Contact one of our advisors now Call 0800 088 6004

Who can determine Mental Capacity, and how do they do it?

Reasons to choose Wilson Browne

The Court of Protection can appoint deputies if it decides that someone no longer has the mental capacity to make decisions for themselves.

To do this, however, the court needs a mental capacity assessment of the individual concerned.

Who can assess mental capacity, and how do they do it?

What Does Lacking Mental Capacity Mean?

Simply, lacking capacity means being unable to make certain decisions as a result of the functioning of the mind being disturbed or impaired.

Someone who lacks capacity may not be able to make decisions like:

  • Where they live
  • Whether to sell their property
  • How to look after their finances
  • What care they need

Mental capacity is defined under the Mental Capacity Act 2005. It Act is built around 5 key principles:

  • Everyone is assumed to have capacity unless shown otherwise
  • Someone should not be treated as unable to make a decision unless all steps have been taken to help them make that decision and this has not been successful
  • If a decision is unwise, this does not mean they lack capacity
  • Any steps taken on behalf of someone who does lack capacity, should be done in their best interests
  • Anyone making a decision on behalf of someone else should consider if there is a less restrictive option available.

How to Determine Mental Capacity

The Mental Capacity Act sets out the conditions by which someone can act on another individual’s behalf, making decisions for them because they lack mental capacity.

This involves two questions:

  • Does the person have a disturbance in their mind or brain function, or an impairment of their mind or brain?
  • Does this disturbance or impairment mean that the person is unable to make specific decisions when they need to?

If the answer to both questions is yes, then this can mean that they lack mental capacity to make decisions.

It’s important to note that lacking mental capacity may not apply all the time to an individual, or to all decisions they make:

  • Someone with mental health problems may be unable to make decisions when they are unwell, but will be able to when they are well
  • Someone with a learning disability may be unable to make major decisions, but will be able to make day-to-day decisions about things like what to wear or eat.

But someone with dementia, for example, may well lose the ability to make decisions as their condition gets more severe.

Who Can Carry Out a Mental Capacity Assessment?

Under the code of practice of the Care Quality Commission, the person who carries out a mental capacity assessment is known as an assessor.

An assessor of someone’s mental capacity does not always have to be a healthcare professional. They can be a family member, a care worker, care service manager or social worker, for example.

In certain circumstances, however, making this assessment may require the opinion of a medical practitioner or other medical professional, such as a psychiatrist or psychologist.

The law assumes everyone has mental capacity to make their own decisions for themselves, given sufficient information, support and time to do so.
Assessing their mental capacity must be according to a specific decision that needs to be made, not simply on the basis of their age, behaviour, appearance, illness or disability.

Making a decision for someone who lacks mental capacity has legal safeguards, and the decision-making must always be in their best interests.

The Court of Protection will only approve an application to become a deputy if it agrees with the assessment of someone’s mental capacity.

For more information about how we can help with making applications to the Court of Protection, please contact us.

Gemma White


Gemma White


Gemma is a Solicitor in the Private Client team at our Northampton office. She assists the team on a variety of matters including Wills, Lasting Powers of Attorney and Estates.