A brief guide to the Mental Capacity Act 2005


This factsheet covers the main points of the Mental Capacity Act.

April 2023 FS18)

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What is mental capacity?

Mental capacity means being able to make your own decisions. Someone lacking capacity may not be able to make a decision at the time when the decision needs to be made.

No one must judge this because of age, appearance, behaviour or any condition the person may have.

What is the Mental Capacity Act?

The Mental Capacity Act is the main law in England and Wales about adults who lack capacity to make some or all of their own decisions and about how those decisions can be made instead.

The Act is based on the idea that all adults have the right to make their own decisions about their lives, including decisions about their care and support. Wherever possible they should be helped and supported to make their own decisions.

The Mental Capacity Act 2005 introduces a clear test of capacity and is supported by a Code of Practice that informs anyone caring for a person over 16 years old – including doctors, social workers, paid carers and other health and social care professionals – what to do when they are working with someone who lacks capacity.

Many decisions are covered by the Act from simple things like what to eat, to more complicated decisions like where to live and what medical treatment to have.

Some decisions such as marriage, civil partnership, consenting to sexual relationships, adoption and voting are not covered by the Mental Capacity Act. This means that no one can make these decisions on behalf of other people.

The principles of the Act

There are five key principles which underpin the Act:

  1. Assume people have capacity.
  2. Provide support for people to make decisions for themselves.
  3. Remember people who make unwise decisions may still have capacity.
  4. Actions taken must be in the best interests of the person who lacks capacity.
  5. The less restrictive option must be considered first.

How is mental capacity assessed?

If a social or health care professional proposes care or treatment and the capacity of the person they are proposing it for is in doubt, they must assess the person’s capacity to make that decision or consent to the care or treatment.  

They will need to be clear about what specific decision needs to be made, since people may have capacity to make one decision but not another. They must also make this assessment at the time the decision needs to be made, because people’s capacity to make decisions can change.

They then undertake a 2 stage capacity test by answering the following questions

Stage 1: Does the person have an impairment or disturbance in the functioning of the mind or brain?

Stage 2: If so, does this mean that the person is unable to make the decision at the time that the decision needs to be made?

  • Can the person understand the information about the decision that needs to be made?
  • Can the person remember the information long enough for the decision to be made?
  • Can the person weigh up the information available to make the decision?
  • Can the person communicate their decision?

Who decides if a person lacks capacity?

A family member, health, social care or other professional might need to decide if a person is unable to make a particular decision. They will do this using the 2 stage capacity test described above.

In particular, where consent is needed for treatment or an examination, the doctor or health care professional will decide whether a person has capacity to make a particular decision.

What happens when a person cannot make their own decisions?

The Act says you should be supported to make your own decision.

If you are unable to make a particular decision and you have not made plans about this in advance, then someone else such as a carer or professional will have to decide what should happen in your best interests.

How does someone work out what is in a person’s best interests?

Best interests can be described as what is best for the person, all things considered.

The Act says there are certain things to consider in working out what is in a person’s best interests. Everyone involved should consider the Act’s ‘best interests checklist’. Sometimes it is useful for the people involved to meet to discuss what is in the person’s best interests.

Best interests checklist

  • Working out what is in someone’s best interests cannot be based on age, appearance, condition or behaviour.
  • All relevant circumstances should be considered when working out someone’s best interests.
  • Every effort should be made to encourage and enable the person who lacks capacity to take part in making the decision.
  • If there is a chance that the person will regain the capacity to make a particular decision, then it may be possible to put off the decision until later if it is not urgent.
  • The person’s past and present wishes and feelings, beliefs and values should be taken into account.
  • The views of other people who are close to the person who lacks capacity should be considered, as well as the views of an attorney or deputy.

Providing care or treatment if you lack capacity

The Act allows people to carry out tasks to do with care or treatment if they believe that the person lacks capacity and that the care is in the person’s best interests. Where there are different options, the Act says that everyone should aim to choose the less restrictive option.

Protecting a person from ill-treatment or wilful neglect

There are 2 criminal offences under the Act:

  • Ill treatment of a person without capacity.
  • Willful neglect of a person without capacity.

These offences carry a sentence of up to 5 years imprisonment and/or a fine.

Planning ahead

In law, the term 'next of kin' has no status when you are alive.

