A vote in the Northern Ireland Assembly this week demonstrated how Brexit is going to remain a persistent feature of Northern Ireland politics.
It concerned an obscure regulation – content requirements for organic pet food.
It was not a regulation drawn up by a Stormont minister or assembly member, instead it was piece of EU law flowing from the Brussels regulatory system.
The assembly was voting on whether it should be added to the body of EU law which continues to regulate the production and sale of goods in Northern Ireland.
In this case, it was relatively uncontroversial as the practical effect of the regulation is to align UK and EU rules.
Most unionists who voted were content to back the regulation as failing to do so would create more divergence between Great Britain and Northern Ireland.
That means the regulation got the necessary cross-community support and will be implemented.
However the first of these “applicability motions”, on an equally obscure area of regulation, did not get cross-community backing.
The UK government now has to decide whether it will make this a subject of negotiation with the EU or impose the regulation without unionist support.
There will be a conveyer belt of these applicability motions for as long as Northern Ireland is in the single market for goods and the rest of the UK is not.
The potential for them to become a focus of political disagreement is obvious: between unionists and nationalists in the assembly, between the local parties and the UK government and between the UK and the EU.
This week’s debate also pointed to the continued potential for intra-unionist tensions.
The TUV leader Jim Allister, who voted against the motion, decried the DUP position and also described that party’s benches as having some “notable absentees”.
Some 15 DUP assembly members supported the new EU law but nine DUP members were not present for the vote.
