Material Risk

Before Montgomery, doctors' disclosure obligations were largely judged by reference to responsible medical practice — what a reasonable body of doctors would have disclosed. Montgomery reoriented the test around the patient, asking what risks a reasonable person in that patient's position would want to know about, or that the particular patient would want to know about, and required that these be discussed rather than withheld on paternalistic grounds. The GMC's current professional standards on Decision Making and Consent operationalise this: doctors should usually discuss 'recognised risks of harm that you believe anyone in the patient's position would want to know', 'the effect of the patient's individual clinical circumstances on the probability of a benefit or harm occurring', and 'risks of harm and potential benefits that the patient would consider significant for any reason.'

The GMC guidance also makes clear this is not a box-ticking exercise requiring every conceivable risk to be listed: 'it wouldn't be reasonable to share every possible risk of harm, potential complication or side effect. Instead, you should tailor the discussion to each individual patient, guided by what matters to them.' One category is treated as effectively always material regardless of statistical likelihood: 'any risk of serious harm, however unlikely it is to occur' should generally be raised, reflecting Montgomery's insistence that materiality depends on significance to the patient, not just probability.