How should health professionals discharge their duty of care in ensuring patients consent to treatment is informed?

Posted by Eve Piffaretti on
Case of Montgomery v Lanarkshire Health Board [2015] UKSC 11 ("Montgomery") (judgment handed down on 11 March 2015).


An adult with capacity is entitled to decide which, if any, of the available treatments to undergo and the patient's consent must be obtained before any treatment is carried out. In considering what information to provide, the doctor should try to ensure that the patient is able to make an informed judgement on whether to give or withhold consent.

Previously, the test surrounding what information a health practitioner should disclose was found in the case of Sidaway – v – Bethlem Royal Hospital Governors [1985] AC 871. In this case the House of Lords held that it was a matter for doctors to decide how much to tell patients about the risks of treatment, and consequently, that a patient could not sue a doctor in negligence for failing to inform the patient of a risk if other reasonable doctors would not have informed the patient of that risk (applying the Bolam Test to the disclosure of information).

However, in Montgomery the Supreme Court departed from this judgment and expressed the view that a doctor has a duty to take reasonable care to ensure that the patient is informed about any material risks involved in the recommended treatment, and of any reasonable alternative treatments. The test of materiality is whether, in the circumstances, a reasonable person in the same position as the patient would be likely to regard a particular risk as significant, or the doctor is or should reasonably be aware that the patient would be likely to attach significance to it, and it was impossible to reduce to percentage terms the assessment of the materiality of risks.  

The 'therapeutic exception' is a limited exception to the general principle, and it does not allow doctors to prevent their patients from taking an informed decision, as it is the doctor's responsibility to explain in comprehensible terms to the patient why one of the available treatment options is medically preferable to the others, after taking care to ensure that the patient is aware of the considerations for and against each of them.

A doctor is, however, entitled to withhold from the patient information as to a risk if he reasonably considers that its disclosure would be seriously detrimental to the patient's health. From that principle, three points arise:

  1. The assessment of whether a risk is material cannot be reduced to percentages;
  2. The doctor's role would only be performed if the information provided was comprehensible; and
  3. It is important that the therapeutic exception is not abused.


Mrs Montgomery sought damages on behalf of her son who had suffered severe and continuing injuries as a result of shoulder dystocia at the time of his birth. She argued that his injuries had been caused by the failure of a doctor employed by the defendant health board to advise her of the risk of shoulder dystocia, and of the possibility of delivery by elective caesarean section, for which she would have opted had she been properly advised.

Two separate grounds for negligence were advanced by Mrs Montgomery. The first was that she should, during her antenatal care, have been advised about the risk that as the baby was larger than average, his shoulders would not pass easily through her pelvis during a vaginal delivery, (shoulder dystocia), and that delivery by elective caesarean section should be considered. The second concerned the management of her labour, and the argument that there had been negligence in the failure to perform a caesarean section when the cardiotocograph traces indicated a cause for concern. She was considered to be at high risk during pregnancy and delivery because she was small in stature and diabetic.

Although Mrs Montgomery had been informed that she was carrying a larger than usual baby, and had raised concerns about vaginal delivery, the doctor failed to tell her that a diabetic woman had a 9–10% risk of shoulder dystocia during a vaginal delivery. The doctor had taken the view that the risk of this was very small and, that if women were informed about the risks, most would ask for a caesarean section, which she thought was not in their best interests.

Rejecting the claim, the Lord Ordinary had held that as Mrs Montgomery had not asked about any specific risks of vaginal delivery, failure by the doctor to warn her of the risks involved did not amount to a breach of her duty of care. 

On the basis of the expert evidence, the Lord Ordinary had taken the view that the omission was accepted as proper by a responsible body of medical opinion; and even if she had been advised about the risk of serious harm to the baby as a result of shoulder dystocia, she would not have opted to have a caesarean section. Mrs Montgomery's reclaiming motion was refused by an Extra Division of the Inner House of the Court of Session. She appealed to the Supreme Court.


Allowing the appeal, an adult with capacity was entitled to decide which treatment to undergo, and the consent of Mrs Montgomery should have been obtained before any treatment was carried out. The court held that:-

  • A doctor has a duty to take reasonable care to ensure that the patient is informed about any material risks involved in the recommended treatment, and of any reasonable alternative treatments.
  • The doctor should have advised Mrs Montgomery of the risk of shoulder dystocia in the course of a vaginal delivery and should have discussed with her the alternative of an elective caesarean section.
  • On the evidence, there was no basis for the view that Mrs Montgomery, if she had been appropriately advised, would not have opted to have a vaginal delivery.


This is a landmark decision and marks a departure from the traditional test set out in Sidaway v Bethlem Royal Hospital Governors [1985]. It represents a shift in attitude towards how doctors (and other health professionals) discharge their duty of care in ensuring patients provide informed consent to treatment. This was recognised at paragraph 75 of the leading judgment by Lord Kerr and Lord Reed at which they said:

"Since Sidaway, however, it has become increasingly clear that the paradigm of the doctor-patient relationship implicit in the speeches in that case has ceased to reflect the reality and complexity of the way in which healthcare services are provided, or the way in which the providers and recipients of such services view their relationship.

One development which is particularly significant in the present context is that patients are now widely regarded as persons holding rights, rather than as the passive recipients of the care of the medical profession. They are also widely treated as consumers exercising choices: a viewpoint which has underpinned some of the developments in the provision of healthcare services."

Further, the Supreme Court was critical of the approach taken in Sidaway where the onus was placed upon the patient to ask questions of the doctor regarding their treatment and the implication of  the that judgment  being that only in those circumstances only would a doctor be under a duty to provide information in response to the patient's questions. Post Montgomery this is no longer the case. At paragraph 58 of the Montgomery judgment Lord Kerr and Lord Reid state:

"The significance attached in Sidaway to a patient's failure to question the doctor is however profoundly unsatisfactory. In the first place… there is something unreal about placing the onus of asking upon a patient who may not know that there is anything to ask about. It is indeed a reversal of logic: the more a patient knows about the risks she faces, the easier it is for her to ask specific questions about those risks, so as to impose on her doctor a duty to provide information; but it is those who lack such knowledge, and who are in consequence unable to pose such questions and instead express their anxiety in more general terms, who are in the greatest need of information.

Ironically, the ignorance which such patients seek to have dispelled disqualifies them from obtaining the information they desire. Secondly, this approach leads to the drawing of excessively fine distinctions between questioning, on the one hand, and expressions of concern falling short of questioning, on the other hand: a problem illustrated by the present case.

Thirdly, an approach which requires the patient to question the doctor disregards the social and psychological realities of the relationship between a patient and her doctor, whether in the time-pressured setting of a GP's surgery, or in the setting of a hospital. Few patients do not feel intimidated or inhibited to some degree."

This is a judgment of the Supreme Court and will be binding on the lower courts.

For further information please contact Eve Piffaretti, contact details below. 

About the Author

Eve heads our Commercial team in Wales and the Public Law Group. She acts for public sector organisations across the UK advising on public law and regulatory issues.

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