At some point in the next few weeks or so, unless President Donald Trump stages a constitutional crisis—something that, given his habits, can hardly be ruled out—he will almost certainly have to take questions from Robert Mueller, the special counsel investigating possible Russian interference in the 2016 Presidential election. The details—whether the interview will be in writing or in person, and, if the latter, where it will be, who will be present, and whether it will be recorded on video—have yet to be settled. (Replies via Twitter will presumably be disallowed.) “I would love to do it,” Trump said last Wednesday, just before leaving for Davos, “subject to my lawyers, and all of that.”

That is a significant caveat: on Thursday, the Times reported that, last June, Trump decided to fire Mueller, but was held off from doing so by the White House counsel, Don McGahn. (“Fake news, folks,” the President said, in response.) The conditions of Mueller’s employment are not incidental to his investigation. His most consequential questions for Trump might not be about Russian influence over American voters but about the power that the President of the United States believes he has to control, or to abrogate, the rule of law.

To that end, Mueller might ask Trump why he has, or has not, fired various people. He might start with James Comey, the former director of the F.B.I., who was running the inquiry last May, when Trump dismissed him. Trump gave several explanations, before offering that “this Russia thing, with Trump and Russia” was “a made-up story” and that Comey was “a showboat.” Trump’s firing of the man who was investigating a matter that involved his campaign is what made the appointment of a special counsel inevitable. Now Mueller has the capacity to look not only at the Russia case but also at other malfeasance he may find along the way, including possible financial crimes and, in particular, obstruction of justice.

Mueller also will likely ask Trump why he fired Michael Flynn, his first national-security adviser, and what assurances he might have given him at the time. Flynn was already in legal jeopardy, because he had hidden his contacts with Russians and because his lobbying firm had taken money from Turkish interests without reporting it. Comey testified that Trump nonetheless asked him to go easy on Flynn. Mueller has now reached a deal with Flynn, under which he pleaded guilty to lying to the F.B.I., and attested that some of his contacts were directed by at least one member of Trump’s transition team.