It has been widely suggested that the DUP and others are misconceived (or worse) in their opposition to the backstop laid out in a protocol to the Withdrawal Agreement agreed by negotiators in November last year. What’s the big problem with “extra checks at Northern Ireland’s seaports and airports” asked David Green in a Spectator blog.

In the Times, Northern Irish businessman Mark O’Connell noted that “With so many existing differences already in the law between Northern Ireland and the rest of the UK, regulatory alignment clearly doesn’t exist now and it is ridiculous to assert that we have to have it.”

But these arguments seem to be missing a very important point, which is that it is not the existence of differences or the possibilities of checks on movement of goods between Great Britain and Northern Ireland that causes consternation.

The issue is not whether all laws are the same, or that there will be no trade frictions. Clearly devolution and localism mean there will inevitably be different laws and policies throughout the United Kingdom, and the existence of the Irish Sea presents something of a barrier to frictionless trade.

But there is a huge difference between divergences in laws that arise within the UK by operation of UK lawmakers and devolved powers, in which the voters of Northern Ireland are represented, and the imposition of laws by an outside body in which voters have no control or accountability.

For Northern Ireland this is particularly sensitive and supporters of the Union are concerned that under the backstop the Irish government would effectively have more say over some issues than either the Westminster government or any government in Stormont would have.

From a business and economic perspective (and putting aside, for now, important political and cultural sensitivities), it has been widely claimed that NI would have a “best of both worlds” position, being in both the EU and UK single markets for goods and enjoying unfettered access to each.

But the economic benefits from this are far from clear and the economic argument often put forward is not the full picture.

It is often noted that Ireland is the destination for 35% of Northern Ireland’s exports, but this figure does not account for sales to Great Britain, which are not counted as exports.

Using figures from the Northern Ireland Statistics Authority (NISRA) that take sales to Great Britain into account, sales to Ireland comprise just 6% of Northern Ireland’s turnover and sales to GB 20%. In recognition of this, the Withdrawal Agreement provides that the UK will be able to guarantee unfettered access to the Great Britain market for goods from Northern Ireland.

But let ‘s move away from this Trumpian obsession with exports. Northern Ireland depends heavily on goods from outside its territory. And at present 64% of the goods brought in to Northern Ireland come from GB, as against 12% from Ireland.

Of the goods from Great Britain, a great majority are destined straight for the high street, benefiting small business and consumers, but, in the words of NISRA “local manufacturers are dependent on purchases of goods from GB businesses”.

Goods from Great Britain account for 30% of all goods purchased by manufacturers in Northern Ireland.

While the Westminster government can take steps to keep the Great Britain market open to goods from Northern Ireland, and is specifically permitted by the Withdrawal Agreement to do so, it is not within its power or that of the Government of Northern Ireland to give the same guarantee for goods coming from Great Britain to Northern Ireland.

Being part of a single market does not just mean being able to sell in it: without the unfettered right to buy from it, Northern Ireland will not be a full part of the UK market.

Although there is a provision in the Withdrawal Agreement for the parties to use their best endeavours to minimise barriers within the UK’s internal market and avoid controls at the ports and airports of Northern Ireland “to the extent possible”, the default is that for goods travelling from Great Britain to Northern Ireland, customs formalities (in the form of a paper ‘movement certificate’ physically stamped by customs authorities) and regulatory checks on a third country basis would apply).

The intention is for a Joint Committee to work on mitigating and improving this process before the backstop comes into effect (“alternative arrangements” anyone?) but there is no guarantee that this will be achieved.

Critics of the backstop could ask how, if a joint committee can be tasked to deliver solutions to avert a hard border between Great Britain and Northern Ireland during the transition period, why such commitments could not be deployed instead to the land border, where after all there are already trade frictions and formalities associated with VAT, excise duty, currency exchange and regulatory differences.

Such solutions, it can be argued, could be implemented without breaching the principle of consent and in fact by using and building on all the institutions of the Good Friday Agreement — North/South and East/West.

Unionists may justifiably have reservations about commitments outlined so far to ensure that UK laws in general will remain aligned with those Northern Ireland would be obliged to maintain under the backstop. The Prime Minister’s repeated assurances that there would be no border between Great Britain and Northern Ireland have proved to be somewhat qualified, and in any event, no Parliament can bind its successor.

Given that the commitment to maintain alignment between Great Britain and Northern Ireland would also mean that the UK as a whole would effectively be a rule taker, without any guarantee from the EU side that corresponding recognition will be accorded, it is surely questionable how long this could be maintained if it came under pressure from MPs from other parts of the UK.

These are some of the Northern Ireland specific issues. More widely for the UK as a whole, the assurances that the backstop is, after all, not intended to come into effect sound hollow.

The wording of the backstop and the political declaration clearly envisages that the arrangements to come into force as a permanent solution, either to avert the backstop or to bring it to an end if they are not agreed in time, will effectively be some form of permanent customs union and wide-ranging lock-in to EU rules.

Indeed, given the way the commitments to avoid a hard border in the Joint Report of December 2017 have been interpreted (and now carried into legal text in the recitals to the backstop protocol) it’s hard to see how, once on this track, it would be possible to negotiate anything else while the current backstop is the legal default.

This is also why some are sceptical of the value of a time limit or unilateral right of termination being added to the backstop without any other changes to its substance.

The idea that the UK and the 27 EU member states would implement a highly disruptive and complex arrangement that applies not just to Great Britain/Northern Ireland/Ireland trade but to all trade between Great Britain and the EU, for a short period of say five years, only to then move again to another trading arrangement, potentially one that does not involve a trade deal with the EU, seems far fetched.

Although a time limit or termination right would certainly shift the negotiating dynamic and incentivise the EU to agree to a replacement agreement for the future relationship (surely lacking from the current backstop) the most likely direction would still be towards a permanent customs union and form of single market participation. It would also most likely continue the division between Great Britain and Northern Ireland for customs purposes.

This is because unless the UK as a whole were to be a member of the EU’s customs union (as opposed to forming an additional customs union between the UK and the EU’s customs union, with Northern Ireland ensconced in the latter), the validation of goods qualifying for the EU/UK custom union has to be done somewhere, and unless arrangements can be found to do that at the land border without physical infrastructure or related checks and controls (sound familiar?) it will have to be done at the border between Great Britain and Northern Ireland.

At the same time, rejecting a time limit of as long as ten years even in principle raises concerns as to whether the commitment to consider alternative solutions is genuine, as recently noted by Henry Newman in the London Times.

If Irish and EU negotiators do not believe a solution could be available in the near future at all, how could anyone have confidence that the backstop will be a temporary solution, or rather that there could be any way out of it that did not equate to simply formalising essentially the same thing on a permanent basis?

“Hard border and medical shortages in no-deal crisis” by Tiocfaidh ár lá 1916 is licensed under CC BY-ND