June 13, 2018

Capacity Assessments – do you really understand what’s involved?

Below, we set out the relevant core principles from the Mental Capacity Act (“MCA”)with which you should be familiar, as they should form the foundation to an assessment. We explain possible triggers to when a capacity assessment should be undertaken and we highlight common pitfalls which are avoidable.

We want you to feel confident about knowing when and how to carry out assessments but also accept this area can be complicated and help is readily available if needed.

The basics

One of the five core principles of the MCA is that a person must be assumed to have capacity unless it is established they have not. I.e. the burden of proving someone lacks capacity falls entirely on the person who considers it possible a decision may need to be taken on the other person’s behalf.  The standard of proof which needs to be reached is on the balance on probabilities. So, it is for the substitute decision maker to prove a person is more likely than not lacking in capacity.

It is also worth emphasising that the decision maker who needs to be satisfied that the person lacks capacity, is the person who proposes to take the next steps on the basis that it is in the other person’s best interests. That person may or may not be a medical professional and certainly not only medical professionals can undertake capacity assessments. For example, social workers routinely carry out assessments.  At it's most basic, a capacity assessment can be viewed as a discussion with a person, on their terms, applying their value systems.

When should a capacity assessment be undertaken?

If you are the decision maker you need to consider that an assessment is necessary. You need to make sure you have grounds to undertake this step. That might be worries based on a person’s action or inactions. It might be reports you have received from others. Equally, where you have concerns but do not undertake an assessment you may need to justify this inaction.

What makes a good assessment?

If you are undertaking a capacity assessment a useful starting point is the definition of a lack of capacity found in the MCA:

‘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 the brain.’

So, there are two component parts to evidencing a lack of capacity and your assessment needs to prove that these have both been met.

  1. There is a ‘functional’ element: is the person ‘unable to make a decision for himself’; and
  2. There is a ‘diagnostic’ element, whether that person’s inability is due to ‘an impairment of, or a disturbance of the functioning of the mind or the brain’.

Very importantly, there must be a causal link between the above two elements. Namely, the impairment/disturbance of the mind must be the reason why the person cannot make the particular decision. For example, a person may suffer from  Dementia but that doesn’t rule out the possibility they are able to make decisions, but it may satisfy the diagnostic element of the test as to why they cannot make a decision.

The functional and diagnostic elements of a capacity assessment

The Diagnostic test

You may well rely on a clinician’s diagnosis for this part i.e. whether the person does or does not have an impairment or disturbance in the functioning of their mind or brain and if they do, what precisely it is. It should be remembered that these impairments or disturbances can be temporary or permanent. If it’s the former query whether decisions can wait until circumstances have changed.

The Functional Test

The MCA provides guidance on how decision makers conclude that a person is unable to make a decision for themselves. It sets out that if a person is unable to do one of the following that is enough to indicate a lack of ability:

  • Understand the information relevant to the decision; or
  • Retain that information; or
  • Use or weigh that information as part of the decision making process; or
  • Communicate their decision (can be talking, sign language or any other means)

To ensure that an assessment is carried out properly, as decision maker you need to make sure you have identified:

  • the actual decision in hand (capacity is time and decision specific)
  • the information relevant to the decision and provided it to the person you are assessing in the best form/format for them.
  • what steps you could take to ensure the person can participate as best they can. So it may be that before undertaking the assessment you stop to question, when would be the best time of day for it to be undertaken, in which environment might the person be most relaxed, would it be useful for them to be given information to read – for example, if they are hearing impaired.

When it comes to reviewing the person’s responses, never forget, be careful not to conclude that an unwise decision is demonstrative of an inability to make a decision. People are free to make unwise decisions, these alone do not equate to a lack of capacity.


A good capacity assessment makes it clear what precise decision is in question, it evidences that the person being assessed has been given all the salient and relevant information they need to be able to make a decision (if they are able), it shows that where the decision involves choices the person has firm details of the choices available, and it provides more not less information from the assessor. Verbatim notes of questions and answers can be very helpful and overall contemporaneous evidence is always preferable to retropspective.

Finally, the real key to a good capacity assessment is to provide the person being assessed with the best possible forum for them to demonstrate their capabilities rather than their limitations.

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