In general, the law requires jurors to use their common sense and life experience in determining the proper degree of care and vigilance with which people must lead their lives to avoid imperiling the safety of others. Not every accident producing injury gives rise to liability for negligence. Some accidents cannot be avoided even with the exercise of reasonable care. An accident that results from a defendant's sudden and unexpected physical ailment, such as a seizure or a blackout, generally relieves the defendant of liability for harm caused during his period of unconsciousness. However, defendants who have reason to know of such medical problems are expected to take reasonable precautions against the risks they create.
Assumption of risk is another defense to negligence actions.
This defense prevents plaintiffs from recovering for injuries sustained as a result of a relationship or transaction they entered with full knowledge and acceptance of the risks commonly associated with such undertakings. Assumed risks include most of those encountered by spectators attending sporting events. However, the law will not assume that individuals accept the risk of intentionally inflicted harm or damage, such as injuries resulting from assault and battery. In some cases tort law imposes liability on defendants who are neither negligent nor guilty of intentional wrongdoing. Known as strict liability, or liability without fault, this branch of torts seeks to regulate those activities that are useful and necessary but that create abnormally dangerous risks to society.