Why would Mueller have declined? We know it is not because he thought the evidence was inadequate. Indeed, quite to the contrary, Mueller explicitly stated that “if he had confidence” that the evidence was inadequate to prosecute the president, he would have said so. He did not.

Instead, he said that certain issues prevented him from exonerating the president—which is a way of saying that the evidence supported a conclusion that the president had, in fact, obstructed justice. Indeed, any fair reading of the evidence presented in the report reveals a course of conduct—ranging from attempts to remove the special counsel to direct and indirect contacts with witnesses in an effort to get them to limit their testimony—that demonstrates the president’s obstructive intent.

This perspective is confirmed by the remainder of Mueller’s discussion, which is an extended legal analysis of precisely why claims of exoneration were not well founded. Mueller examined the legal claim (also advanced by Attorney General William Barr) that the obstruction statute doesn’t apply to the president’s conduct when he is acting in his capacity as chief executive—and rejected that reading of the law. He examined, as well, the constitutional claim that Congress could not, lawfully, have criminalized presidential actions—and he rejected that as well.

Yoni Appelbaum: The Mueller report is an impeachment referral

Having thus gone to great lengths to establish the grounds for a criminal charge, both factually and legally, Mueller nonetheless declined to offer an opinion on whether or not the evidence supported the conclusion that the president committed crimes.

He did not do so for the following reason: A prevailing Justice Department opinion prohibits the indictment of a sitting president; since the normal forum to contest innocence is in response to an indictment, it is unfair to accuse any individual of criminality in a report to which he cannot respond; and it is especially unfair to a sitting president, since the stigma of such an allegation would resonate far beyond the criminal sphere.

So when Barr said at this morning’s press conference that departmental policy against indicting presidents was not a “but for” cause of Mueller’s reticence, that was, strictly speaking, true—yet fundamentally misleading. Mueller’s decision was bottomed, ultimately, on the president’s unique status.

That is the only reasonable explanation for why the special counsel took a fundamentally inconsistent view of the legal obligations of those under his investigation. As Mueller recounts, several individuals affiliated with the Trump campaign lied to the investigation, and those lies materially impaired the investigation. As a general matter, it is difficult to see how those lies were material and impaired the investigation, but the 10 different events orchestrated by the president and intended to influence or short-circuit the special counsel’s investigation were not likewise material. The only way to square the circle is the unique nature of the presidency.