[Sephiroth]

A deal on NI is challenging. A way has to be found to narrow the ECJ's writ on UK soil. That they should rule on interpretation of EU law is reasonable on the face of it; but who calls in the ECJ is the problem.

EU law applies to the single market aspects of goods arriving into NI. The solution may be as simple as a Union Flag flying over the green lane and the EU flag flying over the red lane!