What happens next as Trump's travel ban heads through the courts

Amid duelling legal maneuvres, the nationwide suspension ofDonald Trump's controversial executive order remains in effect, keeping U.S. borders opento people from seven predominantly Muslim nations.

For now.

A federal appeals court has scheduled oral arguments for Tuesday on whether to restore the ban, which attorneys from Washington state and Minnesota argue would "unleash chaos again." The fate of thetemporary block on Trump's decreewill be determined by the Ninth Circuit Court of Appeals in San Francisco, with a ruling expected this week.

• Everything you need to know about the Trump travel ban
• Court denies Trump request to immediately restore travel ban

Ultimately, the showdown over Trump's reportedly hastily issued order which caused a global uproar last week, along with logistical uncertainty at major airports and human anguish worldwide is likely to wind up before America's highest court.

Legal experts expect a quick ruling from the San Francisco court, possibly within a couple days, after the courthas heardoral arguments.

Washington state and Minnesota, plaintiffs in the suit, have made their position known in their legal brief. They contendthat "thousands" of lives will be disrupted if the ban is restored, and that enforcing Trump's orderwill result in "separating families, stranding our university students and faculty, and barring travel."

In the Department of Justice brief filed on Friday before 6 p.m. ET, the government argues the executive order "is a lawful exercise of the President's authority over the entry of aliensinto the United States and the admission of refugees."

How we got here

In Seattle on Friday, U.S. District Senior Judge James Robart issued a ruling to temporarily halt Trump's order, writing that it would cause "significant and ongoing" harm to residents in the two states challenging the ban. Robart'sinjunction applied nationwide.

The White House said the Department of Justice would file an emergency stay "at the earliest possible time." Early Sunday, the federal appeals court rejected the U.S. government's request to reinstatethe travel ban.

The ruling by Robart, an appointee of George W. Bush, occurred just hours after a short-lived victory for Trump's order. Earlier Friday,a Boston federal courtrefused to renew the halt on the travel ban originally set to expire over the weekend. That decision wasquickly superceded by the outcome in Seattle.

Robart's ruling is the broadest yet and is considered a "global order," says David Bier, an immigration policy analyst with the Cato Institute.

"The other rulings are modest by comparison," Bier says. "Whereas the other orders affected people inside the U.S., or who had been to the U.S., this one affects people who had never been to the U.S. before and were seeking to come."

Immigration experts and constitutional scholars critical of the ban have laid out at least four constitutional and statutory reasons the ban might not stand.

What happens next

Now that briefs from both sides have been received, a three-judge panel in the Ninth Circuit appeals court will consider whether or not to extend the temporary ban.The federal judges in the liberal-leaning San Francisco court of appeals will includeappointeesby Jimmy Carter, Barack Obama and George W. Bush.

Given the scenario, it wasn't unexpected that the court would decide to question litigators in oral arguments, "in which case it could take a couple days," saysYvonne Tew, a professor of constitutional law at Georgetown University. Until then, Tew says the block on Trump's order will stand.

Whichever side loses is likely to take the case to the Supreme Court.

This could be triggered by a conflict among two lower courts. For example, the federal Ninth Circuit appeals courtoverlooking Western U.S. districtsmight announce the executive order is unconstitutional or unlawful, while a different court of appeals from another region might uphold it.

"That's why the Supreme Court is required to resolve the conflict. So the federal law applies uniformly across the country," says Peter J. Johnson, a constitutional law professor with Georgetown University.

Why this might take a while

What the trial judge in Seattle granted was an emergency measure known as a "temporary restraining order," which typically lasts for a few days and would put a freeze on the government's actions until the district court can hear both sides of the case.

Regardless of whether the Ninth Circuit Court of Appeals in San Francisco decides to lift the restraining order, the appeals court will likely send the case back to Robart's district court in Seattle to decide on whether to grant a "preliminary injunction" while the merits of the case are argued.That preliminary injunction serves the same purpose as a restraining order, only without the same limitations on duration.

"If the district court judge does issue a preliminary injunction," Bier predicts, "you're looking at potentially a year-long battle over the issue."

Depending on the appellate court's ruling this week, either side could request immediate intervention from the Supreme Court. The San Franciscodecision will standif the high court, which has still not officially filled the vacancy of its ninth seat, comes to a 4-4 split.

Ilya Shapiro, editor-in-chief of the Cato Supreme Court Review, notes that the Supreme Court is very unlikely to get involved in this early stage, as the justices prefer to let lower courts make decisions if they can.

"The government has already said it won't seek Supreme Court review of the temporary restraining order, and by the time you get all that done, it naturally expires anyway."

What caused this whole legal battle

Trump's unilateral action, the "Protecting the NationFrom Foreign Terrorist Entry Into the United States" executive order, was signed on Jan. 27 as part of a stated goal to reduce terror threats. It imposes restrictions on three groups:

• It temporarily imposes a ban on all refugees for a period of 120 days;
• It indefinitely halts all refugees from Syria from entering the U.S.;
• And it imposes a ban on citizens from seven predominantly Muslim countries for a period of 90 days. Those countries affected are: Iraq, Syria, Iran, Libya, Somalia, Sudan and Yemen.

The president's directive immediately touched off a wave of global protest, as families were left in limbo overwhether friends and loved ones would be deported or detained upon entering the U.S. Some travellers were already in the air while the travel ban came into effect.

(The White House has sparred with reporters over how to characterize the order, insisting it is not a "ban."Trump himself has referred to the move as a "ban" on Twitter.)

Who has been affected

Trump vented on Twitter that only 109 people in total were detained and held for questioning. White House press secretary Sean Spicer later admitted the 109 figure only accounted for people who were en route to the U.S. as the executive order was being signed.

A Washington Post fact check puts the number of people affected by the travel suspension at about 90,000. Spicer later updated the White House's estimates, saying the administration believes 60,000 people were affected.

As part of the Washington and Minnesota suit, 97 technology companies,including Apple,GoogleandUber,filed an amicusbrief saying the travel ban is bad for business.

• Canada looking at legality of enforcing Trump travel ban on Canadian soil

Prominent former officials who worked in the state department, including former secretaries of state John Kerry and Madeleine Albright, also wrote a letter to the U.S. Court of Appeals for the 9th Circuit asking to keep blocking Trump's travel ban, reasoning the executive order will "endanger U.S. troops" and sendan "insulting message" to Muslim nations.