Mueller couldn’t say, with any “confidence,” that the president of the United States is not a criminal. He said, stunningly, that “if we had confidence after a thorough investigation of the facts that the President clearly did not commit obstruction of justice, we would so state.” Mueller did not so state.

That’s especially damning because the ultimate issue shouldn’t be — and isn’t — whether the president committed a criminal act. As I wrote not long ago, Americans should expect far more than merely that their president not be provably a criminal. In fact, the Constitution demands it.

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The Constitution provides for impeachment and removal from office for “Treason, Bribery, or other high Crimes and Misdemeanors.” But the history and context of the phrase “high Crimes and Misdemeanors” makes clear that not every statutory crime is impeachable, and not every impeachable offense need be criminal. As Charles L. Black Jr. put it in a seminal pamphlet on impeachment in 1974, “assaults on the integrity of the processes of government” count as impeachable, even if they are not criminal.

And presidential attempts to abuse power by putting personal interests above the nation’s can surely be impeachable. The president may have the raw constitutional power to, say, squelch an investigation or to pardon a close associate. But if he does so not to serve the public interest, but to serve his own, he surely could be removed from office, even if he has not committed a criminal act.

By these standards, the facts in Mueller’s report condemn Trump even more than the report’s refusal to clear him of a crime. Charged with faithfully executing the laws, the president is, in effect, the nation’s highest law enforcement officer. Yet Mueller’s investigation “found multiple acts by the President that were capable of executing undue influence over law enforcement investigations.”

Trump tried to “limit the scope of the investigation.” He tried to discourage witnesses from cooperating with the government through “suggestions of possible future pardons.” He engaged in “direct and indirect contacts with witnesses with the potential to influence their testimony.” A fair reading of the special counsel’s narrative is that “the likely effect” of these acts was “to intimidate witnesses or to alter their testimony,” with the result that “the justice system’s integrity [was] threatened.” Page after page, act after act, Mueller’s report describes a relentless torrent of such obstructive activity by Trump.

Contrast poor Richard M. Nixon. He was almost certainly to be impeached, and removed from office, after the infamous “smoking gun” tape came out. On that tape, the president is heard directing his chief of staff to get the CIA director, Richard Helms, to tell the FBI “don’t go any further into this case” — Watergate — for national security reasons. That order never went anywhere, because Helms ignored it.

Other than that, Nixon was mostly passive — at least compared to Trump. For the most part, the Watergate tapes showed that Nixon had “acquiesced in the cover-up” after the fact. Nixon had no advance knowledge of the break-in. His aides were the driving force behind the obstruction.

Trump, on the other hand, was a one-man show. His aides tried to stop him, according to Mueller: “The President’s efforts to influence the investigation were mostly unsuccessful, but that is largely because the persons who surrounded the President declined to carry out orders or accede to his requests.”

As for Trump’s supposed defense that there was no underlying “collusion” crime, well, as the special counsel points out, it’s not a defense, even in a criminal prosecution. But it’s actually unhelpful in the comparison to Watergate. The underlying crime in Watergate was a clumsy, third-rate burglary in an election campaign that turned out to be a landslide.

The investigation that Trump tried to interfere with here, to protect his own personal interests, was in significant part an investigation of how a hostile foreign power interfered with our democracy. If that’s not putting personal interests above a presidential duty to the nation, nothing is.