Eggshell skull
The eggshell skull doctrine in tort law means that the defendant in a civil litigation who is at fault is responsible for all the consequence of his action, even the plaintiff has a preexisting medical condition or other vulnerability, such as if the plaintiff's skull is as fragile as an eggshell. This doctrine is often used in battery litigations.
A famous case that invoked the eggshell skull doctrine is Vosburg v. Putney, which a student kicked another student in the shin, causing serious injury that he did not foresee because the victim had a preexisting condition. The court decided that the student was fully liable even if he did not intend to cause serious harm.
It is controversial whether the eggshell skull doctrine should be applied to severe mental distress ("eggshell psyche"), due to that psychological injury can manifest in physical injury, and purely mental injury can be faked. The past cases on this issue have been inconclusive.