When is a patient's consent to treatment informed?

In its landmark decision set out in Montgomery v Lanarkshire Health Board (2015), the Supreme Court 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. This decision 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.

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:

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