The Hong Kong Government has backed marriage as being between one man and one woman during a court case on legalising same-sex marriage.
The current law is being challenged by a woman who wants to enter a civil union with her girlfriend.
A Government lawyer defended the situation, arguing introducing same-sex marriage would “dilute and diminish” marriage between opposite-sex couples.
Stewart Wong said: “Not all differences in treatment are unlawful. You are not supposed to treat unequal cases alike.”
He added that marriage is already clearly defined in Hong Kong and “cannot be trumped”, while also arguing against civil partnerships.
“To recognise an alternative form of same-sex relationships which we say is tantamount to [marriage] is to undermine the traditional institution of marriage and the family constituted by such a marriage.”