Factsheet: A guide to the Mental Capacity Act 2005

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Summary

April 2026

This factsheet explains the Mental Capacity Act 2005.

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What is mental capacity?

Mental capacity means being able to make your own decisions. Someone may be able to make one decision but not another.

All adults have the right to make decisions about their life. This includes decisions about their care and support. They should be helped to do this if they can’t do it on their own.

What is the Mental Capacity Act?

The Mental Capacity Act is the main law in England and Wales that protects people who lack capacity.

It covers simple decisions like what to eat, and important decisions like where to live and what medical treatment to have.

There are rules for anyone caring for someone over 16 years old. This includes health and social care professionals and paid carers. It tells them what to do when they are working with someone who lacks capacity.

Some decisions are not covered by the Act. These include marriage, civil partnership, consenting to sexual relationships, adoption and voting. Nobody can make these decisions for someone else.

The five key principles

Assume people have capacity.
Support people to make decisions for themselves.
People who make unwise decisions may still have capacity.
Actions must be in the best interests of the person who lacks capacity.
Consider less restrictive options first.

Assessing mental capacity

If a health or social care professional thinks that someone lacks capacity, they must do a mental capacity assessment. This must happen before they ask them to agree to any care or treatment.

A family member or professional might need to decide if someone can make a particular decision.

How to check if someone has capacity

You must check that the person can make the decision at the time that it needs to be made.

To make a decision, they must be able to:

understand information about the decision
remember the information long enough to make the decision
weigh up the options and decide
communicate their decision (in whatever way they can)

What happens when someone cannot make a decision?

People should be supported to make their own decisions.

If they cannot make a decision and they do not have a legal representative then someone else, like a carer or professional, will have to make a ‘best interests decision’.

Working out what is in someone’s best interest

Best interest means what is best for a person, once all things have been considered.

The Act has a ‘best interest checklist’. It can be useful for people involved in someone’s care to meet as a group to discuss what is in their best interest.

Best interests checklist

To work out what is in someone’s best interest:

do not base decisions on age, appearance, condition or behaviour
consider all relevant circumstances
help the person to take part in making the decision
consider if they may regain capacity. If so, can the decision wait? (if it is not urgent)
think about the person’s wishes and feelings, beliefs and values – in the past and now
ask their friends and family what they think
ask their attorney or deputy what they think (if they have one)

Protection from harm

It is a crime to:

badly treat a person without capacity, or
wilfully neglect a person without capacity

These offences carry a sentence of up to five years imprisonment and/or a fine.

Planning ahead

It’s important to plan who will make decisions for you in the future if you lose capacity. A ‘next-of-kin’ has no legal status when someone is alive. They cannot:

agree to treatment on someone's behalf
see their medical records
access their money or belongings
take over their banking and bills

To do these things, you must become a power of attorney.

Lasting power of attorney

A lasting power of attorney (LPA) lets someone appoint a person to make decisions for them if they lose capacity in the future.

There are two types and you can have both:

property and finance
health and welfare

There is more information about this in our factsheet: Managing someone’s affairs

Advance decisions to refuse treatment

Someone can make an advance decision or ‘living will’. This covers treatment that they do not want if they lose mental capacity in the future.

Advance decisions are legally binding. Doctors and health staff must follow them, as long as:

the person is 18 or over
they had mental capacity when they made the decision

The decision should say which treatments are being refused and when this applies.

An advance decision does not need to be in writing but is helpful if it is.

Advance decisions to refuse life-sustaining treatment

‘Life-sustaining treatment’ is medical care needed to keep someone alive.

If someone wants to refuse this treatment in advance, it must:

be in writing
state that it applies even if their life is at risk
be signed by the person (or someone they have chosen, in front of them)
be signed in front of a witness
be signed by the witness in front of the person

Court of Protection

The Court of Protection (the Court) protects the rights of people who do not have mental capacity. It makes decisions on:

capacity
property and finance
health and welfare
disagreements about best interests

What is a deputy?

If someone does not have a lasting power of attorney, the Court can appoint a deputy. They will make ongoing decisions for someone who lacks capacity.

The deputy must be 18 years or over and can be a relative, friend or professional.

For more information, visit Deputies: make decisions for someone who lacks capacity | GOV.UK

Independent mental capacity advocates

An independent mental capacity advocate is specially trained to help people who:

lack capacity to make important decisions
have no family, friends or a legal representative

An advocate must be involved if the decision is about:

serious medical treatment, or
a change of accommodation (more than 28 days in hospital or 8 weeks in a care home)

For more information, read our factsheet: Independent advocacy

Challenging decisions and raising concerns

Sometimes people disagree about decisions made under the Act. These can be sorted out using:

informal meetings (may include advocacy services)
a complaints process, such as the NHS or local council
speaking to the Office of the Public Guardian (if there are concerns about a lasting power of attorney)

The Court of Protection has the final say about disagreements.