Mental Capacity Act 2005

IMPORTANT NOTICE – DOCUMENTS UNDER REVIEW

The documents on this page are currently under review following the Supreme Court’s judgment in[2026] UKSC 16, which unanimously overruled the majority decision in Cheshire West [2014] UKSC 19. The content may not fully reflect the current legal position and should be read in conjunction with the Supreme Court judgment until the review process is complete. The full judgement is available https://supremecourt.uk/cases/uksc-2025-0042

What is the Mental Capacity Act 2005?

The Mental Capacity Act 2005 is a piece of law that explains what to do when a person is not able to make decisions for themselves. The MCA applies to anyone 16 years old, and over, who has a mental impairment that might affect their ability to make decisions.
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Decision making

We all have the right to choose how to live our lives. The right to make our own decisions is the basis of the MCA and other laws such as the Human Rights Act 1998. Decisions can be small decisions such as what to wear, or big decisions such as where to live or whether to have medical treatment.

Some people are more able to make decisions at certain times than other times. For example, a person might have good days and bad, and only be able to make bigger decisions on their good days. Just because a person is not able to decide all of the time doesn’t mean they can’t decide some of the time.

The MCA applies whenever a person is unable to make a decision because of a mental impairment; for example, a brain injury, dementia, learning disability or mental health condition. The impairment doesn’t have to be permanent and could be because of something temporary like a urine infection, or because they have been drinking alcohol or taking drugs. No one should assume that an impairment means a person can’t make a decision, without checking first.

When a person can’t make a decision because of a mental impairment, even with help, the MCA says they ‘lack capacity’ to make that decision.

If there is a good reason to think someone might not be able to make a decision, we will assess their capacity. Assessing capacity means we check carefully whether or not a person can make a decision, taking into account what the MCA tells us. For example, when a person is being discharged from hospital, a social worker might assess their capacity to decide where they should be cared for next. This could be in a care home, or in their own home, for instance.

Assessing capacity

If there is a good reason to think someone might not be able to make a decision, health or care professionals will assess their capacity. Assessing capacity means checking carefully whether or not a person can make a decision, taking into account what the MCA says.

In a health and care context the assessor is likely to be a social worker, nurse, doctor, psychologist or other professional involved with the person’s care. The assessor must have a good understanding of the information that is key to the decision that needs to be made, so they can explain it to the person. For instance, a doctor assessing whether a person can decide to take a type of medicine will need to know the advantages and disadvantages of the medicine, and the consequences of deciding to take it or not take it, so they can explain this to the person.

Each capacity assessment relates to a specific decision, because a person might have capacity for one decision but not for another. For that reason, the same person might have more than one capacity assessment with more than one assessor. For example, a social worker may be assessing whether the person can decide about moving to a care home. The social worker will know the information relevant to the decision about whether to move; they may not know the information relevant to a decision about medical treatment, so a separate assessment of capacity will be needed about that treatment, from someone who understands more about the treatment decision, such as a doctor.

An assessor might ask the person’s friends and family about them in advance, to help them make their assessment. For example, the assessor might ask about the best ways of communicating with the person, or the ideal time to speak to them. The assessor might ask for help to communicate with the person, such as from a speech and language therapist, or sign language specialist.

The assessor will usually meet the person face to face. Sometimes a ‘virtual assessment’ such as by Zoom or Facetime is better. The person might be assessed on their own, or when supported by others if that makes them more relaxed. Support could come from anyone the person is comfortable with such as family or friends, or a professional such as an advocate or care worker.

Ideally the assessment should happen where the person is comfortable such as at home, or in a favourite room at their care home. The area should be private and free from distractions. Sometimes, there isn’t much choice about where and when the assessment happens if the decision is urgent, but the assessor should still think about what best suits the person in the circumstances.

Ideally, a capacity assessment should happen as soon as possible after it’s noticed that the person is struggling with making the decision that needs to be made.

The decision may be urgent, such as a decision about emergency housing or medical treatment, so an assessment will be needed right away. If the decision can wait, an initial assessment might be made and the decision delayed until more information, support and guidance can be given to help the person make the decision for themselves. A further assessment could be made later, to see if the person can now make the decision. Thought should always be given to the timing of an assessment and whether a decision can be delayed to a time that’s better for the person.

Sometimes people can make a decision on some days, or at some times, and not others because of their condition. This is often called having ‘fluctuating capacity’ because the person’s ability to make a decision changes. For people with fluctuating capacity, assessments might happen over days or even weeks to give a clearer picture of their capacity.

A capacity assessment is a ‘snapshot’ of whether a person can make a decision at a specific time. An assessment of capacity should be reconsidered when a new decision is needed, even if the decision is on the same topic, in case the person’s capacity has changed. The person themselves, or someone on their behalf, can ask for capacity to be reconsidered if they think something has changed.

Sometimes it can help if it is the same professional that assesses capacity each time an assessment is needed, but this might not always be possible. For example, because each assessment is decision specific it may not be possible for a social worker who previously assessed the person about decisions for care to also assess the person about decisions for medical treatment. The professional who is the most relevant to the decision to be made should make the capacity assessment, at the time the decision needs to be made.

