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What is mental capacity?

Mental capacity is the ability to make decisions about your life. Making decisions could be affected by a disability or medical conditions such as dementia, brain injury, or stroke. You may not be able to do the following:

  • understand the information given to you to make a particular decision
  • remember that information long enough to be able to make the decision
  • use or weigh up the information to make the decision
  • communicate your decision (even if it's a blink of an eye or a squeeze of a hand)

People who cannot do these things lack the mental capacity to make decisions. This can apply to major decisions, for example about personal finance, social care or medical treatment, or everyday decisions such as what to wear or eat.

Some important points to note are:

  • everyone is assumed to have the capacity to make decisions for themselves if they are given enough information, support and time
  • an unwise, or eccentric decision is not an indication of lack of capacity
  • a lack of capacity can be temporary or permanent
  • the lack of mental capacity may not apply to all decisions at all times, for example, someone with dementia might be able to think more clearly at certain times of the day
  • any action or decision made on behalf of someone must be in their best interest
  • any action or decision should aim to not restrict a person's rights and freedom of action

Who decides?

Anyone can assess mental capacity. Relatives and carers are best placed to judge whether or not someone has the capacity to make day to day decisions. For decisions about things like medical treatment or legal issues, professionals such as doctors or solicitors may need to assess mental capacity.

The Mental Capacity Act Code of Practice must be used when you are supporting someone that lacks mental capacity.


An Independent Mental Capacity Advocate (IMCA) is someone who can help people without the mental capacity to express their views and wishes.

IMCAs mainly become involved in decisions about medical treatment or accommodation where it is provided by the NHS or local authority. NHS bodies and local authorities have a duty to consult the IMCA in such decisions involving people who have no family or friends.

Independent Mental Capacity Advocate information on the government website.

Dorset Advocacy provides the IMCA service in Dorset.

Helping someone who lacks mental capacity

Lasting Power of Attorney

If you are able to make decisions for yourself but think that you might not be able to in the future, you could consider making a Lasting Power of Attorney.

Contact the Office of the Public Guardian for help with filling out forms.

Court of Protection

If you have already lost the capacity to make decisions you can't grant power of attorney to another person.

In this case, the Court of Protection could make a decision on financial or welfare matters on your behalf.


A deputy is usually a friend or relative of the person who lacks capacity but could also be a professional. Becoming a deputy is a serious undertaking - you will be responsible for decisions about welfare, healthcare and financial matters as authorised by the Court. You will need to make decisions in the best interests of the person lacking capacity.

This can be a long and expensive process so it's important to act early and set up a Lasting Power of Attorney while you still have the capacity to do so.

Apply on the Government website to become a deputy


You can apply to become an appointee in order to manage another person's state benefits. This means you can make and maintain benefit claims, receive the money and spend it in the claimant's best interests. Appointees can be:

  • a friend or relative
  • an organisation or representative of an organisation, for example, a solicitor or local authority

There can only be one appointee for each claimant.

Apply on the Government website to become an appointee

Future planning

Lasting Power of Attorney

Lasting Power of Attorney allows you to elect someone to make decisions on your behalf. This is for use if a person still has the capacity to make decisions, but feels they may lose this (perhaps because of dementia). Regardless of health, everyone should consider a Lasting Power of Attorney. It's never too early to set up a Power of Attorney, you don't need to be unwell.

Contact the Office of the Public Guardian for help with filling out forms.

Note that from 1 October 2007, 'Lasting Power of Attorney' (LPA) replaced 'Enduring Powers of Attorney' (EPA). EPAs signed and witnessed before October 2007 can still be used. However, if you lose mental capacity, your attorney must register the EPA in order to start or continue to use it. More details are on the government website.

Create a Lasting Power of Attorney online

The importance of having a Power of Attorney

If you need help and advice about how to set up an LPA, you can contact the following organisations:

Advance Decisions

An Advance Decision allows you to write down any treatments that you don't want to have in the future, in case you later become unable to make or communicate decisions for yourself.

My Decisions is a free and simple website where you can create an Advance Decision document to print, sign, witness and share.

Making a will

Making a will lets you decide what happens to your money, property and possessions after your death.