A next of kin does not have legal liabilities, cannot consent on your behalf and cannot be given access to your medical history, has no claim on your finances or personal possessions. This means that your next of kin cannot take over your banking and the paying of your bills if you are in a position where it would be difficult for you to look after your own bank account.

If you do wish to nominate a person to look after issues regarding your property or finances, you need to make a lasting power of attorney (LPA) for property and financial affairs. If you wish to nominate someone to look after your welfare you can also make an LPA for health and welfare.

There is only one situation where the term ‘next of kin’ is legally valid; this is if you die without leaving a will. In this case your estate will be passed on to the person or people who are your closest blood relation.

A LPA allows a person to appoint someone to make decisions on their behalf in the future if they lose the capacity to do this for themselves. This could be decisions about property and finance or health and welfare matters, or both.

For more information, see: managing someone’s affairs.

Advance decisions to refuse treatment

This allows a person to state any treatment that they do not want, should they lack the capacity to decide this in the future.

Advance decisions are legally binding and must be followed by doctors and other health staff, as long as the person is 18 or over and has the mental capacity to make the decision.

The decision should say which treatments are being refused and the circumstances the refusal refers to.

An advance decision does not need to be in writing but is helpful if it is.

Making advance decisions about life-sustaining treatment

‘Life-sustaining treatment’ is treatment that is needed to keep you alive and without which, you might die. There are some specific rules if you want to make an advance decision to refuse life-sustaining treatment.

This type of advance decision must:

  • be in writing
  • state that it applies even if the person’s life is at risk
  • be signed by the person (or by someone else that has been appointed by the person, in front of the person)
  • be signed in front of a witness
  • be signed by the witness in front of the person

Recording the person’s wishes and feelings about the treatment and care

The person can write down or tell people their wishes and preferences about future treatment or care. There must be consideration of achieving these when deciding what is in their best interests.

Court of Protection

The Act created a new Court of Protection (the Court) which makes decisions on:

  • capacity
  • property and finance
  • health and welfare
  • disagreements about best interests.

The Court (in England and Wales) protects the rights of people who do not have mental capacity.

What is a Deputy?

For a person who lacks capacity the Court can appoint a Deputy on the person’s behalf to make ongoing decision for the person. The person must be 18 years or over and can be a relative, friend, or a professional.

The powers of a Deputy can relate to dealing with the financial affairs and/or the personal and welfare issues of the person without capacity. The Court sets out the scope of the Deputy's authority.

Independent Mental Capacity Advocates (IMCA)

The purpose of an IMCA is to help people who lack capacity to make important decisions when they have no family or friends to be consulted with about a decision.

An IMCA is an independent advocate funded by local authorities, who are specially trained to support people who lack capacity. They must be involved if the decision is about:

  • serious medical treatment or a change of accommodation (more than 28 days in hospital or 8 weeks in a care home)
  • the person does not have capacity to decide this for themselves; and
  • the person does not have anyone who can be spoken to about the decision

An IMCA may also be involved in some accommodation reviews, safeguarding adult enquiries and deprivation of liberty safeguards.

Challenging decisions and raising concerns

Sometimes there may be disagreements about decisions made under the Act, such as the assessment of capacity to make a decision. There are a number of ways that disagreements can be sorted out.

It is recommended that the following are tried:

  • Informal meetings (may include advocacy services).
  • Using the complaints procedure of an organisation, for example the National Health Service or Local Authority.
  • Speaking to the Office of the Public Guardian if there are concerns about the way a LPA is being used.

The Court has the final say about disagreements.

Useful resources

Mental Capacity Act (2005) Code of Practice

Deprivation of liberty safeguards code of practice 

Office of the Public Guardian

Information on becoming an appointee, deputy or power of attorney.

Website: Office of the Public Guardian

Next of kin: understanding decision-making authorities

Local resources

Making a complaint

We want to provide quality services for everyone in East Sussex, so it’s always helpful when you tell us what you think.

If you want to make a complaint, a good start is to contact the person or team who has been involved in the situation you want to complain about. They will try to sort things out quickly.

If you would rather speak to someone else contact our Complaints and Feedback Team.

More information

See further leaflets and factsheets

Contact us to get more copies of this factsheet, or any of the other leaflets or factsheets mentioned.

Email: Health and Social Care Connect
Phone: 0345 60 80 191
Minicom : 18001 0345 60 80 191

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