Washington (CNN)The date for arguments is on the calendar. The questions that the justices will have to decide are clear. Even the amount of time lawyers will have to make their case is set in stone.
Who will fight for gay marriage at SCOTUS?
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But there's still one mystery heading into next month's historic gay marriage case at the Supreme Court: Who will get to argue before the justices that same sex marriage should be legal across the nation?
The roster of lawyers for each side is still being worked out. And like many things related to the law, it's complicated. Six legal challenges in four states have been consolidated into one case. And to make things even more dicey, there are actually two separate legal questions before the court.
Still, this is a rare opportunity to argue before the highest court to shape the law on one of the most consequential modern social issues. It's no wonder that any lawyer -- from recent law school grads to titans of the profession -- would dream of a chance to snag a piece of the debate.
"It will be a very sensitive negotiation among the lawyers," said Adam Winkler, a professor at the UCLA School of Law. "Everyone involved in this case would love to be the one to argue."
Those supporting marriage for same sex couples have already filed their opening briefs with the court, and in the coming days they will huddle to consider who should stand on the podium when arguments are made on April 28.
In general, the court leaves the decision up to the parties. The plaintiffs on Tuesday proposed that their time to make their case be divided — a practice the Court usually frowns upon.
If the justices decline the request, plaintiffs will have to winnow down their choices.
That will be tough because scores of lawyers have been involved with the challenge, including some of the best litigators in the country.
The parties could choose a private attorney who has been with the case all along such as Alphonse A. Gerhardstein, a civil rights attorney from Cincinnati or Carole M. Stanyar, who is based in Ann Arbor.
"The choice could also depend upon whether the parties ask, and the court agrees, to allow them to designate two lawyers to argue," said Amy Howe, the editor of Scotusblog.
They could opt for someone with vast experience arguing before the the Supreme Court. Both Jeffrey L. Fisher, of Stanford Law School, and Douglas Hallward-Driemeier, who used to work in the Solicitor General's office, have appeared multiple times before the justices.
Another option would be to pick a lawyer affiliated with one of the movement groups that has been working in the trenches for years on a state-by-state strategy to build political momentum on the issue. Top contenders would include Mary Bonauto of the Gay and Lesbian Advocates and Defenders and James Esseks of the ACLU.
"Everyone involved wants to win more than anything else," said Winkler.
It would be unusual for the parties to choose a lawyer unaffiliated with the case at hand.
For instance, Theodore Olson and David Boies, the political odd fellows who came together in 2012 to fight California's ban on same sex marriage, backed a different challenge this time around in Virginia. The Supreme Court ultimately declined to take up that case, making it harder for the power lawyers to be involved in next month's case.
At least one big name is expected to argue for those in favor of same-sex marriage: Solicitor General Donald B. Verrilli Jr. The Obama administration filed an amicus brief in the case two weeks ago and as the government's lawyer before the court, Verrilli would typically get some time before the justices.
But from there, it's anyone's guess.
The court is considering two questions. The first concerns the central issue of whether states can ban gay marriage. The second question gives the justices an off ramp if they decide against issuing a sweeping ruling. That question concerns whether states must recognize the marriage of couples legally married out of state.
State officials in the four states involved -- Michigan, Ohio, Tennessee and Kentucky -- have to go through a similar process to decide who will lead arguments defending state bans on same-sex marriage.
On Friday, Michigan's attorney general announced that Special Assistant Attorney General John Bursch, the former Michigan solicitor general, will present the state's oral argument. And according to Dan Tierney, the spokesperson at the Ohio Attorney General's Office, Joseph F. Whalen, Tennessee's associate solicitor general, will handle the second question.
Deciding who will argue the case will mark one of the last strategic decisions the parties will have to make before the issue goes to the justices.
For the challengers, the moment has been years in the making as they worked toward the overall aim to get the Supreme Court to issue a nationwide ruling.
Some longtime gay rights advocates were nervous a few years ago when opponents of California's Prop 8 chose to push their case to the Supreme Court. The advocates felt the better choice was to move more incrementally and first ask the Supreme Court to rule on a section of the Defense of Marriage Act (DOMA) -- a federal law that denied benefits to same sex couples who were legally married in the states.
As it turned out, both cases arrived before the court in 2012, and it ultimately struck down a section of DOMA and dismissed the Prop 8 case on procedural grounds.
Since the DOMA ruling, the victories for gay rights advocates have been astounding.
In the last two years, challenges to same sex marriage bans have been successful in nearly 60 lower court decisions according to the group Freedom to Marry.
That's led some to believe it's a foregone conclusion that the court will rule in favor of marriage for same sex couples this summer.
"I'm reluctant ever to call anything a 'done deal'" said Scotusblog's Howe.
But she points out that in October, the Supreme Court cleared the way for thousands of marriages to take place in Virginia, Utah, Oklahoma, Indiana and Wisconsin when it declined to take up an earlier set of same sex marriage petitions.
"As a legal matter, the Court could of course uphold the bans, but as a practical matter it would be very hard to put the genie back into the bottle, so to speak, and hold that -- notwithstanding all of the marriages it has allowed to go forward in the last few months -- there is no longer a right to same-sex marriage," she said.