McGhee v National Coal Board [1973] 1 WLR 1
McGhee v National Coal Board addresses proof of causation where medical science cannot identify when a cumulative industrial disease began. A negligent extension of exposure that materially increases the very risk which occurs may support liability, but later cases carefully restrict the reach of that reasoning.
Facts
Mr McGhee worked in brick kilns and was repeatedly exposed to abrasive brick dust. Some exposure was unavoidable even if the employer exercised reasonable care. The National Coal Board nevertheless breached its duty by failing to provide showers at the workplace. Mr McGhee therefore had to cycle home with dust adhering to his skin, prolonging the exposure before he could wash. He developed dermatitis. Medical experts could say that longer exposure increased the risk of dermatitis, but scientific knowledge could not establish whether the disease began during the unavoidable kiln work or during the additional period caused by the absence of washing facilities. The lower courts considered ordinary proof of causation unsatisfied and rejected his claim.
Legal Issue
Could causation be established where the employer's breach materially increased the risk of dermatitis, but medical science could not show whether the disease was initiated during lawful or negligent exposure to the same dust?
Held
The House of Lords allowed Mr McGhee's appeal. The employer's failure to provide showers materially increased the duration of exposure to the same harmful dust and therefore increased the risk of the very disease that occurred. Their Lordships refused to let scientific uncertainty about the precise biological mechanism defeat the claim. The speeches were not identical in their reasoning: some treated material increase in risk as enough in the circumstances, while others regarded it as supporting a robust inference that the breach materially contributed to the injury. The decision was tied to a single harmful agent and a breach that extended exposure to it. It did not establish that every increase in a general risk automatically proves factual causation.
⭐ Legal Principle
Where a defendant's breach materially increases exposure to the same agent that may have caused the claimant's disease, and medical science cannot identify when the disease process began, the court may treat the causal requirement as satisfied. The reasoning is exceptional and must not replace ordinary but-for proof whenever a breach merely raises risk.
Significance
McGhee became a foundation for the exceptional approach in Fairchild v Glenhaven Funeral Services, although its precise basis was debated in Wilsher v Essex Area Health Authority. Fairchild applies a material-increase-in-risk rule to a tightly defined class involving mesothelioma and multiple wrongful exposures. McGhee itself involved one agent and both innocent and negligent periods of exposure by the same employer. The distinction matters: a claimant cannot generally recover merely by showing that negligence made an injury more likely, and ordinary factual causation remains the starting point illustrated by Barnett.
Common exam questions about this case
Why could Mr McGhee not prove causation in the ordinary way?
Medical science could not determine whether his dermatitis was initiated by unavoidable exposure while working in the kilns or by the additional exposure while cycling home without first showering. He could prove that the breach prolonged contact with the same dust and increased the risk, but not that the disease would probably have been avoided if showers had been provided.
Did McGhee create a general rule that increasing risk always proves causation?
No. The decision responded to scientific uncertainty where the breach extended exposure to the same agent capable of producing the disease. Later authorities have resisted converting every material increase in risk into proof of injury. Ordinary but-for causation remains the rule, while Fairchild recognises a carefully controlled exception for particular circumstances rather than a universal alternative test.
How should McGhee be distinguished from Fairchild?
McGhee involved one employer, one harmful agent and a mixture of unavoidable and negligently prolonged exposure. Fairchild concerned several employers who wrongfully exposed workers to asbestos, while science could not identify which exposure caused mesothelioma. Fairchild drew on McGhee but formulated an explicit material-increase-in-risk exception for its defined problem of multiple possible wrongful sources.