The president, moreover, can move quickly, while court cases take time. “At the point at which the economy is melting down, who cares what the Supreme Court is going to say?” Professor Balkin said. “It’s the president’s duty to save the Republic.”

Another possible reaction to unilateral action from Mr. Obama is impeachment. Professor Tribe said that was “not politically a very plausible scenario.”

Professor Levinson was less certain. Impeachment by the House of Representatives “seems to me quite likely.” But, he added, “it is also literally unimaginable that the Senate would convict.”

A third possible response is what some law professors call “popular constitutionalism.” The meaning of the Constitution, these professors say, is in the end what the public believes it to be.