A court has reversed a judgment from two years ago which found that a couple who had an Islamic wedding ceremony could legally divorce.
The High Court ruled in 2018 that the couple's Islamic "nikah" ceremony fell within English marriage law.
But the Court of Appeal has now said it was an "invalid" non-legal ceremony.
Judges said the fact they intended to have a further civil ceremony meant they must have known their Islamic marriage had no legal effect in the UK.
The Attorney General appealed against the original court decision.
The case involved the divorce of Nasreen Akhter and Mohammed Shabaz Khan, who have four children.
The couple had an Islamic wedding ceremony in a west London restaurant in 1998 in the presence of an imam and about 150 guests, but no civil ceremony subsequently took place, despite Mrs Akhter repeatedly raising the issue.
They separated in 2016 and Mr Khan tried to block his wife's divorce petition two years ago on the basis they had not been legally married in the first place.
'Sharia law only'
Mrs Akhter argued their Islamic faith marriage was valid, as was her application for divorce, and that she was entitled to the same legal protection and settlement offered in the UK to legally married couples.