The High Court has today enabled two environmental campaign groups, Mums for Lungs and ClientEarth, to proceed with their applications to intervene in the Dieselgate litigation. The ruling recognises the strong public interest in uncovering the truth about the ongoing legacy of the Dieselgate scandal.
A recent report commissioned by ClientEarth highlighted the staggering health and economic impacts of the high emissions likely linked to the use of prohibited defeat devices. In the UK alone, between 2009 and 2024, these excess emissions have caused an estimated 16,000 premature deaths and £96 billion in costs.
A trial scheduled for October 2025 will decide whether certain diesel vehicles manufactured by Mercedes-Benz, Renault, Nissan, Peugeot Citroën, and Ford were fitted with prohibited defeat devices. It is alleged in claims brought by vehicle owners that these devices artificially lowered NOx levels during emissions testing in order to circumvent legal emissions limits.
As part of their applications, both Mums for Lungs and ClientEarth (who are not parties to the litigation) ask the Court to grant access to material from the proceedings that explains the operation and impact of any alleged defeat devices in the vehicles. In particular, they ask the Court to lift redactions applied by the vehicle companies to information which shows how the alleged defeat devices functioned, including at what temperature, speed, torque and other thresholds they were operational.
At the moment, this information is either redacted or behind a confidentiality barrier that members of the public cannot access. Unless these restrictions are removed, it is likely that almost all of the Dieselgate trial in October will need to be conducted behind closed doors.
Today’s ruling means that the organisations will not be expected to pay the other parties’ costs if they are ultimately unsuccessful in obtaining the material they seek at a hearing due to take place in July.
Jemima Hartshorn, Founder of Mums for Lungs, commented:
“I founded Mums for Lungs because of the huge health impact air pollution has, particularly on children. Children across the country are growing up with stunted lungs and asthma caused by air pollution, tens of thousands of children are admitted to hospital every year struggling for their breath which is so scary, and they then miss school, playing with their friends, having dinner at home with their family. Diesel cars are a major contributor to air pollution.
"We are all affected by air pollution, every breath we take, and the public therefore has a direct interest in understanding the circumstances in which any alleged historic defeat devices operated and what alleged impact these devices have had, including whether they resulted in NOx emissions above the legal limits.”
Andrea Lee, campaigner at ClientEarth, said:
“Dieselgate has already cut thousands of lives short and placed a huge burden on public health and the NHS.
“For too long, auto manufacturers have tried to sweep this scandal under the rug. This case could finally bring crucial information to light and reveal the true scale of what happened.
“Public access to this material is essential, not just to ensure justice is done, but to help guide government investigations and ensure action is taken to finally clean up this mess.”
Shazia Yamin, Partner at Mishcon de Reya, who is acting for Mums for Lungs and ClientEarth in these proceedings, said:
"We welcome today's Court ruling to grant some cost protection to our clients. Securing this protection was important as without it, there was a significant risk that our clients would not be able to proceed with their applications, which are brought in the interests of the wider public and open justice. We look forward to the next step which will be a hearing in July to decide whether public access to the information sought by our clients is granted."