Mental Capacity

Mental Capacity is the ability to make your own decisions at the time at which the decision needs to be made. The mental capacity act was designed to protect and empower people who lack the mental capacity to make their own decisions about their care and treatment. It applies to those aged 18 and over.

There are five principles of the Mental Capacity Act (MCA)

  1. Everyone is presumed to have capacity until proven otherwise.
  2. Adequate support should be given to help patients make decisions e.g. Interpreters/drawing diagrams/writing things down.
  3. Patients have the right to make unique decisions.
  4. All decisions should be made in the patient’s best interests.
  5. The least restrictive option should always be chosen.

As a junior doctor, you will often have to assess a patient’s capacity to make a specific decision. Common examples of these include:

  1. Consenting a patient for a procedure including blood transfusions/blood taking etc.
  2. Patient’s wanting to leave the ward/ self-discharge.
  3. Patient refusing to take their medication.
  4. Patient refusing a lifesaving operation.

Examples of things that can cause an impairment of, or disturbance in the functioning of the mind or brain:

  • Dementia
  • Significant learning disabilities
  • Long term effects of brain damage
  • Physical or medical conditions causing confusion/drowsiness/loss of consciousness
  • Delirium
  • Concussion following a head injury
  • Symptoms of alcohol or drug use


The key thing to remember is that capacity is decision and time-specific. Sometimes people will make sweeping statements about capacity e.g., “they have dementia, they do not have capacity” – this is NOT true.

A patient may have capacity to make decisions about certain things but NOT others and someone’s capacity can fluctuate with time. It may be useful to reassess capacity at a different time to allow the person to make the decision if appropriate. It is also vital to check capacity for every decision that is needed to be made.

There are two main stages to assess capacity:

Stage 1: Is there an impairment of, or disturbance in the functioning of the mind or brain?

Stage 2: Is the patient capable of making a decision regarding the specific question at hand?

  • It is fundamental to provide adequate support, examples of how to do this include:
  • Have you given the person all the relevant information?
    • Have they been given the information about alternative solutions?
    • Can the information be explained in a different way? e.g., Simpler language/diagrams and visual aids
    • Have you tried different methods of communication? – British sign language/ interpreters
    • Would someone be able to help communicate with the patient such as a family member/carer or advocate?
    • Does the patient have everything they need to feel orientated? e.g., Hearing aids/ glasses
    • Could the decision be delayed until they may feel better/more comfortable to make the decision?

To assess stage two, the patient must be able to:

  1. Understand the information,
  2. Retain the information.
  3. Weigh up the pros and cons.
  4. Communicate the decision back to you.

Only if the patient is able to demonstrate all of the four above, they deemed to have capacity.

Best interests

  • If a patient has been evaluated and it is felt that they are lacking capacity, then any decision made for the patient should be made in their best interest (Principle 4 of the MCA).
  • In hospital this responsibility usually falls on the consultant in charge. However, in cases where decisions are a bit more complicated such as a possible change in destination after leaving hospital (i.e., from living at home to moving to a nursing home) a best interest meeting would be arranged so that the MDT team and possibly family members would be able to join in for the best interest meeting.

Advanced statements

  • These are written by the patient and may include what their values and beliefs are and what their wishes and their preferences are.
  • They are NOT legally binding
  • Aim to provide a guide to help make decisions in the patient’s best interest when the patient themselves has lost the capacity to do so for themselves.
  • It can detail any of the patient’s future health or social care.

Advanced Decision (Advance Decision to Refuse Treatment/living will)

  • An advanced decision to refuse treatment (ADRT) is legally binding
  • Allows patient over 18 years of age to refuse specific medical treatment for a time in the future when they do not have the capacity to refuse the treatment.
  • Must be valid and appropriate to the present circumstance. As such, it would be the same as if the patient had the capacity to make said decision and the decision should be respected.
  • If the ADRT being written reduces life-sustaining treatments, it requires:
    • To be in writing, to be signed and witnessed.
    • It needs to evidently state that the decision applies even if the patient’s life is at risk.

