A Chinese woman whose child was born in Belfast should be able to live legally in the UK, according to a preliminary ruling by the European Court of Justice.
Man Navette Chen travelled to Belfast in 2000
Man Navette Chen travelled to Belfast in 2000 and gave birth to a baby girl.
Her lawyers had argued because her child was an Irish citizen, she should automatically be allowed to reside in another EU member state.
The case is one of the reasons the Irish Government wants to close the loophole on citizenship through the forthcoming referendum.
The final ruling will be made later this year.
At Tuesday's hearing, the Advocate General ruled that because the child had a right of residence in the UK, her mother should also have the same right in the interests of her daughter and the family unity.
If confirmed, it will mean the court has established that a child with nationality of one member state can legally live in another, provided they qualify under residency conditions.
Irish minister Mary Coughlan said the considered legal opinion of the Advocate General underlined "the sound legal basis for the proposed referendum on citizenship".
"The practical effect of the Advocate General's opinion is to give a clear indication to people who may wish to circumvent the immigration controls of other EU member states that Ireland's citizenship laws are a back-door into Europe.
"The consequence will be an increase in the number of pregnant women travelling to Ireland to give birth here, with all the knock-on effects that will have for the health of the mothers, the situation in our maternity hospitals and the integrity of our citizenship laws."