Over the weekend, the Trump administration ignored a federal judge’s order not to deport a group of Venezuelan men, violating an instruction that could not have been plainer or more direct.

Justice Department lawyers later justified the administration’s actions with contentions that many legal experts said bordered on frivolous.

The line between arguments in support of a claimed right to disobey court orders and outright defiance has become gossamer thin, they said, again raising the question of whether the latest clash between President Trump and the judiciary amounts to a constitutional crisis.

Legal scholars say that is no longer the right inquiry. Mr. Trump is already undercutting the separation of powers at the heart of the constitutional system, they say, and the right question now is how it will transform the nation.

“If anyone is being detained or removed based on the administration’s assertion that it can do so without judicial review or due process,” said Jamal Greene, a law professor at Columbia, “the president is asserting dictatorial power and ‘constitutional crisis’ doesn’t capture the gravity of the situation.”

Mr. Trump raised the stakes on Tuesday by calling for the impeachment of the judge who issued the order, James E. Boasberg of the Federal District Court in Washington, describing him on social media as a “Radical Left Lunatic.”

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