Ambiguity of deal language stores up trouble for NI in the longer term
The DUP objection to 'continued regulatory alignment', the compromise on the border produced in Brussels this week, was predictable and should have been foreseen. They will always oppose anything that sets up barriers between Northern Ireland and the rest of the UK.
But the Irish government are also right when they say that the only way to avoid a hard border between Northern Ireland and the rest of the island is to ensure that there is 'no regulatory divergence'.
If Ireland, north and south, have different customs policies then, as a point of logic, there will have to be border checks.
Otherwise Northern Ireland would become a gaping back door to the EU, and the traditional smugglers of south Armagh would look like amateurs by comparison with those that replace them.
That is why countries have borders. You can ameliorate the impact of the border checks through technology but it will still be a hard border.
To find a way round this clash the British negotiators in Brussels reached for the familiar tool of constructive ambiguity to solve the problem.
'Continued regulatory alignment' sounds like the Irish position but actually it could mean alignment only on a few largely technical issues related to the Good Friday Agreement.
Both sides could project on to the words what they wanted them to mean.
We have some experience of constructive ambiguity in Northern Ireland.
The Good Friday Agreement in 1998 was ambiguous about what would happen on the decommissioning of IRA weapons.
Even if we had stayed in Castle Buildings for three years rather than three days and nights we would still not have bridged the gap between the two sides so we opted for words onto which both sides could project the meaning they wanted.
That ambiguity allowed us to get to an agreement but it rapidly led to trouble as both sides were disappointed when their understanding of the agreement was not implemented in practice.
The whole peace process came close to collapsing.
The same risk hangs over the constructive ambiguity on Brexit.
In the next few days negotiators in Brussels will doubtless come up with new clever wording in order to get us into the next stage of negotiations on the future trading relationship between the UK and the EU before the December deadline.
But even if they succeed in finding words acceptable to the Irish government and the DUP, we are simply storing up problems for the longer term in Northern Ireland.
Logically the only way to avoid a hard border is for Northern Ireland to remain in the single market and the customs union so that there is no regulatory divergence. Otherwise there will have to be border checks.
The DUP, however, will not accept that the province should have a special status with the dividing line in the Irish Sea between Northern Ireland and Britain.
If we accept these two conclusions, and if we accept the British Government is genuine when it says it is determined to avoid a hard border, then the only way to square the circle is for the whole UK to remain in the Single Market and the customs union.
And it is that logical conclusion that has thrown hard Brexiteers in the Cabinet into panic.
They can see where this debate is heading and it is towards Norway minus, effectively in the single market, and not Canada plus, with a free trade agreement and a hard border not just in Northern Ireland but in the whole of the UK.
Jonathan Powell was chief government negotiator in Northern Ireland from 1997 to 2007