Special counsel Robert S. Mueller III in Washington in June 2017. (Joshua Roberts/Reuters)

For months, President Trump’s lawyers and special counsel Robert S. Mueller III have danced around whether the president will agree to be interviewed by prosecutors. It appears that dance may finally be coming to an end.

The New York Times reported on Tuesday that Mueller may agree to accept written answers from the president on at least some topics. But written answers are a very poor substitute for a face-to-face interview, so why would Mueller agree?

It has been clear for some time that Trump was unlikely to agree to a voluntary interview. Despite the president’s repeated protestations that he wants to talk to Mueller, his lawyers have consistently advised against it. In addition to possibly implicating himself in criminal activity, there’s a high likelihood Trump would lie about something and expose himself to false-statement or perjury charges. Just this week, excerpts released from Bob Woodward’s forthcoming book “Fear: Trump in the White House ” revealed how, back in January, Trump attorney John Dowd conducted a mock interview with the president seeking to persuade him that speaking to Mueller was a bad idea. Trump reportedly failed the faux showdown miserably.

But for Mueller to accept written answers would be an unusual concession — prosecutors don’t usually do that. Though written answers may be signed by Trump, they will be carefully crafted by lawyers, not by the president himself. Written questions don’t allow prosecutors to observe the president’s demeanor, or see how he responds when confronted with unexpected documents or difficult facts. They don’t allow the questioner to ask follow-up questions or pursue new lines of inquiry that may be suggested by the president’s answers.

So why would Mueller assent to written answers? If a witness refuses a voluntary interview, a prosecutor typically would respond not by accepting written answers, but by subpoenaing the witness to the grand jury. The president of the United States, however, is not just any witness, and there could be any number of reasons Mueller will not go that route.

Justice Department policy, which Mueller is required to follow, dictates that targets of an investigation — those considered likely to be indicted — generally will not be subpoenaed to the grand jury. It’s unclear whether Mueller believes Trump is a target. Indeed, because Justice Department policy also holds that a sitting president cannot be indicted, some argue that Trump, by definition, could not be a target under any circumstances while he’s in office. In any event, the general policy against subpoenaing targets is not an absolute prohibition.

Even though Mueller likely believes he has the option of subpoenaing the president, he has to consider what he is likely to gain. The president’s legal team would undoubtedly mount various legal challenges to a subpoena. Whether a sitting president can be compelled to testify before a grand jury has never been definitively resolved. Precedent suggests Mueller would ultimately win that fight, though it could delay his investigation for months.

Trump’s lawyers could also raise claims of executive privilege in an attempt to block some of the questioning. The outcome of any such claims would be uncertain; the scope of executive privilege is a notoriously murky area of the law. Regardless of the outcome, the litigation would, once again, likely result in a lengthy delay.

Even if Mueller fought it out in court for months and prevailed on every issue, the president could then go before the grand jury and refuse to answer questions by asserting his Fifth Amendment right not to incriminate himself. To be sure, doing so might have political implications for Trump, but it also would mean Mueller delayed his investigation only to end up with no more information from the president than when he began.

Mueller could reasonably conclude that the interests of justice — and interests of the country — are better served if he completes his investigation expeditiously without the benefit of the president’s testimony. After all, it’s not unusual for prosecutors to conclude investigations without testimony by those at the center of the inquiry. And accepting written answers for now would not preclude Mueller from insisting on an interview or seeking a subpoena later, particularly if he was not satisfied with the answers. At this point, it’s better than nothing — and if Mueller chooses to fight, in the end, nothing may be exactly what he gets.