Proximate Cause in Medical Malpractice

Proximate cause is a technical term that is often misunderstood by almost everyone, including some attorneys. In general, proximate cause refers to causation in fact. Most people believe proximate cause only refers to “but for proximate cause” — as in, “But for the fact you turned off the oxygen, the patient would not have died.” This is a cause-and-effect way of saying,  “Your action of turning off the oxygen caused the death.”

However, there is a second, more troubling proximate cause concept referred to as the “legal proximate cause.” This type of proximate cause is merely the limitation the courts or state legislatures have placed upon an actor’s responsibility for the consequences of his/her conduct.

Legal proximate cause is established when the statutory or legal underlying principles are proven. Under this concept, the law establishes when someone may potentially be liable.

For example, in failure-to-diagnose cases, many state statutes require a probability threshold before legal proximate cause is established. If the plaintiff brings a claim for failing to diagnose breast cancer, the following facts must be established by a preponderance of the evidence (more-likely-than-not standard):

1. 1. The defendant owed a duty to the plaintiff;
   2. The defendant breached that duty; 
   3. The breach caused the injury (but for cause); and
   4. The plaintiff’s probability to achieve a better result was reduced by more than 50% percent.