Smith v Leech Brain & Co Ltd [1962] 2 QB 405
Smith v Leech Brain & Co Ltd is the leading English authority on the thin-skull rule. Once a defendant negligently causes a foreseeable kind of personal injury, an unusual vulnerability of the claimant does not reduce responsibility for the injury's full consequences.
Facts
Mr Smith worked as a galvaniser for Leech Brain & Co. His job involved lowering metal into a tank of molten material. The employer negligently failed to provide an adequate protective shield, and molten metal struck and burned Mr Smith's lip. The tissue at that site contained a pre-existing condition that made it vulnerable to cancer. Medical evidence established that the burn acted as a promoting agent and caused cancer to develop. Mr Smith later died from the disease. His widow brought a claim under the Fatal Accidents Act. The employer accepted responsibility for the initial burn but argued that the fatal cancer was an exceptional and unforeseeable consequence for which damages should not be awarded.
Legal Issue
Was the cancer and death too remote because Mr Smith's unusual physical susceptibility made the consequences far more serious than the burn that could ordinarily have been foreseen?
Held
The Queen's Bench Division held the employer liable for the consequences of the cancer and death. Lord Parker CJ treated the burn as a foreseeable personal injury of the relevant kind. The medical evidence showed that it promoted the cancer, so factual causation was established. Once the defendant had negligently caused that initial injury, it had to take Mr Smith as it found him, including the pre-existing vulnerability in his lip. The precise severity and fatal progression did not need to have been foreseeable. The thin-skull rule therefore prevented the employer from reducing liability merely because an ordinary person would probably have suffered much less harm from the same burn.
⭐ Legal Principle
A defendant who foreseeably causes personal injury must take the claimant as found. If a pre-existing physical vulnerability makes the injury unusually severe, the defendant remains liable for the full resulting damage, provided the breach factually caused it. Foreseeability concerns the relevant kind of initial harm, not its exact extent.
Significance
The decision is the standard authority for separating foreseeability of the kind of harm from foreseeability of its extent. It works with the remoteness approach in The Wagon Mound while ensuring that vulnerable claimants are not under-compensated. Hughes v Lord Advocate likewise shows that the precise manner or scale of a foreseeable type of injury need not be predicted. The rule addresses the claimant's condition; it does not eliminate the separate requirements of breach, factual causation and an unbroken chain of responsibility.
Common exam questions about this case
What is the thin-skull rule illustrated by Smith v Leech Brain?
The defendant must take the claimant with all existing physical vulnerabilities. If negligence causes a foreseeable form of personal injury, liability is not limited to the harm an average person would have suffered. The defendant bears the full consequences when the same injury is aggravated by the claimant's unusual condition, so long as the breach actually caused the resulting damage.
Why was the fatal cancer not treated as too remote?
A burn from molten material was a foreseeable personal injury created by the unsafe working conditions. Medical evidence showed that the burn promoted cancer in tissue already susceptible to it. The employer did not need to foresee the cancer or death in detail. Once the relevant initial injury and causation were established, Mr Smith's vulnerability affected only the extent of damage.
Does the thin-skull rule remove the need to prove causation?
No. The claimant must still show that the defendant's breach caused the injury for which compensation is sought. In Smith, medical evidence linked the burn to the development of cancer. The thin-skull rule then prevented the unusual susceptibility from limiting damages. It does not make a defendant responsible for an unrelated condition or for harm that the breach did not cause.