ONE year ago, stung by what he termed “ridiculous” judicial defeats for his travel ban and sanctuary city policies, Donald Trump tweeted, “see you in the Supreme Court!” On April 25th, Mr Trump followed through on that promise. Trump v Hawaii asks whether the third version of the president’s restrictions on travel from primarily Muslim countries is consistent with immigration law and the constitution. After lower courts repeatedly froze Mr Trump’s edicts for discriminating against Muslims, the travel ban found a friendlier audience among the nine justices.

First up at the podium was Noel Francisco, the solicitor-general. The latest restrictions, announced in September, were based on a “worldwide, multi-agency review”, he told the court, and applied to countries that fail to provide enough information to vet their travellers. The proclamation “omits the vast majority of the world”, he said, including the “vast majority of the Muslim world”. If the restrictions were a “Muslim ban” in disguise, they were “the most ineffective Muslim ban that one could possibly imagine”.

Justice Samuel Alito picked up this theme in a question to Neal Katyal, the lawyer representing the ban’s challengers. Would a reasonable observer really read Mr Trump’s proclamation, which applies to only 8% of the world’s Muslims and only five of 50 majority-Muslim countries, as a “Muslim ban”? Mr Katyal acknowledged that the text alone does not damn the travel rules. But the “circumstances around it”, he said, including Mr Trump retweeting missives from an anti-Islam hate group to his tens of millions of followers, show the true motive behind the ban.

The most telling question of the morning came from Justice Elena Kagan, who asked Mr Francisco if there would any legal problem with a vehemently anti-Semitic president who got his staff to draft a travel order banning Israelis from entering America. If his cabinet “honestly” thought there was a threat to national security from Israelis, Mr Francisco said, the president “would be allowed to follow that advice”. But it is quite unlikely that a president would do such a thing. Well, Justice Kagan pressed on, tongue almost imperceptibly in cheek, and drawing laughter in the courtroom, “this is a out-of-the-box kind of president in my hypothetical.”

Should courts really have the duty to assess “whether or not there is...a national exigency” that would permit a president to limit foreigners’ access to America, asked Justice Anthony Kennedy? Is Mr Trump’s proclamation really, as Mr Katyal characterised it, “a power no president in 100 years has exercised”?

Justice Neil Gorsuch, Mr Trump’s appointee, and Chief Justice John Roberts also voiced scepticism about the challengers’ case against the travel rules. On Mr Katyal’s theory, the chief intimated, a president who acts on advice to launch an air strike against Syria could be seen as “discriminat[ing] against a majority-Muslim country”—a ludicrous conclusion. And since Congress may not be “prescient enough” to write laws that address “any particular factual situation that might arise”, he said, courts should afford presidents a wide berth to curtail travel. A decision in this showdown over presidential power should arrive by the end of June.