A decade after the Dieselgate emissions scandal first erupted, two major legal showdowns have begun on both sides of Europe — one in Germany and one in the United Kingdom.

The court actions seek justice for what has been called one of the largest cases of corporate deception in modern history.

This ongoing case revolves around the misrepresentation of official exhaust emissions figures by large manufacturers to improve sales.

Reckoning

In Germany, the Higher Regional Court of Braunschweig has opened proceedings against former Volkswagen executives accused of orchestrating a vast emissions fraud.

At the same time, in London, the UK’s biggest-ever class action lawsuit, involving more than 1.6 million motorists, has commenced at the High Court.

It is targeting 14 major car manufacturers, including Mercedes, Ford, Renault, Nissan, Peugeot, and Citroën.

At the heart of both cases are allegations that automakers deliberately installed “defeat devices” in their diesel vehicles.

This software is designed to detect when cars are undergoing official emissions tests and temporarily reduce harmful pollutants to pass regulatory checks.

Once on the road, however, the same vehicles are alleged to have emitted nitrogen oxides and particulates far above legal limits, contributing to air pollution and serious public health risks.

The big guns

In the UK trial, led by law firm Leigh Day and supported by 21 other firms, the first phase will focus on whether the lead manufacturers — Mercedes, Ford, Renault, Nissan, and Peugeot/Citroën — used such prohibited devices.

The three-month trial is expected to conclude before Christmas, with legal submissions continuing into March 2026.

A final judgment is anticipated in summer 2026, followed by a separate hearing on damages later that year.

“This is a landmark moment for accountability,” said Martyn Day, senior partner at Leigh Day.

“A decade after the Dieselgate scandal first came to light, UK motorists now get their chance to establish whether their vehicles contained technology designed to cheat emissions tests. If proven, it would demonstrate one of the most egregious breaches of corporate trust in modern times.”

Pogust Goodhead, another firm representing thousands of affected drivers, echoed the sentiment. CEO Alicia Alinia said: “This trial is a mammoth feat by the justice system, reflecting the scale of the alleged wrongdoing by car manufacturers. Drivers were told they were buying cleaner, compliant cars. Many paid more to have an environmentally friendly vehicle and breathed dirtier air instead. They deserve answers, accountability, and compensation.”

Driving deeper

Meanwhile, in Germany, prosecutors allege that senior Volkswagen executives, including former CEO Martin Winterkorn, knowingly approved the use of defeat devices to give the company a competitive edge in the diesel market.

Volkswagen has already paid more than €30 billion in global fines and settlements since the scandal broke in 2015 but maintains that only a small group of engineers were responsible.

Environmental advocates argue that both trials represent a long-overdue reckoning for the auto industry.

“Since Dieselgate first broke a decade ago, manufacturers have faced no real accountability,” said Emily Kearsey of ClientEarth.

“The British public wants polluters to pay. Otherwise, public health will continue paying the price.”

Big numbers

According to analysis by the International Council on Clean Transportation and the True Initiative, up to 6.9 million vehicles in the UK may have emissions so high as to suggest the presence of illegal software.

As the trials unfold, they are expected to reveal new details about how one of the world’s largest industrial scandals persisted for years.

This could reshape the future of emissions regulation, corporate governance, and environmental justice across Europe.