Montgomery v Lanarkshire Health Board [2015] UKSC 11

A doctor failed to warn a diabetic mother about the risk of shoulder dystocia. The baby was born with severe disabilities. The Supreme Court ruled doctors must inform patients of all material risks of a treatment and any reasonable alternatives, establishing a patient-centred test for informed consent.

Facts

The appellant, Mrs Montgomery, was a woman of small stature and a type 1 diabetic. During her pregnancy, it was known that the baby of a diabetic mother is often larger than normal, which carries a 9-10% risk of shoulder dystocia during vaginal delivery (where the baby’s shoulders become stuck after the head has been delivered). This is an obstetric emergency which can result in severe injury to the baby, including oxygen deprivation and cerebral palsy. Mrs Montgomery had expressed concerns to her consultant obstetrician about her ability to deliver a large baby vaginally. The consultant did not disclose the specific risk of shoulder dystocia, nor the alternative of an elective caesarean section. The consultant’s reasoning, accepted as standard practice at the time, was that if the risk were mentioned, most diabetic mothers would opt for a caesarean, which was not considered to be in the maternal interest. During delivery, shoulder dystocia occurred, and the baby, Sam, suffered from oxygen deprivation, resulting in cerebral palsy and other serious, lifelong injuries.

Issues

The central legal issue was the scope of a doctor’s duty of care to a patient in relation to the disclosure of risks. The question was whether the standard of care should be determined by the standard of a responsible body of medical opinion (the ‘Bolam test’, as applied to disclosure in Sidaway v Board of Governors of the Bethlem Royal Hospital Governors), or whether the law should impose a duty on doctors to disclose any risk which a reasonable person in the patient’s position would consider significant (a patient-centred test).

Judgment

The Supreme Court unanimously allowed the appeal, finding the health board liable. The leading judgment was delivered by Lord Kerr and Lord Reed.

The Majority Judgment

The Court fundamentally departed from the reasoning in the previous leading case of Sidaway, which had applied the professional practice standard (the Bolam test) to the issue of informed consent. The Court held that the assessment of whether a risk should be disclosed is no longer a matter of clinical judgment to be judged by professional standards. Instead, it is a duty determined by the patient’s right to make an informed decision.

Lords Kerr and Reed stated the new test for the duty of doctors to inform patients as follows:

An adult person of sound mind is entitled to decide which, if any, of the available treatments to undergo, and her consent must be obtained before treatment interfering with her bodily integrity is undertaken. The doctor is therefore under a duty to take reasonable care to ensure that the patient is aware of any material risks involved in any recommended treatment, and of any reasonable alternative or variant treatments.

They went on to define what constitutes a ‘material risk’:

The test of materiality is whether, in the circumstances of the particular case, a reasonable person in the patient’s position would be likely to attach significance to the risk, or the doctor is or should reasonably be aware that the particular patient would be likely to attach significance to it.

The judgment stressed that the doctor’s advisory role involves a dialogue with the patient to ensure they can make an informed choice. The Court found that in Mrs Montgomery’s case, given her diabetes and her specific concerns about the size of her baby, the risk of shoulder dystocia was a material risk. The reasonable alternative of a caesarean section should have been discussed with her. Had she been properly informed, the court concluded she would have chosen a caesarean delivery, and her son would have been born unharmed.

Implications

The decision in Montgomery is a landmark case that fundamentally reshaped the law on informed consent in the United Kingdom. It marked a definitive shift away from medical paternalism, epitomised by the Sidaway decision, towards a model based on patient autonomy and shared decision-making. The judgment clarifies that the duty to warn a patient of risks is not determined by what doctors think a patient needs to know, but by what a reasonable patient would consider significant to their decision. This has required a significant change in practice for healthcare professionals, demanding greater communication and a dialogue-based approach to consent, ensuring patients are empowered to make choices about their own bodies based on adequate information on risks, benefits, and reasonable alternatives.

Verdict: The appeal was allowed.

Source: Montgomery v Lanarkshire Health Board [2015] UKSC 11