The Eggshell Skull Rule
The eggshell skull rule, also known as the thin skull rule, is a principle which says that the frailty, weakness, sensitivity, or feebleness of a victim cannot be used as a defense in a tort case. Attorneys often invoke the eggshell skull rule when the negligence of the defendant aggravates a victim’s pre-existing injury or condition.
In simple terms, the rule says you must take the victim as he or she is found and cannot speculate on what might have happened if the victim had “normal” health or did not have a particular condition that predisposed them to a severe injury. This rule protects victims from their own vulnerability, something over which they have no control.
The term comes from the idea that if an individual’s skull was especially fragile—like the shell of an egg—and another person struck them in the head, the defendant (in the event of a lawsuit) would be liable for any damages they caused when they struck the thin-skulled person. In this case, a “normal” person might have suffered from headaches or mild bruising based on the force of the blow, whereas someone with an especially fragile skull might suffer brain damage or die from the exact same hit.
Regardless of the condition of the victim, however, the eggshell skull rule says the plaintiff bears no fault for their condition and that the defendant must take full responsibility for the injuries he or she caused.