A High Court judge has been asked to decide whether an estranged couple who took part in an Islamic wedding ceremony in a London restaurant are validly married.
Nasreen Akhter, 46, says her "Islamic faith marriage" to Mohammed Shabaz Khan, also 46, constituted a "valid marriage". Mr Khan disagrees.
Mr Justice Williams is analysing the case at a hearing in the Family Division of the High Court in London days after the Home Office published an experts' independent review into the application of Sharia law in England and Wales.
Lawyers say his ruling will have implications.
The judge began analysing evidence on Tuesday and the case is expected to end later this week.
He heard the couple, who have a Pakistani background, had taken part in a ceremony in a restaurant in Southall, west London, in 1998 and lived in Pinner, Harrow.
Mrs Akhter, who wants a divorce, said the ceremony had been conducted by an Imam before about 150 guests.
She said Mr Khan had become her "husband" and he had considered her his "wife".
"From my limited understanding of Islam at the time it did comply with all the requirements," she said.
"I saw him as my husband. There was no question in my mind at all."
She added: "He always introduced me as his wife".
Mr Khan wants to block Mrs Akhter's divorce application on the basis that "we are not legally married".
Barrister Paula Rhone-Adrien, who is leading Mr Khan's legal team, said issues being considered went to the heat of the understanding of the law of marriage and divorce in British society.
She said the judge's ruling was likely to be "considered in full" by Muslims.
An experts' review into the application of Sharia law was published earlier this month after being commissioned by the Home Office.
Prime Minister Theresa May had asked for a review when she was Home Secretary and wanted to explore whether Sharia law was being applied in a way that was incompatible with domestic legislation.
A panel of experts, which included an academic and lawyers, said Muslim couple should be required to undergo civil marriages in addition to Muslim ceremonies to bring Islamic marriage legally into line with Christian and Jewish marriage.