The High Court has mostly sided with five major car makers accused of using illegal defeat devices to manipulate emissions tests in the UK’s largest group lawsuit.
In a 369-page liability judgment marking the latest stage of the Diesel Pan-NOx emissions litigation, Lady Justice Cockerill, sitting as a High Court Judge, ruled that the ‘ambit’ of the claim was ‘much reduced’, prompting prominent claimant lawyers to argue that she had departed significantly from established EU case law.
This case is the largest group litigation in the history of the English courts, consolidating 1.6 million claims for damages from diesel vehicle purchasers. It followed extensive costs litigation before trial.
The case involved an array of law firms and dozens of barristers, including 23 from Henderson Chambers.
Cockerill said it had been “an unusual pleasure and privilege to be involved in this case”. She explained that “the parties have responded admirably to judicial ‘encouragement’ to co-operate and assist the court” in what she called a “behemoth of litigation”.
Her judgment, which was published on 10 July, followed a 13-week trial to decide whether a range of diesel vehicles made by Mercedes, Ford, Nissan, Renault and Peugeot-Citroën (and associated parties) contained so-called ‘prohibited defeat devices’, designed to alter a vehicle’s performance during test conditions and to circumvent emission control levels.
If they did, the court was asked whether the devices gave rise to claims involving allegations of breach of contract, breach of statutory duty and deceit, worth billions of pounds. Volkswagen settled earlier litigation against it in 2022. All the manufacturers denied any wrongdoing.
Cockerill held: “For a defeat device to be found, there needs to be an intentional and/or impermissible purpose of causing the [emission control system] to operate differently when it senses it is being tested. It is therefore unnecessary to calibrate ‘normal driving conditions’ or determine the meaning of ‘reduces the effectiveness’.”
The judgment clarified that a defeat device is a device that monitors certain test parameters, including their boundaries, and, upon recognising a test cycle, adjusts to make the emissions control system perform better than it would during normal driving. Additionally, there must be an intent to alter the system’s operation when the device detects it is under testing.
Cockerill ruled: “On whichever analysis of the relevant provisions is pursued, the ambit of the claim is much reduced.”
However, Cockerill did find that the statutory framework created a private law right of action by the claimants
She also made adverse findings about a device in Mercedes cars, later remedied, and about one used in some Peugeot-Citroën vehicles.
In addition, the judgment discussed the proper approach to post-Brexit Court of Justice of the European Union (CJEU) case law and the enforceability of EU regulations, offering an interpretation of the legislation that arguably diverged from earlier CJEU authority.
Martyn Day of claimant firm Leigh Day said the judge had “surprisingly disagreed with the established EU case law on what a defeat device is”. He added: “If this ruling is followed in Great Britain, then this is now the only significant place in Europe where manufacturers are free to build and sell cars that contain these types of devices.”
Pogust Goodhead said the court adopted a significantly narrower interpretation of the law than in other European jurisdictions. “It is that interpretation, and the important legal issues flowing from it, which will now require careful consideration,” said partner Anna Varga.
Renault’s lawyer, Tom Snelling of Signature Litigation, said: “This ruling reflects the fact that the allegations made against our clients were always misguided and intellectually incoherent.
“The claimants’ case was built, gelatinously, on the false assumption that Renault vehicles contained a ‘cycle recognition device’ like that at the heart of ‘VW Dieselgate’. The claimants ignored engineering reality, doubling down instead on what Lady Justice Cockerill has called their ‘dream car fallacy’.”
There were six lead claimant law firms, including Pogust Goodhead, Leigh Day, KP Law, Milberg, Hausfeld and Johnson Law Group, plus other associated law firms, with a core counsel team led by Tom de la Mare KC of Blackstone Chambers.
BMW, Ford, Mazda, Nissan and Suzuki all instructed teams at legacy Hogan Lovells, while Hyundai-Kia was instructed by Quinn Emanuel. Toyota and Mercedes-Benz both instructed Herbert Smith Freehills Kramer. Renault instructed Signature Litigation, while Peugeot Citroën turned to Kennedys and CMS acted for JLR. Cleary Gottlieb represented Volvo.
Some 23 counsel from Henderson Chambers were instructed for various parties, while Brick Court, Crown Office Chambers, Fountain Court, 2 Temple Gardens, Maitland Chambers, Monckton Chambers and One Essex Court, among others, were also instructed.
A further trial is scheduled for October 2026 “to determine the consequences of any actionable breaches and any issues relating to damages or other remedies”, according to a summary of the judgment provided by the England and Wales judiciary.
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