Causation
Understanding Medical Causation
Breach of the standard of care is only half a case. Causation is where most medical malpractice matters are won or lost.
Causation asks a narrower question than most attorneys initially appreciate: did the specific breach of the standard of care, more likely than not, cause the specific injury alleged? A physician can fall below the standard without causing harm, and a patient can be harmed without any physician falling below the standard. The two analyses are independent, and both must be established for a plaintiff to prevail.
Medical causation reasoning follows a defined pathway. First, identify the injury with clinical precision — not 'brain damage' but 'hypoxic-ischemic encephalopathy affecting the basal ganglia, presenting with dystonic cerebral palsy.' Second, identify the mechanism — the pathophysiologic sequence by which a breach could produce that injury. Third, evaluate whether that mechanism operated in this patient by comparing the timing, imaging, laboratory findings, and clinical course against what the mechanism would predict. Fourth, rule out alternative explanations — genetic conditions, unrelated infections, intercurrent events — that could produce the same injury independent of any breach.
The 'more likely than not' standard sits at 51%. In medicine, that threshold is often uncomfortable because clinicians are trained to reserve judgment until certainty is high. Expert testimony bridges the gap by translating clinical probability into legal probability, always anchored to peer-reviewed literature. A causation opinion that cannot cite the evidence supporting its mechanism will not survive cross-examination or a Daubert challenge.
The most common failure mode is causation that sounds strong on breach but weak on mechanism. A missed diagnosis of appendicitis is only causally connected to a bowel resection if the record supports that earlier diagnosis would have prevented perforation. A delayed cardiac workup is only causally connected to arrest if the arrest occurred within the window when intervention would have changed the outcome. When the mechanism does not fit the timing, the case does not survive summary judgment.