Consent to treatment - Assessing capacity to give consent

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.