The assessor will talk to the person. The assessor might need to check (for example) that the person has their hearing aid in, and their glasses on, before talking to them. The assessor might also need to use communication tools, such as pictures, to make sure the person can join in with the assessment. They will think about how the person responds to information the assessor gives them, and how they reply to questions the assessor asks. When making an assessment, the assessor will think about whether:

The person understands the information relevant to the decision – the assessor should give the person enough information to make the decision, and give it to them in a way they can understand. This might mean breaking down complex information into ‘chunks’ or providing ‘easy to read’ written information. How much the person needs to understand depends on how complex or serious the decision is. The person should understand the reason the decision is needed, the effect of making the decision, or of making no decision at all.
The person can retain the information – the person doesn’t have to retain the information perfectly or for a long period of time. The person should be able to remember the information long enough to make a decision. The assessor can check this by going back to the most important points throughout the discussion, or at the end.
The person can use and weigh the information in coming to a decision – this can be the most difficult part of the assessment for the assessor because sometimes a person can understand information, but their mental impairment stops them using it to make decisions. The assessor will look for whether the person can apply the information to the decision and use it to make a choice.
The person can communicate the decision – communication doesn’t need to be verbal, as long as the person can communicate in some way. The assessor should help the person to communicate, with support from specialists such as interpreters, or speech and language therapists if needed.

If the person is assessed as not able to do one or more of these four things (understand, retain, use/weigh, communicate) because of a mental impairment, then they will be assessed as lacking capacity for that decision at that time.

You can read our local capacity assessment template (Word, 48KB) to understand more about how we record a capacity assessment.

Sometimes there is disagreement about a person’s capacity. Everyone involved should try hard to resolve any differences. In difficult cases where no agreement can be reached, it might be necessary to apply to the Court of Protection for a decision on the person’s behalf. There are likely to be costs attached to going to court.

If you are not sure where to look for help with a concern about capacity, you can contact The Experience Team.

Best interests

When a person is assessed as lacking capacity to make a decision, that decision may need to be made for them, in their best interests. Best Interests isn’t defined in the MCA but deciding what’s in a person’s best interests includes thinking about things like their mental, physical, financial, social, and cultural interests.

The MCA puts the person’s past and present wishes and feelings at the heart of decision making. The MCA also says that decision makers must think about the person’s beliefs and values and how they might influence that person’s decision making, along with anything else the person might take into account if they were able to make a decision for themselves.

Anyone who is responsible for making a best interests decision for a person who can’t make that decision for themselves, must speak to others before doing so. The decision maker must speak to anyone that person has previously said should be included in any decisions about them, and anyone who is caring for them or interested in their welfare. This includes care workers, informal carers, family and friends, for example. These are the people who are likely to know the person best, and who will be able to give information about what the person might want, to support the decision making process.

Deciding what might be in a person’s best interests is sometimes a balancing act between decision makers choosing what the person might want if they could decide for themselves, and choosing what is likely to be best for the person, considering their overall wellbeing and safety. Although it’s not always decisive, significant weight should be given to what the person themselves would probably decide to do, if they could.

In some cases, a person may already have made the decision that needs to be made, in advance. An Advance Decision to Refuse Treatment or ADRT, if it is valid and applies to the situation that has prompted the need for a decision, must be respected. A valid and applicable ADRT means the person has already made the decision for themselves and recorded it, so there is no best interests decision to be made on their behalf.

The decision-maker is a person who holds the legal authority to make the decision that needs to be made, such as someone holding a valid power of attorney or a court appointed Deputy.

If there is no appointed decision maker such as an Attorney, a decision will need to be made by a relevant professional. This is usually the professional that says a decision is needed; for example, a doctor who thinks that the person needs some treatment that the person lacks capacity to decide about. Sometimes a group of professionals will make a decision together, but there should always be a clearly identified professional who is accountable for the decision and who makes sure the decision is recorded. The record of the decision should show clearly what the decision is, who has been part of making it, and why the decision has been made in one way or another.

You can read our local capacity assessment template (Word, 48KB) to understand more about how we record a best interests decision.

Whoever is making the decision – an appointed decision maker such as an Attorney or Deputy – or professionals – must take into account the views of others when they do so. And as far as possible, they must encourage the person who the decision is about to contribute to making it. People involved might be asked to give their views separately, or at a shared meeting.

If you want to understand more about making decisions for young people preparing to become adults you may find this guide from the Department of Health and Social Care useful: Making finance decisions for young people: parent and carer toolkit.

Sometimes there is disagreement about what is in a person’s best interests. Everyone involved should try hard to resolve any differences. In difficult cases where no agreement can be reached, it might be necessary to apply to the Court of Protection for a decision on the person’s behalf. There are likely to be costs attached to going to court.

If you are not sure where to look for help with a concern about best interests decisions, you can contact the Experience Team.

Further information can be accessed on our Court of Protection and Deprivation of Liberty pages.