How Boris Johnson’s Brexit plan would work

Analysis: Here’s what the prime minister’s proposals would mean in practice for trade in Northern Ireland – and how his idea is different from Theresa May’s

The easiest way to understand the real-world implications of Boris Johnson’s proposed Brexit deal is through the medium of chicken. In fact, an inexpensive chlorinated chicken, of the type that may be imported to Britain under a future US-UK free trade deal.

Under the single market (which harmonises and mutually recognises different nations’ qualifications, rules and regulations), and customs union (which sets a common external trade policy), chlorinated chickens are not allowed to be processed or imported into the EU, including Britain and Ireland.

Under the Theresa May deal a future UK government would have been able to negotiate to import the chlorinated chickens from the US, but, unless other arrangements could be sorted out, the UK, including Northern Ireland, would not be allowed to bring in such poultry. This is because, unless alternative ideas were devised with the joint approval of the UK and EU, the UK – including Northern Ireland – would remain, under the “backstop”, part of the EU customs union area. This was unacceptable to the British parliament (as a whole). The UK would be unable to leave the EU customs union at its own behest, and could not negotiate its own trade treaties.

The strength of this idea is that there would be no customs border between Ireland and Northern Ireland, in line with the Belfast Good Friday Agreement, an international treaty. Thus a fresh round of violence would be avoided, and trade would be frictionless.

Boris Johnson’s idea is for Northern Ireland to come out of the EU customs union and there to be no “backstop” keeping it in there. Instead Northern Ireland would, in large part, remain inside the EU single market instead. In the case of the chlorinated chicken, it would mean that processing or importing such a bird would not be possible in Northern Ireland under EU rules. Thus, under a new regulatory border down the Irish Sea, no chlorinated chickens imported to Britain from the US could then be transported from England, Wales or Scotland to Northern Ireland. On the other hand, non-chlorinated chickens, like everything ease, could flow freely into the rest of the UK from Northern Ireland. If a Northern Irish person wanted to consume chlorinated chicken they would have to fly or sail to mainland Britain to do so.

As Northern Ireland and Ireland would be in separate customs regimes, there would be a need for customs checks – but, under the Johnson plan, these could take place far away from the border, and be minimised in any case.

Whether the EU likes such an idea or not, the Northern Ireland Executive and Assembly (on which the DUP would have a substantial presence) would have the right, every four years, to withdraw from the EU single market if it so wished, and cancel part of the UK-EU withdrawal agreement without EU approval. Thus a sudden taste for chlorinated chicken would take Northern Ireland out of the EU single market, and create a new regulatory border with Ireland.

So the Johnson proposal is not necessarily permanent, even if the UK and EU have concluded a free trade agreement on the basis of it and of Northern Ireland staying in the single market. In which case there would be a further need for an Ireland-Northern Ireland border. Nor would the UK be under any strict legal obligation to set the highest standards of worker and environmental protections indefinitely (eg banning chlorinated chickens would not be a legally binding commitment). These future uncertainties may be why Michael Barnier has described the Johnson deal as a “trap” for the EU.