The High Court Considers the Guidelines for Diagnosis and Quantification of Military Noise-Induced Hearing Loss

This blog reviews the High Court decision in Barry v Ministry of Defence [2023] EWHC 459 (KB) and the ongoing uncertainty surrounding the application of the Moore et al. Guidelines for Diagnosis and Quantification of Military Noise-Induced Hearing Loss.

Those who practise in the field of noise induced hearing loss (“NIHL”) are waiting with bated breath for some authoritative guidance on the application of the controversial medicolegal guidelines proposed by Professor Brian Moore et al. Amendments are proposed to the Coles, Lutman and Buffin 2000 (“CLB”) method in an industrial context, in respect of which my colleague Katie McFarlane has recently written an incisive analysis (which may be found here) and, in addition, an entirely new set of diagnostic criteria have been proposed for the diagnosis of so called ‘military noise induced hearing loss’ (“M-NIHL”).

The High Court is currently dealing with thousands of claims advanced on the basis of the new M-NIHL diagnostic criteria. Those cases are being case managed together and a selection process will determine which cases will be treated as lead claims to proceed to trial for resolution of the generic issues. In the meantime, county court claims which turn on the same issues are approaching trial with little/no indication as to how the Moore Guidelines are likely to be received by the court.

The High Court has, in the last few days, confirmed that we will have to wait a little longer for a resolution to the question of the application of the Moore et al. method.

Mr Barry is an ex-member of the Royal Marines. He suffered NIHL arising from his military service, the majority of which was thought to have been occasioned by one particular training exercise, ‘Black Alligator’. Breach of duty was admitted. The Defendant instructed Professor Mark Lutman who opined that the Claimant was, indeed, entitled to a diagnosis of NIHL using the CLB/LCB method. The Claimant, who relied upon the evidence of Mr Hisham Zeitoun and Professor Brian Moore, suggested that the new M-NIHL Guidelines should be applied and that, if they were accepted, the quantum of his hearing loss would be slightly greater.

Professors Lutman and Moore gave oral evidence at the trial and the Claimant urged the court to make a determination as to which methodology should be preferred for assessing the diagnosis and quantification of the Claimant’s NIHL. However Johnson J ultimately agreed with the Defendant that it was not necessary for him to make a determination as to which methodology should be applied, citing ten reasons as to why it would be improper for him to so do:

[87] First, it is common ground that Mr Barry has suffered hearing loss as a result of noise exposure in the course of his military service. So far as diagnosis is concerned, there is no live issue between the parties. It is not therefore necessary to investigate different diagnostic criteria.

[88] Second, Mr Barry satisfies both the CLB guidelines and Professor Moore’s original criteria and Professor Moore’s revised criteria. His case is not therefore apt for evaluating the respective merits of the different methodologies.

[89] Third, there is a difference between Professor Lutman and Professor Moore as to the extent of Mr Barry’s noise hearing loss. That difference results from their differing methodologies. For this reason only it might be said that there is a need, in the circumstances of this particular case, to make a finding as to the methodology that is to be preferred. However, the difference in outcome on the different methodologies is not significant. The experts agree that the binaural noise induced component of Mr Barry’s hearing loss is of the order of 20dB. Professor Lutman estimated an average noise induced hearing loss of approximately 16dB in the 1-2-4kHz range. Professor Moore’s estimate was 17dB (and 22dB for the 1-2-3kHz range). Despite the logarithmic nature of the decibel as a unit of measurement, these differences are not significant. The experts explicitly agreed that “there is no meaningful difference in outcomes between the two methods in the present case.”

[90] Fourth, there is a larger difference between the outcomes of the respective methodologies when applied to the left ear alone. The average noise induced loss at the 1, 2 and 3khZ frequencies is 32.7dB or 25.3dB depending on whether Professor Moore’s method or Professor Lutman’s method is used. The corresponding figures at the 1, 2 and 4kHz frequencies are 29.3dB and 21.7dB. In each case the difference is around 7.5dB. However, neither expert suggests that it is appropriate to consider the respective outcomes by reference to each individual ear in isolation. In their joint report they focus on the binaural loss and, on that measurement, there is no significant difference.

