Michael Holmes v Poeton Holdings Limited

For an indivisible injury, a defendant whose breach materially contributes to the injury is liable for the whole injury. The claimant need not also prove that the injury would not have occurred but for the breach. A material contribution must, however, be an actual causal contribution exceeding the de minimis threshold.

Evidence that an exposure increased the risk of disease, or that a plausible causal mechanism exists, does not by itself establish material contribution. The claimant must prove both that the agent was capable of causing or contributing to the disease and that the tortious exposure probably contributed in the individual case. The court may apply the civil standard rather than a scientific standard, but it cannot fill evidential gaps by speculation.

The claimant developed Parkinson’s disease after many years of employment by the defendant, during which he was exposed to trichloroethylene. The County Court found that the defendant had breached statutory and common law duties by exposing him to unsafe levels and held that the exposure materially contributed to the disease. It awarded liability for all consequences of the disease.

The defendant did not appeal against the findings of breach. It challenged the legal test for causation, the findings concerning exposure, and the proof of generic and individual causation. The central questions were whether the material-contribution principle applies to an indivisible disease and whether the evidence proved that trichloroethylene could cause, and did materially contribute to, the claimant’s Parkinson’s disease.

1. Appeal allowed. The Bonnington material-contribution principle applies to indivisible injuries. Where a tortious factor makes an actual contribution to an indivisible injury which is more than de minimis, the defendant is liable for the whole injury. The claimant need not additionally establish that the injury would not have occurred but for the tortious factor. The Court was bound by Bailey v Ministry of Defence [2009] 1 WLR 1052 and rejected the contrary analysis in AB v Ministry of Defence [2010] EWCA Civ 1317.

2. That principle concerns a contribution to injury, not merely a contribution to risk. It therefore did not relieve the claimant of proving that trichloroethylene was capable of causing or contributing to Parkinson’s disease and that the defendant’s tortious exposure actually made a material contribution in his case. The Fairchild exception was not relied upon and its possible future invocation was not determined.

3. The trial judge was entitled to find that the claimant was regularly exposed above the short-term occupational limit and, on a significant number of days, above the long-term limit. The findings were nevertheless extremely general. They did not quantify the frequency, duration or incremental amount of tortious exposure. The finding that cold degreasing exceeded the long-term limit was unsupported because the factual condition on which the experts’ opinion depended was absent.

4. The evidence did not prove generic causation. Epidemiological research did not establish a causal association between trichloroethylene and Parkinson’s disease. Animal studies demonstrated only a plausible neurological pathway, used doses greatly exceeding typical occupational exposure, and could not presently be extrapolated reliably to humans. A plausible mechanism and an elevated risk were insufficient, whether the legal or scientific standard of proof was applied.

5. Individual causation was also unproved. The evidence did not show that the tortious exposure damaged the claimant’s dopaminergic neurons or otherwise contributed to his disease. Other genetic and environmental factors, including non-tortious exposure, remained possible. The court could not replace the missing evidence by appealing to the perceived reality of the situation or by speculation.

6. It was unnecessary to decide whether the case fell within Wilsher, whether responsibility can sometimes be apportioned for an injury conventionally regarded as indivisible, or whether the case involved oversubscribed causes. Phillips LJ and Underhill LJ agreed with Stuart-Smith LJ.

1. Court of Appeal (Civil Division): The defendant’s appeal was allowed. The finding that its tortious exposure of the claimant to trichloroethylene caused or materially contributed to Parkinson’s disease was set aside.

2. County Court at Cardiff: HHJ Harrison found breaches of regulation 7 of the COSHH Regulations, section 29 of the Factories Act 1961, and the common law duty to provide a safe workplace and system. He held that the exposure materially contributed to the claimant’s Parkinson’s disease and imposed liability for all its consequences. No neutral citation was stated.