Court of Appeal clarifies material contribution test in tort causation in Holmes v Poeton case.

Citation: [2023] EWCA Civ 1377
Judgment on


The Court of Appeal’s decision in Michael Holmes v Poeton Holdings Limited addresses the complex legal principles surrounding causation in tort law, specifically in the context of indivisible injuries and diseases. This article analyzes the key topics and legal principles deliberated in the case, providing insights into the appellate court’s reasoning and the application of established legal doctrines to the facts at hand.

Key Facts

Michael Holmes, a former employee of Poeton Holdings Limited, claimed that his Parkinson’s disease was causally linked to his long-term occupational exposure to the solvent Trichloroethylene (“TCE”). The trial judge upheld his claim that Poeton’s breach of duty concerning TCE exposure materially contributed to the development of his Parkinson’s disease, granting him full damages. Poeton appealed, challenging the judge’s legal and factual conclusions on the issues of causation.

The appeal raised several pivotal topics:

  1. The applicability of the “material contribution” test in cases of indivisible disease;
  2. The judge’s analysis of levels of exposure to TCE;
  3. Whether exposure to TCE was capable of causing Parkinson’s disease (generic causation);
  4. Individual causation between TCE exposure and Mr. Holmes’ disease;
  5. The relevance of the principles in Wilsher v Essex Area Health Authority to the case.

Material Contribution and the “But For” Test

A central theme in the appeal is the interpretation of the “material contribution” test, origination from Bonnington Castings v Wardlaw, within the realm of indivisible injury and its relationship with the conventional “but for” test. The Court of Appeal clarifies that the Bonnington principle indeed applies to cases of indivisible injury, affirming that where a defendant’s wrongful act materially contributes to the claimant’s injury, full liability may ensue, negating the need for the injury to satisfy the “but for” test.

The Bradford Hill Criteria and Generic Causation

The case discusses the application of the Bradford Hill criteria to establish a causative link between an exposure and a disease. The Court scrutinizes the available epidemiological evidence, concluding that it falls short of establishing that exposure to TCE caused Parkinson’s disease.

Individual Causation and “Wilsher” Principle

While not necessary for the final decision, the Court contemplates whether the multi-factorial causation of Parkinson’s disease might require an analysis analogous to Wilsher, which tackles multiple potential causes of injury. Although the case ultimately does not turn on this point, the Court acknowledges the existing complexity in applying “Wilsher” to diseases with not fully understood etiologies.


The appeal was allowed on the basis that the trial judge’s determination of causation between TCE exposure and the material contribution to Mr. Holmes’ Parkinson’s disease was not supported by the available evidence. This decision underscores the court’s insistence on a thorough and evidence-based approach to causation, irrespective of the acknowledged risk factors or potential mechanisms.


The Court of Appeal’s judgment in Holmes v Poeton articulates with clarity the circumstances under which the “material contribution” test may be invoked in tort causation, especially in cases involving indivisible diseases. The decision highlights the importance of a robust scientific underpinning when drawing a causal link between exposure and disease. Furthermore, it demonstrates the court’s reticence to accept speculative causation based on identified risk factors alone, reinforcing the necessity for claimants to present compelling evidence of causation. This judgment serves as an authoritative guide for legal professionals in similar tort cases, detailing the nuanced application of established legal principles to the intricate realm of causation in personal injury and occupational disease claims.

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