As established in this case (1-), Where a competent patient makes it clear that he does not wish to receive treatment which is, objectively, in his medical best interests, it is unlawful for doctors to administer that treatment. Personal autonomy or the right of self-determination prevails.This is a very extreme and rigidly held area of the law. For example, doing a C-section on a pregnant woman to save both her life and the life of her fetus was found to be unlawful as it was carried out despite her refusal to consent (2-).
If treatment is given without consent (implied, such as holding out an arm for a vaccine or express, or written/verbal), then the doctor is guilty of battery (touching without consent)!
Consent depends on the quality of information given to the patient before the procedure was conducted, and whether or not they understood what was going to happen.
In order for consent to be valid, the one giving it must be a competent adult – that is, the patient must be able to (1) understand the information they are given, (2) retain that information and use it to come to an informed decision, (3) without being subject to coercion or undue influence, (4) and then communicate this decision to others (3-). Well technically, it’s just 1, 2 and 4 that are the 3 steps to determining competency, but the thing about undue influence is really important too.
If you’re interested, there was a case where a 20-year old was pregnant when she was injured in a car accident (4-). She desperately needed a blood transfusion, but had been brought up as a Jehovah’s Witness (they don’t believe in blood transfusions). She refused blood transfusions twice but the doctors basically gave them to her anyway because of the “undue influence” of her mother who was proper hardcore Jehovah’s Witness and was effectively poisoning her daughter’s mind. There’s a bit more to the story but it’s not necessary – the point is that the patient must not be subject to undue influence when consenting to (or refusing) treatment.
Importantly, a person’s decision does NOT have to be considered reasonable for them to be considered competent to make it. Patient C (paranoid schizophrenic at Broadmoor) suffered an injury that caused his foot to become gangrenous and require amputation, without which there was an 85% chance he would die. As he understood that the doctors thought he was going to die and weighed this information to come to the decision himself that they were wrong and he did not want the operation, he had the capacity to decide not to consent and so the doctors were not allowed to perform the amputation (again, sorry about the mouthful). His mental health issues did not render him automatically incompetent and his autonomy was upheld (5-).
Lawful treatment can be given without consent in circumstances of necessity where emergency intervention is required to prevent grave injury/ death and the patient is not in a position to consent (passed out). Under the Mental Health Act, patients may be given compulsory treatment and admission for assessment, but only for the mental disorder in question.
A child is considered to be anyone under the age of 18 and in accordance with the Children Act (1989) anybody with parental responsibility on behalf of the child can give consent so long as the decision safeguards/promotes the welfare of the child.
The Family Reform Act 1969 allows children aged 16 or 17 to consent to treatment and have increasing levels of autonomy. However, the child will have to display Gillick Competence (6-), named after the first case in which a competent child was acknowledged- Mrs. Gillick challenged the legality of doctors providing contraceptive advice and treatment to children under the age of 16 without parental consent so long as the child is able to show that they are intelligent enough to understand fully what it is they are consenting to.
If a child and parent disagree, then the child’s rights to autonomy are increasingly valued the older they are, and if necessary the courts can intervene and their decision is upheld above either the parents or the child. Certain procedures require court approval regardless of who wants it – non-therapeutic sterilisations, refusal of life-saving treatment, abortion and donation of non-regenerative tissue.
How to answer a question about consent
Consent essentially means that the patient understands what is to be done to them and agrees that they give permission for it to be done. Of the four principles, autonomy is clearly the most important one here and as we move away from medical paternalism and more and more towards patient-centred care, autonomy is increasingly important. As a doctor you may often think that your patient is making the wrong decision, but it is their decision to make. If they don’t want treatment you cannot force them to have it, so long as they understand the consequences of refusing.
1- R (on the application of Burke) v GMC  3 FCR 169, paragraph 30
2- S v St George’s
3- Mental Capacity Act, section 3(1)
4- Re T (Refusal rendered invalid by misinformation and undue influence
5- C (Adult: Refusal of Treatment)  1 WLR 290 (FD)
6- Gillick v W Norfolk AHA,  3 All ER 402