McWilliams v Sir William Arrol & Co Ltd [1962] 1 WLR 295 (HL)

Facts

Mr McWilliams, a construction worker, was employed to work on a crane. He was required to wear a safety belt, but he failed to do so.

The crane collapsed, and he was killed. His widow claimed that the employer had been negligent in failing to ensure he wore the belt, arguing that proper supervision would have prevented the death.

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Issue

Did the employer’s breach causally contribute to the employee’s death, or would the accident have occurred regardless?

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Decision

The House of Lords held that the employer was not liable. Evidence showed that even if the safety belt had been worn, it would not have prevented the fatal accident. Therefore, the breach did not satisfy factual causation.

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Legal Principle

Reinforces the “but for” test: the breach must be a factual cause of the harm. Negligence cannot be established if the harm would have occurred regardless of the defendant’s actions. Highlights the need for causal connection, not just breach.

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Importance

• Key authority on causation in personal injury cases.

• Demonstrates that even obvious breaches may not lead to liability if harm is inevitable.

• Frequently cited in employment and medical negligence cases.