EGGSHELL-SKULL RULE

Torts. The principle that a defendant is liable for a plaintiff's unforeseeable and uncommon reactions to the defendant's negligent or intentional act. • Under this rule, for example, if one person negligently scrapes another who turns out to be a hemophiliac, the negligent defendant is liable for the full extent of the plaintiff's injuries even though the harm to another plaintiff would have been minor. — Also termed eggshell-plaintiff rule; thin-skull rule; special-sensitivity rule; old-soldier's rule. 

EGGSHELL-SKULL RULE, Black's Law Dictionary (9th ed. 2009)