Brexit: UK looks likely to trigger Article 16 - then what? - BBC News
An in-depth look at the likely consequences if post Brexit talks on the Northern Ireland border fail.
This has not been a good week for Boris Johnson.

The Conservative Party has been battered by allegations that some of its MPs are on the take.

The way the prime minister has reacted to the situation has been publicly criticised, and privately slammed by many on his own side.

Even some of Boris Johnson's most stalwart backers in parts of the Conservative press have called foul.

But if you think this has been bumpy, it's not impossible that the government might find itself in a much more dramatic and risky situation with much further-reaching consequences for us all.

It sounds harmless enough: Article 16, an obscure set of three paragraphs agreed as part of the Brexit withdrawal deal between the UK and EU.

So first off, it's important to understand it is part and parcel of the agreement that both sides grappled to achieve, and then signed up to in October 2019.

You might remember that the Brexit arrangements left Northern Ireland, of course part of the UK, essentially in the EU's huge trading bloc for goods.

This meant that goods could go backwards and forwards over the land border on the island of Ireland without hassle.

That sorted out one aspect of the geographic reality - but it also meant that there would be checks and controls on goods going into Northern Ireland from the rest of the UK.

From the off, that created an inbuilt difference between Northern Ireland and the rest of the UK.

Both sides were perfectly aware that these arrangements might be tricky in practice, so the deal included Article 16.

The Article gives either side the ability to cry foul and take their own "safeguard measures" if it's all going wrong - if trade is going haywire, or the deal is causing real suffering.

Either the UK or the EU has the right to take its own action, after giving a month's notice.

Boris Johnson celebrates his Brexit trade deal with the cabinet in December 2020

That could mean, for example, the UK stopping checks on goods that are being sent across the Irish Sea, intended only for use in Northern Ireland.

In other words, if something's made in Bolton, but sold in Belfast, it wouldn't go through customs checks.

But the actions could be more dramatic, suspending more of the deal the two sides agreed, whether that's product standards, customs checks, or VAT rules.

Working out how far to go, and what is justified, is a hard first step.

As one cabinet minister told me: "The mechanics aren't controversial, the difficult decision is how far you want to go."

Article 16 could be used to carry out a few tweaks, or to tear through the existing agreements. In turn, that would also have an impact on how the EU reacts.

Why though would the UK want to go down that road in any case, whether using it as a big bazooka or just trying to fiddle around with a few elements?

Some in the Nationalist community had a message for the PM on a 2019 visit

One diplomat told me that triggering Article 16 would be "lose, lose, lose", and could cause a "total breakdown of trust, and a deep freeze in relations" between the EU and the UK.

Former Prime Minister Sir John Major, who it's fair to say is no fan of the current occupant of Downing Street, has said it would be "absurd".

The main opposition parties would likely condemn the move.

But for months, the UK government has been saying the impact of the arrangements and how they are being implemented can't last, even though, as things stand, the part of the deal relating to Northern Ireland - known as the protocol - is certainly not being implemented in full.

But its effects have already caused lots of different concerns - whether that would be, as one source describes it, companies being "buried under mountains of new paperwork", warnings over shortages of medicines, difficulties moving pets around, or the issue that's taken up most column inches, the so-called "sausage wars" over the sale of chilled meats.

The UK believes the EU adopted an overly vigorous approach to pursuing the rules, when a lighter touch would do.

In turn of course, the EU says the UK signed up to the deal, why are they surprised when Brussels insists its followed in full?

Dominic Cummings claims the government always intended to ditch the parts they didn't like

As ever in high-tension diplomatic spats like this, the situation is not binary, and both sides have reasons for frustration.

Of course, intense politics are at play here too.

Unionist politicians in Northern Ireland largely can't stand the protocol, and have deep concerns about being able to keep a lid on tensions.

One source warns "if the government doesn't move and show a bit of teeth, things could implode".

The DUP leader has even said if there isn't movement he could pull his support.

With an election due by May 2022, they are pushing for action as soon as possible.

There's political mistrust between the UK and the EU side too over Boris Johnson's original attitude to the deal, and whether he ever intended to stick to the legal promises he made.

That was stoked by his controversial former adviser, Dominic Cummings, who said publicly the government had always intended to "ditch" the bits they didn't like.

