Chester v Afshar [2005] 1 AC 134

A consultant neurosurgeon the appellant, appealed against a finding that he was liable in damages for his failure to warn the respondent of a risk inherent in surgery that he had performed on her. The respondent suffered repeated episodes of lower back pain and had been referred to surgery by the appellant who was experienced in disc surgery. The respondent underwent the surgery and suffered a rare complication known as cauda equina syndrome which was a risk that the appellant had failed to warn her about in advance of the surgery. The judge at first instance had not found that the appellant had been negligent in the actual performance of the surgery.

• The issues in the case relate to where the liability pointed for the respondents’ injuries and whether causation could be proved between, the surgery, lack of advice and the subsequent condition contracted by the respondent.

By a majority, the House of Lords upheld liability for the failure to warn. The surgeon had not negligently performed the operation, but had failed to warn of the very risk which materialised. The patient established that a proper warning would have led her to postpone the operation, although she could not show that she would never undergo similar surgery. The majority accepted a narrow modification of conventional causation reasoning to give effect to the patient's right to an informed choice. Lord Bingham and Lord Hoffmann dissented. The decision does not establish that any failure to warn creates damages liability without a causal connection to the injury.

Chester recognised a narrow causal approach where failure to warn deprived a patient of an informed choice and the undisclosed surgical risk materialised. It did not dispense generally with causation in consent cases or make a surgeon liable for every complication following inadequate advice.

Chester is an exceptional authority about causation and patient choice. It must be distinguished from the general duty to disclose material risks, developed in Montgomery, and from negligence in performing surgery. The supplied source attributed the majority's justification to dissenters and overstated liability without causation. A strong examination answer identifies the risk which should have been disclosed, what the patient would have done, and why the particular causal exception is said to apply.