Claimant's negligence must be a cause of, not merely incidental to, the sustained injury. For example, a negligent rider on a traxcavator who was injured after being struck from behind by the careless driver of a dumper truck was found to be contributorily negligent. However, the court pointed out that contributory negligence would not have been a defense had he been injured instead by an incidental stray shot from a negligent sportsman.
In a recent Tennessee case, a patient sustained a cardiac arrest because of negligent monitoring during a CT scan. His antecedent negligence stemmed from the fact that he had alcohol in his blood upon arrival at the hospital following a car accident. The state Supreme Court found the hospital 100% liable and disallowed the jury's assessment of 30% comparative fault, holding that “principles of comparative fault did not apply such as to allow fault to be assessed to patient, and thus jury should not have been allowed to consider patient's antecedent negligence in assessing fault.”