Natanson v. Kline, 186 Kan. 393, 350 P.2d 1093 (1960), opinion on rehearing, 187 Kan. 186, 354 P.2d 670 (1960) (Kan. Sup. Ct.)
Natanson v. Kline is a foundational informed consent case that helped define the contours of a physician's duty to disclose risks of proposed treatment.
What is the scope of a physician's legal duty to disclose risks of a proposed medical treatment to obtain a patient's informed consent, and must the plaintiff offer expert testimony to establish the standard and breach of that duty?
A physician has a duty to make a reasonable disclosure to the patient of the nature of the ailment, the nature and probable risks of the proposed treatment, and, where appropriate, feasible alternatives, sufficient to enable the patient to make an intelligent decision. The scope of this duty is measured by the professional standard—what a reasonable medical practitioner in the same or similar circumstances would disclose—not by an absolute or lay standard. Except in the rare case where the need for disclosure is within the common knowledge of laypersons, the plaintiff must present expert medical testimony to establish the standard of disclosure and any deviation from it. Recognized exceptions include emergencies, incapacity, or circumstances in which disclosure would, in the physician's sound medical judgment, pose a serious threat to the patient's well‑being (therapeutic privilege).
The court recognized a physician's duty to make reasonable disclosure of risks but held that the extent of disclosure is governed by the professional standard and generally must be proven by expert testimony. Because the plaintiff failed to offer expert evidence establishing the applicable standard of disclosure and breach, the verdict for the physician was sustained.
Natanson is an early and influential articulation of informed consent in negligence, adopting a professional standard for disclosure and requiring expert testimony to prove it. It frames the classic tension between physician‑centered custom and patient‑centered autonomy, paving the way for later doctrinal divergence (e.g., Canterbury's reasonable‑patient standard). It remains a principal case for understanding expert proof in medical malpractice and the scope/limits of the therapeutic privilege.