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Assessing a person's capacity to engage in sexual relations

In A Local Authority (Respondent) v JB (by his Litigation Friend, the Official Solicitor) (Appellant) ( the Supreme Court considers the assessment of capacity under the Mental Capacity Act 2005 (“MCA”) for the first time. 

In his leading judgment, Lord Stephens considers what the relevant information should be when assessing a person’s capacity to engage in sexual activity. The judgment raises issues of profound significance” for people with impairments of the mind or brain “which potentially make them unable to make a decision for themselves in relation to having sexual relations”. This is because consent to sexual relations cannot be given on behalf of someone who lacks capacity by virtue of section 27(1)(b) of the MCA, so if a person is deemed to lack capacity in this area they are not able to have a sex life.


JB is a 38-year-old man who lives in a supported residential placement funded by a local authority (“LA”). JB has severe epilepsy and an autistic spectrum disorder (“ASD”), namely Asperger’s syndrome. He is described as “likeable” by his support staff and it is important to him to feel liked. JB struggles with social functioning and this has caused problems in his relationships with women. He has become fixated on particular women; he was asked to leave college due to violent and inappropriate sexual behaviour; and in 2011 he was banned from a ballroom dancing club following complaints from women who said he had touched them inappropriately.

JB’s care plan is restrictive in respect of his access to the community, social media and his contact with others. In particular he has 1:1 supervision when in the community and around women. JB told Dr Thrift, one of the psychological experts jointly instructed by the LA and the Official Solicitor (OS), that his “number one priority” was “to get a woman as a sexual partner”. He expressed to Dr Thrift that he does not value the companionship aspects of a sexual relationship”.

It is clear throughout the psychological evidence that JB finds it difficult to read signs from others, including whether a woman is consenting to his sexual advances. JB puts the onus on the woman to show obvious signs she does not consent. He does not appear to understand that consent once given can be withdrawn during a sexual act. He lacks insight into his behaviour and it is the view of the experts that he is not motivated to change or to undertake treatment to change his behaviour.

History of proceedings

Proceedings were initiated by the LA in the Court of Protection and the matter was heard before Mrs Justice Roberts on 15 July, 2019. The parties had reached agreement on all areas of JB’s capacity apart from his capacity to consent to sexual relations. 

The issue centred on what constituted the “relevant information” to the decision and this needed to include an understanding that the other person also needed to be able to consent. The LA was concerned “that if this component was absent then sexual offences might be committed by JB and that to permit such a situation would be a derogation of responsibility by the Court of Protection”. 

Roberts J concluded that the relevant information did not include the consent or otherwise of the other person and granted a declaration that JB had capacity to consent to sexual relations.

The LA appealed to the Court of Appeal. Handing down judgment on 11 June, 2020, Lord Justice Baker reframed the test so as to consider the question of whether a person has the capacity to “engage in” rather than “consent to” sexual relations, which widened the scope of the decision to include consideration of the consent or otherwise of the other person, and allowed the appeal.

Permission to appeal to the Supreme Court was granted on 13 April 2021. Due to the public importance and potential implications of the case, two charities were allowed to participate in the appeal as interveners. 

The charity Respond provided submissions from the perspective of people learning disabilities and autism; and the Centre for Women’s Justice from the angle of challenging male violence towards women.

The Supreme Court

On 24 November, 2021, the Supreme Court dismissed the appeal on all five grounds raised by the OS on behalf of JB. In particular, the Supreme Court dealt with the OS’s first two grounds as follows:

  • The formulation of ‘the matter’ for the purposes of section 2(1) of the MCA

The OS argued that the Court of Appeal was wrong to recast the matter as “engaging in” sexual relations because the wording used in MCA s27(1)(b) is “consenting to sexual relations”. Lord Stephens rejected this argument on the grounds that s2(1) is not controlled by s27. The function of s27 is to identify decisions that no one may take on behalf of someone who lacks capacity, it does not define the matter.

