McGhee v National Coal Board

The House of Lords held that where a defendant's breach of duty materially increases the risk of a type of harm and that harm subsequently occurs within the area of that risk, the breach may be treated as having materially contributed to the injury even though medical science cannot segregate the precise causal contribution. The court applied a practical, common-sense approach to causation in industrial disease cases. The decision follows and applies the principle in Wardlaw v Bonnington Castings and analogous authorities that a material increase in risk by the defendant can suffice for liability when the injury falls within that created risk.

The appellant, an employee, contracted industrial dermatitis after working in hot, dusty brick kilns and travelling home still coated with sweat and dust. He sued his employers for failing to provide adequate washing facilities (showers). The Scottish courts accepted negligence but found that causation was not proved on the balance of probabilities because medical opinion could not say the absence of showers probably caused the disease. The House of Lords re-examined whether proof that negligence materially increased the risk of dermatitis, together with the occurrence of the disease, suffices to establish causation when medical science cannot apportion causal contribution between compound factors.

1. Disposition: The House of Lords allowed the appeal and reversed the Court of Session's refusal; damages were to be awarded at first instance in accordance with the remit. (Per Lord Reid, Lord Wilberforce, Lord Simon of Glaisdale, Lord Kilbrandon and Lord Salmon.)
2. Primary legal holding: Where an employer's breach of duty creates or materially increases the risk of an industrial disease and the disease occurs within that risk, the employer may be liable even if medical opinion cannot precisely apportion causal responsibility between cumulative or successive factors. The breach need not be shown to be the sole cause. (Leading reasoning developed by Lord Reid and amplified by Lords Wilberforce, Simon, Kilbrandon and Salmon.)
3. Analytical rationale: The Lords rejected a rigid logical distinction between proof of an increased risk and proof of a material contribution when the evidential gap is inherent and unavoidable. They adopted a practical causation standard suited to industrial disease where medical knowledge cannot segregate causes.
4. Authority and precedent: The House applied and followed the principle in Wardlaw v Bonnington Castings Ltd and Nicholson v Atlas Steel Foundry & Engineering Co. as proper analogies for cumulative-exposure causation. These authorities support drawing an inference that the defendant's contribution was material when it materially increased the aggregated risk. (Cited and applied by the majority.)
5. Practical guidance: Employers who create or fail to remove a foreseeable risk should bear the consequences of that risk when injury of the type occurs even though precise medical apportionment is impossible. The decision emphasises policy and commonsense in assigning the burden of loss where the defendant created the risk.
6. Order: Appeal allowed. The House recalled the interlocutors and remitted the case to the Court of Session with directions to award damages and costs in accordance with the House's order.

• House of Lords: Appeal allowed; interlocutors of the Court of Session recalled and matter remitted with directions (15 November 1972). [1972] UKHL 7
• Court of Session (First Division): Refused reclaiming motion; upheld Lord Ordinary's dismissal (see judgment).
• Lord Ordinary (Scotland): Initially assoilzied defenders on some grounds but found negligence in failing to provide adequate washing facilities; dismissed claim for want of proved causation.