The Court of Appeal has ruled that a marriage recognised in Bangladesh under Sharia law is not legal in the UK.
The Court of Appeal said the man could not have given his consent
The 26-year-old British bridegroom had the mental capacity of a three-year-old and could not consent to the marriage, the court decided.
His marriage with a woman in Bangladesh took place in August 2006 over a speaker phone.
Since the man's family planned to bring his bride to the UK, English law on consent must prevail, said the court.
The man, identified only as IC, was said to be highly suggestible and vulnerable.
The case was brought by Westminster Social and Community Services Department, which provides care for him.
His parents, Bangladeshi but long-term residents in the UK, chose his bride for him and arranged for the wedding to take place over the phone.
It was intended that his wife, referred to as NK, would then obtain a visa and join him in the UK.
IC and NK have never met, and a court order prevents contact between the pair.
Lawyers for IC's parents said that, as the marriage was valid in Bangladesh and under Sharia law, it should also be recognised in the UK.
However, three judges said IC was unable to give valid consent to the marriage.
The judgement describes the marriage arranged by IC's parents as "potentially if not actually abusive of IC".
It reads: "He has not the capacity to understand the introduction of NK into his life and that introduction would be likely to destroy his equilibrium or destabilise his emotional state.
"Physical intimacy is an ordinary consequence of the celebration of a marriage. Were IC's parents to permit or encourage sexual intercourse between IC and NK, NK would be guilty of the crime of rape under the provisions of the Sexual Offences Act 2003."
IC's future welfare will be decided by a High Court judge later this year.