It should go without saying that having both knowledge and experience is paramount when taking on work as an expert witness. However, a recent case is not the first in which a judge has had to emphasise this point.
In the 24 April judgment, Abbott & Ors v Ministry of Defence [2026] EWHC 941, the judge highlighted why theoretical knowledge of the in-depth issues at question in a case is no substitute for practical expertise.
The judgment followed a hearing of two test cases and a series of claims for damages for noise induced hearing loss (NIHL) brought by former members of the armed forces.
The issue that led the judge to articulate preference for one expert witness over another involved cumulative damage to the hearing of a former Royal Marine.
There were multiple aspects to his claim, general damages for his hearing loss and the cost for his hearing aids. Most relevant to the performance of the experts in this case was the potential for his NIHL to have a negative effect on his future earning potential. The former Royal Marine had left the military in 2021 to pursue a career as a defence and security consultant.
Both sides called experts to give an opinion on whether the former Royal Marine’s hearing loss was likely to have had an impact on his potential future career prospects. The judge found that where the two experts differed in opinion, he preferred the evidence of the defendant’s expert, who had a military background as a naval officer as well as extensive consulting experience.
The expert evidence
The claimant’s expert was a security expert but had no military or defence sector experience, or experience in management consulting beyond his own work.
The judge, Mr Justice Garnham, said: “He based his evidence substantially on [the claimant’s] own account. There appeared to have been little attempt to test or challenge what [the claimant] said.”
Instead, the claimant expert “simply adopted his account” and his evidence was criticised for showing “little analytical rigour”.
The argument made both by the claimant and the claimant’s expert was that without the hearing loss injury, the claimant would be likely to become a managing consultant within two to five years and then proceed to partner level by the age of 60.
However, the defendant’s expert highlighted the above-average progression of the claimant throughout his career, as well as the fact that his military personnel records showed no impact and noted the absence of medical documentation indicating impairment during service.
Commenting on the strength of the defendant’s expert, the judge said he preferred his evidence “without hesitation” and said he had “provided what I regard as balanced and authoritative evidence”.
The judge added: “He was a very impressive witness who, throughout, demonstrated genuine expertise in the subject area and true independence of thought and analysis.”
The judgment
The judge concluded that the claimant’s “progress through the ranks was remarkable at almost every stage he was marked out as someone fit for promotion and then achieved that promotion and managed the new role with conspicuous success”.
Mr Justice Garnham continued: “His choice of career path, in intelligence, was entirely sensible and made possible pursuit of an interesting career both in and after the armed forces, together with the proper accommodation of his hearing disability. There is no evidential basis on which I could find that he would have done even better if he had not suffered NIHL, whether in the intelligence Corps or elsewhere in the military.”
Whilst he did award £64,800 for loss of future earning (significantly less than the £370,000 claimed), his decision could not be attributed to the evidence of either witness. Instead, he concluded that “it is impossible to predict the future of commercial organisations, or any organisation for that matter, with any great confidence and there remains a risk that for some, currently unpredictable, reason at some, unpredictable, point in the next 14 years, the claimant may find himself on the labour market”.
While the judge saw it as unlikely that the claimant would find himself in this situation or struggle to achieve further promotion, he emphasised that it was possible.
Mr Justice Garnham concluded: “I find as a fact that his hearing loss has reduced his chances of further promotion, but the comparison is not between a certainty and a likelihood but between a greater likelihood and a lesser likelihood.”
Summary
This case reiterates the principles we have seen time and time again, of a judge preferring the evidence of an expert who has practical experience directly relevant to the issues in question.
Whilst of relevance to solicitors in their instruction of experts, it also serves as a useful reminder to experts of the value of “genuine experience in the subject area” when opining on a case. Before accepting instruction as an expert, always consider if you have the experience, skills and qualifications commensurate to the issues in dispute.
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