All adults are presumed to have sufficient capacity to decide on their own medical treatment, unless there is significant evidence to suggest otherwise.

What is ‘capacity’?

“Capacity” means the ability to use and understand information to make a decision, and communicate any decision made.

A person lacks capacity if their mind is impaired or disturbed in some way, and this means the person is unable to make a decision at that time.

Examples of how a person’s brain or mind may be impaired include:

• mental health conditions – such as schizophrenia or bipolar disorder
• dementia
• severe learning disabilities
• brain damage – for example, from a stroke or other brain injury
• physical or mental conditions that cause confusion, drowsiness or a loss of consciousness
• intoxication caused by drug or alcohol misuse

Someone with such an impairment is thought to be unable to make a decision if they cannot:

• understand information about the decision
• remember that information
• use that information to make a decision
• communicate their decision by talking, using sign language or by any other means 

How capacity is assessed

As capacity can sometimes change over time, it should be assessed at the time that consent is required.

This will usually be done by an appropriately trained and experienced health professional who is either recommending the treatment or investigation, or is involved in carrying it out.

If the health professional feels you have the capacity to give your consent, your decision will be accepted and your wishes will continue to be respected, even if you lose capacity at a later stage.

If the health professional feels you don’t currently have the capacity to give consent, and you have not made an advance decision or formally appointed anyone to make decisions for you, they will need to carefully consider what is in your best interests before making a decision.

Respecting personal beliefs

If someone makes a decision about treatment that other people would consider to be irrational, it does not necessarily mean they have a lack of capacity, as long as they understand the reality of their situation.

For example, a person who refuses to have a blood transfusion because it is against their religious beliefs would not be thought to lack capacity. They still understand the reality of their situation and the consequences of their actions.

However, someone with anorexia who is severely malnourished and rejects treatment because they refuse to accept there is anything wrong with them would be considered incapable. This is because they are regarded as not fully understanding the reality of their situation.

Determining a person’s ‘best interests’

If an adult lacks the capacity to give consent, a decision on whether to go ahead with the treatment will need to be made by the health professionals treating them. In order to make a decision, the person’s “best interests” must be considered.

There are many important elements involved in trying to determine what a person’s best interests are, including:

• considering whether it is safe to wait until the person can give consent, if it is likely they could regain capacity at a later stage
• involving the person in the decision as much as possible
• trying to identify any issues the person would take into account if they were making the decision themselves, including religious or moral beliefs; these would be based on views the person expressed previously, as well as any insight close relatives or friends can offer

If a person is felt to lack capacity, and there is no one suitable to help make decisions about medical treatment, such as family members or friends, an independent mental capacity advocate (IMCA) must be consulted.

Involving the Court of Protection

In situations where there is serious doubt or dispute about what is in an incapacitated person’s best interests, healthcare professionals can refer the case to the Court of Protection for a ruling. This is the legal body that oversees the operation of the Mental Capacity Act (2005).

Situations that must always be referred to the courts include:

• sterilisation for contraceptive purposes
• donation of organs or regenerative tissue, such as bone marrow
• withdrawal of nutrition and hydration from a person who is in a permanent vegetative state or minimally conscious state 

Changes in capacity

A person’s capacity to consent can change. For example, they may have the capacity to make some decisions but not others, or their capacity may come and go.

In some cases, people can be considered capable of deciding some aspects of their treatment but not others. For example, a person with severe learning difficulties may be capable of deciding on their day-to-day treatment, but incapable of understanding the complexities of their long-term treatment.

Some people with certain health conditions may have periods when they are capable and periods when they are incapable. For example, a person with schizophrenia may have periods when they are considered capable, but they may also have psychotic episodes (when they cannot distinguish between reality and fantasy), during which they may not be capable of making certain decisions. 

A person’s capacity can also be temporarily affected by shock, panic, fatigue (extreme tiredness) or medication.

If a person knows that they may eventually not be capable of making certain decisions, they can make an “advance decision” (previously known as an advance directive or “living will”), stating any treatments they would like to refuse in case of future incapacity, or they can formally give someone power of attorney to make decisions about their health for them.

Advance decisions and power of attorney

If a person knows their capacity to consent may be affected in the future, they can choose to draw up a legally binding advance decision.

An advance decision sets out the procedures and treatments that a person refuses to undergo. This means the healthcare professionals treating the person cannot perform certain procedures or treatments against their wishes.

For an advance decision to be valid, it must be specific about what the person does not want done and under what circumstances. For example, if they want to refuse a certain treatment, even if by doing so their life is at risk, they must clearly state this.

