Brexit has become central to a multibillion-pound lawsuit over diesel emissions, as lawyers acting for UK motorists battle with carmakers over the degree to which court rulings from Europe should help determine the outcome.
A long-awaited High Court trial began this week in a case which 1.6mn vehicle owners have brought against manufacturers including Mercedes-Benz, Ford, Peugeot-Citroën, Renault and Nissan over claims they installed “defeat devices” to manipulate tests for nitrogen oxide emissions.
The lawsuit, among the largest collective actions in English legal history, comes a decade after Volkswagen sent shockwaves through the global car industry by admitting it had cheated on emissions tests.
VW is not one of the five “lead defendants” in the first part of the highly complex case that began on Monday but is part of a larger group of 13 carmakers that could be affected by the eventual ruling.
Although the UK is no longer part of the EU, European emissions regulations that took effect long before its departure are central to the High Court case because the rules have been “assimilated” into domestic law.
Since Brexit, however, judges at the European Court of Justice in Luxembourg have issued rulings that interpret the question of what constitutes a “defeat device” in a way that is more onerous for carmakers.
While the courts in England and Wales are generally not bound by post-Brexit rulings from the ECJ, legislation that enacted Britain’s departure from the EU at the end of 2020 said judges “may have regard” to such decisions.
Lawyers acting for Mercedes-Benz, which is defending the largest number of claims in the diesel emissions case, said at the start of the trial that the High Court should not follow the European rulings, which were “wrong in principle”.
“Since the court is not bound to follow these flawed decisions, it should not do so,” counsel for the German car group said in written arguments.
But lawyers acting for the motorists contend that the post-Brexit rulings are “highly persuasive” and the High Court should not depart from them without “sufficiently compelling legal reasons”.
A divergent interpretation would “undermine legal certainty” and mean different rules apply in Northern Ireland, which “creates obvious practical problems”, counsel for the claimants said in written arguments.
Under the Windsor framework, which sets out the post-Brexit status of Northern Ireland, some ECJ rulings are binding on the province but not the rest of the UK.
Opening the claimants’ case on Monday, Thomas de la Mare KC told the court that “on the defendants’ take, mainland Great Britain becomes some kind of defeat-device Brexit island” that is “cut off from the mainstream law of the EU”.
The manufacturers deny the claims made against them, variously arguing that the claimants are erroneously seeking to associate the entire industry with the VW dieselgate scandal, have misunderstood the emission control systems and that their case is fundamentally flawed.
The trial began on Monday after the presiding judge declined to sign off on a request made by one of the main firms representing motorists to stand aside as a lead solicitor on the case.
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Pogust Goodhead said last week it wanted to relinquish its central role following departures of senior staff. It said the carmakers were making “attempts to exploit” the situation, which “risked becoming a serious distraction”.
Mrs Justice Sara Cockerill told parties in the case on Friday that while she was “not shutting the door” entirely on the request, its implications were “far from clear” and she was “not currently prepared to make the order sought”.
Pogust Goodhead said it welcomed her decision “that the status quo is the best course at this time, which means that Pogust Goodhead will continue as lead solicitor, along with Leigh Day”.
Additional reporting by Suzi Ring
