Brexit Northern Ireland protocol is lawful, supreme court rules

A lorry leaves Larne port, Northern Ireland. The court ruling is a setback for the DUP, which argued the NI constitutional position had been weakened by having to observe EU trade laws. Photograph: Paul Faith/AFP/Getty Images

The Northern Ireland protocol is lawful, the supreme court has ruled, rejecting a legal challenge to the Brexit arrangements by a group of unionist leaders including the former first ministers the late David Trimble and Arlene Foster.

Five law lords presiding in the highest court in the UK unanimously dismissed the appeal on all three grounds including the claims that the Brexit trading arrangements breached the 1800 Act of Union and the Northern Ireland Act 1998.