If the person specifically states in their advance decision that they do not want to undergo a particular treatment, this is legally binding. The only exception may be if that person is being held under the Mental Health Act (1983). This is an act that allows some people with mental health problems to be compulsorily detained in a psychiatric hospital.

The healthcare professionals must follow the advance decision, providing it is valid and applicable. If there is any doubt about the advance decision, the case can be referred to the Court of Protection.

You can also choose to formally arrange for someone, often a close family member, to have lasting power of attorney (LPA) if you wish to anticipate your loss of capacity to make important decisions at a later stage. Someone with LPA can make decisions about your health on your behalf, although you can choose to specify in advance certain treatments that you would like them to refuse.

Read more about advance decisions and power of attorney.

There is guidance on whether life-sustaining treatment should be withheld or withdrawn when it is not possible to ask a person for consent.

If a person is being kept alive with supportive treatments – such as ventilation of the lungs – and they have not made an advance decision outlining the care they would refuse to receive, a decision about continuing or stopping treatment will need to be made based on what that person’s best interests are believed to be.

To help reach a decision, the healthcare professionals responsible for the person’s care should discuss the issue with the relatives and friends of the person receiving the treatment.

They should consider, among other things:

• what the person’s quality of life will be if treatment is continued
• how long the person may live if treatment is continued
• whether there is any chance of the person recovering

Treatment can be withdrawn if there is an agreement that continuing treatment is not in the person’s best interests.

If an agreement cannot be reached, or a decision has to be made on whether to withdraw treatment from someone who has been in a state of impaired consciousness for a long time (usually at least 12 months), the case will need to be referred to the courts before any further action can be taken.

It is important to note that there is a difference between withdrawing a person’s life support and taking a deliberate action to make them die – for example, by injecting a lethal drug. The latter is illegal.

People aged 16 or over are entitled to consent to their own treatment, and this can only be overruled in exceptional circumstances.

Like adults, young people (aged 16 or 17) are presumed to have sufficient capacity to decide on their own medical treatment, unless there is significant evidence to suggest otherwise.

Children under the age of 16 are presumed to lack capacity, but can consent to their own treatment if it is thought that they have enough intelligence, competence and understanding to fully appreciate what is involved in their treatment. Otherwise, someone with “parental responsibility” can consent for them.

When their consent can be overruled

If a young person refuses treatment, and by doing so this may lead to their death or a severe permanent injury, their decision can be overruled by the Court of Protection. This is the legal body that oversees the operation of the Mental Capacity Act (2005).

The parents of a young person who has refused treatment may consent for them, but it is usually thought best to go through the courts in such situations.

Parental responsibility

If a child who is under 16 does not have the capacity to consent, someone with parental responsibility can consent for them, but that person must have the capacity to give consent.

If a parent refuses to give consent to a particular treatment, this decision can be overruled by the courts if treatment is thought to be in the best interests of the child.

If one person with parental responsibility gives consent and another does not, the healthcare professionals can choose to accept the consent and perform the treatment in most cases. If the people with parental responsibility disagree about what is in the child’s best interests, the courts can make a decision.

In an emergency, where treatment is vital, and waiting to obtain parental consent would place the child at risk, treatment can proceed without consent (see when consent isn’t needed for more information).

Who has parental responsibility?

A person with parental responsibility for a child could be:

• the child’s mother or father
• the child’s legally appointed guardian
• a person with a residence order concerning the child
• a local authority designated to care for the child
• a local authority or person with an emergency protection order for the child

Consent to treatment is the principle that a person must give their permission before they receive any type of medical treatment or examination. This must be done on the basis of a preliminary explanation by a clinician.

Consent is required from a patient regardless of the intervention – from a physical examination to organ donation.

The principle of consent is an important part of medical ethics and the international human rights law.

It can be given:

• Verbally – for example, by saying they are happy to have an X-ray.
• In writing – for example, by signing a consent form for surgery.

Patients may passively allow treatment to take place – for example, by holding out an arm to show they are happy to have a blood test. However, since the capacity to consent has not been tested, and the benefits and risks have not been explained, this is not the same as consent (see below).

“Capacity” means the ability to use and understand information to make a decision, and communicate any decision made.

Defining consent

For consent to be valid, it must be voluntary and informed, and the person consenting must have the capacity to make the decision. These terms are explained below:

• Voluntary – the decision to either consent or not to consent to treatment must be made by the person themselves, and must not be influenced by pressure from medical staff, friends or family.
• Informed – the person must be given all of the information in terms of what the treatment involves, including the benefits and risks, whether there are reasonable alternative treatments and what will happen if treatment does not go ahead.
• Capacity – the person must be capable of giving consent, which means they understand the information given to them, and they can use it to make an informed decision.

