Chester v Afshar

The House considered whether conventional causation rules should be modified where a surgeon negligently fails to warn a patient of a small but inherent risk of surgery and that very risk materialises, although it cannot be shown that, if warned, the patient would never at any time have undergone the operation. The court confirmed that a surgeon owes a duty to warn patients of material risks so that they can decide whether, when and by whom to be operated on. A majority of the House held that, in the unusual circumstances of this case, the normal 'but for' test of causation should be adapted so as to allow recovery where the injury is within the scope of the duty to warn and the claimant would have delayed or sought further advice rather than have the operation when and by whom it was performed.

Background and parties:

The claimant (Miss Chester) consulted a consultant neurosurgeon (Mr Afshar) and, three days later, underwent lumbar surgery which resulted in cauda equina syndrome. The trial judge found that the surgeon had not negligently performed the operation but had failed to warn her of a small (about 1%-2%) risk of serious neurological injury and that, if warned, she would have delayed and sought further opinions. The surgeon (appellant) appealed against the finding of liability based on failure to warn. The Court of Appeal upheld the trial judge; the case came to the House of Lords on appeal.

Nature of the claim and relief sought:

• The claimant sought damages in negligence for the physical injuries she suffered, grounded on the surgeon's failure to warn of the material risk and thereby vitiating informed consent.

Issues framed:

• Does the doctor owe a duty to warn of small but serious risks (scope and rationale of the duty)?
• Can causation be established where the claimant would have postponed or sought further advice but cannot show she would never have had the operation?
• Should conventional causation principles be modified in such cases?

Court's reasoning:

The House reviewed authority (including Sidaway, Fairchild and Chappel v Hart) and academic commentary. The majority regarded the duty to warn as central to patient autonomy and held that, where the injury sustained is within the scope of the very risk about which the patient should have been warned and the patient would have deferred or sought alternatives, the normal causation approach may be modified so that liability follows. The minority would have applied orthodox causation principles (the 'but for' test) and allowed the appeal, holding that the claimant had not shown the breach caused the injury because the risk was inherent and equally likely at any later time or at another surgeon's hands.

Appeal dismissed. By a majority the House held that where a surgeon breaches the duty to warn of a material risk and the injury which occurred is the very risk within the scope of that duty, the claimant who would have delayed or sought further advice (even if she could not show she would never have had the operation) may establish causation and recover damages. The minority would have applied ordinary 'but for' causation and allowed the appeal.

Appeal to House of Lords from the Court of Appeal: [2002] EWCA Civ 724; [2003] QB 356. Trial at first instance before Judge Robert Taylor (liability findings as to failure to warn upheld on appeal to Court of Appeal).