The recent High Court case, Patricia Andrews & Ors v Kronospan Limited [2025] EWHC 2429 (TCC) provides clear direction to experts as to when a change of approach is likely to be permitted by the courts, and when it is likely to be looked at “particularly critically”.
1. Background of case
This is a class action whereby the claimants (a group of residents from a large village) sought damages and other relief against the defendant (the UK arm of a group of companies operating a local factor) alleging environmental nuisance caused by dust particles, odour and noise.
Each side instructed two expert witnesses in relation to the dust claim.
All four experts initially agreed a common approach with regards to the modelling of dust data. However, at a later stage, the claimants’ experts attempted to add to and refine their approach based upon different criteria, which impacted the common approach.
The defendant’s experts disagreed with the results of both revised approaches and maintained their initial opinions.
The judge was sceptical of the claimants’ experts’ revised approaches.
2. Why did the claimant experts seek to change their initial approach?
Both claimant experts were dissatisfied with the initial results of their respective exercises and were resolved to undertake a second stage analysis.
One of the experts sought to re-program the model by adjusting the input data which had been previously agreed by one of the defendant’s experts and the previously instructed claimant expert. “This was on the basis of what she considered were inconsistencies between the results and what she considered would have been expected”. After re-running the data, she gave results that she claimed, “were both reliable and provided strong support for the claimants’ case”.
The other expert sought “undertaking a visual examination of all the samples…[as] she was concerned that the automated analysis was missing wood fibres which might be present. Having done so, she considered that in the vast majority of cases there was evidence of very much smaller wood fibres, which could have emanated from the Kronospan site. This of course provided support for the Claimants’ case.”
3. Why did the judge take issue with claimant experts’ resolve to change their approach?
Whilst none of the expert evidence was “so comprehensively exposed as wrong in cross-examination” that it could confidently be discounted, the judge was keen to interrogate the new evidence put forward by the claimant experts because it:
- Departed from the initial common approach in “a significant and material manner”.
- Produced results “more favourable to their clients’ case” than the initial results, which were “adverse to their clients’ case”.
He then went on to state that if experts want to change their initial approach, the court must be satisfied that:
- It was appropriate to do so on a purely objective basis.
- The results of the second analysis are preferred to the results of the initial analysis.
Whilst the judge did not question the conduct of the claimant experts, he concluded that their change of approach was subjective – in that it was “at least partially influenced by their desire to see whether or not further analysis would benefit their clients’ case more than their existing analysis”.
In addition, he did not find a reason to prefer their revised opinions to those made by the defendant’s experts who proceeded based on the initial common approach.
4. Conclusion
This case provides clear direction to experts on how to navigate situations where they wish to change their initial evidence or approach and when this is likely to be permitted by the court.
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