Plaintiff Cobbs consulted defendant Dr. Grant, a general surgeon, for severe upper abdominal pain and related gastrointestinal symptoms. Diagnostic workup suggested a peptic (duodenal) ulcer. Dr. Grant recommended surgery to treat the condition, and Cobbs signed a written consent for the procedure after a brief preoperative conversation. Cobbs later contended he was not advised of specific material risks or alternatives—such as the risk of injury to adjacent organs or the option of continued medical management. During the operation, while mobilizing the stomach and surrounding tissues, Cobbs's spleen was inadvertently torn, necessitating a splenectomy to control life-threatening bleeding. He subsequently suffered serious postoperative complications, including pancreatitis and additional abdominal surgery, with prolonged recovery and permanent sequelae. Cobbs sued, asserting causes of action for medical negligence and lack of informed consent, and at points characterized the claim as battery. The trial court effectively required proof of community medical standards regarding disclosure and, due to the absence of expert testimony establishing a professional disclosure custom, entered judgment for the defense on the informed consent claim. Cobbs appealed.
Does a physician's duty to obtain informed consent require disclosure measured by professional standards of the medical community, or by what information is material to a reasonable patient's decision; and, relatedly, is a failure to disclose material risks actionable as negligence rather than battery absent proof of no consent or a substantially different procedure?
A physician must disclose to the patient all material information necessary to make an informed decision about proposed treatment. Information is material if a reasonable person in what the physician knows or should know to be the patient's position would be likely to attach significance to it in deciding whether to consent. Material information ordinarily includes the nature and purpose of the proposed procedure, the significant risks and their likelihood, available alternatives (including the option of no treatment), and the risks of declining treatment. The duty is not defined by medical profession customs; expert testimony may be used to explain medical risks and probabilities but is not required to establish the legal standard of disclosure. Failure to make adequate disclosure, where it causes injury through the occurrence of an undisclosed material risk, is negligence, not battery, unless the physician performs a procedure without any consent or one substantially different from that authorized. Causation is assessed objectively: the plaintiff must prove that a reasonable person in the patient's position would have declined or chosen differently had adequate disclosure been made. Limited exceptions apply, such as emergencies and a narrowly circumscribed therapeutic privilege when disclosure would pose a serious and immediate threat to the patient's well-being.
The California Supreme Court adopted a patient-centered materiality standard for informed consent and held that inadequate disclosure is a negligence claim, not battery, when the patient consented to the general procedure. Because the trial court improperly required proof of professional community disclosure standards and directed a verdict against Cobbs for lack of expert testimony on such standards, the judgment was reversed and the matter remanded for proceedings under the correct legal standard.
The court reasoned that the core of informed consent is the patient's right of bodily self-determination. That right is served only if the patient receives the information a reasonable person would deem important to deciding whether to undergo the procedure. Tethering disclosure to professional custom invites medical paternalism and insulates nondisclosure practices behind a wall of expert consensus; it also misaligns incentives because the medical community controls the standard. In contrast, a materiality standard places the decision-making authority where it belongs—with the patient—and empowers juries to determine what a reasonable patient would want to know. In distinguishing negligence from battery, the court explained that battery addresses unauthorized touching—either no consent or a substantially different procedure than the one authorized. When a patient consents to the general nature of the operation, a physician's failure to disclose risks sounds in negligence, which appropriately focuses on the reasonableness of the physician's disclosure and the causal link to injury. The court emphasized an objective causation test: rather than relying on a plaintiff's subjective hindsight, the fact-finder asks whether a reasonable person in the patient's position would have declined or chosen differently if fully informed. This avoids speculative and self-serving testimony while still vindicating autonomy. The court also clarified evidentiary contours. Although the standard of disclosure is legal—not a matter of medical custom—expert testimony may be necessary to identify the existence, nature, and probability of medical risks and alternatives, and to explain technical matters beyond lay understanding. The court recognized narrow exceptions to disclosure: true emergencies where consent cannot be obtained and immediate action is necessary; and a limited therapeutic privilege when disclosure itself would pose a serious and immediate threat to the patient's well-being. These exceptions are not carte blanche; the physician bears the burden to justify them, and they must be applied sparingly to avoid undermining patient autonomy. Applying these principles, the trial court erred by conditioning liability solely on proof of a professional disclosure custom and by taking the case from the jury for lack of such evidence.
Cobbs v. Grant is a foundational informed consent case in California and a staple of torts and health law curricula. It modernizes disclosure law by adopting the reasonable-patient materiality standard, clarifies that inadequate disclosure is negligence rather than battery, and sets an objective causation framework. The case also delineates the role of expert testimony and cabins exceptions like therapeutic privilege and emergencies. Together with Canterbury v. Spence and later California cases (e.g., Truman v. Thomas), Cobbs anchors the doctrine that patient autonomy drives the scope of informed consent.
Cobbs v. Grant reoriented informed consent toward the patient's right to decide what risks to assume, replacing deference to professional disclosure practices with a legal duty anchored in what a reasonable patient would find material. By clarifying that inadequate disclosure is negligence rather than battery and by adopting an objective causation test, the decision establishes a clear analytic framework for litigating and adjudicating informed consent claims.