At a time of intense national debate, the U.S. Supreme Court for the first time ever will hear oral arguments next week on whether marriage rights for gay couples are protected under the U.S. Constitution.

Attorneys on both sides will make their arguments in two separate cases, on two separate days and regarding two separate anti-gay measures, but the state of marriage equality across the country could be altered depending on the rulings in either of the cases.

On Tuesday, the court will hear arguments on Proposition 8, a ballot measure approved by California voters in 2008 that stripped away existing marriage rights in the state for same-sex couples. The next day, the court will listen to arguments on the federal Defense of Marriage Act, which prohibits federal recognition of same-sex marriage.

Chris Stoll, a senior staff attorney at the National Center for Lesbian Rights, said the oral arguments provide an opportunity for observers to glean what justices are thinking based on their line of questioning.

“It’s true that appellate courts, I would say, mostly base their decisions on the written submissions on the briefs,” Stoll said. “The main purpose of oral argument is to let the justices have questions that they have answered by the lawyers, and so, what the lawyers come in to say isn’t really the focus; it’s really what the justices want to have answered.”

Mary Bonauto, civil rights director for Gay & Lesbian Advocates & Defenders, said oral arguments are a “filtering process” that provide justices the opportunity to explore possible outcomes of their rulings and persuade each other.

“That’s part of why they’re so active,” Bonauto said. “They’re trying to influence each other’s votes and perspectives on it, and, effectively, argue the case themselves. If you ever read a Supreme Court transcript, it’s usually very difficult to read because there are so many interruptions.”

In the Prop 8 case, known as Hollingsworth v. Perry, Ted Olson, a former solicitor general under President George W. Bush, will argue against the constitutionality of the measure on behalf of the American Foundation for Equal Rights. Based on the legal brief he filed, Olson will likely argue against the merits of Prop 8 on the basis that it violates due process and equal protection of gay plaintiff couples under the U.S. Constitution.

The ban on same-sex marriage will be defended by anti-gay groups, such as ProtectMarriage.com, because California state officials have declined to defend the marriage ban. The lawyer arguing on behalf of the anti-gay measure will likely be private attorney Charles Cooper, who defended Prop 8 during the district court trial in 2010.

Depending on the scope, a ruling in the Prop 8 case in favor of the plaintiffs could be a jackpot for same-sex couples. Justices could affirm the limited ruling from the U.S. Ninth Circuit Court of Appeals, which affected only California; determine that the nine states, including California, that offer domestic partnerships must offer same-sex marriage; or issue a sweeping ruling that brings marriage equality to all 50 states.

In the DOMA case, known as Windsor v. United States, Roberta Kaplan, a New York-based attorney, is set to argue against the constitutionality of the anti-gay law in a coordinated effort with the American Civil Liberties Union. Kaplan’s client is Edith Windsor, an 83-year-old lesbian who was forced to pay $363,000 in estate taxes upon the death in 2009 of her spouse, Thea Spyer, because of DOMA.

James Esseks, director of the ACLU’s LGBT Project, said preparations have been underway for oral arguments, including moot courts where individuals impersonate justices to ask possible questions that the real ones may pose.

“People do that for Supreme Court arguments, people do that for appeals court arguments, people do that for trial court arguments — we’ve done that all along,” Esseks said. “It’s just the normal thing that people do.”

On the other side of the DOMA case will be Paul Clement, another former U.S. solicitor general from the Bush administration. He was hired at a rate of $520 an hour by the House Republican-led Bipartisan Legal Advisory Group to defend DOMA in court.

The stakes in the DOMA case are high as well. A ruling striking down DOMA would have multiple impacts on married gay couples. Among other things, they’d have access to medical leave if their spouses need attention because they’re gravely ill or injured and Social Security survivor benefits would become available.

A ruling that strikes down DOMA would also remove a barrier for gay service members seeking spousal benefits in the wake of “Don’t Ask, Don’t Tell” repeal. According to a report published last month from the Center for American Progress and OutServe-SLDN, the average gay military family pays $5,615 out-of-pocket each year for health care insurance because they aren’t eligible for military coverage known as TRICARE.

Both oral arguments will share a common participant: U.S. Solicitor General Donald Verrilli. Since the Obama administration stopped defending DOMA in court, it has participated in litigation against DOMA and will have speaking time in arguments before the Supreme Court. Similarly, in the wake of filing a friend-of-the-court brief against Prop 8, the Justice Department will also have speaking time to argue against it thanks to a request.

In either or both cases, the Supreme Court could determine as part of its ruling that laws related to sexual orientation should be subject to heightened scrutiny, or a greater assumption they’re unconstitutional. That’s the view the Justice Department has articulated in legal briefs against DOMA and Prop 8.

Such a decision would also have a sweeping impact because it would create a precedent that guides other courts when evaluating the constitutionality of anti-gay laws, such as bans on same-sex marriage.

But the merits issue — the question of whether Prop 8 and DOMA are constitutional — will only form part of the discussion in the cases as other issues such as standing and jurisdiction must be addressed. These issues may ultimately form the basis of the court’s rulings.

In the Prop 8 case, the question is whether proponents of the measure have standing to defend the measure in court. It’s possible — as Olson and his team have argued — the court would rule they lack standing because they aren’t harmed by Prop 8. Such a ruling would leave unanswered questions about the constitutionality of same-sex marriage in California, but likely restore same-sex marriage in that state.

The questions about standing and jurisdiction in the DOMA case are more complex. The court asked attorneys when taking up the case whether BLAG has standing to participate and whether the Obama administration’s agreement with lower courts that DOMA is unconstitutional deprives the Supreme Court of jurisdiction. It’s unclear what the fate of DOMA would be if the court decides to rule on those grounds.

GLAD’s Bonauto said she thinks the stronger argument is the court has jurisdiction to consider DOMA and will decide on the merits — but noted “they asked the question for a reason” and questions emerge if the court decides to rule on DOMA on the basis of standing.

“Most people think the Second Circuit decision goes away, then the question is what happens to the district court ruling,” Bonauto said. “Does Edie get her money back, or is there an argument that the district court ruling goes away because the U.S. switched positions in the district court. I’d like to think, at a minimum, Edie would get her money back.”

Vicki Jackson, a Harvard law professor hired by the court, will argue BLAG doesn’t have standing in the lawsuit and the court doesn’t have jurisdiction to hear the case. Deputy Solicitor General Sri Srinavasan is set to address the standing issue on behalf of the Justice Department. BLAG also has been allocated time to assert it has standing in the case, but Windsor’s attorneys weren’t granted time to talk about jurisdiction or standing.

NCLR’s Stoll said any decision from justices that would extend rights to gay couples — whether on the merits or through issues of standing — would be a “milestone” for the LGBT community.

“We have already been seeing tremendous changes in society and the level of acceptance for gay and lesbian people and for legal recognition of them through marriage,” Stoll said. “I think that if the Supreme Court ruled in whatever way in favor of the plaintiffs in these cases, that it would be a real milestone and landmark moment for our movement.”