Enter the Court of Appeal: clarity on determining mental capacity in the vulnerable

Reconciling an individual’s dignity, self-determination against the need for protection and support is a fine balance. This latest decision looks at the factors relevant to determining if a vulnerable adult has capacity to make decisions about where to live, consent to sexual relations and use of social media.

On 11 June 2019 the Court of Appeal handed down its judgment in B v A Local Authority which addressed two important questions which will be of interest to health and care professionals working in a range of settings.

We hear from the CoA on two questions:

  1. The factors relevant when determining mental capacity to:
    1. decide to use social media;
    2. consent to sexual relations; and
    3. decide on residence.
  2. The approach to take when a declaration of capacity to make one decision conflicts with the declaration of capacity to make another decision.


B is a 31- year-old woman with a learning disability. She frequently uses social media to communicate with strangers sharing intimate photographs, engaging in sex chats and searching for boyfriends who she quickly meets in person. Through this activity she met Mr C, a man in his seventies convicted of multiple sexual offences and subject to a Sexual Harm Prevention Order. Although advised of the risks, B refused to believe his offending history. She wishes to live with him and have his baby.

On 21 February 2019 the trial judge made declarations in relation to B’s capacity to make decisions which included her residence, care, contact with others, sexual relations and social media usage. He set out “relevant information” for decisions in respect of such issues.

This was an appeal by B (through her litigation friend, the Official Solicitor) and a cross appeal by the local authority.

What did the court say about:

Relevant factors?

The Official Solicitor did not challenge the trial judge’s declarations regarding B’s capacity; instead they objected to his reasoning. They argued he had erred in his formulation of the relevant information (guidance) which B needs to be able to understand, retain and use or weigh for the purposes of making the decision to use social media, to access the internet and to consent to sexual relations.

The judgment notes that it is a basic principle that an appeal is against an order and not just the reasoning of the judge in support of the order (which is not objected to). In addition, it does not matter if the guidance is a long or short list, it is simply guidance to be expanded or contracted or adapted to the facts of the particular case.

The appeal of B was ultimately dismissed.

Conflicts between declarations of capacity?

The trial judge decided that B had capacity to make decisions in relation to residence, i.e. to live with Mr C. However, the trial judge had also decided that she lacked the capacity to make other decisions, including the persons with whom she had contact with and consent to sexual relations. The local authority argued this made their care for and treatment of B practically impossible.

The Court of Appeal acknowledge that the Mental Capacity Act requires a decision specific assessment of capacity and the trial judge himself noted this can sometimes produce anomalous results. However, they concluded that it is important to take into account all relevant information. For example, in deciding that B had capacity to decide whether to live with Mr C, it was relevant that she did not have capacity to decide the persons who she has contact with.

The appeal of the local authority was ultimately upheld.


The judgment reminds us of the difficulty in reconciling a person’s right to autonomy when they are also vulnerable and need protection. We must not discriminate against those suffering from a mental disability by imposing too high a test of capacity.

Also, we must absolutely avoid deciding whether an individual has capacity simply by whether they make a good or bad decision.

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