So it turns out that, indeed, President Donald Trump was not exonerated at all, and certainly not “totally” or “completely”, as he claimed.

Special counsel Robert Mueller didn’t reach a conclusion about whether Trump committed crimes of obstruction of justice – in part because, while a sitting president, Trump can’t be prosecuted under long-standing Justice Department directives, and in part because of “difficult issues” raised by “the president’s actions and intent”.

Those difficult issues involve, among other things, the potentially tricky interplay between the criminal obstruction laws and the president’s constitutional authority, and the difficulty in proving criminal intent beyond a reasonable doubt.

Still, the special counsel’s report is damning.

Mr Mueller couldn’t say, with any “confidence”, that the president of the United States is not a criminal.

Mueller investigation: The key figures Show all 12 1 /12 Mueller investigation: The key figures Mueller investigation: The key figures Robert Mueller is the special counsel overseeing the investigation into Russia's meddling in the 2016 election, and potential obstruction of justice by the president. Mr Mueller has a pristine reputation in Washington, where he was previously in charge of the FBI. Throughout his investigation, he and his team have been notoriously tight lipped about what they know and where their investigation has led. REUTERS Mueller investigation: The key figures Former FBI director James Comey was the catalyst that led to the appointment of special counsel Robert Mueller. Mr Comey was fired by the president after Mr Trump reportedly asked him to drop his own Russia investigation. Mr Trump has long maintained that the investigation is a "witch hunt". AFP/Getty Images Mueller investigation: The key figures Deputy attorney general Rod Rosenstein had authority over the special counsel investigation for much of the two years it has been active. Mr Rosenstein found himself with that responsibility after then-attorney general Jeff Sessions recused himself from that oversight. AP Mueller investigation: The key figures Attorney general Jeff Sessions's decision to recuse himself from oversight of the special counsel investigation may have cost him his job in the end. Mr Sessions resigned last year, after weathering a contentious relationship with Donald Trump who vocally criticised his attorney general for taking a step back. Mr Sessions recused himself from the oversight citing longstanding Justice Department rules to not be involved in investigations overseeing campaigns that officials were apart of. AP Mueller investigation: The key figures Attorney General William Barr is currently responsible for oversight of the special counsel investigation. Mr Barr's office will be the first to receive the Mueller report when it is finished. His office will then determine what portion or version of that report should be delivered to Congress, and also made public. EPA Mueller investigation: The key figures Michal Cohn is the president's former personal lawyer, who has been helping the special counsel investigation as a part of a plea deal over financial crimes, and campaign finance crimes, he has pleaded guilty to. Among those crimes, Cohen admitted to facilitating $130,000 in hush money payments to adult film actress Stormy Daniels during the 2016 campaign. Cohen has said he did so at the direction of Mr Trump. Cohen has also admitted that he maintained contacts with Russian officials about a potential Trump real estate project in Moscow for months longer than Mr Trump and others admitted. The talks continued well into 2016 during the campaign, he has said. AP Mueller investigation: The key figures Stormy Daniels has alleged that she had an affair with Donald Trump in 2006, soon after Melania Trump gave birth to Baron Trump. The accusation is of particular importance as a result of the $130,000 hush money payment she received to keep quiet about the affair during the 2016 campaign. AP Mueller investigation: The key figures Paul Manafort was Donald Trump's former campaign chairman. Manafort was charged alongside Rick Gates for a slew of financial crimes, and was convicted on several counts in a Virginia court. He then pleaded guilty to separate charges filed in a Washington court. Manafort has been sentenced to just 7.5 years in prison for his crimes — in spite of recommendations from the special counsel's office for a much harsher sentence. AP Mueller investigation: The key figures George Papadopoulos was one of the first individuals associated with the Trump campaign to be charged by the Mueller probe. He ultimately received a 14 day prison sentence for lying to investigators about contacts he had with Russian officials. AP Mueller investigation: The key figures Roger Stone is a well known political fixer and operative, who has made a name for himself for some dirty tactics. He has been charged by the Mueller probe earlier this year, and he has been said to have had prior knowledge that WikiLeaks planned on publishing stolen emails from the Hillary Clinton campaign in 2016. Getty Images Mueller investigation: The key figures Rick Gates was charged alongside former Trump campaign chairman Paul Manafort for a range of crimes. Gates, who worked alongside Manafort for a pro-Russia Ukrainian political party. The two were charged with conspiracy and financial crimes. Gates pleaded guilty. AP Mueller investigation: The key figures Former national security adviser Michael Flynn was one of the first casualties of the Russia scandal, and was forced out of his position in the White House weeks after Donald Trump took office. Flynn pleaded guilty in 2017 to "willfully" making fraudulent statements about contacts he had with Russian officials including former Russian ambassador to the US Sergey Kislyak. Flynn then lied to Vice President Mike Pence about that contact. REUTERS

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”. Mr 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 probably a criminal. In fact, the constitution demands it.

The constitution commands the president to “take care that the laws be faithfully executed.”

It requires him to affirm that he will “faithfully execute the office of president” and to promise to “preserve, protect and defend the constitution”.

And as a result, by taking the presidential oath of office, a president assumes the duty not simply to obey the laws, civil and criminal, that all citizens must obey, but also to be subjected to higher duties – what some excellent recent legal scholarship has termed the “fiduciary obligations of the president”.

Fiduciaries are people who hold legal obligations of trust, like a trustee of a trust.

A trustee must act in the beneficiary’s best interests and not his own. If the trustee fails to do that, the trustee can be removed, even if what the trustee has done is not a crime.

So too with a president.

The US constitution provides for impeachment and removal from office for “treason, bribery, or other high crimes and misdemeanours”.

But the history and context of the phrase “high crimes and misdemeanours” makes clear that not every statutory crime is impeachable, and not every impeachable offence need be criminal.

Donald Trump says he's 'having a good day' following Mueller report release

As Charles Black 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 Mr Mueller’s report condemn Donald 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 Mr Mueller’s investigation “found multiple acts by the president that were capable of executing undue influence over law enforcement investigations”.

President Trump tried to “limit the scope of the investigation”.

He tried to discourage witnesses from co-operating 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, Mr Mueller’s report describes a relentless torrent of such obstructive activity by Trump.

US attorney general William Barr says there was no collusion between Trump campaign and Russia during the 2016 presidential election

Contrast poor Richard 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 Mr Helms ignored it.

Other than that, Mr 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. Mr Nixon had no advance knowledge of the break-in. His aides were the driving force behind the obstruction.

Donald Trump, on the other hand, was a one-man show.

His aides tried to stop him, according to Mr 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 defence that there was no underlying “collusion” crime, well, as the special counsel points out, it’s not a defence, 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.

White House counsel John Dean famously told Nixon that there was a cancer within the presidency and that it was growing. What the Mueller report disturbingly shows, with crystal clarity, is that today there is a cancer in the presidency: President Donald Trump.

Congress now bears the solemn constitutional duty to excise that cancer without delay.

The Washington Post