The administration is complying with the order. But Trump's tweets and this type of rhetoric about the judge's authority begs the question: What if it didn't? What if Trump - or any president - decided too much was at stake or that he didn't recognise (in his words) "this so-called judge's" authority? Farzaneh Ahmadi Darani, left, and her sister Shadi Ahmadi Darani hold each others' hands during a news conference in Philadelphia. Attorney Ayodele Gansallo speaks. Credit:AP It's something experts on executive authority have been chewing over. Given Trump's populist campaign, admiration for authoritarian leaders and expressed skepticism toward the political establishment, some think it's it's possible he takes on the judicial establishment, too. "They're spoiling for a fight, and that's what populists do," said Daniel P. Franklin, a professor at Georgia State University. "And I think that's the way it plays out - maybe not on this issue, but on something."

I'll emphasise upfront that the Trump administration has given no indication that they'll actually ignore this particular court order - or any other. (They're appealing, and the 9th Circuit declined to immediately reinstate the ban early Sunday morning.) And doing so would take things further than most any president ever has; Franklin said he's not aware of when a president "purposely ignored a direct court order." But sometimes presidents have interpreted court decisions in ways that lead to discord between branches of government, leading to the threat of constitutional crises. President Donald Trump. Credit:AP The most oft-cited example of a president allegedly ignoring a court ruling just happens to involve the populist president that Trump's team seems most interested in comparing to Trump: Andrew Jackson. After the Supreme Court and Justice John Marshall struck down a Georgia law that allowed for the seizure of Native American lands, saying it violated federal treaties, Jackson ignored it or at least initially declined to get involved - depending upon the account. He is remembered to have said, "John Marshall has made his decision; now let him enforce it," though there is debate about the accuracy of that quote.

Adrian Hegeman holds a sign while joining other opponents to new immigration restrictions to protest an executive order signed by President Donald Trump. Credit:AP According to Native American scholar Frank Pommersheim: "While others consider the statement apocryphal, there is no doubt that President Jackson supported Georgia's claimed sovereignty over Cherokee land. The constitutional imbroglio was only averted when the impending nullification crisis convinced President Jackson that such a constitutional crisis was not in the national interest." An earlier and plainer example also involved Marshall - and a Founding Father, Thomas Jefferson. Jeffrey Rosen wrote for PBS that a showdown between the two pitted Jefferson's federalist views against Marshall's view that the Supreme Court had authority over all US laws: "The culmination of Marshall's national vision came in McCulloch v. Maryland (1819), in which he wrote an opinion for a unanimous Court upholding Congress' power to charter the Bank of the United States. Marshall resurrected the same arguments that Alexander Hamilton had used to persuade George Washington to charter the bank over Jefferson's objections: namely, that the Constitution gives Congress the authority to pass all laws "necessary and proper" for executing its constitutional powers, and that those words should be construed broadly, in a practical spirit. -- Although the decision was popular in the middle and Northern states, it precipitated a backlash against the Court in the Southern and Western states.

"Jefferson's reaction to McCulloch was especially peevish and extreme. He endorsed attacks on the decision published by the radical states' rights partisans Spencer Roane and John Taylor, agreeing that the Supreme Court had no power to review the constitutionality of state laws or to second-guess the decisions of state courts. Later, he seemed to deny entirely the Supreme Court's power to hand down binding interpretations of the Constitution. This proved too radical for Jefferson's protege, James Madison, who wrote to his patron that he had no doubt that the framers of the Constitution intended the federal courts to be a final arbiter of conflicts between federal and state law. On his deathbed, just before he expired on July 4, 1826, Jefferson criticised Madison for being too accommodating." Another potential parallel involves Abraham Lincoln's suspension of habeas corpus during the Civil War. From history.com: "John Merryman, a state legislator from Maryland, is arrested for attempting to hinder Union troops from moving from Baltimore to Washington during the Civil War and is held at Fort McHenry by Union military officials. His attorney immediately sought a writ of habeas corpus so that a federal court could examine the charges. However, President Abraham Lincoln decided to suspend the right of habeas corpus, and the general in command of Fort McHenry refused to turn Merryman over to the authorities. "Federal judge Roger Taney, the chief justice of the Supreme Court (and also the author of the infamous Dred Scott decision), issued a ruling that President Lincoln did not have the authority to suspend habeas corpus. Lincoln didn't respond, appeal, or order the release of Merryman. But during a July 4 speech, Lincoln was defiant, insisting that he needed to suspend the rules in order to put down the rebellion in the South. "Five years later, a new Supreme Court essentially backed Justice Taney's ruling: In an unrelated case, the court held that only Congress could suspend habeas corpus and that civilians were not subject to military courts, even in times of war."

If Trump were to ever go down this road, Franklin said, the ultimate arbiter would be the other, third, branch of government. He said Trump could be held in contempt of court, and it would then be up to the House of Representatives. "(Contempt of court), in my opinion, is a 'high crime or misdemeanor' in the meaning of the Constitution, and he would be subject to impeachment," Franklin said. "Whether or not the House of Representatives would see it that way is another question. It is at that point their call." The other big question with Trump - should he opt to question the legal authority of a judge who runs afoul of him - is whether the government agencies who would need to go along with Trump's decision would actually do so. Trump's Defence and Homeland Security secretaries, for example, are military generals who are accustomed to a chain of command. Would they ignore a court order in favor of Trump? Loading It's all very hypothetical, but Trump's rhetoric -- not just about the judge's decision, but the judge's actual authority -- and his apparent desire to press his case for his own authority suggest it's not out of the question.

Washington Post