Mental Capacity Act 2005

The Mental Capacity Act sets out in law what happens when adults are unable to make particular decisions for themselves. 

In the case that an individual has trouble making certain decisions about their life, support for health treatment and social care must be provided. 

If the person is aged over 16 years old and living in England or Wales, then the Mental Capacity Act provides a legal framework for how professionals and other paid carers are to work with them (Scotland has its own law, the Adults with Incapacity [Scotland] Act 2000). 

Carers and professionals are required to follow the guidance set out in the Act's Code of Practice unless there is a compelling reason not to do so.


The Mental Capacity Act aims to empower and protect people who may not be able to make some decisions for themselves.

It also enables people to plan ahead in case they are unable to make important decisions for themselves in the future.

The Act can apply to all sorts of decisions:

  • Major decisions such as decisions about personal finance, social care or medical treatment
  • Everyday decisions such as decisions about what to wear or eat.

The law works on the principle that everyone must be assumed to have capacity to make decisions for themselves if they are given enough information, support and time, unless and until it is established otherwise.

It protects their right to make their own decisions and to be involved in any decisions that affect them.

A person’s capacity must be judged according to the specific decisions that need to be made, and not solely because of their illness, disability, age, appearance or behaviour.  An important principle is that a person cannot be judged to be lacking capacity just because they are making what seems to be an unwise decision (even if they have an illness or disability).

There are legal safeguards that must be followed when making a decision on behalf of someone who lacks the capacity to do so – it must be done in their ‘best interest’.

Who decides if I lack the mental capacity to make a particular decision?

The Mental Capacity Act says that you should have as much help as is necessary, with the aim of helping you to make your own decisions if it is at all possible.  It explains the manner in which your mental capacity should be assessed to see whether you can make a particular decision at a particular time.


Anyone can assess capacity. For an everyday decision, a relative or carer is the person most likely to need to assess whether you are able to make it.

Professionals are more likely to have to formally assess capacity when decisions are larger, or more complex. If the decision concerns medical treatment then a doctor may assess capacity, whereas if it is a legal decision, a solicitor may do so.


All medical and social care professionals and paid carers, as well as people performing certain roles and functions created by the Mental Capacity Act, must ‘have regard to’ the Code of Practice that accompanies the Act when they are supporting someone who lacks capacity.

This involves paying attention to the Code and being able to demonstrate familiarity with its guidance. If they do not follow the Code, they should be able to give convincing reasons for this.

How could the Act affect me?

If you are unable to make some decisions and you have not planned for this in advance, the Mental Capacity Act allows someone else to take these decisions on your behalf.


However, some types of decision can never be made by another person on your behalf, whether or not you are assessed as lacking mental capacity. These include decisions about marriage or civil partnership, divorce, sexual relationships, adoption and voting.


In contrast, decisions regarding compulsory detention and treatment for a mental disorder may be taken without consent, whether or not someone is deemed to have capacity, under the Mental Health Act 1983. The Mental Capacity Act therefore does not cover these decisions.

The Mental Capacity Act explains the following:

  • That being unable to make a complex decision yourself does not mean you cannot make more straightforward decisions
  • That being unable to make a decision at a certain time does not necessarily mean that you will not be able to make it at a later time or date if the decision can be delayed
  • That someone cannot decide that you lack capacity, or make assumptions about what is in your best interests, merely on the basis of your age, appearance, condition or behaviour
  • That if someone has to make a decision on your behalf, they must still involve you as much as possible
  • That someone making a decision on your behalf must act in your best interests – the Act gives a checklist of factors which they must consider when working out what these are
  • A decision made on your behalf must be made in the way that is least restrictive of your basic rights and freedoms, as long as it is still in your best interests
  • How care or treatment can be carried out if you lack capacity, provided that it is in your best interests,  including safeguards and limitations
  • Additional safeguards for those decisions which involve the withholding or withdrawing of life-sustaining treatment from someone who lacks the capacity to make this decision for themselves.
  • How an Independent Mental Capacity Advocate (IMCA) can represent you if you are unable to make important decisions, and there is no one else who can support you or represent your views.

What is an advocate?

An advocate is an independent person who helps to make sure your wishes are expressed and your voice is heard. An IMCA has a particular duty to help professionals work out what is in your best interests. You can search for organisations that provide advocacy on the Action for Advocacy website.

How can the Act help me to plan ahead?

The Act explains how anyone can plan ahead for a time when they may lack mental capacity. 

They would do so by making use of a Lasting Power of Attorney (LPA) to appoint someone to make decisions on their behalf. This includes decisions about property and financial affairs, as well as health and personal welfare decisions.

LPAs replace the existing Enduring Powers of Attorney (EPAs), although EPAs made before October 2007 may still be used.


The Act also enables you to make an ‘advance decision to refuse treatment’, which would stop you from receiving a particular treatment in the event that you ever lacked the capacity to refuse it.

Advance decisions are legally binding and must be followed by doctors, with the exception of compulsory detention or treatment for a mental disorder under the Mental Health Act.


Should there be any additional things or people you would wish to be considered should you ever lack capacity, you can present them within a ‘written statement’. The Act says that any written statement made by you should be taken into account when deciding on your best interests.

What other safeguards does the Act introduce?

The Act has created the following legal safeguards designed to stop fraud and abuse:

  • The Court of Protection will be able to make final decisions about whether someone lacks capacity.  It can itself make important decisions on their behalf and it can appoint deputies to make decisions on their behalf
  • The Office of the Public Guardian oversees Lasting Power of Attorneys and Enduring Power of Attorneys, supervises deputies, supports the Court of Protection and gives guidance on the Mental Capacity Act to the general public
  • Ill treatment or wilful neglect of a person who lacks capacity is treated as a criminal offence
  • New procedures and safeguards are introduced for involving people in the decision making process should they lack the capacity to consent.

Where can I find out more?

The Office of the Public Guardian website has links to the Code of Practice for the Act and the following booklets about the Act:

  • People who may be unable to make some decisions for themselves who wish to plan ahead for the future
  • Family, friends and unpaid carers people who work in health and social care 
  • Advice workers 
  • Explaining about the Act in Easier Read
  • Explaining the Independent Mental Capacity Advocate (IMCA) service.

The Department of Health website has more information about research, Independent Mental Capacity Advocates (IMCAs), and changes to the Mental Capacity Act that were due to come into force in April 2009.

The Social Care Institute for Excellence (SCIE) website has free training materials available for anyone working in health and social care which help explain how the Act should be used.

The Office of the Public Guardian is the first point of call for enquiries. For advice and information, call their Customer Services Unit on 0845 330 2900.

What is the law in Scotland?

The Adults with Incapacity (Scotland) Act 2000 sets out in law a range of options to help people aged 16 or over who lack the capacity to make some or all decisions for themselves. It allows other people to make decisions on their behalf.


The Act also enables arranging for another person or people to make decisions and manage your affairs on your behalf, in the event of losing capacity in the future.


The Office of the Public Guardian in Scotland is responsible for supervising the people appointed under the Act to manage the affairs of adults who lack the capacity to do so themselves. The Office also provides advice and guidance to the general public.

You can find out more about the Act from the Scottish Government.

What is the law in Northern Ireland?

There is currently no equivalent law on mental capacity in Northern Ireland.

The Bamford Review of Mental Health and Learning Disability is looking at how current law affects people with mental health needs or a learning disability in Northern Ireland.