The Supreme Court and A Local Authority v JB (2021)

In A Local Authority v JB [2021] UKSC 52 the Supreme Court explained that the Mental Capacity Act 2005 (MCA) had broadly adopted a ‘function’ or ‘understanding’ approach to capacity (paragraph 61). This involves considering whether the person understands the general nature and likely consequences of what they are deciding and can communicate their decision.

However, the court went on to clarify that “understanding alone might not be enough to amount to capacity under the MCA. The MCA contemplates instances where a person can understand the nature and effects of the decision to be made, but the effects of his mental disability prevent him from using that information in the decision-making process: see section 3(1)(c) of the MCA…”

This means that an individual may be able to demonstrate the components one, two and four of the functional test of capacity (understand information relevant to the decision, retain that information, communicate the decision), but their impairment/disturbance (including issues where executive dysfunction arises) mean that they are unable to meet the third component (cannot use or weigh the information).

The Supreme Court clarified the correct ordering of the capacity test, noting that you should start with the question of whether the person is functionally unable to understand, retain, use or weigh the relevant information and then, finally, communicate their decision (paragraphs 63-79).