판결 이유
Where a claimant cannot prove which of several negligent defendants caused their injury (because each materially increased the risk), the 'but for' test of causation is modified. Each defendant who materially contributed to the risk is liable.
사실관계
The claimants contracted mesothelioma after occupational exposure to asbestos. Each had worked for multiple employers who had negligently exposed them. Because of the nature of the disease, it was scientifically impossible to determine which employer's asbestos had caused the disease.
판결 요약
The House of Lords modified the 'but for' test, holding that where each defendant had materially increased the risk of the disease, that was sufficient to establish causation. The injustice of leaving the claimant without a remedy outweighed the injustice of imposing liability on a defendant who might not have caused the harm.
주요 인용문
"Any other outcome would be deeply offensive to instinctive notions of what justice requires and what fairness demands."
— Lord Bingham
후속 처리
Applied in Barker v Corus and codified by the Compensation Act 2006, s.3 for mesothelioma cases.