## Facts

- Ms. Chester suffered from chronic back pain affecting her mobility and bladder control.
- Following medical assessment, Mr. Afshar, a neurosurgeon, recommended spinal surgery to address her condition.
- The surgical procedure involved a known 1-2% risk of nerve damage that could result in paralysis.
- Mr. Afshar did not inform Ms. Chester of this specific risk prior to undertaking the surgery.
- The operation was performed with due care and skill; nonetheless, Ms. Chester suffered paralysis—a complication within the identified risk.
- Ms. Chester claimed that, if warned, she would have delayed her decision or sought a second opinion, forming the basis of her negligence claim for lack of informed consent.

## Issues

1. Does a failure by a medical professional to disclose material risks of surgery constitute negligence, even if the procedure itself is performed competently?
2. Should traditional causation principles be modified in cases where a breach of the duty to warn is established, given the uncertainty about whether a patient would have proceeded with the surgery if informed?
3. Can a medical professional be held liable for a risk materializing when the actual harm may not be shown to have resulted directly from the failure to warn, but from the exercise of patient autonomy?

## Decision

- The House of Lords, by a 3-2 majority, found in favour of Ms. Chester.
- The court determined that strict application of the traditional 'but for' causation test would undermine the practical effect of the duty to warn.
- It was held that liability exists for failure to warn of material risks, even where the patient may have consented at another time.
- The judgment was based on the importance of vindicating patient autonomy and right to make informed choices about medical treatment.
- The court explicitly recognized a departure from the conventional causation analysis in these circumstances.

## Legal Principles

- The duty of informed consent requires disclosure of material risks by medical professionals to enable patient autonomy.
- The causation requirement may be modified where upholding standard analysis would negate the purpose of the duty to warn.
- Damages may be awarded for loss of opportunity to make an autonomous medical decision, not merely for physical harm.
- The decision places primacy on patient rights over purely procedural application of causation tests.
- The law distinguishes claims based on failure to inform in medical cases from general tort law causation principles.

## Conclusion

The House of Lords in Chester v Afshar departed from orthodox causation standards to ensure meaningful protection for patient autonomy, holding that a doctor's failure to inform of material risks is actionable in negligence even if the patient may have otherwise accepted the risk at a later date, thereby affirming the centrality of informed consent in medical law.


Chester v Afshar [2005] 1 AC 134