Lasting Powers of Attorney

  • The patient grants lasting power of attorney (LPA) to another person to allow them to make decisions when they no longer have capacity
  • Can be made at any point in time as long as they are age 18 and over AND have the mental capacity at the time of decision making
  • The LPA must be registered to be legally binding
  • Two types of LPA
    • Health and Welfare
    • Property and financial affairs
  • When acting under the LPA, the person that has been appointed by the patient must:
    • Ensure that the patient’s capacity has been assessed – if the patient has capacity, then the LPA is null and void and the patient has the right to make their own decisions
    • Ensure the principles of the MCA are upheld

Deprivation of Liberty Safeguards (for England and Wales)

  • As healthcare professionals, we may need to restrict someone’s liberty in hospitals or care homes. This includes putting them under continous supervision and/or control and/or not allowing them to leave. This is done in someone’s best interests but additional safeguards are necessary to protect the patient – there are termed DoLS which are an ammendment to the Mental Capacity Act (2005)
  • These include different forms of restraint and restriction – for example, applying mittens to stop a patient pulling their cannula out or infecting their wound
  • As always, you should try to discuss these with the patient if they have fluctuating capacity
  • Completing DoLS paperwork is asking the local authority for approval. They facilitate in checking that these decisions are made in the patient’s best interest and other laws aren’t more suitable (e.g. applying a section of the Mental Health Act) .
An Example

If a patient on the ward with dementia is wandering around and trying to leave the ward. You find that they do NOT have the capacity to make a decision to leave. You are worried that they will hurt themselves or get lost by wandering around and want to keep them on the ward to treat them. This is a situation in which a DoLS would be helpful.

Conditions for a Deprivation of Liberty Safeguard
  • The person is aged 18 or over (different safeguards apply for children).
  • The person is suffering from a mental disorder.
  • The person lacks capacity to decide for themselves about the restrictions which are proposed so they can receive the necessary care and treatment.
  • The restrictions would deprive the person of their liberty.
  • The proposed restrictions would be in the person’s best interests.
  • Whether the person should instead be considered for detention under the Mental Health Act.
  • There is no valid advance decision to refuse specific treatments or support, that would be overridden by any DoLS process.

It is important to discuss with the family to help support that it is in their best interests and to identify any advance decisions.

Putting a Deprivation of Liberty Safeguard in place
  • To put a DoLS in place – a form must be completed which must be sent to a supervisory body – the assessor will then decide within 21 days whether to put the DoLS in place or not.
  • This is based on an independent assessment by the supervisory body.
  • If it is urgent, an urgent authorisation can be done by the hospital or care home themselves, before awaiting the supervisory body.
    • A form needs to be signed and sent to the supervisory body – but this means that the DoLS can be in place straight away. Usually, the nursing staff on the ward can complete this form.
  • Deprivation of liberty is different from being detained under the mental health act, as it is NOT done with the main purpose of treating/assessing a mental health condition. It is done for the main purpose of keeping the patient safe when they lack capacity, and for treatment of other health conditions in their best interest. 

Case study

Case 1: A 95-year-old man is admitted with a fall. He refuses carers.

He has felt unsteady on his legs for a few years and sometimes struggles to get up the stairs so sleeps downstairs. He has a background of Alzhimer’s disease and as a result is cognitively impaired.

He lives alone, and his daughter lives in a different town and is worried about him. He is now medically fit for discharge. Since being in hospital, he has been speaking to the occupational therapists who are organising a stairs assessment and for equipment to be delivered to his house. They also advised the patient will need carers to help with personal care. However, the patient does not want to receive any help, he likes living alone and does not want any carers to come and help him. He is refusing any help from the occupational therapist and wants to leave the ward now. His daughter has called him to try and convince him otherwise.

You (the FY1) go to speak to the patient who is walking off the ward. He says he can look after himself and doesn’t need any more help. You take him to a quiet place and explain why you think an OT assessment and carers would be helpful for this man. He understands they are trying to help him, and he knows he may fall again, but he wants to be on his own in the comfort of his own home. He explains this to you and then says he wants to sign the self-discharge papers.

Does this man have capacity to make this decision?

  • The fact he has dementia does NOT automatically mean he does not have capacity.
  • From the case study information, at this point in time, the patient seems to understand the risks, retain the information, weigh up the pros and cons and communicate it back to you. As long as this is true, despite his daughter and the medical team disagreeing, he has the right to make this decision.
  • This is an example of the patient making an unwise decision
  • Despite the patient having an impairment or disturbance to the functioning of their mind/ brain, the patient does seem to have the capacity to make this decision.


