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This chapter provides information for practitioners working with adults who lack mental capacity. It outlines the principles of the Mental Capacity Act 2005, including the two stage test for assessing capacity, and some of the safeguards which exist to safeguard adults who lack capacity.


Best Interests

Consent in Safeguarding Enquiries

Deprivation of Liberty Safeguards


Mental Capacity Act Code of Practice, Office of the Public Guardian

Carrying Out and Recording Capacity Assessments (39 Essex Chambers)

Fluctuating Capacity in Context (39 Essex Chambers) 

Mental Capacity Toolkit (Bournemouth University)

Mental Capacity Act (MCA): e-Learning course (SCIE)

1. Definition

The Mental Capacity Act 2005 (MCA 2005) provides a framework to protect and restore power to those who may lack, or have reduced, capacity to make certain decisions at particular times. It places the adult at the centre of the decision making process.

‘Whenever the term ‘a person who lacks capacity’ is used, it means a person who lacks capacity to make a particular decision or take a particular action for themselves at the time the decision or action needs to be taken.

This reflects the fact that people may lack capacity to make some decisions for themselves, but will have capacity to make other decisions. For example, they may have capacity to make small decisions about everyday issues such as what to wear or what to eat, but lack capacity to make more complex decisions about financial matters.

It also reflects the fact that a person who lacks capacity to make a decision for themselves at a certain time may be able to make that decision at a later date. This may be because they have an illness or condition that means their capacity changes. Alternatively, it may be because at the time the decision needs to be made, they are unconscious or barely conscious whether due to an accident or being under anaesthetic or their ability to make a decision may be affected by the influence of alcohol or drugs.

Finally, it reflects the fact that while some people may always lack capacity to make some types of decisions – for example, due to a condition or severe learning disability that has affected them from birth – others may learn new skills that enable them to gain capacity and make decisions for themselves’ (MCA 2005 Code of Practice, 2007: p3).

The Act:

  • allows adults to make as many decisions as they can for themselves;
  • enables adults to make advance decisions about whether they would like future medical treatment;
  • allows adults to appoint, in advance of losing mental capacity, another person to make decisions about personal welfare or property on their behalf at a future date;
  • allows decisions concerning personal welfare or property and affairs to be made in the best interests of adults when they have not made any future plans and cannot make a decision at the time;
  • ensures an NHS body or local authority will appoint an independent mental capacity advocate to support someone who cannot make a decision about serious medical treatment, or about hospital, care home or residential accommodation, when there are no family or friends to be consulted (see Independent Mental Capacity Advocacy Service);
  • provides protection against legal liability for carers who have honestly and reasonably sought to act in the person’s best interests;
  • provides clarity and safeguards around research in relation to those who lack capacity.

The MCA relates to people over the age of 16 years old. This chapter, however, only applies to those over the age of 18 years (adults) and not to those who are children (before their 18th birthday).

2. Principles of the Mental Capacity Act

Under the Mental Capacity Act, five principles apply:

  • It must be assumed that a person has mental capacity unless it is established that they lack capacity;
  • A person should not be treated as unable to make a decision unless all practicable steps to help them to do so have been taken without success;
  • A person should not be treated as unable to make a decision just because they make an unwise or bad decision;
  • An act or decision carried out for or on behalf of a person who lacks mental capacity must be done, or made, in their best interests;
  • Before the act is done, or the decision is made, staff must consider whether the purpose can be as effectively achieved in a way that is less restrictive of the person’s rights and freedom of action.

The five principles should inform all actions when working with a person who may lack or have reduced capacity and should be evidenced in taking decisions or actions on behalf of a person who may lack or have reduced capacity.

3. Assessing Capacity

Anybody who believes an adult lacks mental capacity about a particular decision should provide proof.

They need to demonstrate, on the balance of probabilities (which means – from the evidence presented – it is more likely than not), the adult lacks capacity to make a particular decision, at the time it needs to be made.

3.1 Two Stage Test

To help assess if a person lacks capacity, the Act sets out a two stage test:

Stage 1: The Diagnostic Test

This test looks at whether the person has an impairment or disturbance of the mind or brain. Examples include:

  • conditions associated with some forms of mental illness
  • dementia
  • significant learning disabilities
  • the long-term effects of brain damage
  • physical or medical conditions that cause confusion, drowsiness or loss of consciousness
  • delirium
  • concussion following a head injury, and
  • symptoms of alcohol or drug use.

If a person does not have such an impairment or disturbance of the mind or brain, they will not lack capacity under the Act.

Stage 2: The Functional Test

This test looks at whether the impairment or disturbance mean that the person is unable to make a specific decision when they need to?

The person must first be given all practical and appropriate support to help them make the decision for themselves. Stage 2 can only apply if all practical and appropriate support to help the person make the decision has failed.

3.2 Inability to make a Decision

A person is considered unable to make a decision if they cannot:

  1. understand information about the decision to be made (‘relevant information’);
  2. retain that information in their mind;
  3. use or weigh that information as part of the decision making process; or
  4. communicate their decision (by talking, using sign language or any other means).

If there is evidence that the person cannot do one of these things, it must be due to their specific impairment.

3.3 The Causative Nexus

Once the person has been identified as having an impairment or disturbance in the functioning of the mind or brain, it is important to determine whether the inability to make the decision is because of this impairment. This is known as the ‘causative nexus’ (PC and NC v City of York Council [2013] EWCA Civ 478). Only where it can be reasonably said that the person cannot make the decision because of the impairment of their mind, can it be said that they lack capacity to make the decision.

