In January 2019 (here), we circulated a detailed case note on the High Court ruling in Mackenzie v Alcoa Manufacturing (GB) Ltd  EWHC 149 (QB), which concerned breach of duty in a noise-induced hearing loss claim, with the alleged exposure period having occurred ‘50 years’ prior.
We deliberated that Mr. Justice Garnham had erred in finding that ‘the defendant was under a duty to conduct noise surveys from 1970’, on the basis that the only available guidance at that time was the Ministry of Labour publication, Noise and the Worker (1963), and the Department of Employment publication, The Code of Practice (1972). Unlike the Noise at Work Regulations (1989), these publications are purely guidance – they were not intended to be binding on employers.
We went further, in our critical analysis, contending that the judge had failed to distinguish Keefe v Isle of Man Steam Packet Company  EWCA Civ 683 on the facts. In Keefe, Lord Justice Longmore reasoned, at paragraph 19, that:
‘If it is a defendant's duty to measure noise levels in places where his employees work and he does not do so, it hardly lies in his mouth to assert that the noise levels were not in fact excessive. In such circumstances the court should judge a claimant's evidence benevolently and the defendant’s evidence critically’.
In industrial disease claims, especially NIHL claims, the High Court has expressed that reconstructing exposure levels ‘is not a precise science’ – see HHJ Inglis in Parkes v Meridian Ltd  EWHC B1 (QB). Thus, to ‘benevolently’ interpret merely ‘anecdotal’ witness evidence, which may be the only available evidence, is unfair on defendant employers that are unable to locate decades-old documents:
‘... I do not think that the decision on noise levels at any of these factories, given the scientific evidence that there is, can in these cases be affected by the lay witness evidence referred to above. I do not think it appropriate to take a level or bracket coming from the engineering evidence, and adding to it because of the description given by witnesses’.
This week, His Honour Judge Eyre QC added to the body of case authority on historic recollection of evidence, albeit not in the context of an occupational disease claim. The National Union of Mineworkers v Organisation Internationale De L'Energie Et Des Mines  EWHC 1359 (Comm) should be cited by defendants at trial, if they wish to discourage the potentially damaging influence of subjective and unreliable witness evidence on exposure level calculations. At paragraphs 28 to 32, the judge warned:
‘I … have to be conscious of the fact that any witness is inevitably recollecting matters from a particular viewpoint. I have regard to the common human capacity and tendency for a witness genuinely but mistakenly to recollect past events as having actually happened in the way in which the witness now with hindsight believes they would, or indeed should, have happened. In that respect I have also had regard to the cautionary note sounded by Leggatt J in Gestmin SGPS S A v Credit Suisse (UK) Ltd & another  EWHC 3560 (Comm) at  –  as to the unreliability of human memory.
Those difficulties are compounded … by the very considerable period of time which has passed since the key events. Moreover, it was apparent that there are still high feelings about the events … and their aftermath …
In many cases the difficulties inherent in relying on the recollection of witnesses cause the court to say that the witnesses' evidence must be viewed through the prism of the contemporaneous documents and that the safest course is for findings of fact to be based on inferences drawn from such documents …
… My consideration of the documents as well as of the witness evidence must be undertaken in the light of the context and date of the documents and having regard to the inherent likelihood or unlikelihood of the parties' contentions as to what was done or intended.
Consequently, HHJ Eyre QC went on to conclude, at paragraph 38, that:
‘It would not be appropriate to draw an adverse inference based on ... witness ... evidence about events nearly thirty years before the trial’.
Full text judgment can be accessed here.