In a significant development in the ongoing ‘Dieselgate’ case, a High Court judge has ruled that a crucial trial on compensation must proceed this autumn, even though the claimants suffered a near-total defeat on the core issue of liability.
The ruling, handed down by Mr Justice Constable on 7th August 2026, denies an application by hundreds of thousands of car owners to delay the proceedings.
The background to this decision is the liability judgment delivered just a month earlier, on 10th July 2026, by Lady Justice Cockerill. In that ruling, the court found that only a small fraction of the engine software devices challenged by the claimants were illegal ‘defeat devices’ designed to cheat emissions tests.
Out of 10 alleged devices in Mercedes vehicles, only one was found to be prohibited. Similarly, only one out of six Peugeot Citroen devices was ruled illegal, while none of the alleged devices in Ford, Renault or Nissan vehicles were found to breach the rules.
In light of this overwhelming defeat on liability, the claimants, who represent around 450,000 Mercedes owners alone, asked the court to cancel the upcoming quantum trial (which determines how much compensation is owed) scheduled for October 2026. The claimants argued that, since they had lost on most of the factual issues, the trial was now ‘deprived of content’ and should be postponed until after they had a chance to appeal.
All the car manufacturers supported this delay with the exception of Mercedes, who argued that the trial should go ahead anyway. They contended that even if they were the only defendant left, the trial would still settle critical legal questions about how compensation should be calculated. These principles, they said, would be applicable across the entire litigation and could help unlock a commercial settlement for all parties.
Mr Justice Constable agreed with Mercedes. In his judgment, he stated that the upcoming trial could be ‘dispositive in practice’ for the entire case, meaning it could effectively decide how all claims should be valued. He also noted that postponing the trial would waste the substantial costs already spent preparing for it and could cause years of delay while appeals were heard.
The judge concluded that the costs of proceeding were modest compared to the overall scale of the litigation and that it ‘makes clear sense to proceed.’ The quantum trial against Mercedes will therefore go ahead as planned in October.
Photo: Victor Sutty
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