Almost from the moment she was assigned the case in June, Judge Cannon, who was appointed by Mr. Trump in his waning days in office, has handled the proceeding in an unorthodox manner.

She has put off making several legal and logistical decisions. And she has spent time at hearings entertaining a series of unusual arguments by Mr. Trump’s lawyers that many federal judges would have rejected out of hand.

The legal gamesmanship she has encouraged over how to handle Mr. Trump’s Presidential Records Act defense is all the more bizarre because the argument itself is legally dubious.