.

Another justice who has joined others in refusing to grant stays on lower court decisions in favor of marriage equality is U.S. Associate Justice Samuel Alito, leading to speculation that he might be willing to join others in ruling for same-sex marriage.

Schaeffer, however, said Alito isn’t likely to be receptive to arguments in favor of same-sex marriage like Roberts or Kennedy.

“In Justice Alito’s dissent in Windsor, he said this, and Justice [Clarence] Thomas joined him in this,” Schaeffer said. “I’m going to quote, ‘Same-sex marriage presents a highly emotional and important question of public policy, but not a difficult question of constitutional law. The Constitution does not guarantee the right to enter into a same-sex marriage.’ I think he’s already decided that question. It wasn’t presented to him, but he went ahead and stated his views, as did Justice Thomas.”

For Bonauto, the focus now is preparing for the upcoming arguments, but she expressed confidence a majority of justices would issue a nationwide ruling in favor of marriage equality.

“What we’re doing is we’re making the best arguments we can for all nine justices and hope at the end of the day that we have a majority,” Bonauto said. “I hope it’s a strong majority, but a majority is fine.”