A Seattle federal judge has put a nationwide block on US President Donald Trump's week-old executive order that had temporarily barred refugees and nationals from seven countries from entering the US.
The judge's temporary restraining order represents a major setback for Trump's action, although the White House said late on Friday that it believed the ban to be "lawful and appropriate" and that the US Department of Justice would file an emergency appeal.
Still, just hours after the ruling, US Customs and Border Protection told airlines they could board travellers who had been affected by the ban.
Trump's January 27 order caused chaos at airports across the US last week as some citizens from Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen were denied entry. Virtually all refugees were also barred, upending the lives of thousands of people who had spent years seeking asylum in the US.
The State Department said that almost 60,000 visas were suspended in the wake of Trump's order; it was not clear whether that suspension was automatically revoked or what travellers with such visas might confront at US airports.
While a number of lawsuits have been filed over Trump's action, the Washington state lawsuit was the first to test the broad constitutionality of the executive order. Judge James Robart, a George W Bush appointee, explicitly made his ruling apply across the country, while other judges facing similar cases have so far issued orders concerning only specific individuals.
The challenge in Seattle was brought by the state of Washington and later joined by the state of Minnesota. The judge ruled that the states have legal standing to sue, which could help Democratic attorneys general take on Trump in court on issues beyond immigration.
Washington's case was based on claims that the state had suffered harm from the travel ban, for example students and faculty at state-funded universities being stranded overseas. Amazon.com and Expedia, both based in Washington state, had supported the lawsuit, asserting that the travel restrictions harmed their businesses.
Tech companies, which rely on talent from around the world, have been increasingly outspoken in their opposition to the Trump administration's anti-immigrant policies.
Judge Robart probed a Justice Department lawyer on what he called the "litany of harms" suffered by Washington state's universities, and also questioned the administration's use of the September 11, 2001, attacks on the US as a justification for the ban.
Robart said no attacks had been carried out on US soil by individuals from the seven countries affected by the travel ban since that assault. For Trump's order to be constitutional, Robart said, it had to be "based in fact, as opposed to fiction".
The White House said it would file an appeal as soon as possible.
"At the earliest possible time, the Department of Justice intends to file an emergency stay of this outrageous order and defend the executive order of the president, which we believe is lawful and appropriate," the White House said in a statement.
"The president's order is intended to protect the homeland and he has the constitutional authority and responsibility to protect the American people."
Washington Governor Jay Inslee celebrated the decision as a victory for the state, adding: "No person - not even the president - is above the law."
The decision in Washington state came at the end of a day of furious legal activity around the country over the immigration ban. The Trump administration has justified its actions on national security grounds, but opponents have labelled it an unconstitutional order targeting people based on religious beliefs.
