Summary
The Claimant asserted that the Defendant had infringed their patent for an electric shower-waster pump and control unit. The trial related to liability only. Both sides criticised the other’s expert. The Judge rejected these criticisms noting that, while he reached conclusions that differed from the experts in various places, he did not consider either expert to be unreliable or that their evidence generally should be discounted.
Learning points
Learning points for instructing parties
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An expert can be incorrect without being biased or an advocate.
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Ensure that you have convincing evidence before criticising an expert’s independence or competence.
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Expending significant resources to support ad hominem attacks is unlikely to be money well spent.
Learning points for experts
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Your expertise and a complete understanding of your duties are your best defences against attacks on your independence and competence.
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Your past actions may be used as the basis for an attack. You should take the time to consider if there are any potential bases for these types of attacks and, if so, how you would respond should they arise.
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Avoid using adjectives like “strange” to describe the views of the opposing expert.
The case
The Claimant asserted that the Defendant had infringed their patent for an electric shower-waster pump and control unit. The trial related to liability only. The Defendant counterclaimed that the patent was invalid on the basis of lack of novelty and/or obviousness. The Judge noted that, despite the case appearing to be comparatively straightforward, procedural manoeuvres were alleged in both directions, and extreme positions were taken on several issues, including the expert witnesses.
The expert witnesses
The Claimant relied on the expert evidence of Mr V, who trained in electrical engineering and had had various roles involving pump technology. The Defendant called Mr T, who had worked in engineering since 1998, including in relation to plumbing and heating. Both experts filed reports, reply reports, and were cross-examined. Each side criticised the other’s expert.
The criticism of Mr V
The Defendant asserted that Mr V was not independent on four bases.
The Defendant asserted that Mr V had left his former employer in contentious circumstances in 2013 and that he still bore a grudge, such that his ability to assist the Court as an independent expert was compromised. After considering Mr V’s evidence on this matter, the Judge found that Mr V bore no hostility toward his former employer at the time he produced his reports and when he was cross-examined.
The second criticism of Mr V’s impartiality related to his not raising the issue of the use of a switch which was released 4 days after the Priority Date. Mr V had been instructed to consider the situation at the Priority Date. While the Defendant accepted that Mr V's statements on the matter were true, they considered that his failure to consider this product was a serious failure. The Judge rejected this criticism, finding that an expert asked to consider the position at the priority date is entitled to comply with those instructions.
The Defendant asserted that Mr V had failed to correct errors in respect of a product called Archimedes 4. The Judge found that Mr V’s comments on this product were not relevant as the product was not central to any issue before the court. He rejected this criticism to the extent it was suggested that he should discount Mr V’s evidence as a whole.
Mr V’s impartiality was questioned on the basis of the way in which he gave his oral testimony, which was said to be evasive and advocative rather than neutral. The Judge did not find any basis for this criticism noting again that Mr V came to court to assist as an impartial expert.
The Defendant also argued that Mr V did not have the expertise that he professed to have and therefore lacked the ability to educate the court with relevant knowledge about what the skilled addressee would have known and done.
The Judge agreed with the Claimant’s counsel that this was an unpresented and exceptionally aggressive ad hominem attack on Mr V which included seeking out former employers in attempts to unearth some basis for accusing him of having giving misleading evidence about his professional experience. The Judge also rejected this attack, finding that Mr V answered fairly and straightforwardly the questions put to him in cross-examination about his expertise and did not exaggerate his CV or his expertise or experience more generally.
The criticism of Mr T
The Claimant’s counsel made a number of criticisms of Mr T including that he slipped into advocacy, with the intensive period for the production of his first report resulting in his starting to view the task as to help the Defendant. In particular, counsel argued that Mr T attacked Mr V by describing some of his opinions as “strange”. In his reply report to Mr V’s report, Mr T stated that “this is a strange comment to me which just suggests that [Mr V] has never been involved in design or manufacture”. The Judge noted that, whilst this comment may have been indelicately expressed, he did not consider it evidence of a wider flaw in Mr T’ impartiality.
The Judge had carefully watched and listened to Mr T give evidence and noted that the vast bulk of Mr T’s evidence was not challenged. He considered him an appropriately impartial expert who came to assist the court, giving his evidence fairly.
Judge’s conclusion on the criticism of the experts
The Judge rejected the criticism of the experts, finding that both assisted the court in an appropriate fashion. While the Judge reached conclusions that differed from the experts in various places, he did not consider either expert to be unreliable or that their evidence generally should be discounted.