Montgomery v Lanarkshire Health Board

1. Case Citation and Basic Information

Case Name: Montgomery v Lanarkshire Health Board

Citation: [2015] AC 1430; [2015] UKSC 11

Court: Supreme Court of the United Kingdom (on appeal from the Court of Session, Scotland)

Date of Decision: 11 March 2015

Bench: Lord Neuberger, Lady Hale, Lord Kerr, Lord Clarke, Lord Wilson, Lord Reed and Lord Hodge

Leading Judgment: Lord Kerr and Lord Reed (with whom the other Justices agreed)

2. Introduction

Montgomery v Lanarkshire Health Board is extensively regarded as the leading case on informed consent in UK medical negligence law.^[1] Decided by the Supreme Court in 2015, the case departed from the House of Lords’ previous decision in Sidaway v Board of Governors of the Bethlem Royal Hospital,^[2] and changed the test for determining when a doctor is under a duty to warn a patient of risks associated with a proposed treatment. Instead of leaving the decision to the medical professionals, the Court held that patients themselves should determine which risks are significant to them. This shift was significant as it not only changed the legal test, but also the broader recognition that patients, rather than medical professionals, are best suited to weigh the risks relevant to their own treatment decisions.

The case began under Scots delict law, originating from the Court of Session before reaching the UK Supreme Court, which is the final court of appeal for civil cases from Scotland, England and Wales, and Northern Ireland. Even though the case was decided under Scots law, the ruling on informed consent has since been applied equally in English law, replacing Sidaway^[3] across all jurisdictions in the UK.

3. Facts of the Case

The appellant, Nadine Montgomery,was a pregnant woman with insulin-dependent diabetes mellitus. She was also of small stature. Women with her condition often face a maternity increased risk that, during vaginal delivery, the baby’s shoulder may struggle to pass through the pelvis after the head is delivered, a complication known as dystocia. In her case, medical professionals expected her risk of this complication at approximately nine to ten percent.^[4]

Mrs Montgomery’s antenatal care was handled by Dr Dina McLellan, an obstetrician at Lanarkshire Health Board. Although Dr McLellan was aware of the increased risks, she did not bring it up with Mrs Montgomery, and did not mention the alternative option of an elective caesarean section either. Dr McLellan later explained that in her practice, she routinely avoided disclosing the risk of dystocia to diabetic patients because, in her judgement, most patients would choose to have a C-section, an outcome that she believed would not be in their best interests.^[5]

On 1 October 1999, Mrs Montgomery underwent vaginal delivery. Shoulder dystocia occurred, and the complications that followed, including a period of occlusion of the umbilical cord, resulted in her son being born with severe disabilities, including cerebral palsy. Mrs Montgomery later sued for negligence, arguing that if she was informed of the risks, she would have chosen the alternative method of a caesarean delivery and her son’s injuries would have been avoided.^[6]

4. Legal Issues

• Whether the Bolam test, which checks if a doctor has acted within the line of medical opinion, is the appropriate standard for deciding a doctor’s duty to disclose risks of treatment to a patient.^[7]
• Whether, if the test does not apply, a doctor has a duty to disclose the material risks of a suggested treatment and reasonable alternatives, and how materiality should be judged.
• Whether Dr McLellan’s failure to disclose the risk of shoulder dystocia and the alternative of caesarean section amounted to a breach of that duty.
• Whether the breach of duty caused the injury suffered by Mrs Montgomery’s son, in the sense that proper disclosure would have led her to choose the alternative option of delivery by caesarean section.

5. Arguments Presented

5.1 Appellant’s (Montgomery’s) Arguments

Mrs Montegomery’s counsel argued that the Bolam test, as applied in Sidaway, was no longer the right approach and should be departed from.^[8] They submitted that disclosing risks is different from diagnosing or treatment, it is about giving patients the information they need to exercise personal choice, not a matter requiring specialist medical skills. The appellant argued that the correct approach should question whether a reasonable patient in her position would have considered the risk of dystocia as significant, and that Dr McLellan’s own evidence showed that such a risk was material. They further argued that if she had been properly informed, Mrs Montgomery would have chosen a caesarean section, so the failure to disclose the risk directly led to her son’s injuries.

5.2 Respondent’s (Lanarkshire Health Board’s) Arguments

The Health Board defended the approach taken by lower Scottish courts, arguing that the Bolam test, as endorsed by the majority in Sidaway, was still the correct approach for judging whether a doctor’s failure to disclose risk amounted to negligence.^[9] It argued that Dr McLellan’s decision not to disclose the risk of dystocia was a responsible clinical judgment, backed by evidence that other competent doctors would have done the same. The board also disputed causation, arguing that even if the risk had been disclosed, there was no certainty Mrs Montgomery would have chosen a caesarean section over vaginal delivery.

6. Court’s Reasoning and Analysis

The Supreme Court held that the majority approach in Sidaway, which applied the Bolam test to risk disclosure, should no longer be followed.^[10] It reasoned that Bolam was meant for matters needing clinical expertise, like diagnosis and treatment situations. Decisions about what information to give a patient before they consent, however, is different as it does not primarily depend on medical expertise; they concern what an individual patient would wish to know in order to make an informed decision, which is tied more to patient autonomy.

The Court set out on a new test: a doctor must take reasonable care to make sure a patient knows about any material risks of a treatment, and any reasonable alternatives.^[11] A risk is material if a reasonable person in the patient’s position would likely see it as significant, or if the doctor is aware that the patient would. The Court emphasized that materiality is not to be assessed by reference to statistical probability alone, it depends on a combination of factors, such as severity of the potential risks, nature of the risk, and its significance for the patient’s circumstances and values.

