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Montgomery v Lanarkshire Health Board (Scotland)

16 March 2015

The Supreme Court has handed down judgment in the case of Montgomery v. Lanarkshire Health Board with the effect of reversing the previous House of Lords authority on the law governing informed consent. The claimant’s claim was allowed and damages of £5.25 million were awarded.

The test now requires an explanation of all material risk to a patient unless the situation is one of medical emergency or where the practitioner considers that explanation of the risk would be to the detriment of the patient’s health.

The Judgment brings the law into line with current GMC guidance and supports the approach adopted by the lower Courts since 1999.

Mrs Montgomery’s Case

Mrs Montgomery brought a claim on behalf of her son in respect of his birth in 1999.

As the Claimant suffered with diabetes, the pregnancy was deemed to be high risk, by virtue of the fact that diabetic mothers are likely to have babies that are larger than normal, with a particular concentration of weight round the shoulders. This creates 9-10% risk that during delivery the shoulders are too wide to pass through the birth canal, a process known as shoulder dystocia.

If this occurs there is a small risk (put at 0.1%) that the umbilical cord will become occluded, causing hypoxia and resulting in consequential cerebral palsy or death.

Mrs Montgomery was not informed of the risk of shoulder dystocia, but claimed that if she had been informed, she would have opted for a delivery by caesarean section.

At birth shoulder dystocia did occur and the cord became occluded, causing hypoxia and resulted in her son sustaining severe brain injury. A claim was brought again the health authority on the basis of the failure to explain the risk of shoulder dystocia.

The Law as it Stood

The law was governed by the House of Lords authority in Sidaway v. Board of Governors of the Bethlem Hospital and Maudsley Hospital and Ors (1985) which related to spinal surgery provided in 1973. In that case a general discussion with regard to the surgery was deemed sufficient to alert the patient to the inherent risk of surgery, and in the absence of the patient asking any questions it was deemed that a reasonable body of skilled practitioners would have done no more (the Bolam test).

It was on the basis that both the Court at first instance and the lower appeal court dismissed Mrs Montgomery’s claim.

The Supreme Court Judgment

The Supreme Court overturned Sidaway unanimously. The test now to be applied was outlined by Lord Reed:

  • In all adults of sound mind, there is a duty to take reasonable care to ensure the patient is aware of any material risks involved in any recommended treatment.
  • A risk is material if it is one where, 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 particular individual patient has attached significance to a risk.
  • The patient is required to understand the seriousness of the risk and the anticipated benefits and risk of the proposed treatment and reasonable alternatives.
  • Informed consent is neither “bombarding the patient with technical information which cannot be reasonably understood” nor a process “demanding a signature on a consent form”.

There are two exceptions to the rule:

  1. A medical practitioner is entitled to withhold from the patient information as to the risk if it is considered that disclosure would be seriously detrimental to the patients’ health (the therapeutic exemption);
  2. In circumstances of necessity, where treatment is required urgently but the patient is unconscious.

The Court agreed that Mrs Montgomery would have opted for a caesarean section had the risk been explained.


  1. In cases of informed consent, there is no longer a defence that a medical practitioner failed to explain a minimal risk, even those risks with a grave consequence, on the basis that a reasonable body of opinion would support that omission. The law now requires explanation of all material risks.
  2. The requirement explicitly applies to all those engaged in healthcare provision. From a current practice point of view, this mirrors the GMC guidance which has been in place since 2008. The test effectively codifies the approach of the lower Courts in England.
(see Pearce v. United Bristol Healthcare NHS Trust 1999))
  1. The test of materiality will be applied retrospectively. It is noteworthy that Mrs Montgomery’s case pre-dated the GMC guidance and the new test will apply in all cases.
  2. The circumstances where the therapeutic exception defence will be very rare. The Court did not give any example of this other than the exception “should not be abused” and is “limited”. 

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The content on this page is provided for the purposes of general interest and information. It contains only brief summaries of aspects of the subject matter and does not provide comprehensive statements of the law. It does not constitute legal advice and does not provide a substitute for it.

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