What happens if Trump decides to ignore a judge's ruling?

US President Donald Trump has spent the better part of the last 24 hours bashing a Washington state judge's decision to temporarily halt his travel ban executive order.

First came a White House statement calling the ruling "outrageous" (the word was later taken out). Then came Trump's many tweets, which were scattered throughout the day yesterday and actually seemed to question the judge's authority.

And then, in its appeal, the Trump Administration said the lower-court judge shouldn't be "second-guessing" the President.

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?

It's something experts on executive authority have been chewing over. Given Trump's populist campaign, admiration for authoritarian leaders and expressed scepticism towards the political establishment, some think it's possible he takes on the judicial establishment, too.

"They're spoiling for a fight, and that's what populists do," said Daniel 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.) 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.

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.

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."

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, 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."

Refugee groups are seizing the opportunity and booking plane tickets. https://t.co/Dh4BK1vdEo

— NPR (@NPR) February 5, 2017

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 misdemeanour' 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 favour of Trump?

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.