  • Given the patient is medically fit for discharge, this should not be a self-discharge but instead the next best alternative should be offered and his discharge should be facilitated. Just because a patient refuses optimal care, does not mean they should get none at all.
  • If a patient does want to self-discharge, you should try and explain the risks of self-discharging and any compromises you could come to.
  • If they still want to discharge, you should document the conversation clearly and you must include the alternatives that have been provided in attempt to try and keep the patient in hospital.
  • The patient needs to sign a form explaining they understand the risks of leaving.  
Case 2: An 88-year-old lady is admitted with a UTI declines a blood transfusion.

She has a background of Alzhimer’s disease and as a result is cognitively impaired. She is treated with oral antibiotics, which she consented to on admission. She is on day 4 of her antibiotic treatment. On her routine blood tests, you notice her Hb has dropped from 120 on admission, to 88. There is no evidence of any source of bleeding, but after a discussion with your registrar, you decide to give her a blood transfusion. However, when you go to consent the patient, she does not seem to respond to your questions. She asks you to leave as you are disturbing her sleep. You try to return at which time she says she is happy to speak to you. You ask her if she knows what a blood transfusion is and she says yes. She has had one before and doesn’t want one. When you ask her why she doesn’t answer properly. When you try to explain the benefits, she does not seem to be taking it in.

Does the patient have the capacity to make the decision to refuse treatment?

  • The patient does have an impairment of the functioning of the mind, due to her dementia.
  • She does NOT seem able to retain, weigh up the pros and cons or explain back to you the decision
  • She therefore does NOT have the capacity to make this decision

Her daughter informs you she does struggle to communicate and is very afraid of needles which is probably why she is declining.

  • However, this does NOT necessarily mean you need to do the procedure. You decide, with the registrar, that monitoring her may be a kinder option, instead of the blood transfusion. This is in her best interest and the least restrictive option.

Blood tests are repeated and her Hb is now 68, and her blood pressure has dropped. The patient also appeared more drowsy and pale.

You ask her again whether she consents to a blood transfusion, however, she still does not seem to compute what you are saying or communicate her decision to you. She seems drowsy and keeps saying she just wants to sleep.

  • At this point, she does NOT have capacity to make this decision AND giving the blood transfusion would be in her best interest.

References & Further Reading

Edited by Mudassar Khan (Y4 Medical Student)

How useful was this post?

Click on a star to rate it!

Average rating 4.9 / 5. Vote count: 24

No votes so far! Be the first to rate this post.

As you found this post useful...

Follow us on social media!

We are sorry that this post was not useful for you!

Let us improve this post!

Tell us how we can improve this post?

Related Posts

Junior Doctor Pay Calculator
Doctor's Pay Calculator 2024
We’ve created a pay calculator to help you better understand...
Dealing with a complaint
Dealing with a complaint
Everyone will receive a complaint – this is inevitable....
Medical Podcasts
Medical Podcasts that are worth a listen!
We asked on social media what your favourite podcasts were &...

Leave a Comment

Your email address will not be published. Required fields are marked *

Follow us



Trending Now

Doctor's Pay Calculator 2024
We’ve created a pay calculator to help you better understand your salary, how much tax you’ll...
Paracetamol Overdose
Paracetamol overdose is a common presentation in A&E and so you may often find yourself looking after...
Understanding the MSRA
The Multiple Specialty Recruitment Assessment (MSRA) is a computer-based exam increasingly being used...
How to take a psychiatric history
Psychiatry, as a specialty is unique in that diagnostic methods, rely very heavily on symptomatology,...
Common Viral Infections (exanthem) in Paediatrics
Viral infections are extremely common in paediatrics and a common presentation to paediatric A&E...
Essential Apps
Here’s a list of apps that are in order of how essential we find them. There’s probably more...
Audits & Quality Improvement Projects (QIPs)
Audits & QIPs are a way to identify issues, drive changes and assess the effects they have. It is...

Sign up for our awesome resources

Join over 40,000 users who have signed up for our free weekly webinars, referral cheat sheet & other exclusive content!