Old Soldier’s rule is a principle of tort law that a party who harms another should bear the risk and will be fully liable for any aggravated injury caused to the injured person. According to this rule, an individual who harms another, intentionally or unintentionally, runs the risk that the person s/he injures may have a condition causing the injury to be far more serious than had such person not had the condition. This principle makes the tortfeasor take his/her victim as s/he finds him/her. For example, if one person negligently scrapes another who happens 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.
Old soldier's rule is also known as eggshell-plaintiff rule; thin-skull rule; special-sensitivity rule.