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Understanding and using the Mental Capacity Act

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The Mental Capacity Act exists to safeguard patients who lack mental capacity to make decisions for themselves and the health professionals who care for them


The Mental Capacity Act aims to safeguard patients who lack mental capacity to make decisions about their treatment or care, and gives legal protection to the health professionals who care for them. It must be adhered to whenever there is doubt about a patient’s mental capacity and a decision is required about their care or treatment. All health professionals working in hospitals and care homes should understand when and how the act should be used and feel confident doing so. This article explains the main points of the act, and when and how to use it.

Citation: Mughal AF (2014) Understanding and using the Mental Capacity Act. Nursing Times; 110: 21, 16-18.

Author: Aasya F Mughal is barrister, director of Edge Training and Consultancy, and co-author of Working With the Mental Capacity Act 2005.


The Mental Capacity Act 2005 (HM Government, 2005) is all about consent. For consent to be valid, the person giving it must have the mental capacity to understand what they are consenting to; it is the same as any other contract or agreement. Anyone buying a car would want to understand which car they were buying, how much it would cost and how it was to be used - the same applies to health and social care.

However, not all patients needing medical care and treatment know what it will involve or why they need it, even after detailed explanation. This is not because they are being badly advised or misled by health professionals, but because they have a condition or an impairment in the functioning of their mind or brain (MCA s.2(1)) that is limiting their ability to understand or weigh up information involved in making the decision. For example, a patient with dementia may need a blood test but not understand what it will involve or why it is necessary.

The majority of patients are able to consent to care and treatment, and this must be a default assumption for health professionals; section 1 of the MCA states that people must be assumed to have mental capacity unless it is proved otherwise.

Unfortunately, there is a risk that patients who lack mental capacity merely comply with health professionals when asked to consent to an intervention, and are recorded as having consented without a mental capacity assessment having been carried out. In other cases, patients’ next of kin may be given a consent form to sign, even though they have no power to authorise treatment or care on the patient’s behalf; family members or friends only have such a power if they have a valid and applicable personal welfare lasting power of attorney or deputyship.

In 2013, the House of Lords Select Committee on the MCA (2013) scrutinised how the act was being applied in practice. The committee heard about a case in which an older man had had a severe stroke. Although it was recorded contemporaneously in his patient notes that his eyes were closed and that he was unresponsive and uncommunicative, the notes also said he had consented to having a nasogastric tube inserted. The MCA does not say that everyone who has a stroke automatically lacks mental capacity - it is clear that a diagnosis alone cannot be used to judge mental capacity (MCA s.2(3)(b)). However, in this case, the contemporaneous notes suggest that the effects of the stroke in this patient’s case left him unable to give or refuse consent. Unfortunately, no mental capacity assessment had been recorded.

Significance of the Mental Capacity Act

Every time they touch a patient, nurses and other health professionals need legal protection; in the majority of cases, that legal protection comes from the patient’s consent. In other words, the patient has the mental capacity to give the nurse valid informed consent, for example, to take a blood sample. This means the patient broadly understands why the blood test is necessary and what it will involve.

A patient who lacks mental capacity may be compliant when being offered treatment, for example by extending an arm for a blood sample to be taken. However, compliance should not be confused with consent. If a patient lacks capacity about a decision at the time it needs to be made, you cannot record that you have obtained their consent, even if the patient complies. Instead, a “best-interests decision” needs to be made (see below).

Decisions about mental capacity are made using the MCA; when working with the act, the principles in Box 1 must be followed. Health professionals assessing mental capacity do not have to be 100% sure about the outcome of their assessment; the act simply requires that they have a reasonable belief on the balance of probabilities. In other words, they must have carried out the legal assessment and have decided what is most likely to be the right outcome.

Box 1. Principles of the Mental Capacity Act

  • Assume the patient has mental capacity unless it is proven otherwise by undertaking the mental capacity assessment
  • Take all practical steps to support the patient with the assessment before you decide they lack mental capacity
  • A patient should not be judged to lack mental capacity just because they make an unwise decision
  • Any decision made on behalf of a patient lacking capacity should be made in their best interests
  • Consider whether any best interests decision may be achieved in a less restrictive way

Source: Mental Capacity Act 2005. s.1 

Assessing mental capacity

Mental capacity is tested by using a legal (not psychiatric) assessment described in sections 2 and 3 of the MCA.

A person cannot be judged to lack mental capacity simply because they make an unwise decision. Incapacity can only be shown or evidenced by carrying out the mental capacity assessment. The assessment may be carried out by anyone who needs a patient’s consent if they are concerned about the patient’s mental capacity to give that consent. Health professionals must record their mental capacity assessments in patient notes and be able to justify them if required to do so later.

The first step is to clarify the decision for which the patient’s consent is needed (for example, that a blood test is necessary) and then check whether at the time consent is needed, the patient is capable of all the processes in stage 1 of the assessment (Box 2). A patient able to complete stage 1 has mental capacity (about that specific decision, at that time); inability to complete any of the four processes in stage 1 means the patient lacks mental capacity if this is because of an impairment of or a disturbance in the functioning of the mind or brain (because of delirium, intoxication, dementia, learning disability or unconsciousness for example). This two-stage mental capacity assessment follows the order recommended by the Court of Appeal in the case PC & Anor v City of York Council [2013] EWCA Civ 478, although many staff complete it the other way around by checking for an impairment or disturbance first.

