Institutions of American democracy assure themselves and us that their collective cross-checking power and integrity can and will survive and recover from whatever depredations Trump and his cabal wreak. Don't be so sure ...

“The real scandal here is that classified information is illegally given out by “intelligence” like candy. Very un-American!”— Donald Trump, February 15, 2017.

Very true, Mr President, and we now see what you meant when you said you use quotation marks to denote metaphor.

The humour descends as the lunacy rises. Poking fun at a self-basting buffoon is an easy lark, but not so much when he’s in the Oval Office handing the Russians classified intelligence information belonging to a US ally. Of course, we don’t and won’t know what it really was and whether it’s as world-ending as “sources” are saying. The fatal damage isn’t to operations or relationships but to our perception of the ultimate guarantor of the safety of the world.

If the most powerful man in the world — who has, in his various personae, held the keys to our collective annihilation or preservation for the past 70 years — is not merely personally corrupt, beholden to evil interests, not very bright or basically irresponsible, but actually completely fucking nuts, then we’re looking for a word with more import than “existential” to describe where we’re now at.

The first 100 days of the Trump presidency have proceeded along the relatively orderly lines of constant chaos emanating from the White House, while all the other institutions of American democracy assure themselves and us that their collective cross-checking power and integrity can and will survive and recover from whatever depredations Trump and his cabal wreak.

That’s thought of as a reasonable assumption, particularly given how comfortably the US navigated the Nixon presidency’s scandals. Nixon, it should be remembered, spied on his political opponents, used the power of his office to go after his enemies, and corrupted the justice process. In the end, the system beat him and democracy sailed on.

Nixon was not, however, a pathological liar and a recalcitrant twit. Trump has no boundaries and no concerns apart from his immediate gratification. He won’t slow down and he won’t concede a thing.

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This is incredibly challenging for the US constitutional system, which is, in this respect, completely different from the Westminster system, which we inherited from the UK. Responsible government in Australia is built on the subjection of all three arms of government — executive, legislature, judiciary — to the constitution and the ultimate repository of authority: the Crown. The monarch, acting as the last backstop of peace and order, plays no active role in governing and is therefore theoretically immune from corruption.

In the United States, the head of state is the President. That person performs two functions: he or she is the head of state and therefore, like a king, the repository of sovereign power. But he also runs the executive arm of government. He is, in effect, the public service personified. He is the commander in chief of the armed forces and the head of every department. All appointments are ultimately in his gift; the buck, as Truman said, stops with him.

The consequence of this odd arrangement is that the President is both the executor of the law and effectively immune from its operation. Like a medieval king, the President sits above the law. In the American system of checks and balances, the gap left by the abolition of monarchy was filled by the person of the President. It was thought, presumably, that the President would be kept practically in check by two expedients: his own sense of integrity, awed by the office he holds; and the threat of impeachment. We’ll come to that in a bit.

The weakness in this design is playing out right now. President Trump has allegedly, either intentionally or recklessly, disclosed classified secrets relating to Islamic State to the Russians. In doing so, he almost certainly has not broken the law. If any other person in America, or any other American anywhere in the world, did the same they would commit a number of extremely serious crimes.

[Should we trust Trump more than Putin on Syria’s chemical weapons?]

Trump, however, won’t be prosecuted for what he’s done. As President, he is the ultimate classifier and declassifier of secrets. He has power to, on the spot and at his whim, declassify material and share it with whomever he chooses. As kings once had the power to decide such things, so does the President today.

Our Prime Minister is, like the President, equipped with official secrets. He or she knows things the rest of us don’t. The difference is that, if he or she breaches that trust, they will also break the law. The President won’t.

Which brings us to impeachment. The important thing to understand is that impeachment is a political, not legal, process. The constitution empowers Congress to remove a sitting President for “treason, bribery, or other high crimes or misdemeanours”. These terms aren’t defined.

The procedure is that the House of Representatives must first vote to impeach the President. That’s effectively the indictment; it doesn’t cause the President to lose office. There is then a “trial” in the Senate, which can convict the President and order him removed from office.

The process is clothed in legal wording and procedure, but it lacks the protections of law. The Supreme Court has no power to override Congress’ determination as to what is or is not a high crime or misdemeanour. The Senate is a political chamber; as with all its other deliberations, its decision on impeachment is regulated only by the subjective opinions of its own members, whereas the decisions of judges are regulated by precedent. Congress could validly remove one President and not another for exactly the same conduct.

This then is the only means by which the United States can protect itself from a President who doesn’t understand or care about the conventions or responsibilities of his office, as is clearly the case with Trump. Congress, the elected representatives of the nation, has an arbitrary and untrammelled power to simply kick the President out.

With both houses of Congress in the hands of a Republican party which appears to have basically lost the plot (Senator John McCain, sworn enemy of Trump and by all accounts incorruptible, could only muster “troubling” as his reaction to his President handing state secrets to Russia), the last backstop of American democracy is paper thin.

Whether impeachment comes into play for Trump is impossible to predict. This President will certainly continue to expose every weakness in the American system, because he is that most dangerous beast: a child uncontained.