[91] Fifth, the court’s role is to resolve the issues between the parties in a particular case. The intense factual focus on the circumstances of a particular case means that there are dangers in making findings as to the appropriate scientific methodology that should be applied more generally. To take the present case, Mr Barry was a relatively young man at the time his hearing deteriorated. None of the experts suggest that age-related hearing loss is a significant factor in his hearing loss. Mr Barry was able to give a clear account of his noise exposure in both the military and other contexts (motorbikes, discos), which was not subject to significant challenge. There is no suggestion that, apart from military noise exposure, he has been exposed to levels of noise that could explain his hearing loss. Other cases will be less clear cut.

[92] Sixth, there is an important difference between the exercise on which Professor Lutman and Professor Moore are engaged in terms of deriving diagnostic criteria, and the court’s task of making findings as to causation and damage. Diagnostic criteria are a tool that can be used by expert witnesses to provide an expert opinion to the court. It is for expert witnesses in each individual case to select and deploy diagnostic criteria as they consider appropriate, alongside a holistic view of the clinical picture. The criteria are not intended to operate algorithmically without expert interpretation. The court’s role is to establish, on all the evidence (including but not limited to the expert evidence) whether the claimant has established his case on causation and loss on the balance of probabilities.

[93] Seventh, it is clear that there were some significant misunderstandings as between the expert witnesses, even after their joint statement. So, for example, Professor Lutman had understood that Professor Moore’s methodology had been designed so as to achieve as many positive results as possible in a sample of 58 cases where the individuals were bringing claims for military noise induced hearing loss. That understanding was misplaced – the methodology had been derived from different and larger samples, and the 58 cases had been used as a way of testing its efficacy. The scope for such misunderstandings is considerable: Professor Moore’s methodology is new, has been significantly and recently modified, and has not yet (so far as I was shown) been the subject of further scrutiny in the academic literature (beyond the peer review process that was applied before his papers were published).

[94] Eighth, the fundamental difference between the methodologies is based on Professor Moore’s finding that military noise exposure has an impact in higher frequency ranges than other types of noise exposure. He may be right about that, but it is a contested issue. Professor Lutman says that Professor Moore’s finding was based on his observations of a selection of particular audiograms of military veterans, but that a different finding might have been made if a different (or larger) sample had been used.

[95] Ninth, there were a number of issues between Professor Lutman and Professor Moore as to the design of the various studies which underpinned a number of the published papers, including their own papers. Both experts were clearly seeking to assist the court with their best interpretation of the literature and with evidence that was not dependent in any way on the interests of those who instructed them. Both experts made appropriate concessions. I have no doubt as to their scientific integrity. Mr Steinberg submits that the inherent likelihood is that Professor Moore’s scientific papers were published in good faith, that they represent his true views, that they bring all of his expertise and experience to bear on the subject matter at hand and that they are motivated by a sincere desire to contribute to the canon of scientific scholarship. I agree. The same can be said of Professor Lutman’s work. It is helpful to have the two proponents of the competing methods give evidence – they are more familiar with the methodologies than anyone else; they are the original architects. This does, though, mean that in one sense they are not independent of the underlying issue (ie which of their two methodologies is to be preferred). If, in a future case, that does have to be resolved then it may be helpful to have the benefit of an opinion of a single, jointly instructed, epidemiologist on the issues that arose when comparing the methodologies, including the design of the different studies, the appropriate comparator cohort to test the null hypothesis, the appropriate population statistics to be used, and the calculation of the sensitivity and specificity scores and the positive predictive values for the different methods.

[96] Tenth, many more claims of military noise induced hearing loss are currently before the courts. They are being case managed together. It is proposed that lead claims will be selected as vehicles for the resolution of generic issues. The present case is not part of that group, and it has not been selected as a lead claim for the resolution of more generic issues. The MoD say that Mr Barry’s claim is not a suitable lead case. It is appropriate, in this context, to exercise caution and restraint before making findings that are not truly necessary for the resolution of the issues in this particular case.”

The tenth and final reason given by Johnson J is likely to be at the forefront of the minds of county court judges who are tasked with hearing military noise trials prior to the conclusion of the test litigation. It is likely that, unless it is necessary for the resolution of the particular case, judges are likely to be reluctant to engage in discussions about the merits of the respective methodologies.

With county court trials listed throughout the summer months, various experts will be subject to cross examination about their preferred choice of methodology. It remains to be seen how the M-NIHL Guidelines will be received by circuit judges who are well used to resolving causation issues in NIHL litigation.