A superseding cause is any force which, by its intervention in the sequence of events leading from the defendant's negligence to the plaintiff's injury, legally prevents the defendant from being held liable for the injury even though his negligence has been a substantial factor in bringing the injury about.
To establish that a third person's intervening act was not a superseding cause of an injury, the plaintiff must prove at least one of the following facts: first, that the third person's intervening conduct was not a legal cause of the injury; second, that such conduct was not intentionally harmful; and/or third, that the injury was not outside the scope of the risk created by the defendant's negligence.
