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Mental capacity and making decisions

Mental capacity relates to someone’s ability to understand and make decisions. Someone may lack mental capacity because of their health or a disability. People living with a terminal illness and their carer may need to prepare themselves if there’s a possibility that they will lose their mental capacity.

On this page:

Mental Capacity Act 2005 (England and Wales)

The Mental Capacity Act 2005 is designed to protect people aged 16 and over who live in England and Wales. It applies in situations where someone is believed to lack mental capacity (the ability) to understand and make decisions. This could be because of a mental health condition (for example, dementia) or a severe learning disability, brain injury, stroke or being given end-of-life sedation.

The Mental Capacity Act doesn’t apply to people living in Northern Ireland and Scotland, although some of the practical steps are similar.

The Mental Capacity Act protects people by:

  • enabling them to make as many decisions as they can for themselves
  • enabling them, in advance of losing mental capacity, to make decisions about (and to appoint another person to make decisions on their behalf about) their personal welfare, medical treatment or property
  • allowing decisions about someone’s personal welfare, medical treatment or property to be made on their behalf and in their best interest when they’ve not made any future plans and can’t make a decision at the time
  • ensuring that the person’s local health body or council supports them to make decisions about serious medical treatment or moving to a care home when there are no family or friends available
  • protecting carers from being taken to court if something goes wrong while they’ve honestly and reasonably tried to act in the best interests of the person they look after

About mental capacity

Under the Mental Capacity Act a person should be supported to make their own decisions as much as possible. Many people with dementia, for example, are able to make decisions with the right support and encouragement.

Mental capacity can vary from day to day, and issue to issue. It can also vary according to the type and importance of the decision being taken. A person might be able to decide that they want to live at home (not a care home), but not be able to decide what to do about their Will.

You can only take decisions on someone else’s behalf if that person has been assessed as lacking capacity. Even then, you can only make those decisions that the person assessed as lacking capacity can’t make for themself. For example, if they’re able to decide that they want to live at home, their wishes should be followed, even if they lack capacity to make a Will.

Mental capacity isn’t based on the ability to make a wise or sensible decision.

All practical steps to help a person make a decision must have been taken without success, before someone else can make a decision on their behalf. Practical steps might include:

  • involving a family member, carer or advocate to help them communicate their wishes
  • ensuring written information is made more accessible
  • using visual aids and non-verbal communication if appropriate
  • involving someone who knows them to support them to express their wishes

It may involve an advocate, and this will depend on what kind of advocacy services are available in the area. If they’re in hospital, this could be someone from PALS (Patient Advice and Liaison Service), but that won’t apply if they’re in a care home. It could be someone from the Alzheimer’s Society   if they suffer from dementia and the charity provides a service in the area. There are no specific rules about what counts as an advocate and it’s up to the person and anyone supporting them to find out if there’s anyone else who can help.

How it’s decided whether someone has mental capacity

Providers of services and their staff are required by law to assume that a person is capable. They must offer any support that may help the person to make a decision.

If the person is still unable to make a decision, a capacity assessment will be carried out by a healthcare professional. They will assess whether the person is able to make a specific decision, which includes:

  • being able to understand the information relevant to the decision
  • retain that information and use or weigh up that information to make a decision

If the person can’t do any of these things, or they’re unable to communicate their decision, they’ll be treated as not having mental capacity to make that specific decision.

If it’s felt that they don’t have capacity for a particular decision, their health professionals will need to carefully consider what’s in the person’s best interests. They’ll also need to consider anything that the person has said before and the views of relatives and friends. A person’s wishes should be taken into account as much as possible.

Ways of deciding for someone who lacks mental capacity

If it’s decided that a person lacks mental capacity, two possible ways for someone else to make decisions for them are:

  • where they’ve previously been granted Power of Attorney, which can now be put into effect
  • where they apply to the Court of Protection for a decision to be made on a particular matter and, if there’s a continuing need to make decisions on the person’s behalf, they ask the Court of Protection to appoint them as the person’s deputy (see below).

