What does informed consent actually require?
That a person understands what is proposed, the material risks, and the alternatives, and agrees voluntarily — and the legal standard in the UK changed significantly in 2015, in a way that shifted the focus onto the patient rather than the profession.
The three elements required for valid consent:
Capacity — the ability to understand, retain, weigh and communicate a decision about this specific matter at this time. Capacity is decision-specific and can fluctuate, and adults are presumed to have it unless established otherwise. An unwise decision is not evidence of lacking capacity, which is stated explicitly in the Mental Capacity Act.
Voluntariness — free from coercion or undue pressure, including from family.
Information — sufficient to make the decision.
What changed in 2015: Montgomery. Before it, the test for how much information to give was essentially whether a responsible body of medical opinion would have disclosed it — a professional standard.
Montgomery v Lanarkshire Health Board replaced this. A doctor must take reasonable care to ensure the patient is aware of material risks and of reasonable alternatives. A risk is material if a reasonable person in the patient's position would attach significance to it, or if the doctor is or should be aware that this particular patient would.
This is the crucial shift: materiality depends on the patient, not on professional consensus. A small risk affecting something that matters particularly to this person is material even if it is statistically minor.
What must be discussed: the nature and purpose of the proposed treatment; material risks; reasonable alternatives, including doing nothing, which is frequently omitted and is a legitimate option; and the likely outcome of each.
Consent is a process, not a form. A signature records that a discussion occurred; it does not establish that consent was informed. Consent obtained without discussion is not valid however many forms were signed.
It can be withdrawn at any time, including during a procedure where practicable.
Where capacity is lacking, decisions are made in the person's best interests, accounting for their known wishes, beliefs and values, and consulting those close to them.
General information, not medical or legal advice.