The Trump administration has argued that the ban is necessary to prevent potential militants from entering the country and is not discriminatory because the text of the order does not mention any particular religion.
Washington Attorney General Bob Ferguson signaled on Sunday that he will move aggressively to obtain written documents and e-mails authored by administration officials that might contain evidence the order was unconstitutionally biased against Muslims or Islam. He also said he would also move to depose administration officials.
Legal scholars say this could move the court into uncharted waters.
“The idea of looking at motive has never really been applied to the president,” said John Yoo, a former Justice Department lawyer in the George W. Bush administration.
“It would represent a serious expansion of judicial oversight of what the president and the entire executive branch does,” said Yoo, now a professor at the University of California at Berkeley School of Law.
Trump has harshly criticized the federal judge in Washington for his decision and a top White House aide on Sunday accused the 9th Circuit of a “judicial usurpation of power.”
“The president’s powers here are beyond question,” senior policy adviser Stephen Miller told Fox News Sunday.
US courts have historically been careful about probing the motives behind laws, in part out of respect for the separation of powers between branches of government. But on questions of racial or discrimination, they have sometimes allowed intent to be examined.
In 1993, for instance, the Supreme Court found that an ordinance banning animal sacrifice in Hialeah, Florida, though neutral on its face, was actually intended to discriminate against a Santeria church, which holds sacrifice as a sacred rite.
Stephen Griffin, a professor of constitutional law at Tulane University, said cases like this make it clear that the court can look beyond the words of Trump’s executive order. “Motive is relevant,” he said.
One question in the current case is likely to be which, if any, of Trump’s statements should be admissible in examining the administration’s motives in issuing the order.
“If you are allowed to use evidence from the campaign, the state’s case is very strong,” said Griffin.
In December, 2015, days after a mass attack by Daesh sympathizers in San Bernardino, California, Trump called for “a total and complete shutdown of Muslims entering the US until our representatives can figure out what is going on.” He later said he supported only suspending immigration from areas with a history of terrorism.
Stanford University Law School Prof. Michael McConnell, a former federal appeals judge, said the court should not consider campaign statements, because Trump only swore an oath to uphold the constitution after he became president.
In its complaint, Washington cited an interview the president did on the day the order was signed with the Christian Broadcasting Network, saying he would prioritize Christians in the Middle East for admission as refugees.
Anna-Rose Mathieson, a partner with the California Appellate Law Group said that one person who might be more easily deposed would be presidential adviser and former New York City Mayor Rudolph Giuliani, who told Fox News the president had asked him to put a commission together to figure out how to make a Muslim ban legal.
David Pressman, a partner at Boies Schiller Flexner and former assistant secretary of Homeland Security in the Obama administration, said there are important protections in place so that the executive branch can receive national security advice.
“You do not want a situation in which courts are adjudicating intelligence that is coming to the executive when trying to formulate policy,” said Pressman. Though in this case, Pressman said he did not believe the national security argument for the order was clear, opening the door to further questioning.