Lord Stephens explained that recasting the matter as “engaging” rather than “consenting” fits JB’s situation better as he wants to initiate sex with others rather than consent to sex proposed by someone else. 

He cited two other cases where the same approach had been taken by Munby J (Re MAB; X City Council v MB [2006] EWHC 168 (Fam) - Mental Health Law Online and Local Authority X v MM & Anor (No. 1) [2007] EWHC 2003 (Fam) (21 August 2007) (

He concluded that the test for assessing capacity in relation to sexual relations should be formulated as “engaging in sexual relations” in most cases.

  • The identification, under section 3(1)(a) MCA, of the information relevant to the decision 

The OS sought to argue that including the consent of the other person in the relevant information wrongly extended the MCA into a remit of public protection. Lord Stephens disagreed on the basis that the relevant information should include “reasonably foreseeable consequences” of a decision for both the person in question and others. 

The OS went on to argue that this formulation of the relevant information creates an “impermissibly person- specific” test of capacity. Lord Stephens rejected this argument by stating that what is being considered is “a generalised forward-looking evaluation” of JB’s capacity to have sexual relations with any woman, rather than a specific woman.

The OS argued that JB and people like him were being set up to fail with such a high test. The charity Respond supported this submission and advocated for a less abstract and simpler test. Lord Stephens did not agree, stating that “a potentially incapacitous person is simply required to understand that the other person must be able to consent and does in fact consent throughout”. 

The OS’s submission that this requirement was discriminatory was also rejected. Lord Stephens stated earlier in the judgment that the demand should not be more than that placed on a person with capacity to make the decision.

Implications for practice

Firstly, the judgment provides a useful refresher of the principles of section 1 of the MCA and confirms that the MCA’s approach to determining capacity is a functional (rather than a status or outcome) approach and therefore the functional test should be applied first. 

This is at odds with the MCA Code of Practice which starts with the diagnostic test but is considered by many commentators to be the correct approach as it focusses on whether the person can make the decision first and brings the support principle to the forefront. 

The new draft MCA Code of Practice which is currently out for consultation corrects this by changing the order in which the test of capacity assessment is set out in chapter 4 (Changes to the MCA Code of Practice and implementation of the LPS: consultation document - GOV.UK (

The judgment sets out a clear test for assessing a person’s capacity to engage in sexual relations. They must be able to understand that the other person consents and can withdraw consent. In order to assess capacity the reasonably foreseeable consequences of engaging in sexual relations must form part of the relevant information. These will vary according to the situation, for example, risk of sexually transmitted disease is unlikely in a long-term monogamous relationship, and risk of pregnancy does not occur in same sex relationships.

Therefore, this test will always be the starting point, but there may be situations where there is a reason not to apply the test, for example when a very specific sexual practice, such as auto-erotic asphyxiation, is being considered, or where the person concerned is in a monogamous relationship but wants to pursue an extramarital affair. A decision-specific assessment will be required in these circumstances.

The other area for discussion is the extent to which this judgment extends the MCA into the realms of public protection. The reasonably foreseeable consequences of JB engaging in sex could include him committing an offence (if the other person does not or withdraws consent). 

This raises potential questions as to whether protecting a person from possibly committing a criminal offence is discriminatory, as the same protection is not offered to people who have capacity to engage in sexual relations. However, it should be noted that in his judgment Lord Stephens went on to say “I reject the submission that the purpose of the MCA is solely confined to the protection of P”

So where does this judgment leave JB’s quest for a girlfriend? The matter has been remitted back for reconsideration of his capacity in the light of the new test. Given the psychological evidence, JB is likely to be found to lack capacity to engage in sexual relations due to his lack of understanding of the consent of the other party and this appears to be unlikely to change any time soon.

Find out more about Irwin Mitchell's expertise in dealing with mental capacity cases at our dedicated protecting your rights section.