The 9th U.S. Circuit Court of Appeals will hear arguments Tuesday evening over whether President Trump’s travel ban should remain on hold or go back into effect.

Trump’s executive order temporarily barred visa holders from seven majority-Muslim countries, as well as all refugees, from entering the country. It was signed on Jan. 27 and quickly challenged by an array of lawsuits.

One of those cases resulted in a temporary restraining order, blocking the ban — for now — from going into effect. It’s that restraining order, not the ban as a whole, that lawyers will be arguing over today.

The arguments before a three-judge panel will be held by telephone at 6 p.m. ET (3 p.m. PT), and you can listen live online. Here are a few things to know before the arguments get going:

How did we get here?

Trump’s original executive order (which we’ve annotated here) bars travelers from Iraq, Iran, Syria, Yemen, Sudan, Libya and Somalia for 90 days, suspends new refugee admissions for 120 days, and blocks refugees from Syria indefinitely.

The White House denies that this amounts to a “Muslim ban,” as Trump called for during the presidential election. But all seven of the listed countries are majority-Muslim. The order calls for the eventual prioritization of refugee claims from people of “minority religions” in their country of origin — and in an interview Trump said that Christians from the Middle East would be prioritized.

On Jan. 30, Washington became the first state to sue the administration, arguing that the order is discriminatory and violates the Constitution as well as federal law. (The lawsuit is one of many challenging the travel ban.)

That case — with Minnesota joining Washington — resulted in Judge James L. Robart siding with the states in granting a temporary restraining order that blocked the ban from being enforced until the court case could move forward.

The Department of Justice asked the 9th U.S. Circuit Court of Appeals to immediately reinstate the ban. The court refused to immediately intervene, but asked for the states and the DOJ to make more arguments for and against the restraining order.

Both sides have filed briefs to try to make their case, and will be presenting them again in oral arguments Tuesday night.

What’s at stake today?

The appeals court will not decide the overall legality or constitutionality of Trump’s travel ban. The only thing under consideration today is the temporary suspension of the travel ban.

If the court upholds the temporary restraining order, then the ban will continue to not be enforced as the court case moves forward. If the court sides with the U.S. government, the ban would go back into effect for now — and the case against the order would still move forward.

On the law and policy blog Just Security, Georgetown law professor Marty Lederman — who served in the Justice Department under President Barack Obama — notes that the court’s decision might not actually be that exciting.

“Just so that everyone’s expectations are not unduly raised (and then dashed),” he writes, there’s “a very real possibility” that the court won’t consider the merits of the case at all.

A temporary restraining order can’t usually be appealed, as the government acknowledges. The DOJ argues that it is able to appeal this one, based on technical reasons involving the difference between a temporary restraining order and a preliminary injunction.

Lederman says the judges might well focus on that procedural distinction — whether it can be appealed in the first place — instead of other elements of the case.

What are the arguments on each side?

Aside from the procedural element (which relies on riveting questions like what counts as an adversary hearing, and how long the TRO will be in effect), the two sides are arguing over who’s more likely to win the overall case over Trump’s travel ban. The likelihood of winning is a factor in determining whether a temporary restraining order is appropriate.

The DOJ cites the president’s broad authority on immigration issues as a reason why the government is likely to win this case, eventually. The states, meanwhile, say they’ll win, based on their evidence that the travel ban was designed to discriminate on the basis of religion and violates the right to due process.

Then there’s the question of “irreparable harm.” Washington state originally asked for the restraining order because it argued the travel ban was actively harming its residents. The federal government, meanwhile, argues that suspending the ban is causing harm by violating the separation of powers and exposing citizens to risk, and also because it amounts to “judicial second-guessing” of the president’s judgment on national security. (The state says the temporary restraining order just restores the status quo from before the ban, and that the DOJ’s argument “makes no sense.”)

The DOJ also argues that, even if it were appropriate, the temporary restraining order should have been imposed more narrowly, rather than nationwide — while the states say a nationwide halt was necessary to protect residents who might travel through a port of entry anywhere in the country.

Who are the judges who will decide?

The arguments on each side will be presented to a three-judge panel of the 9th U.S. Circuit Court of Appeals: William Canby Jr., Richard Clifton and Michelle T. Friedland.

Canby was appointed by Jimmy Carter, Clifton by George W. Bush and Friedland by Obama.

What happens next?

As the appeals court considers the DOJ’s request to reimpose the executive order, the case continues to move forward at the district level.

A host of other lawsuits challenging the executive order are also unfolding across the country — The Hill reports that there are more than 50 such lawsuits brought by state attorneys general, religious groups and individuals.

Eventually, one of the cases might well make it before the U.S. Supreme Court. Bob Ferguson, the attorney general of Washington state, told NPR’s Michel Martin he sees that as “entirely possible.”

As NPR’s Nina Totenberg has reported, Senate Democrats have signaled that the executive order might factor into confirmation hearings for Judge Neil Gorsuch, Trump’s nominee for the court’s open seat, as they weigh his position on the legality and constitutionality of the travel ban.

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