Ministry of Defence v Wood

In a civil claim for occupational neurological injury, epidemiological scientific proof is not essential to establishing causation. The court may rely on the totality of the evidence, including the intensity and duration of exposure, scientific evidence of association, biological plausibility, timing, and comparable cases. The applicable standard remains the balance of probabilities. A trial judge’s conclusion will stand where the reasons make the basis of the decision clear, even if the judgment contains errors or could have been more detailed. Assessment of expert credibility and demeanour is primarily for the trial judge. Where actionable exposure materially contributes to an indivisible injury, liability may extend to the whole injury despite earlier exposure.

Shaun Wood, an RAF painter, claimed damages for a neurological condition following exposure to organic solvents during his service. The Ministry of Defence admitted breach of duty for exposure between 1987 and 1995 but disputed both the existence of permanent organic neurological damage and causation.

His Honour Judge Taylor, sitting as a Deputy High Court Judge, found that Mr Wood had a predominantly organic condition, with some psychogenic factors, and that solvent exposure had caused it. The Ministry appealed, challenging the evaluation of the medical evidence, the adequacy of the judge’s reasoning, and the causal inference.

1. Appeal dismissed. Dame Janet Smith gave the leading judgment, with which Lady Justice Black and Lord Justice Moore-Bick agreed. The case was directed to proceed to a trial on quantum if damages could not be agreed.
2. The judge was entitled to find that the claimant suffered a predominantly organic neurological condition, although it could not properly be categorised as Parkinson’s disease, multi-system atrophy, or a specific Parkinsonian syndrome. The clinical signs had been observed over many years by several neurologists. The judge was entitled to prefer Dr Newman’s evidence and to conclude that the condition included some psychogenic features.
3. The judge was also entitled to reject Dr Mumford’s evidence. Assessment of credibility, approach and demeanour was peculiarly a matter for the trial judge. The appellate court found no basis for interfering with that assessment.
4. The reasoning on diagnosis could have been more detailed, particularly in explaining the rejection of Professor Wood’s opinion. Nevertheless, the parties could understand why the judge reached his conclusion. Errors in the treatment of some evidence did not undermine the result.
5. On causation, the civil standard was the balance of probabilities. Scientific proof established by epidemiological studies was unnecessary. The evidence could properly include high and prolonged exposure, studies showing an association between heavy solvent exposure and neurological damage, biological plausibility, the timing of symptoms, the cluster of comparable RAF cases, and the analogy with solvent sniffing. The Geoparkinson study did not disprove causation because it concerned materially lower exposure levels.
6. The evidence established a probable connection between heavy solvent exposure and neurological damage. The claimant’s high exposure, followed by symptoms within a medically consistent period, established that his condition was caused by the actionable exposure. For completeness, even if earlier exposure had contributed, the post-1987 exposure had made a material contribution and would found liability for the whole injury.

• Court of Appeal (Civil Division): The appeal from the order below was dismissed.
• High Court District Registry at Middlesbrough: His Honour Judge Taylor, sitting as a Deputy High Court Judge, decided liability and causation in favour of the claimant on 5 May 2010.