A Singaporean couple has launched a legal challenge at the High Court against a ruling that their marriage be annulled after one of the couple underwent a sex change, making their partnership a same-sex union, and illegal, under Singapore law.

The city-state voided  the marriage of Faith and Bryce Volta, who were married as man and woman in 2015, last year after a ruling by the Registrar of Marriages, according to the Straits Times.

The couple has now asked the High Court to review the decision taken by the registrar, lawyer Eugene Thuraisingam, whose law firm is representing them, told Free Malaysia today on Monday.

Laws dating back to the British colonial era ban same sex marriage and criminalize sex between two men, though the latter is not actively enforced.