Re MAB; X City Council v MB  EWHC 168 (Fam)
MAB's parents had wanted to arrange a marriage for him in Pakistan. It was declared that MAB did not have capacity to marry; therefore any marriage, even if valid in Pakistan, would not be recognised as valid in English law. His parent's undertakings not to take him to a wedding or out of Britain were accepted and his passport was returned. Any assessment of capacity to marry must take into account the question of capacity to consent to sexual relations. This involved a low level of understanding, which must be same in its essentials as required by the criminal law under the Sexual Offences Act 2003.
MAB was 25 years old, suffered from autistic spectrum disorder and mental impairment. He acted by the Official Solicitor as his litigation friend. His Muslim family had wanted to arrange a marriage with his first cousin R in Pakistan, although it was common ground that he lacked capacity to marry (Sheffield City Council v E  EWHC 2808 (Fam) applied). The medical evidence was that he lacked the capacity to consent to sexual relations.
The proceedings were taken by X after the father had expressed an interest in taking MAB to Pakistan to meet R. The medical opinion was that MAB would not be able for a long-haul flight. The main issue was as to what if any relief, and in what form, should be granted to restrain MAB being married or being taken to Pakistan.
The nature and basis of the court's jurisdiction is to be found in three recent cases: In re SK (An Adult) (Forced Marriage: Appropriate Relief)  EWHC 3202 (Fam), B, M v B (By the Official Solicitor)  EWHC 1681 (Fam), B and Re SA; A Local Authority v MA  EWHC 2942 (Fam), and can be summarised as follows:
- The court is exercising an essentially protective jurisdiction, to protect a vulnerable adult
- The court is justified in intervening if there is a real possibility of harm
- Although any marriage would be voidable, prevention is better than cure
- The jurisdiction is founded on the necessity for the courts to take care of those who cannot take care of themselves
- There must be sensitivity to cultural issues
It was declared that MAB did not have, and never did have, capacity to marry.
As MAB has no capacity to marry in this country, even a valid marriage in Pakistan will not be recognised as valid in English law or by English public authorities, including for the purposes of the Immigration Rules. Under the dual domicile rule, a marriage is (normally) invalid when either of the parties lacks, according to the law of his or her antenuptial domicile, the capacity to marry the other. It would be wrong in principle and law, and unnecessary, to declare that MAB does not have capacity to marry "whether inside or outside England and Wales".
Injunctions would not be imposed and MAB's passport would be released. The family's undertakings not to bring MAB to a marriage ceremony or out of Britain (and to serve medical evidence and apply to court if they wished to apply to vary or be released from their undertakings) were accepted on the basis that they were honourable people. In any event, an undertaking is enforceable in the same way as an injunction. Permission would be granted to the parties to disclose the court papers and reports to the FCO, the British High Commission in Pakistan, and various other bodies.
An order would be made allowing capacity to be reassessed after an extended period of contact with R, which contact could only occur if it became feasable for MAB to fly to Pakistan.
Although not specifically mentioned in Sheffield City Council v E, any assessment of capacity to marry must take into account the question of capacity to consent to sexual relations. This is since a sexual relationship (or at least the right to choose whether to engage in sexual activity) is usualy implicit in a marriage and otherwise there is a risk of offences being committed under the Sexual Offences Act 2003. In assessing capacity to consent to sexual relations, there is a low requirement of understanding: "it is enough that she has sufficient 'rudimentary knowledge' of what the act comprises and of its character to enable her to decide whether to give or withhold consent", R v Morgan (1970) VR 337 applied.
Generally speaking, capacity to marry must include the capacity to consent to sexual relations. And the test of capacity to consent to sexual relations must for this purpose be the same in its essentials as that required by the criminal law. Therefore for present purposes the question comes to this. Does the person have sufficient knowledge and understanding of the nature and character - the sexual nature and character - of the act of sexual intercourse, and of the reasonably foreseeable consequences of sexual intercourse, to have the capacity to choose whether or not to engage in it, the capacity to decide whether to give or withhold consent to sexual intercourse (and, where relevant, to communicate their choice to their spouse)?
Structured analysis, as in In re C (Adult: Refusal of Treatment)  1 WLR 290 and Re MB (Medical Treatment)  EWCA Civ 3093 B, is not likely to be necessary or helpful; the average layman does not require expert advice, in contrast with litigation or medical treatment.
Note that the Mental Capacity Act 2005 does not allow substituted decision making in relation to consenting to marriage or sexual relations.