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Mental Capacity Act 2005

A general guide on how the Mental Capacity Act affects you and how you can plan ahead for when you no longer have the mental capacity to make decisions for yourself.

  • This information applies to England and Wales.
  • This information applies to adults. It doesn't apply to children unless specifically stated.

What does 'lacking capacity' mean?

Section 2 of the Mental Capacity Act 2005 says that “a person lacks capacity in relation to a matter if at the material time he is unable to make a decision for himself in relation to the matter because of an impairment of, or a disturbance in the functioning of, the mind or brain.”

Lacking capacity includes where your ability to make decisions is affected:

  • permanently: this is where your ability to make decisions is always affected. This might be because, for example, you have a form of dementia, a learning disability or brain injury. Or,
  • in the short term: this means your ability to make decisions changes from day to day. This might be because, for example, you are confused because you’re on medication or because of some mental health conditions, or you are unconscious.

Example 1

Ava has a mild form of dementia which affects her short-term memory. After she spends money, she will often forget how much she has spent, and whether or not she has even bought anything. Her condition is unlikely to improve in the future.

Ava's capacity to make important financial decisions has been permanently affected because of her mental health condition.

Example 2

Paul sometimes hears distressing voices. He is generally able to do day-to-day activities, such as washing, cleaning, and cooking for himself. However, when the voices are at their most distressing, he is not able to do these activities.

Paul's capacity to do day-to-day activities is affected in the short term because of his mental health condition.

Different types of decisions

Whether or not you lack capacity will also depend on the type of decision that you need to make.

  • You will probably need a lower level of mental capacity to make decisions about everyday matters, such as what to eat or where to go.
  • You will probably need a higher level of mental capacity when you are deciding whether to buy a new home or get married.

Section 3 of the Mental Capacity Act says that when someone is assessing your ability to make a decision, they have to ask these questions:

  • Can you understand the information related to the decision?
  • Can you remember the information for long enough to make a decision?
  • Can you weigh up or use the information to reach a decision?
  • Can you communicate the decision in any way at all, such as talking, using sign language or hand signals, or squeezing someone's hand?

To decide whether you lack capacity, they then need to ask whether you are unable to make the decision because of a short-term or long-term condition, such as:

  • an illness
  • the effects of medication
  • being unconscious
  • having a brain injury
  • being in a long-term coma.

The Mental Capacity Act Code of Practice

The Mental Capacity Act Code of Practice says that people should not assume that you lack capacity because of:

  • your age
  • your appearance
  • any mental health diagnosis you may have
  • any other disability or medical condition you may have.

How is my mental capacity assessed?

Before someone can make a decision for you, they have to have a reasonable belief that you no longer have the capacity to make that decision yourself. This means asking questions like:

  • Do you have a general understanding of what decisions need to be made?
  • Do you have a general understanding of the consequences of the decision?
  • Do you show this general understanding in the way you behave and make decisions?

If the decisions are for straightforward day-to-day actions, your friends and family can assess whether or not you have capacity.

If the decisions are more difficult, such as giving consent to medical treatment, a health professional like a doctor may have to assess you.

When health professionals are assessing your capacity, they must remember the following:

  • Anyone assessing you must begin by assuming that you have capacity.
  • They must help you make a decision for yourself.
  • If they make a decision for you because you lack capacity to make it yourself, it must be in your best interests and restrict your freedom as little as possible.
  • What the Mental Capacity Act says about lacking capacity.

The same principles apply to life-changing decisions as they do to routine decisions.

What happens if I am found to lack capacity?

The Mental Capacity Act sets out ways for you to plan for what should happen if you ever lost capacity to make a particular decision.

If you do not plan ahead, and at some point you lose your capacity to make a particular decision, the Mental Capacity Act says that someone else can make that decision for you. Exactly who this would be depends on the circumstances at the time, but it could be a:

  • friend
  • relative
  • unpaid carer
  • paid carer
  • doctor
  • social worker
  • nurse
  • other health care professional
  • court (in some unusual cases).

Even if someone else is making decisions for you, you should still be involved as much as possible when decisions are being made.

If you want to make important decisions for someone because they lack capacity to do so themselves, you may have to arrange for an assessment of that person’s capacity. If the decision you want to make has long-term or irreversible effects, you may need to get legal advice about whether the law allows you to make it, or whether you need permission from a Court of Protection.

Some everyday actions that are part of a person’s care and treatment, such as a carer helping someone to dress, wash or eat, can be taken without a formal capacity assessment having to be made.

If I have a mental health diagnosis or have been detained under the Mental Health Act, will I always lack capacity to make my own decisions?

No, not always. The Mental Capacity Act may apply to you if you have a mental health problem that affects your ability to make a particular decision. However:

  • you may still be able to make some of your own decisions
  • you may get back your capacity to make decisions after a time, or
  • your capacity to make some decisions may be affected only occasionally and for short periods.
< About the Mental Capacity Act Best interests >

This information was published in November 2017.

This page is currently under review. All content was accurate when published. 

References are available on request. If you would like to reproduce any of this information, see our page on permissions and licensing.

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