ON FEBRUARY 3rd, one week after Donald Trump issued an executive order banning travel from seven Muslim-majority countries and suspending America’s refugee programme, a federal judge in Washington state dealt a major blow to the administration’s plan. James Robart, appointed by George W. Bush to the federal district court in Seattle in 2004, was unequivocal in his ruling. There is “no support”, he said, for the government’s argument that its order served to “protect the US from individuals from these countries”. Mr Trump responded with a tweet: “The opinion of this so-called judge”, he wrote, “is ridiculous and will be overturned!”

Observing that Mr Trump’s immigration order had caused “immediate and irreparable injury” in “employment, education, business, family relations and freedom to travel”, Mr Robart granted several states’ request for a temporary restraining order against the ban. While federal courts may not weigh in on the “wisdom” of policy, he concluded, they are duty-bound to ensure that “the actions undertaken by the other two branches comport with our country’s laws, and more importantly, the constitution”. Though temporary, Mr Robart’s ruling has significantly broader implications than the emergency injunction issued on January 28th by a federal judge in Brooklyn. Ann Donnelly’s ruling last week meant that several hundred people who were on their way to America at the moment Mr Trump imposed the ban could not be deported once they landed. Mr Robart’s decision, by contrast, means that untold thousands of refugees and visa-holders from the seven named countries may now board flights destined for America.

The judicial order prompted the State Department to begin allowing valid visa-holders to enter the country. Immigrants-rights activists jumped on the news to encourage people affected by the ban to immediately pack their bags and head to the airport. The window for those seeking to reach America’s shores may be slammed shut again within days, because the Trump administration is preparing to appeal Mr Robart’s decision at the Ninth Circuit Court of Appeals, the appellate court with jurisdiction over several western states, including Washington. The Ninth Circuit, based in San Francisco, has a reputation for being one of America’s most liberal federal appeals courts. This may bode well for the survival of Mr Robart’s restraining order. But because appeals are heard by randomly assigned three-judge panels of the Ninth Circuit’s 44 judges, the assignment has the flavour of a game of roulette. Whatever the Ninth Circuit decides, the losing party will almost certainly ask the Supreme Court for relief, setting up a dramatic interbranch conflict over one of Mr Trump’s signature campaign issues during the first 100 days of his presidency.

The rising drama over the new president’s immigration policy has a dark backdrop: his apparent rejection of the principle that the judiciary is a co-equal branch of America’s government whose decisions—no matter how unpalatable they may seem to him—must be followed. Presidents frequently take issue with judges’ decisions; in 2015, Barack Obama even chastised the Supreme Court for agreeing to hear a case that would have undermined the Affordable Care Act. But there is a difference between criticising a decision and attacking the authority of a duly seated judge. It is incidental that Mr Robart was nominated by a Republican president and earned unanimous Senate approval. In denigrating him as a “so-called judge”, Mr Trump seems unwilling to accept the legitimacy of his ruling. And in a tweet later in the afternoon of February 4th, Mr Trump asked the following rhetorical question: “What is our country coming to when a judge can halt a Homeland Security travel ban and anyone, even with bad intentions, can come into U.S.?” His query betrays an unfamiliarity with a basic principle of American constitutionalism. “It is emphatically the province and duty of the judicial department", wrote John Marshall, America's fourth chief justice, in 1803, "to say what the law is”.