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Understanding mental capacity
Understanding mental capacity

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1.3 The test for mental capacity

For situations where there may be reason to question a person’s mental capacity to make a certain decision at a specific time, the Mental Capacity Act 2005 sets out a two-stage test based on a combination of functional and diagnostic methods. The test is outlined in Box 3.

Box 3 The two-stage test of capacity

Stage 1: The diagnostic test of mental capacity

  • Does the person have an impairment of, or disturbance in the functioning of the mind or brain (it does not matter if this is permanent or temporary)?

Stage 2: The functional test of mental capacity

  • If the answer is yes, does it make the person unable to make the decision? This can be found out if, after all appropriate help and support to make the decision has been given to them, they cannot:
    • a.understand the information relevant to that decision
    • b.retain the information
    • c.use or weigh up that information
    • d.communicate their decision.

If any of these apply, the person lacks the mental capacity to make the decision.

The test of capacity involves a two-step process involving the diagnostic and the functional. It is also important to note that it is based on ‘reasonable belief’. In other words, the assessment has to ascertain if it is more likely than not that the person lacks mental capacity.

Now that you’ve looked at how to assess capacity, the next question is: who should do it?