The High Court’s decision in the Pan‑NOx group litigation has been welcomed by the five car makers involved, even as claimants weigh a possible appeal that could widen the gap between British and European legal standards.
Judgment narrows defeat‑device claims
Lady Justice Cockerill delivered a 369‑page judgment after a 13‑week trial that examined whether diesel vehicles produced between 2012 and 2017 by Mercedes‑Benz, Ford, Nissan, Renault and Peugeot/Citroën contained prohibited defeat devices (PDDs). The court concluded that many of the 1.6 million claimants’ allegations did not meet the legal definition of a defeat device.
According to the judgment, a defeat device requires an intentional or impermissible purpose to alter the emissions‑control system when a test is detected. “It is therefore unnecessary to calibrate ‘normal driving conditions’ or determine the meaning of ‘reduces the effectiveness’,” the judge wrote, noting that not every calibration or emissions‑control strategy qualifies as a PDD.
Mercedes‑Benz issued a statement saying it “welcomed the High Court’s ruling very largely in favour of Mercedes‑Benz.” The automaker disputed the finding that one of four sample vehicles was non‑compliant in a particular function, arguing that the software features are defensible on technical and legal grounds. It added that it is reviewing “all of our available options, including a potential appeal.”
Ford, Nissan, Renault and Peugeot/Citroën all denied wrongdoing throughout the trial, and the judgment trimmed the scope of claims that could proceed under private law.
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Claimants consider appeal amid divergent EU precedent
Martyn Day of Leigh Day, representing the claimants, said the judge “surprisingly disagreed with the established EU case law on what a defeat device is.” He warned that if the ruling stands, Britain could become the only major European market where manufacturers may sell cars containing such devices.
Partner Anna Varga of Pogust Goodhead noted that the court “adopted a significantly narrower interpretation of the law than that applied elsewhere in Europe.” She said the firm will continue to work with co‑lead firms and counsel to assess the judgment and explore every “properly arguable avenue” for their clients.
A separate trial to determine damages is scheduled to begin in October, meaning the litigation will extend beyond the current liability phase.
While the High Court’s approach aligns with a more restrained view of what constitutes a defeat device, the broader European context remains less clear. In earlier EU cases, courts have taken a more expansive view, often finding that software tweaks intended to reduce emissions during testing qualify as illegal.
From a practical standpoint, this divergence may influence how automakers design future diesel engines for the UK market. If the UK continues to apply a narrower standard, manufacturers might prioritize compliance with that definition while still meeting stricter EU requirements elsewhere.
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The dual‑track strategy could add complexity to development cycles, but it also offers some flexibility for firms seeking to balance regional requirements.
Legal experts observe that the case highlights the challenges of applying legacy emissions legislation to modern software‑driven vehicle systems. The judgment highlights the importance of precise legal definitions when technology evolves faster than regulatory frameworks.
Mercedes‑Benz’s spokesperson added that the company is “actively considering all of our available options,” hinting at a possible appeal.
Claimant firms remain poised to challenge the decision, arguing that the narrower interpretation undermines the spirit of emissions‑control law.
Future courts will watch closely.
