Which is more dysfunctional at the moment – government in the US or UK? For Brits in the US, that’s now a standard conversational opener. Walking round the near-deserted streets of Washington DC, emptied out by the shutdown of the federal government, you might think the former.
But even though the standoff between Congress and the President has continued for longer than any precedent, that is a war of choice, by Donald Trump and by the Democrat-controlled House of Representatives, which has declined so far to give him the funding for his “big, beautiful wall” on the Mexican border. That war is, so far, taking place within the rules of the US Constitution.
In contrast, Brexit has strained the UK’s Constitution, which if not exactly unwritten as reputation has it, is still a perpetually evolving mixture of old statutes, precedents and conventions. The willingness of Conservative MPs to defy their own government is taking constitutional rules into new territory.
The UK has shown itself capable of considerable constitutional change in just the past few decades. It has thrived on that. It may yet continue to do, so building on the permanent changes in government and in Parliament that Brexit will bring about, whatever the form of its future relations with the European Union. Seizing the opportunity afforded by minority government it is likely that Parliament will extract – and retain – more powers than it has previously held.
But the fluidity of the constitutional rules only adds to the uncertainty about the outcome of Brexit. In contrast to the US, UK legislators are shaping the future of the way the country governs itself at the same time as battling over a policy that will determine its relations with the rest of the world.
In the past few days, Parliament has established one new precedent that gives backbenchers new powers, and may soon secure another that is even more important. Last week John Bercow, the Speaker of the House of Commons, allowed Dominic Grieve, the former Attorney General, to amend a government motion that according to convention, would have been impossible to amend.
He may not, as he later suggested, have intended to set a precedent with his ruling that Grieve could try to amend a motion that was to be voted on “forthwith”. But that was its effect and the effect may well last.
The constitutional challenge of the coming week will lie in the attempt of some MPs, according to reports, to secure the power to put their priorities ahead of the Government’s in Parliament’s agenda. If Theresa May’s bid to win support for her deal with the European Union is defeated on Tuesday, as expected, they will be able to amend any motion she brings after that.
All kinds of amendments may then burst into the light, such as demands for a second referendum. But the one that would carry most constitutional significance would be a demand to overturn the rule that has persisted since the 1880s, that the “business” of the Government has priority in the House.
If MPs secure this change, they will have wrested from the Government the power to determine what happens in Parliament and when. That is a change that would outlast the Brexit debate, and enormously diminish the powers of any government.
None of this is to diminish the significance of the standoff between Trump and Capitol Hill, now resulting in a longer closure of the federal government than any previous such episode. His impact on the US in just the first two years of his presidency has gone far beyond what many expected, including both fans and critics.
Trump’s judicial appointments, not just to the Supreme Court, even though those get most international attention, will shape the US for decades to come; his disdain for judicial independence has already begun to undermine the Constitution’s principles of separation of powers.
The clash between legislature and executive in the US and the UK comes from some of the same roots, too. In a time when voters are less wedded to parties, and scornful of political elites, those representing them in the legislature feel they must respect their voters’ passions. But in the UK, unlike the US, the clash between this new mood and old conventions is changing the constitutional rules of government as we watch.