Another source familiar with the negotiations told me "Article 16 was the route we thought we would go down from the beginning", adding: "it was always clear that unless the EU was willing to back down, we wouldn't be able to stick with it long term".

Now it is not exactly unusual for political deals to leave ambiguities, and some issues unresolved.

Given that the European Court did retain a role in supervising the protocol, that source suggests it was never likely to be "compatible with the autonomy of the UK".

But the admission that Boris Johnson's team believed there was something seriously up with the deal to start with has not exactly put the EU in the mood for compromise.

And what Brussels has been willing to budge on so far has not been nearly enough to satisfy No 10.

For political and practical reasons therefore, it seems almost inevitable that unless the European Union changes its position in a significant way, and soon, that the UK will trigger Article 16.

Lord Frost is still in talks with EU counterpart Maroš Šefčovič

Talks are continuing, and while one source says, "it's not definite", they acknowledge that "optimism has been waning".

In fact, the UK has said publicly since July that the conditions for the trigger to be pulled have indeed been met.

Since then, the UK view is clearly that "the EU solution is just not good enough".

But on the other side, there's sceptism over the UK's desire even to find a way out. Lord Frost, the PM's Brexit lieutenant, is "in problem-finding, not problem- solving mode", one source said.

I'm told that diplomats were reassured by government that the action wouldn't be taken this week, after the talks between that will take place between the two sides on Friday.

But I'm told there have been discussions about starting the process, even early next week.

Don't panic, this does not seem to have yet been resolved.

Some in government are arguing for more explanation of the case to the public before drastic action is taken.

One insider described a "reasonableness test". Another said that the UK government wanted to build an "evidence base" to demonstrate why they felt the action had to be taken, before going public.

Some of the smart money is on the bust-up not coming until December, with one government source suggesting on Thursday: "We're going to see a bit more time pass before it happens."

The border at the centre of the dispute

Whatever the moment, unless something very unexpected happens, or the negotiators and politicians on both sides have personality transplants, it seems like Article 16 will be introduced before too long.

The likely impact of the move seems less certain than whether Boris Johnson and Lord Frost take the decision.

It hasn't happened before, so there is no real precedent.

And there are different schools of thought. First, it's important to understand that triggering Article 16 is starting a dispute process.

It's not one moment, but the start of many.

One source says some Brexiteer MPs "think you trigger it and everyone starts singing Rule Britannia - no one is asking themselves what happens after you trigger".

Theoretically, the process begins with a month of intense technical talks to try to resolve the dispute.

If that doesn't work, there would probably then be an emergency meeting of EU leaders, to take the decision up to prime ministers, not just the EU Commission.

There could be different forms of restrictions on trade, specific sanctions, or they could give notice that they would tear up the whole trade agreement, which Ireland warned might happen this week.

Without getting too technical, the trigger could end up with grumpy talks dragging on over many months with lots of politicking but not much changing practically.

Both sides could, in a genuine way, join together to try to work things out.

Or the trigger could, as one observer warned, boil over into a "full scale trade war that undermines the UK and the EU's post-Covid economic recovery".

The economic consequences of that could be profound for us all, if the argument really went that far.

And what would Number 10 do in the end, if the UK didn't get what it wanted?

If, as another source suggests, Boris Johnson "triggers the process, it finds against the UK….and ultimately the European Court says you must comply - he's snookered".

As explained here, the UK may well want to strip the European Court of Justice of its role overseeing the Protocol.

Technically, the Article 16 process itself does not come directly under the European Court. But if, as some fear is likely, the argument tips into a wider dispute about the application of EU law then the European Court would end up as the final arbiter.

At the risk of hammering the point, the UK could try to reduce the European Court's influence on Northern Ireland by starting a huge legal argument, but actually end up with its influence being confirmed.

Mid-November has been pencilled in for several months, as the moment when an actual decision was going to have to be made.

That final conclusion has not yet been reached.

And given what could be at stake, both sides would still, in theory, like the negotiations to work.

But we are approaching a moment where Downing Street may decide that the huge political and economic risks of triggering Article 16 are worth it, that the downsides of the protocol are no longer tolerable, and efforts to find a compromise have run their course.

Yet the potential outcomes might make the last stormy seven days look like a moment of deep calm.