Overview
- The High Court rejected most of the principal claims in the Pan‑NOx group litigation that about 1.6 million UK owners of Euro 5/6 diesel cars were fitted with illegal 'defeat devices'.
- Lady Justice Cockerill adopted a tight legal test that requires a device to sense test conditions and be intended to make emissions controls work better in tests than in normal driving.
- The court made targeted adverse findings: a coolant‑temperature setpoint in a Mercedes sample (remedied by a December 2015 software update) and a split‑injection strategy in some Peugeot‑Citroën Euro 5 cars were ruled unlawful.
- Both claimants and some manufacturers have signalled they are assessing the judgement and may seek permission to appeal, and a further trial is listed for October 2026 to decide damages and remedies.
- This ruling creates a possible UK–EU divergence because the judge declined to follow several post‑Brexit CJEU decisions, a legal split that could shape how future UK diesel emissions claims are decided and affect motorists seeking redress.