Same-sex marriage supporters demonstrate in front of the Supreme Court on March 27, 2013 in Washington, DC. The rights of married same-sex couples will come under scrutiny at the US Supreme Court on Wednesday in the second of two landmark cases being considered by the top judicial panel. After the nine justices mulled arguments on a California law that outlawed gay marriage on Tuesday, they will take up a challenge to the legality of the Defense of Marriage Act (DOMA). The 1996 law prevents couples who have tied the knot in nine states -- where same-sex marriage is legal -- from enjoying the same federal rights as heterosexual couples. AFP/Getty Images

This article is from the archive of our partner National Journal

The Supreme Court hasn't even heard oral arguments yet in its landmark cases on same-sex marriage — so why is the case so often treated like marriage equality has already won?

In the run-up to a big Supreme Court case, lawyers, pundits, analysts, and reporters are usually full of what-ifs, complex theories about how one justice or another might be persuaded, and hair-splitting. But hardly any of that speculation has greeted the court's cases on same-sex marriage, which sometimes are portrayed more as a coronation than a debate.

"Certainly, the conventional wisdom has set in strong," said Tom Goldstein, a Supreme Court advocate and the founder of SCOTUSBlog. "There seems to be an inevitability."

The justices are scheduled to hear two and a half hours of oral arguments Tuesday over four state laws that ban same-sex marriages, refuse to acknowledge same-sex marriages performed in other states, or both.

(RELATED: What Antonin Scalia Got Right About Same-Sex Marriage)

Usually, the warning is not to read too much into the justices' questions during oral arguments. This time, though, everyone seems to have made up their minds with even less to go on—before any of the justices have given public indications of how they're approaching the latest cases.

"I do think that is the prevailing sentiment. "¦ There may be a little bit of cart before the horse," Stanford University law professor Jane Schacter said.

Legal experts said marriage equality seems inevitable partially because of the dramatic reversal in public opinion and the states. Thirty-seven states now allow same-sex couples to marry, and the shift has accelerated over the past two years. But that doesn't necessarily mean the Supreme Court will be the one to settle the issue once and for all.

"You could never safely say that the case is a foregone conclusion," Goldstein said."There centuries of history that are lined up against the claim here, and we have the most conservative Supreme Court in the nation's history."

(RELATED: Here's What All The Republican Presidential Contenders Think About Gay Marriage)

Still, while legal experts say that technically, anything could happen, the conventional wisdom does have a strong foundation.

For starters, there's the 2013 case in which the court struck down a key part of the Defense of Marriage Act, easing federal restrictions on same-sex marriage. That decision, written by Justice Anthony Kennedy, argued that DOMA was depriving same-sex couples of basic dignity, even teaching their children that their relationships were second-class. Kennedy described the "animus" toward gay people that he saw as a motivation for laws like DOMA.

And while he was careful to say that ruling was only applicable to the federal law, the court's more conservative members said the writing was on the wall even then.

"By formally declaring anyone opposed to same-sex marriage an enemy of human decency, the majority arms well every challenger to a state law restricting marriage to its traditional definition," Justice Antonin Scalia wrote in his dissent.

(RELATED: The Legal Argument Gay Republicans Are Making In Favor of Same-Sex Marriage)

The court's silence since that decision has also spoken volumes, legal experts said. When federal appeals courts struck down states' bans on same-sex marriage, the Supreme Court declined to hear the states' appeals—a move that left the lower-court rulings in place and allowed marriages to proceed in those states. It only intervened after the 6th U.S. Circuit Court of Appeals upheld marriage restrictions in Kentucky, Michigan, Ohio, and Tennessee (the cases before the court now).

This year, the court also declined to step in and delay same-sex marriages in Alabama. Again, the court's conservative wing saw signs of what's to come.

"This acquiescence may well be seen as a signal of the court's intended resolution of that question," Justice Clarence Thomas wrote in a dissent, referring to the question of whether the Constitution gives same-sex couples the right to marry.

In fact, by refusing to reconsider lower-court rulings against states' anti-marriage laws, the Supreme Court has helped accelerate the trend toward marriage equality. If the court ruled this summer that states are still free to pass their own laws restricting marriage, the right to marry could vanish in many states.

(RELATED: The One Election Where Gay Marriage Is Still a Political Liability for Democrats)

Preventing upheaval in states that have already allowed same-sex marriage, by virtue of a court order, could be a factor in Kennedy's thinking, Schacter said.

But the states defending their bans on marriage equality also are targeting their argument squarely at another of Kennedy's favorite causes: federalism.

Part of the argument against DOMA was that the states, rather than the federal government, traditionally decided which marriages they would sanction. They still have that power, according to the four states in this case.

"Both sides can see in [the DOMA ruling] things they like," Goldstein said.

The justices had a chance to address the federalism question in 2013, but punted—the court declined to rule on state marriage laws, falling back on questions about standing.

It will be harder to find an escape hatch—or even a middle ground—this time, legal experts said. The court is hearing two questions—whether states have to allow same-sex couples to marry, and whether they must recognize same-sex marriages performed in states that allow them.

But that distinction isn't conducive to the type of incremental decisions the court often prefers, Schacter said. She suspects both questions will have the same answer, one way or another.

With no easy outs, the court will likely have to go big, one way or another, when it rules this summer. And even though Kennedy has barely said a word in public about the case, almost everyone—from his adversaries on the bench to impartial legal observers—is pretty sure where he'll come down.

"On the whole, the atmospherics, the basic theory favor the plaintiffs," Goldstein said.

This article is from the archive of our partner National Journal.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.