Tort law (2022): Liability: Eggshell rule + Vicarious liability

The eggshell rule (also thin skull rule, papier-mâché-plaintiff rule, or talem qualem rule) is a well-established legal doctrine in common law, used in some tort law systems, with a similar doctrine applicable to criminal law. The rule states that, in a tort case, the unexpected frailty of the injured person is not a valid defense to the seriousness of any injury caused to them.

Law.

This rule holds that a tortfeasor is liable for all consequences resulting from their tortious (usually negligent) activities leading to an injury to another person, even if the victim suffers an unusually high level of damage (for example due to a pre-existing vulnerability or medical condition). The eggshell skull rule takes into account the physical, social, and economic attributes of the plaintiff which might make them more susceptible to injury. It may also take into account the family and cultural environment. The term implies that if a person had a skull as delicate as that of the shell of an egg, and a tortfeasor who was unaware of the condition injured that person's head, causing the skull unexpectedly to break, the defendant would be held liable for all damages resulting from the wrongful contact, even if the tortfeasor did not intend to cause such a severe injury.

In criminal law, the general maxim is that the defendant must "take their victims as they find them", as echoed in the judgment of Lord Justice Lawton in R for example Blaue (1975), in which the defendant was held responsible for killing his victim, despite his contention that her refusal of a blood transfusion constituted an intervening act.

The doctrine is applied in all areas of torts – intentional torts, negligence, and strict liability cases – as well as in criminal law. There is no requirement of physical contact with the victim – if a trespasser's wrongful presence on the victim's property so terrifies the victim that he has a fatal heart attack, the trespasser will be liable for the damages stemming from his original tort. The foundation for this rule is based primarily on policy grounds. The courts do not want the defendant or accused to rely on the victim's own vulnerability to avoid liability.

The thin skull rule is not to be confused with the related crumbling skull rule in which the plaintiff suffers from a detrimental position (from a prior injury, for instance) pre-existent to the occurrence of the present tort. In the "crumbling skull" rule, the prior condition is only to be considered with respect to distinguishing it from any new injury arising from the present tort – as a means of apportioning damages in such a way that the defendant would not be liable for placing the plaintiff in a better position than they were in prior to the present tort.

Example.

In an example, a person who has osteogenesis imperfecta (also known as "brittle bone syndrome") is more likely to be injured in a motor vehicle accident. If the person with OI is hit from behind in a motor vehicle collision and suffers medical damages (such as clavicle fracture), it would not be a valid defense to state that the osteogenesis imperfecta was the cause of the fracture.