Inconveniently for the president, Ms. Daniels’s position turns on questions of fact. Did Mr. Trump and Mr. Cohen ever discuss Ms. Daniels? Was Mr. Trump aware of the obligations he had ostensibly undertaken? Why did Mr. Trump not sign on the signature line? Was he 100 percent ignorant about the agreement? And there are a similar series of crucial factual questions for Mr. Cohen, such as where the $130,000 payment came from.

The standard course for resolving these sorts of factual disputes is to first permit the parties to take discovery. Mr. Avenatti has asked the court for a two-hour deposition of both Mr. Trump and Mr. Cohen. Normally a request to depose the president would seem like a nuisance move, quickly rebuffed. Here, though, it is hard to see how the court resolves the factual issue without hearing Mr. Trump’s version of events.

Worse still for the president, because the hush agreement provides for compulsory arbitration, both sides are relying on the Federal Arbitration Act. That law provides for an expedited jury trial to decide whether the agreement was formed, and Mr. Avenatti’s motion asks the court to schedule a trial within 90 days. The first entry on Ms. Daniels’s witness list in the jury trial would surely be the president of the United States.