The British Home Office's refusal to allow a Chinese woman and her Belfast-born daughter to live permanently in Britain was declared illegal under European Union law today.
In a decision that may have implications for the residency rights in the EU of non-national parents of Irish citizens, the court decreed that the child as an EU national, has the right to stay in the United Kingdom, and that her mother as her carer must have that right too.
European Court judges acknowledged that the woman, Ms Man Levette Chen, deliberately had her child in Belfast to win British residency rights for herself. But they ruled that did not entitle British authorities to refuse to let her or her daughter stay.
The Luxembourg court was told that Mrs Chen was aware that giving birth in Britain would not give her new baby automatic residency rights under the terms of the British Nationality Act.
But she also knew that choosing Northern Ireland guaranteed Irish nationality, which is granted to anyone born anywhere on the island of Ireland .
Once that was achieved, the plan was to take her Irish daughter to live in Britain under EU rules which allow nationals of one member state the right to settle in another.
The child did receive an Irish passport - but the British Home Office unexpectedly challenged her right of residence in Britain.
They argued that as the baby was only eight months old at the time, she could not exercise any EU rights. Even if she could, Mrs Chen could not live in Britain because the law only allowed "dependent relatives" to join their family - and Mrs Chen was not dependent on her baby, it was argued.
The case was passed to the European Court after the Chens claimed their treatment was a breach of EU law.
Lawyers for the British government insisted the Home Office was entitled to stop individuals improperly taking advantage of the EU law - or using EU law as a means to circumventing national legislation.
Papers submitted to the court stated: "Mrs Chen's conduct in travelling to Belfast constitutes an attempted abuse, in that it was a scheme by which a national of a non-member state wishing to reside within (the UK) organises her affairs so as to give birth to a child in part of (the UK) to which (Ireland) applies nationality rules."
The European Commission backed the British position, arguing that the family's interests had to be balanced against the UK's interests in controlling immigration.
But the judges ruled today that Catherine, as an EU national, has the right to stay in the UK, and that her mother must have that right too.
They said: "To refuse Mrs Chen a right to reside with her daughter in the UK would render the daughter's right of residency totally ineffective.
"For Catherine to be able to enjoy her right of residence, she must, as a young child, be entitled to be accompanied by her mother, who is her carer."