ENGLAND — The High Court rejected most claims in a "dieselgate" lawsuit brought on behalf of 1.6 million UK car owners. However, the court found that technologies and strategies in some Mercedes and Peugeot-Citroën vehicles could constitute illegal defeat devices.

Lady Justice Cockerill stated in her judgment that "in the majority of instances, the court found that the relevant strategy did not constitute a prohibited defeat device." The lawsuit alleged that manufacturers, including Nissan, Ford, and Peugeot, installed devices to manipulate emission tests. The claimants argued that manufacturers engineered vehicles with technology designed to reduce nitrogen oxide (NOx) emissions during tests compared with normal driving conditions. The manufacturers denied using prohibited defeat devices.

Lady Justice Cockerill also stated that proving an intention to rig a test was necessary. "Not every calibration or emissions-control strategy amounts to a defeat device," she said. She added, "It was not enough for the claimants simply to establish that the challenged strategies reduced the effectiveness of emissions-control systems outside the relevant testing conditions."

The case focused on 20 vehicles sold by five manufacturers: Mercedes, Ford, Renault, Nissan, and Peugeot/Citroën, from 2009 onward. The judgment noted that "Testing, however, is difficult to interpret and none of the approaches to isolating the effect of a particular calibration on NOx was entirely satisfactory." Lawyers for the claimants indicated they are considering an appeal, citing a divergence between the legal position in Great Britain and much of Europe.

Mercedes-Benz said the court had ruled "very largely in favour" of the manufacturer. The company also stated it was considering an appeal regarding any vehicle deemed non-compliant, and that the functionality in question was removed from vehicles in 2015. Nissan maintained it had always argued that the technologies in its vehicles were not defeat devices. Renault said its cars were "designed, engineered, and manufactured in accordance with all applicable regulatory requirements."

Martyn Day, senior partner at a firm representing claimants, said, "The high court has found that despite their denials, other manufacturers also used VW-style defeat devices." He added, "The judge has also found that many other defeat devices are lawful because she surprisingly disagreed with the established EU case law on what a defeat device is." Day stated, "We are considering with our clients whether to apply for permission to appeal." Anna Varga, a partner at another firm involved in the case, stated that the judgment "does not bring this litigation to an end." She added, "The court has found that certain manufacturers installed unlawful defeat devices, but it also adopted a significantly narrower interpretation of the law than that applied elsewhere in Europe."

Why It Matters

The High Court's judgment on this "dieselgate" lawsuit affects approximately 1.6 million UK car owners and establishes the legal interpretation of "defeat devices" within Great Britain. The distinction between the UK court's interpretation and established EU case law could lead to further legal actions. The decision could also impact how vehicle emission control strategies are regulated and litigated in the future.