4. Safeguarding and Mental Capacity

During a safeguarding enquiry, crucial decisions will have to be made at different stages of the process. It is therefore vital that – where an adult does not have mental capacity – decisions made or action taken on their behalf are in their best interests.

An assessment of an adult’s mental capacity should be considered in all safeguarding cases where:

  • there is a formal diagnosis of cognitive impairment;
  • a neuro-psychological assessment testing suggests they have cognitive impairment;
  • there are concerns about the person’s capacity that have been raised by others;
  • there are discrepancies in the person’s own evaluation of their abilities;
  • there is collateral evidence suggesting a change in their personality;
  • they fail to learn from their mistakes;
  • they repeatedly make risky or unwise decisions.

5. Recording

The two stage test should be used as a framework for recording the assessment of mental capacity so that evidence for decision making is clear.

6. Making Decisions on behalf of Someone who lacks Capacity

If, having taken all practical steps to assist someone, it is concluded that a decision should be made for them, that decision must be made in that person’s best interests. It must also be considered whether there is another way of making the decision which might not affect the person’s rights and freedom of action as much (known as the ‘least restrictive alternative’ principle).

6.1 Decision Makers

Different people may be required to make decisions or act on behalf of someone who lacks capacity to make decisions for themselves. The person making the decision is known as the ‘decision maker’, and it is their responsibility to determine what would be in the best interests of the person who lacks capacity.

For most day to day actions or decisions, the decision maker will be the carer most directly involved with the person at the time.

Where the decision involves the provision of medical treatment, the doctor or other member of healthcare staff responsible for carrying out the particular treatment or procedure is the decision maker.

Where nursing or paid care is provided, the nurse or paid carer will be the decision maker.

In safeguarding cases, it will be the practitioner who is undertaking the enquiry who will be the decision maker for decisions relating to the safeguarding process and provision of care and support.

In some cases, the same person may make different types of decision for someone who lacks capacity. For example, a carer may carry out certain acts in caring for the person on a daily basis, but if they are also an attorney, appointed under a Lasting Power of Attorney, they may also make specific decisions concerning the person’s property and affairs or personal welfare.

A decision may also, at times, be made jointly by a number of people. For example, when a care plan for a person who lacks capacity is being developed, different healthcare or social care staff might be involved in making decisions or recommendations about their care package. Alternatively, the decision may be made by one practitioner within the team. A different member of the team may then implement that decision, based on what the team has ascertained to be the person’s best interests.

6.2 Lasting Powers of Attorney, Court Appointed Deputy and the Public Guardian

A Lasting Power of Attorney (LPA) allows an adult to appoint an attorney to act on their behalf if they should lose capacity in the future and allows them to empower an attorney to make health and welfare decisions.

A Court Appointed Deputy is appointed by the Court of Protection. Depending on the terms of their appointment, deputies can take decisions on welfare, healthcare and financial matters as authorised by the Court of Protection but they are not able to refuse consent to life sustaining treatment. Deputies are only appointed if the Court cannot make a one off decision to resolve the issues.

The Court of Protection has jurisdiction relating to the Mental Capacity Act, with its own procedures and nominated judges.

The Office of the Public Guardian (OPG) is the registering authority for LPA’s and deputies. It supervises deputies appointed by the Court and provides information to help the Court make decisions. It also works with other agencies, for example the police and adult social care, to respond to any concerns raised about the way in which an attorney or deputy is operating.

6.3 Independent Mental Capacity Advocates

See also Independent Mental Capacity Advocacy Service.

Independent Mental Capacity Advocates (IMCA) are appointed to support a person who lacks capacity but who has no one to speak for them. They have to be involved where decisions are being made about serious medical treatment or a change in the adult’s accommodation where it is provided, or arranged, by the NHS or a local authority. The IMCA makes representations about the person’s wishes, feelings, beliefs and values, and brings to the attention of the decision maker all relevant factors to the case.

6.4 Forward Planning

Considering the possibility of losing mental capacity and registering Lasting Power of Attorneys is usually associated with people getting older. But it would be wise to consider such decisions and act on them much earlier in life, in case of unexpected illness or an accident that results in a temporary or permanent loss of capacity.

Using a LPA is not necessarily limited to circumstances where an adult’s capacity is diminished. Due to a physical illness that renders a person (the donor) unable to leave the house for example, a LPA who is registered in relation to property and financial affairs can carry out financial transactions on their behalf and with their permission. In the absence of a registered LPA the alternative would be to borrow the money which could attract charges, or to apply to the Court of Protection.

Although a LPA cannot be used until it has been fully registered and confirmation received, they can be registered before capacity is lost which means that they could be used immediately if it should become necessary.

7. Best Interests

See also Best Interests

The MCA sets out a checklist of things to consider when deciding what’s in a person’s best interests. People should:

  • not make assumptions on the basis of age, appearance, condition or behaviour;
  • consider all the relevant circumstances;
  • consider whether or when the person will have capacity to make the decision;
  • support the person’s participation in any acts or decisions made for them;
  • not make a decision about life sustaining treatment ‘motivated by a desire to bring about his (or her) death’;
  • consider the person’s expressed wishes and feelings, beliefs and values;
  • take into account the views of others with an interest in the person’s welfare, their carers and those appointed to act on their behalf.
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