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Why Montgomery v Lanarkshire Health Board is important

In Montgomery v Lanarkshire Health Board, the Supreme Court concluded that the decision by a doctor on whether to disclose a risk to a patient is not subject to the Bolam principle. This is because the decision is a ‘value judgement’, rather than informed by medical learnings and experience.


Mrs Montgomery suffered from insulin dependent diabetes mellitus. This increases the risk of complications during birth, notably the baby being larger than normal. The primary concern is ‘shoulder dystocia’, which is where the baby’s shoulders are wider than the head. The chances of shoulder dystocia with a diabetic mother is about 9-10%. In some cases, this can result in a more difficult birth. There is a very small chance (0.1/0.2%) that the baby is consequently born with  a severe disability, or dies during birth.

Mrs Montgomery was told her baby was larger than normal, but not about the increased risk of shoulder dystocia.

During birth, there was indeed difficulty because of the child’s size. For about 10 minutes whilst the doctors tried to release the child, the baby was deprived of oxygen. The result was that the child was born with cerebral palsy.


The claimant brought an action against the Health Board. They said the doctors were negligent for two reasons: (1) failing to advise her of the risks of vaginal delivery, and the alternative option of elective cesarean; and (2) in the delivery of the child.

At trial, both grounds of negligence were rejected. The case reached the Supreme Court, but only on the first alleged ground of negligence.

Mrs Montgomery’s evidence was that she would have elected for a caesarean had she been told about the risks.


Whether the doctors failed to take reasonable care by not telling Mrs Montgomery the risk of shoulder dystocia.

The defendant health board defended not telling the claimant, or other mothers in a similar position, about the risk of shoulder dystocia. The doctors’ evidence was that the risk of the child suffering from a serious problem is very small, and she worries that mentioning it to an expecting mother would likely result in her asking for a caesarean. She concluded that a caesarean was not in the maternal interests of the mother.


The Supreme Court held in favour of Mrs Montgomery. Therefore, the doctors failed to take reasonable care by not disclosing the risks of vaginal delivery to Mrs Montgomery.


The Supreme Court distinguished decisions whether to disclose a risk from those involving ‘purely medical considerations’ (such as what treatment to give). Where the decision is whether to disclose a risk to the patient, the Bolam test is inappropriate. The difference is that the former involves a value judgement informed by a doctor’s experience and instinct. Lord Kerr and Reed said:

because the extent to which a doctor may be inclined to discuss risks with a patient is not determined by medical learning or experience, the application of the Bolam test to this question is liable to result in the sanctioning of differences in practice which are attributable not to divergent schools of thought in medical science, but merely to divergent attitudes among doctors as to the degree of respect owed to their patients.

The Court therefore did not ask whether the doctor’s actions are reflected by a reasonable body of medical professionals. Instead, the Court had to decide a more specific test for cases of disclosure. This duty was defined by Lord Kerr and Reed as follows:

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.

One important factor was that current society has moved away from ‘medical paternity’ (where patients are entirely reliant on information by their doctors). Instead, today’s patients are expected to take responsibility for themselves, including the risks of certain procedures. Therefore, they should be given the information required to make a decision.

Applyied to the current facts, because the Health board should have disclosed the risks associated with shoulder dystocia to Mrs Montgomery.

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Breach of Duty

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