Law firm at centre of ‘dieselgate’ trial in ‘internal turmoil,’ court hears

The UK law firm representing 750,000 claimaints in the ‘dieselgate’ class action trial are in ‘turmoil’, the High Court heard.

Pogust Goodhead (PG) is suing Mercedes-Benz, Ford, Nissan, Renault and Stellantis-owned Peugeot and Citroen for allegedly using ‘defeat devices’ to flout crucial emission tests between 2012 and 2017.

Last week PG stated they want to remove itself as a joint lead law firm through an ‘agency agreement’ with Leigh Day who would take over the litigation.

The company acts for some 750,000 of 1.6 million claims in the case.

The judge, Mrs Justice Sara Cockeril said on she was not prepared to grant an order that would allow PG to remove itself from the case.

Lawyers on behalf of Nissan referred to ‘internal turmoil’ in their written skeleton argument: ‘The claimants are represented by 11 different law firms. The largest by claimant number of those is Pogust Goodhead (PG), who act for approximately 42 per cent of the claimant group.

‘On 25 September 2025, PG informed Nissan and the other lead defendants that it would no longer continue as a lead solicitor and it made an application to step down as a lead solicitor on 30 September 2025.

‘PG gave a minimal explanation, merely suggesting that criticism of PG as a firm ‘is causing unnecessary distraction’.

‘As at the time of filing, no replacement lead solicitor has been appointed. Serious questions remain as to PG’s ability to adequately represent the largest group of claimants due to widely reported internal turmoil at the firm, including recent mass partner departures amid allegations of improper influence by the firm’s funder, Gramercy.’

The £6 billion class action lawsuit is the largest in English and Welsh legal history.

Claimants say that Nitrogen Oxide (Nox) emissions were up to twelve times over the test limits, causing destruction to the environment and entitling them to compensation.

The manufacturers insist that the claims are flawed and reject comparisons to the Volkswagen scandal.

The trial will examine a sample of 20 diesel vehicles produced by the relevant manufacturers.

More than one million claimants are suing the car companies for their alleged role in cheating the emissions test using defeat devices.

Thomas De La Mare KC, for the claimants, characterised the attitude of carmakers as being: ‘We would rather cheat than comply with the law.’

He said they had made a ‘conscious decision’ to prioritise customer happiness in the form of ‘sportiness’ over environmental considerations.

Mr De La Mare said despite a ‘wide spread of evidence’ the carmakers ‘deny without exception’ the existence of ‘prohibited defeat devices.’

The companies are accused of making ‘numerous improbably, even fanciful legal arguments’ to avert findings of defeat devices in the sample vehicles provided to court.

Mr De La Mare referred to ‘linguistic’ arguments made about the exact definition of ‘defeat devices’ across various languages.

He described this is a ‘completely misdirected adventure.

‘(This) is one of the rare instances where has a connotation that is lifted from foreign legislation that supplies lock, stock and barrel the relevant definition.’

Mr De La Mare argued a ‘trawl through different languages’ about whether it could mean a ‘deactivation’ or ‘manipulation’ device is a ‘dead-end’.

He said the defendants idea of acceptable emissions-testing would make ‘perfectly legal’ the existence of ‘filthy’ cars operating at ‘just shy of 13x emission limits.’

‘In the real world, if you’re sat behind a Renault Nissan vehicle, it will be performing orders of magnitudes worse – perhaps up to ten times worse – on the emissions test.’

On the destructive effects of excessive NOx emissions, he said: ‘NOx emissions are particularly dangerous in urban areas.

‘Indeed, it is the occupants of vehicles driven in urban areas that generally experience the highest levels of pollution, usually higher than those who walk or cycle.;

NOx emissions damage the environment in two ways.

Firstly they can contribute to the formation of other pollutants, including particulate pollution and ground-level or ‘tropospheric’ ozone, a particularly harmful gas both for human health and greenhouse gas effects.

Secondly, high levels of NOx deposition can harm ecosystems, as NOx also contributes to the acidification and eutrophication of ecosystems, leading to biodiversity loss and damaging habitats.

Mr De La Mare added: ‘The serious human health impacts of NOx emissions in particular are well known.’

A spokesperson for Mercedes had said the mechanisms used in tests were ‘justifiable from a technical and legal standpoint’.

Renault and Stellantis has said the vehicles were compliant with regulations at the time they were sold.

Ford has said the claims have ‘no merit’ while Nissan has said the company is ‘committed to compliance in all markets in which we operate’.

The trial is expected to roll on until mid-2016 with a judgement not expected until next summer.