A recent High Court case revealed the complexity of a highly technical group litigation, where many experts were required to enable the court to understand the various issues at hand.
The Pan Nox litigation, overseen by Lady Justice Cockerill, is the largest group action in English legal history. It included evidence from 21 expert witnesses, across several disciplines: software, mechanical engineering, climatology and driving conditions.
The witnesses were instructed on behalf of 1,600,000 claimants and several defendant car manufacturers, including Mercedes, Ford, VW, Peugeot-Citroën and Renault.
The case sought to clarify whether the car manufactures bore any liability in relation to allegations of unlawful emissions systems being installed in diesel engines sold in the UK.
It was claimed that the systems used were tantamount to “defeat devices”, which are banned under European legislation. The manufacturers argued that the systems were installed as result of legitimate and lawful engineering decisions that balanced numerous factors, of which emissions were one.
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Best, fairest and most impressive expert evidence
The case involved a large volume of evidence relating to complex and technical areas of specialist knowledge such as engine design, software, emissions systems, relevant regulations and climatology. Acknowledging the “incredibly knowledgeable specialists” involved in providing evidence, the judge said it had been a “privilege” to hear their evidence.
The judgment offers expert witnesses a compelling insight into what judges look for in a credible witness. She praised the climatology experts, saying their evidence was “some of the best, fairest and most impressive expert evidence”, she had ever seen. She regularly commented on the experts’ composure under cross-examination and even their ability to inject a little levity into the court proceedings at appropriate times.
Lady Justice Cockerill described one witness for Ford as “acute and jovial”, adding that “despite an appearance of being easy-going, he was plainly extremely intelligent and focused”. He listened carefully to questions and was so keenly focused under cross-examination that he was able to recall questions almost verbatim.
She said: “Aside from the merits of his evidence, he brought a ready sympathy for the Court’s dilemmas in this case and a level of wit not often exhibited in cross-examination.”
Another defendant witness “was a calm, deceptively serious looking witness who stood up to lengthy cross examination by two leading counsel with scrupulous care and enlivening gleams of humour”. She rejected a submission by the claimants that the expert had been “a hired gun, acting solely or predominantly for the manufacturers”.
The judge said: “The balance of the work which he had done, as an experienced
industry engineer often working in calibration for manufacturers … had an input
into his very genuine opinions when it came to matters such as the balancing of
competing factors and the scope for engineering judgment.”
These observations of how a credible expert behaves in court illustrate that success need not be performative. Often experts invite criticism for flamboyance, hubris, or over-confidence, which can undermine their evidence or give the impression of hiding gaps in their knowledge behind bluster.
These two witnesses were able to deliver strong evidence with decorum and confidence but without appearing too serious. In a case of such complexity, this lightness of touch was clearly welcome.
In contrast: Three experts strayed too far from CPR Part 35
Elsewhere, the judge did have “reservations” concerning the evidence of three of the experts. Primarily, these were experts not familiar with the UK court system who at times strayed from the rigidly defined role of an expert witness in Part 35 of the Civil Procedure Rules.
In one instance, the judge said: “I was not entirely convinced he had fully imbibed the ethos of the Part 35 expert process … Specifically, he did repeatedly evidence a wish to get onto the bits of evidence he wanted to talk about, regardless of the question he had been asked. He had a tendency to look for any qualification rather than accepting fairly obvious propositions.”
Likewise, another expert with little prior experience of Part 35 seemed to have read his instructions too broadly and was unable to stick to his specific expertise. As a result, the judge ruled prior to trial that large parts of his report should be struck out. Nonetheless, she said, he continued “to hold the view that the software aspects could not be properly addressed without an analysis (by him) of the various aspects of the mechanical engineering issues. This mindset remained evident in his response to the striking out of parts of his report, where he remained (genially) completely unrepentant”.
While there is clearly a lesson to be learnt here on the importance of following the Part 35 rules, the judge didn’t regard his intentions as anything other than trying to serve the court. Integrity, it seems, will override perfect procedure with a sympathetic judge, and in this case the witness’s “genial approach and ready smile” in court seemed to win some favour. However, she concluded that his “deep, verging on passionate, interest in the issues … at times deprived him of the degree of objectivity which is the stance of the most helpful evidence”.
The same witness discredited himself somewhat by revealing in his report that he had, in the judge’s words, “relied quite heavily on his ‘team’”, none of whom, she added, were Part 35 experts. She went on to flag that: “In one case an internal note from his team arguing for a ‘best case’ result was left in the report when served.”
Another expert’s report was observed to have a “dogmatic style not often seen in the English Court, which contained some inaccuracies and which did not fully reflect the nuance of his views, which as a Part 35 expert he was expected to (and did in person) give”. The expert, who had waived access to an interpreter, was felt to have at points, under cross-examination, a tendency not to fully focus on the question, having to be drawn back to the point by counsel.
In Summary
This case revealed the critical role that expert witnesses play in the judicial system, but also highlighted the challenges posed by a court having to assimilate so much technical information.
The judge explained: “Although a huge amount of work had been put in by both experts and counsel, the sheer level of complexity and the individual complications which arose in relation to a wide range of vehicles created situations where it was apparent either that an answer given by an expert was one which was not instantaneously perfectly comprehended by the counsel team. Or that the very detailed granular questions being asked took the expert beyond the limit of what they were able to hold in their head.”
She said in other instances, experts’ thinking evolved as the case unfolded and they began to offer opinion beyond the scope of their original report. She said: “So, at times it was apparent that issues could not be fully explored.”
The outcome was a mixed judgment with important findings for both sides but ultimately the judge rejected many of the claimants’ allegations.
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