Where necessary, patients should be assisted to complete the processes in stage 1 as far as possible, through practical steps such as assistance with communication methods, giving them more time or offering other support.

The practical steps and time taken to assess capacity will be very brief in emergencies; patients fail the assessment immediately if they are unconscious and therefore unable to understand the information relevant to the decision.

Box 2. Mental capacity assessment

The assessment is time and decision specific, and should be repeated each time consent is needed. However, it may not have to be recorded each time if the person’s capacity has not recovered and their care plan covers the decision (MCA Code of Practice, p104) (DCA, 2007).

Stage 1

  • The patient must be capable of all the following:
  • Understanding the information relevant to the decision, for example the reason for taking a blood test, benefits and disadvantages, and what it will involve
  • Retaining that information (only long enough to make the decision – they could forget it a short while later)
  • Using/weighing up that information (accepting it and taking it into account)
  • Communicating their decision (in any way, such as gestures or behaviour)

Stage 2

  • Has the patient failed the assessment (due to being unable to complete any part of stage 1) because of an impairment of or disturbance in the functioning of the mind or brain (for example, dementia, learning disability, brain injury, intoxication, confusion, however caused, or loss of consciousness)? If yes, they will be said to lack mental capacity. A best interests decision should now be made for them

Assessing best interests

Even if a patient does not have the mental capacity to give or withhold consent, you may still take a blood sample for testing or deliver other treatment/care if you assess this to be in the patient’s best interests.

The legal criteria for a best-interests assessment are in section 4 of the act and summarised in Box 3. Again, in emergencies, this will be a very brief assessment.

Box 3. Best interests assessment

  • Consider all relevant circumstances
  • Consider the patient’s reasonably ascertainable past and present wishes/ statements, their beliefs and values, plus any other factors they would take into account
  • Consult others – for example carers, relatives, attorneys and deputies – as practicable and appropriate to do so
  • Consider if the same result could be achieved in a less restrictive way
  • Will the patient have capacity some time in the future in relation to the matter? Can the decision wait for the patient to make it for themself?
  • Encourage and permit the patient to participate in the decision making
  • Do not base the best-interests decision solely on the patient’s age, appearance, behaviour or condition
  • If the decision is about life-sustaining treatment, do not be motivated by a desire to bring about the patient’s death. 


Staff in hospitals and care homes should receive training on the MCA; there is no legal requirement to be a member of a particular profession to assess mental capacity, providing the act is complied with.

The code of practice accompanying the act (Department for Constitutional Affairs, 2007) says at paragraph 4.38 that the mental capacity assessment should be carried out by the person directly concerned with the patient when the decision needs to be made (for example, a nurse who needs to take a blood-pressure reading). More guidance on this is available in paragraphs 4.39-4.43 of the code of practice.

Record keeping

Although there are no statutory forms to be used to record mental capacity assessments, the code of practice reminds staff to record assessments and best interests decisions in, for example, care plans, patient notes or computerised systems. Staff members need to ensure the legal criteria in Boxes 1-3 are covered. Many hospitals and care homes use pro formas to help staff with this.

Problems in practice

Despite the fact that the MCA has been in force since October 2007, a number of staff in hospitals and care homes admit they do not use it or do not record its use.

As a legal trainer, I often hear from staff who do not realise that the act must be used for all decisions where a person is suspected to lack mental capacity, not just in cases of dispute or where the person refuses care or treatment.


In summary, before patients can consent to care or treatment, they must have mental capacity. If they lack mental capacity, they cannot give or withhold consent (even if they comply with health professionals); in such cases, a best interests decision must be made for them. Fig 1 illustrates the process of correctly using the act.

This article is not a substitute for the Mental Capacity Act 2005 or case law. Nothing in it is intended to be or should be relied upon as legal advice.

Key points

  • Always follow the principles of the Mental Capacity Act
  • If there is any doubt about mental capacity, a legal mental capacity assessment should be undertaken when a decision is needed and recorded
  • Mental capacity assessments should be done by the person directly concerned with the patient at that time
  • Patients should be given as much help as possible to complete stage 1 of the assessment
  • A patient who lacks mental capacity cannot give or refuse consent; the person concerned with the their care must make a best interests assessment
  • 1 Comment

Readers' comments (1)

  • michael stone

    I was agreeing with this author, until I reached the following:

    'Mental capacity is tested by using a legal (not psychiatric) assessment described in sections 2 and 3 of the MCA.'

    Section 3 of the MCA, does not describe how to assess mental capacity - it describes how a patient who possesses mental capacity, consents to or refuses an offered treatment: this difference is subtle, but not insignificant !

    I strongly like this:

    'The legal criteria for a best-interests assessment are in section 4 of the act'

    I have argued with people, about this point - but the Act exists, it can only have been enacted to create law, and it does not 'point at some [vague] 'historical concept' of 'best interests'. So 'the meaning of the term best interests' must logically be 'mined' from section 4 of the Act (and not by looking at medical concepts around best interests, which pre-date the MCA).

    There doesn't seem to be anything else to comment on, in the piece above (in other words, so far as it goes, the rest also looks correct to me).

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