Any plaintiff seeking to recover in tort must prove that the defendant has breached the duty of care. Even after the plaintiff has established the defendant's breach of duty, however, issues of causation and damages remain. These two issues are frequently vexing, both conceptually and in terms of evidentiary demonstration. For example, if a plaintiff proves that a defendant acted negligently, it still may be unclear whether the plaintiff would have been injured even ip the absence of the defendant's negligence. Similarly, in assessing damages, factfinders often :find it difficult to attach a monetary value to a plaintiff's nonpecuniary losses such as pain and suffering. So-called "loss of chance" cases - medical-malpractice cases in which a defend�t's negligence injures a plaintiff who has a preexisting medical condition by reducing the plaintiff's likelihood of recovering from the condition - pose a particularly difficult challenge to courts seeking to define the scope of and place a value on a defendant's liability. According to traditional tort doctrine, in such cases the plaintiff must prove that the decreased likelihood of recovery attributable to the defendant's negligence - as opposed to the preexisting condition itself - more likely than not directly caused her subsequent failure to recover. A person suffering from a preexisting condition with less than a fifty-percent chance of recovery even before diagnosis thus would have no cause of action against a doctor who negligently failed to diagnose the condition, even if the delay brought about by the missed diagnosis caused the person to lose a significant chance of recovering from the condition. For example, a person with a thirty-five percent chance of recovering from her cancer would, according to traditional tort doctrine, have no cause of action against a doctor whose failure to diagnose the cancer caused the person's chance of survival6 to fall to twenty percent, or even to zero.
Todd S. Aagaard,
Identifying and Valuing the Injury in Lost Chance Cases,
Mich. L. Rev.
Available at: https://repository.law.umich.edu/mlr/vol96/iss5/5