London High Court Rejects Most Diesel Emissions Claims

The High Court of Justice in London rejected the majority of diesel emissions claims brought on behalf of 1.6 million UK car owners. Lady Justice Cockerill ruled that most emissions-control strategies used by manufacturers did not constitute prohibited defeat devices, stating that claimants must prove an intention to rig tests for a device to be found illegal.

Following a ten-week trial involving 20 sample vehicles from various brands, the court cleared most manufacturers, including Renault Group, Nissan, and Ford. Renault Group announced it will seek to recover legal costs from the hedge funds and insurers that financed the litigation. However, the judge found that certain technologies in some Peugeot-Citroën vehicles and one Mercedes-Benz car—which was non-compliant prior to a 2015 software update—could constitute defeat devices.

Mercedes-Benz and Stellantis disagreed with the findings against them, asserting that their software and vehicles comply with applicable regulations. Both companies are considering appeals. Conversely, claimants' lawyers from firms including Leigh Day, Pogust Goodhead, and Milberg argued the ruling adopts a narrower legal interpretation than established EU case law and also intend to appeal. A further trial is scheduled for October 2026 to determine damages and remedies for the actionable breaches.