The Court recognized two narrow exceptions to this duty. First, a doctor can withhold information if disclosing the risk would cause harm to the patient’s health, sometimes described as therapeutic privilege. Second, a doctor may avoid disclosure in cases of necessity, such as a situation where a patient requires urgent care and does not have the time to make decisions.^[12] Neither exception was found to be applicable in Mrs Montgomery’s case.

Applying this framework, the Court found the risk of shoulder dystocia was substantial  and that a reasonable patient in Mrs Montgomery’s position should have been informed and given the option of a caesarean section.^[13] The doctor’s failure to do so was a breach of duty, not a clinical judgment. On causation, the Court held that the relevant question was whether disclosure would have led Mrs Montgomery to choose a caesarean section, not whether she would have predicted cerebral palsy specifically.^[14] Since Dr McLellan herself acknowledged that Mrs Montgomery would have probably requested a caesarean section if properly informed, the Court found that causation was established.

7. Judgment and Ratio Decidendi

The Supreme Court unanimously allowed Mrs Montgomery’s appeal. The ratio decidendi of the case can be stated as follows: an adult person of sound mind has the right to decide which, if any, medical treatment to undergo, and a doctor is therefore under duty to take reasonable care to ensure that the patient is aware of material risks inherent in a recommended treatment and of any reasonable reasonable alternatives.^[15] A risk is material if a reasonable patient would likely see it as significant, or if the doctor knows the particular patient would. This duty of disclosure is governed by ordinary principles of negligence related to patient autonomy, and is no longer attached to the Bolam test, which still applies to diagnosis and the selection of treatment.

8. Critical Analysis

8.1 Significance of the Decision

Montgomery represents a major shift in the doctor-patient relationship under UK law. By removing questions of risk disclosure from the Bolam standard, the Supreme Court confirmed that patient autonomy, not professional consensus, should determine what a patient is told before consenting to treatment. This brought the law closer to modern medical ethics, which had been moving away from paternalistic practice towards shared decision-making.

8.2 Implications and Impact

The decision had a considerable impact on clinical practice, leading to more detailed and better-documented discussions of risk and alternative treatments as part of the NHS consent procedures. It has been applied consistently and refined in subsequent case law, including Duce v Worcestershire Acute Hospitals NHS Trust, which looked at what alternative treatments must be disclosed,^[16] and McCulloch v Forth Valley Health Board, where the Supreme Court further clarified how those alternatives should be identified within the Montgomery framework.^[17] The case is now a standard reference point in litigation, clinical negligence practice, and medical education across the UK.

8.3 Critical Evaluation

The judgment has generally been accepted as principle and an overdue recognition of patient autonomy, replacing a test that allowed the medical professionals to define the limits of a patient’s right to information. It is also more consistent with modern standards of consent as a two-way conversation, not just a list of statistics to inform the patient. 

Still, criticism and concern has been raised for this case. The materiality test, while being more patient-centred, creates uncertainty for doctors, since it is difficult to predict what a reasonable patient would consider significant. Some critics have also raised concern that the ruling may encourage more defensive clinical practice, with doctors disclosing an excessive number of risks to avoid liability, which may overwhelm patients rather than help them decide. Additionally, the practice of a thorough, more individualised consent conversation further demands on a doctor’s time within already stretched healthcare systems.

Despite these concerns, the balance found in Montgomery between respecting clinical expertise in diagnosis and treatment, and protecting patient autonomy in matters of consent, is generally seen as workable and sound.

9. Conclusion

Montgomery v Lanarkshire Health Board fundamentally altered the legal landscape governing informed consent in the United Kingdom. By rejecting the Bolam approach to risk disclosure in favour of a patient-centred test of materiality, the Supreme Court affirmed that patients, not doctors, are entitled to determine which risks matter to them when deciding whether to undergo treatment. The case remains the definitive modern statement of the law on informed consent in medical negligence, and its principles continue to shape both clinical practice and subsequent judicial decisions across the UK.

Bibliography

Primary Sources

Cases

Duce v Worcestershire Acute Hospitals NHS Trust [2018] EWCA Civ 1307

McCulloch v Forth Valley Health Board [2023] UKSC 26

Montgomery v Lanarkshire Health Board [2015] UKSC 11, [2015] AC 1430

Sidaway v Board of Governors of the Bethlem Royal Hospital and the Maudsley Hospital [1985] AC 871

Secondary Sources

Websites

UK Supreme Court, ‘Montgomery (Appellant) v Lanarkshire Health Board (Respondent) (Scotland)’ (Press Summary, 11 March 2015) https://www.supremecourt.uk/cases/uksc-2013-0136 accessed 10 August 2026.

^[1]Montgomery v Lanarkshire Health Board [2015] AC 1430.

^[2]Sidaway v Board of Governors of the Bethlem Royal Hospital and the Maudsley Hospital [1985] AC 871.

^[3]Ibid.

^[4]Montgomery (n 1) [10]-[11].

^[5]Ibid [12]-[15].

^[6]Ibid [16]-[18].

^[7]ibid [1]-[2].

^[8]Sidaway (n 2) 899-900 (Lord Diplock).

^[9]ibid 902-903 (Lord Bridge).

^[10]Montgomery (n 1) [78]-[81].

^[11]ibid [87].

^[12]ibid [88], [91].

^[13]ibid [90].

^[14]ibid [102]-[104].

^[15]Montgomery (n 1) [87].

^[16]Duce v Worcestershire Acute Hospitals NHS Trust [2018] EWCA Civ 1307.

^[17]McCulloch v Forth Valley Health Board [2023] UKSC 26.