The Justice Department appealed Judge Robart's order that put a nationwide hold on Trump's Muslim ban, asking the court to immediately restore Trump's immigration order. The Appeals Court said No.
There's one more step, of course, the U.S. Supreme Court. If they split 4 to 4, then the Appeals Court decision stands -- and that would be the end of the judicial line for Trump, at least as far as immediate restoration of the ban. It could of course go to a trial, which would be a lengthy process.
Beyond a trial court's consideration of the legality of Trump's ban, Trump has probably poisoned his own case on the issue of context and motivation for the ban. First, he cannot show that these seven countries are the source of previous terrorist activity in the U.S. And they've said nothing publicly about having intelligence of plots or plans for future attacks.
There is video footage of Rudy Giuliani saying that Trump wanted "a Muslim ban" and asked him to help devise a way to make it legal. Big-mouth Rudy spilled the beans (or is he getting revenge on Trump for not appointing him AG?). Playing that video would be devastating in a courtroom where you're trying to prove it is not "a Muslim ban." In addition, there are multiple videos from the campaign with Trump himself proclaiming that he would put in a Muslim ban.
Add to that pile of incriminating evidence are Trump's tweets since becoming president in which he denounces Judge Robarts as "this so-called judge" and refers to his "ridiculous" decision. It shows a disturbing lack of respect for the judiciary and the rule of law.
So the ultimate question becomes: What if Trump then decides to defy the court order? Unquestionably, this would be a constitutional crisis. How is that handled?
Apparently the only recourse is impeachment, unless some member of his close inner circle (perhaps Ivanka and Jared) could persuade him to resign. Remaining adamant in refusing to obey a court order would constitute an impeachable offense.
It would be up to the House to bring the indictment, which is what impeachment is; then the Senate would hold a trial presided over by the Chief Justice of the Supreme Court. The Senate vote would determines whether he is removed from office.
My guess is that it won't come to impeachment; that, if Trump ever comes to believe that impeachment and conviction are inevitable, he will resign. Then it should be relatively easy to come up with face-saving rationalizations for a resignation, such as: the restrictions on his ability to be involved in his business are endangering the survival of the Trump Organization.
Remember, of course, that I have always been wrong on every prediction I've made about Donald Trump. If he believes that he could be impeached by the House but then acquitted by the Senate, as was Bill Clinton, Trump might relish the fight, thinking he would win -- and he might.