If an adult has the capacity to make a voluntary and informed decision to consent to or refuse a particular treatment, their decision must be respected. This still stands even if refusing treatment would result in their death, or the death of their unborn child.

If a person does not have the capacity to make a decision about their treatment, the healthcare professionals treating them can go ahead and give treatment if they believe it is in the person’s best interests. However, the clinicians must take reasonable steps to seek advice from the patient’s friends or relatives before making these decisions.

Read more about assessing the capacity to consent.

How to give consent

Consent should be given to the healthcare professional directly responsible for the person’s current treatment, such as the nurse arranging a blood test, the GP prescribing new medication or the surgeon planning an operation.

If someone is going to have a major medical procedure, such as an operation, their consent should ideally be obtained well in advance, so they have plenty of time to examine any information about the procedure and ask questions. If they change their mind at any point before the procedure, the person is entitled to withdraw their previous consent.

If they are able to, consent is usually given by patients themselves. However, someone with parental responsibility may need to give consent for a child to have treatment. Read more about the rules of consent applying to children and young people

If someone with little or no chance of recovery requires treatment for the sole purpose of keeping them alive, and the person is unable to make a decision themselves, an agreement about continuing or stopping treatment will need to be reached between the healthcare professionals responsible for their care and the person’s relatives and friends. Read more about consent and end of life issues.

When consent is not necessary

There are a few exceptions when treatment can go ahead without consent.

For example, it may not be necessary to obtain consent if:

• Treatment is needed in an emergency, and the person is unable to give consent because they lack the capacity to do so.
• When, during an operation, it becomes obvious that the person immediately requires an additional procedure to treat a life-threatening problem that was not included in their original consent.
• A person with a severe mental health condition – such as schizophrenia, bipolar disorder or dementia – lacks the capacity to consent to the treatment of their mental health. However, in these cases, treatment for unrelated physical conditions still requires consent, which the patient may be able to provide, despite their mental illness.

Read more about when consent isn’t needed.

There are a few exceptions when treatment may be able to go ahead without the person’s consent, even if they are capable of giving their permission.

These circumstances are outlined below.

Additional procedures

There may be some circumstances when, during an operation, it becomes obvious that the person immediately requires an additional emergency procedure that was not included in their original consent.

For example, they may be having abdominal surgery, when the surgeon notices that their appendix is dangerously close to bursting and needs to be removed.

If it’s felt that it would be too dangerous to delay the additional procedure to get consent, this procedure can go ahead if it is considered to be in the person’s best interests.

However, extra procedures cannot be done just because it would be convenient for the healthcare professionals. There has to be a clear medical reason why it would be unsafe to wait to obtain the person’s consent.

Emergency treatment

If a person requires emergency treatment to save their life, and they are unable to give consent as a result of being incapacitated (for example, they are unconscious), treatment will be carried out.

In these cases, the reasons why treatment was necessary will be fully explained once they have recovered.

Mental health conditions

Under the Mental Health Act (1983), people with certain mental health conditions – such as schizophrenia, bipolar disorder or dementia – can be compulsorily detained and treated at a hospital or psychiatric clinic without their consent, if deemed necessary.

If the person lacks capacity (the ability to understand information and use it to make a decision) and has not previously expressed their wishes, their mental health condition may be treated without consent, as may any related conditions, such as those resulting from self-harm. However, unrelated physical conditions cannot be treated without consent.

An advance decision prohibiting certain types of treatment can be overruled if a person is being held under the 1983 Act, even if they made the original decision when they were capable.

Self-harm and attempted suicide

In cases of self-harm or attempted suicide where the person refuses treatment and was competent when they harmed themselves, it may be necessary to see if they can be treated without consent under the 1983 act. This can happen if a person has a serious mental health condition that requires hospital treatment.

The person’s nearest relative or an approved social worker must make an application for the person to be forcibly kept in hospital and treated. Two doctors must assess the person’s condition.

Risk to public health

Under the Public Health (Control of Disease) Act (1984), a magistrate can order that a person is detained in hospital if they have an infectious disease that presents a risk to public health, such as rabies, cholera or tuberculosis (TB).

Severely ill and living in unhygienic conditions

Under the National Assistance Act (1948), a person who is severely ill or infirm and is living in unsanitary conditions can be taken to a place of care without their consent.