The boy’s genetic father is British, and the Irish plaintiff was also granted a parental order under British law in 2015. The couple have a second child who has an Irish passport as his genetic father is the Irish man in the couple.

In a two-day hearing last week in the High Court, lawyers for the State said the only legitimate interpretation of the 1956 Irish Nationality and Citizenship Act is for “parent” to be defined as a child’s birth mother or genetic father.

However, the plaintiffs argued that the definition has evolved since 1956 due to developments such as the introduction of same-sex marriage in 2015. The couple said they could both be regarded as the boy’s parents. Campaigners against same-sex marriage in 2015 said demands to recognise same-sex couples as the legal parents of children would inevitably follow changing the definition of marriage.