Eggshell Skull Rule

The eggshell skull rule — sometimes called the "thin skull rule" or "you take your victim as you find him" — is a principle of common law tort and criminal law providing that a wrongdoer is fully liable for all consequences flowing from their wrongful act, regardless of whether those consequences were magnified by a pre-existing vulnerability in the victim that the defendant could not have foreseen.

The classic illustration: if A negligently strikes B on the head, and B happens to have an unusually thin skull that causes death where an ordinary person would only have been bruised, A is liable for the death — not merely for the foreseeable bruise. The defendant cannot reduce damages by arguing the victim was abnormally susceptible.

The rule is most often traced in English law to Smith v. Leech Brain & Co. [1962] 2 QB 405, where an employee's burn from molten metal triggered a pre-cancerous condition leading to death; the employer was held liable for the full loss. In the United States, the doctrine is widely cited through Vosburg v. Putney, 80 Wis. 523 (1891), in which a schoolboy's minor kick aggravated a latent leg infection.

Key features:

• Scope of harm, not duty: The rule governs the extent of damages once liability is established; it does not create a duty where none existed.
• Foreseeability: The type of injury must generally be foreseeable, but the extent need not be.
• Applies to physical and psychiatric harm: Courts in jurisdictions including the UK, Canada, and Australia have extended the principle to mental injuries, though with more caution.
• "Crumbling skull" distinction: Where a victim's condition would have deteriorated anyway, damages may be reduced to reflect the pre-existing decline (see Athey v. Leonati, [1996] 3 SCR 458, Supreme Court of Canada).

The doctrine reflects a policy choice that wrongdoers, not innocent victims, should bear the risk of unusual vulnerability.