If there's nobody with Power of Attorney and no friend or relative who is suitable or willing to act, the possibilities include the following:

  • If an NHS body has to decide whether someone needs medical treatment or a local council has to decide if someone should enter a care home, it can arrange for the person to have an independent mental capacity advocate (see below).
  • The Court of Protection can appoint a professional deputy from its panel (see below).

Independent mental capacity advocate

If someone lacks mental capacity and an NHS body has to decide whether they need medical treatment, or a local council has to decide if they should enter a care home, it can arrange for the person who is lacking capacity to have an independent mental capacity advocate (IMCA). The NHS body or council has to arrange one if there’s no one else, such as a family member or friend, available instead.

An IMCA cannot start working with the person lacking capacity until they’ve been instructed by an appropriate person, like a doctor, who is qualified to make serious medical treatment decisions.

If a friend or family member feels that the person lacking capacity should be referred to an IMCA, they cannot refer the person themselves, but they can contact the local IMCA provider, which may be able to help. There’s a list of IMCAs across England and Wales on the Social Care and Institute for Excellence website  .

Being a deputy for someone who lacks mental capacity

You can apply to become someone’s deputy if they lack mental capacity. A deputy is usually a family member or someone who knows the person well. As a deputy, you’ll be appointed by and authorised by the Court of Protection to make decisions on their behalf in one or both of these areas:

Health and welfare deputyships are much rarer than property and financial deputyships, and the Court of Protection will usually only grant these in exceptional circumstances. 

You can apply to be just one type of deputy or both. See the website   for more details.

If there's no friend or family member who is suitable or willing to act, the panel of approved professionals   can appoint a deputy from a panel of approved professionals.

Mental capacity in Northern Ireland and Scotland

The Mental Capacity Act doesn’t apply if to people living in Northern Ireland or Scotland, but some of the processes are similar.

Northern Ireland

In Northern Ireland the test to decide if a person has mental capacity includes asking these questions:

  • Can the person understand and retain information about their treatment?
  • Does the person believe that information?
  • Can the person assess the information, balancing risks and needs, to make a decision?

The Mental Capacity Bill for Northern Ireland is currently being reviewed, so the law may change. Visit the Law Centre NI website   for more information or contact one of the advisers listed below.


Scotland has its own mental capacity legislation called the Adults with Incapacity (Scotland) Act. It allows a person to give someone else Power of Attorney and to make an advance decision to refuse medical treatment.

Power of Attorney in Scotland is similar to the lasting Power of Attorney under the Mental Capacity Act in that there are two types:

  • the continuing Power of Attorney, which covers areas where money and property are involved
  • the welfare Power of Attorney, which relates to decisions about health, personal care and welfare

Read more about Power of Attorney.

In Scotland, a person can make an advance decision (previously known as an advance directive) to refuse medical treatment. Although this isn’t legally binding, and could be challenged in the courts, it’s a way of refusing treatment in advance of a time when that person can’t communicate their wishes, or doesn’t have the capacity to make a decision.

Read more about advance decisions.

Making a decision for someone who lacks capacity

If you need to make a decision for someone who lacks capacity in Scotland, there are several options. These are all available through the Office of the Public Guardian  .

  • If it’s a one-off decision, you’ll need to get an Intervention Order  .
  • If you need to make straightforward financial decisions on an ongoing basis, contact the Office of the Public Guardian about the Access to Funds scheme  (PDF). This will give you access to the person’s bank account so you can manage their day-to-day affairs.
  • To make all the decisions about the person’s finances and property, you can apply to be a Financial Guardian  .
  • To make the decisions about the person’s health or personal welfare, you can apply to be a Welfare Guardian  .
  • If you need to make all the person’s decisions, find out about a combined financial and welfare guardianship.

For more details about the Adults with Incapacity (Scotland) Act, visit the Office of the Public Guardian in Scotland website  , the Mental Welfare Commission for Scotland website  , or the Compassion in Dying website  .

External websites

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