THE worrisome start to Donald Trump’s presidency has lessons for Scotland too. He threatens a constitutional upheaval in the world’s oldest republic, but it is only the scale of his country and the importance of its global role that makes the British equivalent look minor. We too are in the midst of a constitutional upheaval, one that is much more profound and existential. And it has been going on for 20 years. There is still no sign of an end, or much idea what the end will look like. Scotland lies at the heart of it: Scotland will still be here, striving to better itself, long after the last Brexit vote is taken.

Some things we have in common with our cousins across the Atlantic ocean. What started the trouble for Trump was his pronouncement, almost immediately on taking office, of an executive order that banned Muslims from seven countries entering the US, or even re-entering if they happened to be already resident. This so clearly breached their constitutional rights – against religious discrimination, guaranteeing due process – that lawyers quickly found a federal judge who would suspend the ban.

The judge who saved Trump’s innocent victims was James Robart in faraway Seattle, where the state of Washington brought the action. It’s good that Robart was no bleeding-heart liberal. He is a Republican, and George W Bush appointed him to the bench. In the US the judiciary has been steadily politicised in recent times, so that in the Supreme Court we can tot up the votes and forecast the outcome of certain important cases on partisan lines. But in constitutional terms all judges remain independent, and many of them still live up to that ideal, Robart evidently included. His most famous obiter dictum to date concerns the high death rate of one section of American society at the hands of the police. He said: “Black lives matter.”

Theresa May has chosen to team up with Trump, after suffering her own judicial shock early on in her premiership. She began in an arbitrary style much like his, trying to make Brexit a matter of the royal prerogative. This meant the government could order it to happen regardless of the Parliament at Westminster. The US has a hero and we had a heroine, Gina Miller, who raised the case that at length came before our own Supreme Court. It declared that what we had all won by statute, in particular what we enjoy as European citizens, could only be taken away again by statute, so Parliament needed a say. The judges might have put it like this: “Citizens’ rights matter.”

The Scottish Government felt happy at that yet at the same time unhappy with another part of the judgment, the one which denied the devolved governments could have any formal part in Brexit. Foreign relations are reserved to Westminster, and there is nothing more to be said. What it all amounted to was a strong reassertion of the absolute sovereignty of Parliament, as strong as any made for a couple of centuries. Incidentally this killed stone-dead the airy intellectual speculation of recent times that the British constitution is somehow stealthily federalising itself. Overall, I would say that day in the Supreme Court represented a net loss for Scotland. We see it in the present frustration of the Scottish Government, and the urge to appeal beyond the formal political structures to the people once again, in a second referendum on independence.

The coincidence of Trump and May is also likely to underline some of the political differences we have with our cousins across the Atlantic ocean. Trump seems to me doomed to fail as a president. He appears to think he can rule the country by shouting insults at the persons or disparaging the laws he disapproves of, or else just striking them down by executive order and presidential prerogative. He did, immediately on taking office, pull out of the Trans-Pacific Partnership, negotiated by Barack Obama to free up trade with a dozen nations round the shores of the ocean (which Trump claimed would destroy American jobs). But that was only because it had not yet been approved by Congress. If it had been, he could not have touched it. When Trump came up against Robart he was reduced to bluster about a “so-called judge” whose ruling was “ridiculous”: it’s the level of invective that on this side of the pond we expect of Ukip.

The normal operation of the American constitution is anything but populist. The men who wrote it more than two centuries ago were not democrats and they feared demagogues. They set out to frustrate any straight translation of the people’s will, aroused by some passing fad, into law. This is the famous system of checks and balances. You can see what it means in practical terms today by watching clips of Barack Obama or Bill Clinton actually at work in the Oval Office. They spent hours on the phone cajoling various Congressman to vote for their measures – at the price, naturally, of a highway here or a fracking contract there. Will Trump have the same persistence and patience, or will he just throw tantrums? If the latter, he will get nowhere.

When I was at school, learning a subject paradoxically called British constitution, we were taught we would never need any such thing, at least in written form. Our people were so full of good sense, moderation and compromise that we did by instinct what lesser breeds had to be told to do. A few decades of imperial decline, political instability and social tension have rather put paid to that notion. The British constitution’s central doctrine of absolute parliamentary sovereignty all the same remains intact, though now turned by this troubled history to more oppressive ends: the uncontrolled surveillance, the manipulation of the media, the persecution of honest, hard-working immigrants, the denial of equal rights to the smaller nations.

The difference that really stands out between the British and the American way of doing things is that in the UK we have had no means to halt these insidious developments. The basic reason is that we possess no written constitution to protect us against them. Perhaps the UK Supreme Court, an innovation dating only from 2009, can start to reverse the trend but it is obviously going to take a long time. Meanwhile, does the US have uncontrolled surveillance, media manipulation, persecution of immigrants and inequality among the states? No, the US does not, and because of its constitution never will have.

I remain confident that before long we will be writing a constitution for an independent Scotland too. Meanwhile we should ponder the choice of basing it on some notion of absolute sovereignty or on a system of checks and balances. The Scottish Government is not much given to abstract reasoning, but it seems to me it most often acts on the assumption of absolute sovereignty. It is a creation of Westminster and in this respect fully embodies the spirit of Westminster. In principle it believes itself omnipotent: it can and should intervene everywhere in private and public life. I hope that, when the time comes, we will have been able to alter this perilous point of view.