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A federal appeals court on the West Coast will hear oral arguments Tuesday afternoon that could keep a hold on travel restrictions created by President Donald Trump on foreigners from seven countries.

Three judges designated to hear emergency appeals to the Ninth Circuit Court of Appeals, based in San Francisco, will conduct the hearing via a telephone conference call with lawyers from the Justice Department and two states that filed a lawsuit to block the executive order — Washington and Minnesota.

Related: Which Side Is Donald Trump on in the Fight Over Legal Immigration?

Those two states, with the support of 15 others that filed a friend of court brief Monday, argue that Trump's order violates a federal immigration law which prohibits discriminating against visa applicants "because of race, nationality, place of birth, or place of residence."

They also say the action was unconstitutional because it discriminates on the basis of religion.

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"President Trump has made clear that one purpose of the order is to favor Christians at the expense of Muslims," they argue in their legal submission to the appeals court.

A demonstrator holds an American flag during an immigration rally at San Francisco International Airport on Jan. 28, 2017 in San Francisco. Stephen Lam / Getty Images, file

The Justice Department counters by saying that a federal law explicitly gives the president the authority, in the words of the statute, "to suspend the entry of all aliens or any class of aliens" for national security purposes.

In restricting travel for 90 days from Iran, Iraq, Libya, Somalia, Sudan, Syria, and Yemen, Trump was focusing on countries that Congress and the State Department had already deemed to be "associated with a heightened risk of terrorism" and that lack sufficient resources to allow thorough vetting of those wishing to come to the United States.

As for the constitutional claim, the government says the executive order does not favor Christians over Muslims. Recognizing that religious minorities are more likely to face persecution than members of a country's dominant religion is a well-established principle of immigration policy, the Justice Department argues.

James Robart, a federal district court judge in Seattle, issued a temporary restraining order Friday that blocked enforcement of the Trump travel restrictions. He acted after the states said the Trump order hurt their universities, stranding students and faculty overseas or preventing others from traveling for research.

On Monday, nearly 100 mostly high-tech companies, including global giants like Apple, Microsoft, Google and Twitter, filed a friend-of-the-court briefing that said the travel restrictions were harming their ability to recruit the world's brightest job applicants.

Related: Trump Administration Floats Compromise in Fight Over Travel Ban

And two former secretaries of state, John Kerry and Madeleine Albright, have joined former top intelligence officials in saying that the Trump immigration order harms national security by both giving ISIS a new propaganda tool and discouraging Muslims in the U.S. from reporting potential trouble they see to law enforcement.

In a court filing late Monday, the Trump administration offered a possible fallback position, in the event the appeals court is inclined to rule for the states. The court could let most of the executive order be enforced again but provide an exemption for people who were allowed into the country once before and now want to return, or people here on visas now who want to travel and then come back.

"At most, the injunction should be limited to the class of individuals on whom the states' claims rest," the government said, referring to students, scholars and high-tech employees who have already been allowed into the United States. That would limit the executive order to covering only those who seek to enter the country for the first time.

Once the appeals court rules on whether to keep Robart's order in place, whichever side loses will undoubtedly ask the U.S. Supreme Court to step in.

"Hopefully it doesn't have to," Trump said.