Case Law Update: Holmes v Poeton Holdings Limited [2023] EWCA Civ 1377


The Court of Appeal has recently issued a significant judgment on the causation of indivisible injuries in personal injury law. The case, Holmes v Poeton Industries Ltd, clarifies the application of the Bonnington principle of “material contribution” to indivisible injuries and provides some useful guidance for practitioners dealing with such cases.


The Claimant in Holmes worked for the Defendant for 38 years and was exposed to unsafe levels of Trichloroethylene (TCE), an organic solvent, during his employment. In 2014, the Claimant was diagnosed with Parkinson’s disease, which he argued was an indivisible condition. He sued the Defendant for damages, alleging that his exposure to TCE had caused or materially contributed to his disease.


The general principle in personal injury law is that a claimant is entitled to recover damages for injuries caused or materially contributed to by the defendant’s negligence. However, the issue of causation can be complex in cases involving indivisible injuries, where it is difficult to determine the exact contribution of any particular factor, whether tortious or non-tortious, to the development of the disease.

The Bonnington principle, established in Bonnington Castings v Wardlaw [1956] AC613, stated that a claimant did not need to show that an injury would not have occurred but for the defendant’s negligence, but only that the defendant’s negligence materially contributed to the injury. This principle has been applied in cases of divisible diseases, where it is possible to quantify the contribution of each factor. However, the case law, considered in the judgment in Holmes was far from clear as to whether material contribution could be applied to indivisible diseases.

Court of First Instance

At first instance the trial judge found breaches of duty that led to the Claimant being exposed to TCE. The judge went on to consider the expert evidence and found that the TCE exposure created a material contribution to the risk of the Claimant suffering from Parkinsons disease (emphasis added). The Defendant appealed arguing that the evidence fell short of establishing that the exposure to TCE materially contributed to the Claimant actually developing Parkinsons (as opposed to the risk of developing the disease).

Court of Appeal’s Judgment

The Court of Appeal in Holmes confirmed that the Bonnington principle applies to indivisible diseases. The Court also confirmed that Parkinsons was an indivisible condition as once contracted, the severity of the condition was not affected by the level or duration of exposure. However, on review of the evidence, the Court also held that there was insufficient evidence to establish that the Defendant’s exposure of the Claimant to TCE had either caused or materially contributed to the Claimant developing Parkinson’s disease.

The Court emphasised that a risk factor is not sufficient to prove material contribution in cases of indivisible injuries. Instead, there must be an established causative link between the breach of duty and the injury itself. Simply proving tortious exposure, even though it could possibly cause the injury, was not sufficient to prove ‘but for’ or ‘material contribution’ causation.

In Mr. Holmes’ case, the available evidence only established that TCE was a risk factor for Parkinson’s disease, and there was insufficient scientific evidence to establish that the exposure directly caused the disease. Given the range of other potential causes, the Court concluded that the evidence did not support a finding of material contribution.

The Court of Appeal identified two key aspects in determining whether material contribution will apply in cases of indivisible injuries:

  1. Generic causation: This is the question of whether the defendant’s exposure to the substance can cause or materially contribute to the development of the injury. In Holmes, the Court concluded that there was insufficient evidence to establish generic causation for Parkinson’s disease.
  2. Individual causation: This is the question of whether the defendant’s exposure to the substance caused or materially contributed to the individual claimant’s injury. In Holmes, the Claimant was unable to provide evidence to support individual causation.


The judgment in Holmes is significant for practitioners in the fields of personal injury, industrial disease, and clinical negligence. It clarifies the application of the Bonnington principle to indivisible diseases and provides a clear framework for establishing causation in such cases.

The Court’s emphasis on the need for both generic and individual causation is important, as it highlights the challenges of proving causation in complex medical cases. Practitioners will need to carefully assess the available scientific and expert evidence to determine whether it is sufficient to satisfy both tests.

Overall, the judgment in Holmes provides a comprehensive analysis of previous judgments dealing with material contribution and gives valuable guidance for practitioners dealing with causation issues in indivisible disease cases.


Martin Lanchester

Call: 2001

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