What is the statutory test for assessing someone's mental capacity?

The Mental Capacity Act sets out the relevant test. This has been considered by the Supreme Court in a recent case, where the court determined the questions to be answered as follows, and in this specific order:

1. Is the person unable to make the decision for themselves? The answer to this can be found in section 3 of the Mental Capacity Act 2005 which asks the following questions:
   
   1. Can the person understand the information relevant to the decision?
   2. Can the person retain the relevant information for long enough to make the decision? The emphasis on ‘long enough’ is important as people are not expected to remember the information indefinitely.
   3. Can they use and weigh up the relevant information?
   4. Can they communicate their decision?

Case law has outlined what the relevant information is for each decision-making area. It is crucial that the assessor provides this information to the person when carrying out the assessment. 

Once the above assessment has been completed, the assessor will then need to ask themselves if there is a link between the person’s inability to make the decision for themselves and an impairment of, or a disturbance in the functioning of, the person’s mind or brain. A number of conditions can be classed as an impairment or disturbance in the functioning of someone’s mind, including dementia and mental health conditions such as schizophrenia.