Mental capacity

The information on this page gives an overview of capacity and the Mental Capacity Act. For a more comprehensive explanation it is advised that you use the links at the end of the page to access more further information on other websites.

What is capacity?

It is important to know whether someone has the mental capacity to make a decision.

If someone can make a decision for themselves, they are said to have the mental capacity to make that decision. If they aren't able to make a decision, because of some form of mental impairment, they are said to lack the mental capacity to make that decision. The impairment may be either temporary or permanent and could be caused by:

  • dementia
  • brain injury
  • a stroke
  • alcohol or drug misuse
  • the side-effect of medical treatment
  • any other illness or disability.

A person must be assumed to have capacity unless it is established they don't.

Whether the person you care for has mental capacity or not will affect the option for them to nominate you to deal with their affairs on their behalf, such as whether it is still possible to make a lasting power of attorney (LPA) or an advanced decision.

The Mental Capacity Act

The Mental Capacity Act 2005 (MCA) is designed to protect people who may lack the mental capacity to make their own decisions about their care and treatment. It is a law that applies to individuals aged 16 and over. The main principles are:

  • a presumption of capacity must be assumed
  • individuals are to be supported to make decisions
  • individuals have a right to make what may seem unwise decisions
  • all decisions must be based on protecting an individual's best interests
  • decisions must be the least restrictive to an individual's rights and freedoms.

Everyone has the right to make his or her own decisions. Health and care professionals should always assume an individual has the capacity to make a decision themselves, unless it is proved otherwise through a capacity assessment.

Deciding if someone has capacity

Carers and family can and should make assessments of capacity for simple decisions – such as whether someone can decide what to wear or eat. Some people will be able to make decisions about some things but not others. For example, they may be able to decide what to buy for dinner, but be unable to understand and arrange their home insurance or decide whether to go ahead with an operation. Of course, the more serious the decision, the more formal the assessment of capacity should be.

If it is suspected a person lacks mental capacity, a formal Mental Capacity Assessment will be carried out. This is usually done by a mental health social worker but it will depend what professionals are involved with the person’s care. The person’s carers and/or family should be consulted and will be able to voice their opinions.

If you feel the person you care for needs an assessment of their care and support needs and/or mental capacity, contact Derbyshire County Council Adult Care on Tel: 01629 533190

The MCA has a two-stage test of capacity:

1) Does the individual concerned have an impairment of, or a disturbance in the functioning of, their mind or brain, whether as a result of a condition, illness, or external factors such as alcohol or drug use?

2) Does the impairment or disturbance mean the individual is unable to make a specific decision when they need to? Individuals can lack capacity to make some decisions but have capacity to make others, so it is vital to consider whether the individual lacks capacity to make the specific decision.

Also, capacity can fluctuate with time – an person may lack capacity at one point in time, but may be able to make the same decision at a later point in time. Where appropriate, people should be allowed the time to make a decision themselves. Needing more time to understand or communicate doesn’t mean you lack mental capacity. For example, having dementia does not necessarily mean that someone is unable to make any decisions for themselves.

In relation to the second question, the MCA says a person is unable to make a decision if they cannot:

  • understand the information relevant to the decision
  • retain that information
  • use or weigh up that information as part of the process of making the decision.

Where someone is having difficulty communicating a decision, an attempt should always be made to overcome those difficulties and help the person decide for themselves. If they still aren't able to do any of the above three things or communicate their decision (by talking, using sign language, or through any other means), the MCA says they will be treated as unable to make the specific decision in question.  


If a person lacks mental capacity and has no family members or carer to look after their interests, they may be supported and represented in decision making processes by an independent advocate

The Court of Protection

The Court of Protection oversees the operation of the Mental Capacity Act and deals with all issues, including financial and serious healthcare matters, concerning people who lack the mental capacity to make their own decisions.

The Court tries to resolve disputes when the person's carer, healthcare worker or social worker disagree about what's in the person's best interests, or when the views of the attorneys in relation to property and welfare conflict.

The Court hears important cases, such as whether the NHS should withdraw treatment, whether a serious medical treatment decision is in a person's best interests, or whether it is in a person's best interests to be deprived of their liberty. Cases can be brought to the court by family members, as well as advocates and professionals involved in decisions.

Legal advice

Mind have a 'legal line' telephone helpline which offers advice about legal issues around mental health including mental capacity. The line is open Monday to Friday from 9am to 6pm on tel: 0300 466 6463.

Rothera Sharp Solicitors are working with Derbyshire Carers Association to provide free legal advice clinics to carers in Derbyshire. Rothera Sharp may be able to advise you about the MCA, mental health law in general and any other legal issues you may face as a carer.  More clinics / venues are planned around the county as the scheme progresses but you can also request advice by email or phone. 

Other helpful websites

This information was last updated on 08/04/2019

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