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New judgment on patient consent

Post date: 30/06/2017 | Time to read article: 2 mins

The information within this article was correct at the time of publishing. Last updated 07/07/2021

The law on informed consent has changed following a Supreme Court judgment.

Doctors must now ensure that patients are aware of any “material risks” involved in a proposed treatment, and of reasonable alternatives, following the judgment in the case Montgomery v Lanarkshire Health Board.

This is a marked change to the previous “Bolam test”, which asks whether a doctor’s conduct would be supported by a responsible body of medical opinion. This test will no longer apply to the issue of consent, although it will continue to be used more widely in cases involving other alleged acts of negligence. 

The new test

In a move away from the ‘reasonable doctor’ to the ‘reasonable patient’, the Supreme Court’s ruling outlined the new test: “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.”

It is notable that this decision enshrines in law principles that are already in the GMC’s guidance on consent, Consent: Patients and Doctors Making Decisions Together (2008), and which are reflected in MPS’s own advice materials on consent [read bespoke advice for doctors in EnglandWalesScotland and Northern Ireland].

This was confirmed in a statement from GMC chief executive Niall Dickson, who said: “We are pleased that the court has endorsed the approach advocated in our guidance on consent. Good Medical Practice and Consent: Patients and Doctors Making Decisions Together make it clear that doctors should provide person-centred care. They must work in partnership with their patients, listening to their views and giving them the information they want and need to make decisions.”

The case

In 1999, Nadine Montgomery gave birth by vaginal delivery to Sam. The birth was complicated by shoulder dystocia. Medical staff performed the appropriate manoeuvres to release Sam but, during the 12-minute delay, he was deprived of oxygen and subsequently diagnosed with cerebral palsy.

Mrs Montgomery is diabetic and small in stature and the risk of shoulder dystocia was agreed to be 9-10%. Despite expressing concern to her consultant about whether she would be able to deliver her baby vaginally, the doctor failed to warn Mrs Montgomery of the risk of serious injury from shoulder dystocia or the possibility of an elective caesarean section. 

Mrs Montgomery brought a claim against Lanarkshire Health Board, alleging that she should have been advised of the 9-10% risk of shoulder dystocia associated with vaginal delivery notwithstanding the risk of a grave outcome was small (less than 0.1% risk of cerebral palsy). 

It was also alleged that delivery by caesarean section ought to have been offered to Mrs Montgomery, and that this would have prevented the child’s injury.

Lanarkshire Health Board argued that only the risk of a grave adverse outcome triggered the duty to warn of such risks and that, because the risk of such an outcome was so low and that an expression of concern was not the same as a direct question requiring a direct answer, no warning was required.


The Supreme Court held that the question should have been about Mrs Montgomery’s likely reaction if told of the risk of shoulder dystocia. The unequivocal position was that she would have chosen to give birth by caesarean section.

The Bolam test was deemed unsuitable for cases regarding the discussion of risks with patients, as the extent to which a doctor may be inclined to discuss risks with patients is not determined by medical learning or experience.

The court ruled that Mrs Montgomery should have been informed of the risk of shoulder dystocia and given the option of a caesarean section.

Mrs Montgomery was awarded £5.25 million in damages.

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