Send this page to someone via email

Washington State Attorney General Bob Ferguson said on Sunday he will depose Trump administration officials to uncover “what truly motivated” U.S. President Donald Trump‘s executive order on immigration if the case he brought against it goes to trial.

Documents and emails authored by administration officials may contain evidence that the order was an unconstitutional attempt to ban Muslims from entering the United States, and Ferguson will use “every tool” at his disposal to bring those to light, he told ABC’s This Week.

A White House official launched a blistering attack on the federal appeals court that blocked Trump’s executive order Sunday, calling its ruling a”judicial usurpation of power.”

READ MORE: Opponents of Donald Trump’s travel ban looking for another win

The Trump administration has faced multiple legal setbacks to its travel ban issued on Jan. 27, and the Republican president has said he may issue a new executive order rather than go through lengthy court challenges.

Story continues below advertisement

“The president’s powers here are beyond question,” White House adviser Stephen Miller said on the Fox News Sunday program.

Miller referred to immigration law that the executive order is based on that gives the U.S. president broad powers to restrict who enters the country on national security grounds.

Congratulations Stephen Miller- on representing me this morning on the various Sunday morning shows. Great job! — Donald J. Trump (@realDonaldTrump) February 12, 2017

However, the same law forbids discrimination on race, sex, nationality or place of birth or residence. The case also could involve First Amendment protections involving religion.

The executive order Trump issued banned entry into the United States to refugees and citizens of seven Muslim-majority countries, triggering nationwide protests and legal challenges.

WATCH: The 9th Circuit has a long history of overreaching’: Trump policy adviser

5:31 ‘The 9th Circuit has a long history of overreaching’: Trump policy adviser ‘The 9th Circuit has a long history of overreaching’: Trump policy adviser

A week later, a federal judge in Seattle issued a temporary restraining order that put the president’s travel ban on hold, eliciting a barrage of angry Twitter messages from Trump. The judge’s suspension was upheld by a three-judge panel of the 9th U.S. Circuit Court of Appeals in San Francisco on Thursday.

Story continues below advertisement

READ MORE: Donald Trump is considering new travel ban

Miller, appearing on several television news shows, criticized the court and its ruling.

“The 9th Circuit has a long history of being overturned and the 9th Circuit has a long history of overreaching,” he said on the Fox news show. “This is a judicial usurpation of power.”

WATCH: Former NSA and CIA boss says Trump travel ban could have opposite effect of making people safer

1:05 Former NSA and CIA boss says Trump travel ban could have opposite effect of making people safer Former NSA and CIA boss says Trump travel ban could have opposite effect of making people safer

The powers to restrict entry into the United States “represent the very apex of presidential authority,” he added.

“We have multiple options and we are considering all of them,” Miller said while appearing on ABC’s This Week. Tweet This

Story continues below advertisement

Those include formulating a new executive action, appealing the 9th Circuit panel’s decision to the full appeals court and appealing the emergency stay to the Supreme Court, he said.