In 1064, Harold Godwinson was a “guest” of Duke William of Normandy. Before being allowed to return home, William asked Harold to lay his hand on a table and swear to support William’s claim to the English throne. Doubtless, Harold just wanted to get out of his predicament and swearing an oath under duress seemed wise, especially as such oaths could be set aside. Unfortunately for him, William had hidden a pile of saints’ bones beneath the table, rendering it an inviolable oath.

Certainly, this was enough for Pope Alexander II to consent to the invasion of England, and for other European powers to offer diplomatic support. The rest, as they say, is history, 1066 and all that.

It could be argued that this is an early example of international law. It came to mind this week when considering another agreement made insincerely by a leader without better options but considered to be a sacred oath by those who stand to benefit from it.

It’s likely that the words “specific and limited” are going to haunt Brandon Lewis for the remainder of his political career. MPs and Peers are aghast that Britain might break international law by disregarding a treaty that it had signed the previous year. The EU is suitably outraged, and Nancy Pelosi, perhaps casting herself in the role of Pope Alexander, has decreed that no UK/USA trade deal will pass Congress unless the Northern Ireland Protocol is respected.

I do not propose to argue the finer points of international law here, merely to consider some of the implications. According to a report in The Sun, what prompted this diplomatic outrage was a threat from the EU negotiating team to not give the UK “Third Country” status in the event of a “no-deal” at the end of the Brexit transition period. This would make it illegal to export products of animal origin (meat, fish, shellfish, eggs and dairy) from the rest of the UK into Northern Ireland.

So, in a nutshell, obeying international law would prevent an independent country from guaranteeing food supplies to one of its regions. Well, pace Mr Bumble, if the law supposes that then the law is an ass. What sovereign nation could possibly agree to comply?

Perhaps it was a sign of the incompetence of the Johnson government that they overlooked such a provision. Another reason, which is not inconsistent with the first one, is that it’s an example of too-clever lawyers trying to apply leverage by inserting seemingly benign clauses that they mean to later exploit. The trouble with there being too many lawyers in politics is that they often forget that the law exists to serve the people, not the other way around. When the majority of the population insists that a law is unjust, it is the law that breaks.

In reality, it was stupid of the UK government to announce plans to break the agreement. It would have been much better just to break it as required and argue about it later. After all, the EU and its member states also take a rather “flexible” approach to treaties, from the breaches of the fiscal compact (Germany has run an illegal surplus for years, and France an illegal deficit), to illegal bail-outs of member states, the illegal ban of British beef, and even the means by which a British judge was kicked off the European Court of Justice yesterday.

But perhaps most egregious was the way that the institutions of the EU and the International Monetary Fund were perverted in order to bail out French and German banks under the guise of bailing out Greece (only 5% of bailout funds were used to bolster the Greek economy).

None of this has stopped the somewhat sanctimonious outcry that Britain of all countries should be seen to break international law. John Major captured the tone in a statement:

For generations, Britain’s word – solemnly given – has been accepted by friend and foe. Our signature on any Treaty or Agreement has been sacrosanct. […] If we lose our reputation for honouring the promises we make, we will have lost something beyond price that may never be regained.

Well, as Matthew Parris pointed out, Britain’s international reputation is rather closer to “perfidious Albion” than to Sir John’s vision. There are few countries in the World which have not been guiled by the UK at one time or another. Even Commonwealth nations like Australia and New Zealand have previously felt betrayed when the UK joined the EEC, creating steep barriers to trade.

Other commentators were at pains to note the importance of treaties and agreements. The Institute for Government’s Raphael Hogarth listed examples of when the UK has relied on international law:

Condemning the use of chemical weapons in Syria.

Condemning the National Security Law that China imposed upon Hong Kong.

Condemning the poisoning of Sergei and Yulia Skripal.

Condemning Iran’s numerous violations of international law and detaining an ambassador.

Condemning Russia’s annexation of Crimea and attacks on civilians in Idlib.

Of course, it might be noted that there was an awful lot of condemnation in that list, but not many tangible outcomes as a result. Neither the Chinese, the Russians, the Iranians, or the Syrians have felt obliged to modify their behaviour as a result of a cross word from a British politician, no matter how furrowed the brow.

The fact is that international law is frequently and flagrantly disregarded by those powerful enough to do so. China is in breach of international law in the South China Sea, but ignores it. Turkey and Greece are squaring off in the Mediterranean because of legal disputes about where their maritime borders lie. China and India are inching closer to war in the Western Himalayas over disputed territory. The UK’s continued possession of the island of Diego Garcia is regarded as illegal, but even if the UK could be guilt-tripped into surrendering it, the chance of the Americans abandoning a strategically invaluable base in the Indian Ocean is approximately zero. And who is going to make them?

Many people regard the Iraq war as illegal, but that it did not prevent it from happening. International law did not stop the Rwandan genocide, nor the attempted genocide in Kosovo – NATO, with by Tony Blair in the vanguard, acted illegally in ending the carnage. Nor does international law compel China to stop its genocide of the Uighur Muslims. The fact that it might prevent the illegal distribution of steak in Northern Ireland should not be a comfort to anyone.

Pro-Remain voices in the UK have often argued that we need to be realistic about our position in the world. So here is the reality: we are not so mighty that we can act unilaterally with impunity, but neither are we so powerless that we should permit ourselves to be casually rolled over by lawyers and bureaucrats. Equally, we are not so pure of spirit that we should pretend to always occupy the moral high ground in international relations, even if Britons can reasonably note that few countries have contributed as much to creation and maintenance of the present world order as much as theirs.

International law is increasingly a fiction that many hide behind as they pretend that the world is not being carved up by countries and interests more powerful and less bothered by international opinion than our own. Our rivals and foes are not impressed by our observance of rules, but they just might be deterred by our determination to protect our interests when pressed. In an increasingly uncertain world, that, ultimately, is the only international law that matters.