JB, a 38-year-old man with autism and brain damage, sought to engage in sexual relations but lacked understanding that sexual partners must consent throughout. The Supreme Court held that capacity to decide to engage in sexual relations under the Mental Capacity Act 2005 requires understanding that the other person must be able to consent and maintains consent throughout.
Facts
JB is a 38-year-old man living in supported residential accommodation with autism spectrum disorder (Asperger’s syndrome) and brain damage resulting from severe epilepsy. His primary desire was to engage in sexual relations with women, which he described as his ‘number one priority’. However, expert evidence established that JB could not understand that sexual partners must consent throughout sexual activity. He believed that once consent was given, it could not be withdrawn, and considered intoxicated women to be ‘fair game’. JB had a history of inappropriate sexual behaviour towards women, particularly targeting vulnerable individuals, and posed a moderate to high risk of sexual offending.
Proceedings Below
The local authority sought declarations regarding JB’s capacity in various matters. Roberts J at first instance held that information relevant to the decision to consent to sexual relations did not include information about the other person’s consent, declaring JB had capacity. The Court of Appeal allowed the local authority’s appeal, recasting the relevant decision as ‘engaging in’ rather than ‘consenting to’ sexual relations, and held that understanding the other person’s consent was part of the relevant information.
Issues
1. Whether ‘the matter’ for purposes of section 2(1) of the Mental Capacity Act 2005 should be formulated as ‘engaging in’ or ‘consenting to’ sexual relations.
2. Whether the information relevant to the decision includes the fact that the other person must be able to consent and gives and maintains consent throughout.
3. Whether the Court of Appeal’s test creates an impermissible difference with criminal law.
4. Whether the test is compatible with Article 8 ECHR and Article 12(2) of the UN Convention on the Rights of Persons with Disabilities.
Judgment
The Supreme Court unanimously dismissed the appeal. Lord Stephens delivered the judgment with which all other Justices agreed.
Formulation of the Matter
The Court upheld the Court of Appeal’s formulation of ‘engaging in’ rather than ‘consenting to’ sexual relations:
I also consider that this formulation is not inconsistent with the decision of Munby J at para 65 of X City Council v MB [2006] EWHC 168 (Fam); [2006] 2 FLR 968 in which he referred to both the ‘capacity to consent to sexual relations’ and ‘the ability to choose whether or not to engage in sexual activity’.
Relevant Information
The Court held that information relevant to the decision must include the other person’s consent:
Sexual relations between human beings are mutually consensual. It is one of the many features that makes us unique. A person who does not understand that sexual relations must only take place when, and only for as long as, the other person is consenting is unable to understand a fundamental part of the information relevant to the decision whether or not to engage in such relations.
The Court rejected arguments that this test was too complex or ‘person-specific’:
The inclusion of an understanding of the other person’s consent as part of the relevant information does not, … recast the test as ‘person-specific’.
Protection of Others
The Court emphasised that the MCA serves to protect both P and others:
as a public authority, the Court of Protection has an obligation under section 6 of the Human Rights Act 1998 not to act in a way which is incompatible with a right under the European Convention of Human Rights… Within the court, that obligation usually arises when considering the human rights of P, but it also extends to the rights of others.
Criminal Law Consistency
While acknowledging desirability of consistency between civil and criminal law, the Court found any differences were not impermissible, noting countervailing policy reasons supporting the protection of others and P himself.
Implications
This judgment has profound significance for persons with mental impairments in relation to sexual relations. It clarifies that capacity to engage in sexual relations under the MCA requires understanding that potential partners must be able to consent and must in fact consent throughout. The decision emphasises that the MCA serves protective functions for both P and potential victims of sexual harm. The case was remitted for reconsideration of whether JB lacks capacity, with emphasis on section 1(3) MCA requiring all practicable steps to help him achieve capacity. The judgment balances autonomy principles with protection from harm, recognising that where P cannot understand the consensual nature of sexual relations, deprivation of sexual relations may be the necessary consequence.
Verdict: Appeal dismissed. The Court of Appeal’s decision was upheld. The matter was remitted to the judge for reconsideration as to whether a final declaration should be made that JB lacks capacity to make a decision to engage in sexual relations.
Source: A Local Authority v JB [2021] UKSC 52
Cite this work:
To cite this resource, please use the following reference:
National Case Law Archive, 'A Local Authority v JB [2021] UKSC 52' (LawCases.net, April 2026) <https://www.lawcases.net/cases/a-local-authority-v-jb-rev1-2021-uksc-52/> accessed 11 June 2026
