Consent to Medical Treatment: The Role of the Expert

6 Min Read

Paul Sankey - Enable LawIn 2015 the law governing patient consent to treatment changed with the Supreme Court decision in Montgomery v Lanarkshire Health Board. With that decision, the role of medical experts in relation to advice and consent also changed.

Consent to Treatment: The Law

Before Montgomery, whether medical advice was adequate was judged by the standards of the medical profession. The test was whether a responsible body of doctors practicing the same discipline would have given similar advice. This was the Bolam test, which still applies to diagnosis and treatment. So if a GP’s advice was in question, the test was whether a responsible body of GPs would have given similar advice. If they would, the advice was adequate and there was no breach of duty.

With the decision in Montgomery, the law changed. The Bolam test no longer applied to advice. A doctor was under a duty to take reasonable care 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. A risk is material if, in the circumstances of a 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 attach significance to it.

Patients and Autonomy

Key to the Supreme Court’s decision was patient autonomy – the patient’s right to decide what risks to run. From the patient’s point of view this is not just a medical decision. It will be influenced by other considerations – their values, goals and concerns generally. Different patients will regard different factors as significant. They will weight risks differently.

Interestingly, research by the Kings Fund (Patient Preferences Matter) suggests that doctors are actually quite poor at understanding what their patients want. By way of one example, doctors thought 71% of patients with breast cancer rated preserving the breast as a top priority. When patients were asked the figure was in fact only 7%. This suggests that enshrining patient autonomy in the law of consent is a much-needed corrective.

In the light of Montgomery, the doctor must now take reasonable care to identify what amounts to a material risk for each patient. This involves considering what a reasonable person like this patient would want to be told and providing that information to the patient. There should be dialogue between doctor and patient, sufficient for the doctor to identify the patient’s concerns and work out what information to give. With the right information, patients can make their decision. They can properly exercise autonomy.

Advice to Patients: 2 Roles

The Supreme Court saw the tasks of advising a patient as involving 2 distinct roles. The first involves the use of uniquely medical skill. The second does not.

The first role is considering what the reasonable treatment options are available. There always be an alternative to a particular treatment, even if it is no treatment. The next part of the role is to consider the risks and benefits. Fulfilling this role involves exercising medical skill.

The second role is identifying what risks are material for this individual patient – what a reasonable patient in this patient’s position would expect to know. This is not a task requiring a uniquely medical skill. The doctor will need to take into account the particular concerns of this individual with his or her values, priorities and concerns. Some of those considerations will be non-medical. They will be different for each patient.

Consent: The Role of Expert Evidence

The role of expert evidence is to assess the exercise of the first role but not the second.

This involves

  • identifying the range of reasonable treatment options; and
  • identifying the risks and benefits of those options.

The expert should not comment on the exercise of second role. This is not a matter of uniquely medical skill and therefore not a matter for expert evidence. The expert should not therefore be commenting on:

  • the nature and extent of discussion with the patient; and
  • whether risks are material risks for this individual patient.

These issues fall within the second role. They involve an assessment of whether a patient’s rights have been respected. As Lords Kerr and Reed said in Montgomery, ‘Responsibility for determining the nature and extent of a person’s rights rests with the courts, not with the medical professions.’

Recent Cases

2 judgments from 2017 help to demonstrate the expert’s role.

  • Thefaut v Johnson [2017] EHWC 497

Mrs Thefaut was found not to have given valid consent to spinal surgery because the advice her surgeon gave was inaccurate. In terms of the 2 roles identified above, the surgeon’s advice fell within the first category. Experts gave evidence at trial as to the percentage risks and benefits of surgery as opposed to conservative treatment. The court found that the surgeon had got his figures wrong. He had under-estimated the risks of surgery, over-estimated its benefits and failed to advise on the benefits of conservative management as an alternative to surgery.

  • Webster v Burton Hospitals NHS Foundation Trust [2017] EWCA Civ 62

This case concerned an obstetrician who failed to advise a mother of the risk of antenatal death associated with unusual abnormalities observed on ultrasound scans. Details of this risk and its significance for the management of the birth of her child in effect fell within the first role. These issues were properly the subject of expert evidence. However, the nature of the discussion with the mother fell within the second role.

The claim was heard a few months before the Supreme Court decision in Montgomery. The judge therefore applied the Bolam test to the question of consent. The medical expert for the Defendant thought a responsible obstetrician would not have considered the abnormalities significant and would not therefore have advised the mother. The expert for the Claimant only thought a discussion necessary had the obstetrician taken an unusual course in failing to induce. Applying the Bolam test, the claim failed at trial. However, an appeal was heard after the decision in Montgomery. The Court of Appeal rejected the views of both experts. It thought the mother was entitled to be told of the risk, as for her it was a material one. Making this assessment formed part of the second role. It was not a matter for experts and the Court of Appeal disregarded their views in making its decision.


The change in the law of consent with the Supreme Court’s decision in Montgomery has changed the role experts play in giving evidence. Expert evidence is appropriate as to whether a doctor has correctly identified what amount to reasonable treatment options. It is also appropriate as to the risks and benefits of those alternatives. However, the nature and extent of a doctor’s discussion with a patient is not a matter for expert evidence. Assessing the advice given is not a matter of uniquely medical skill. Similarly identifying what amounts to a material risk is not a subject for expert evidence.

Address these issues goes beyond an expert’s remit. They are matters for the court.