A teenage girl and her mother have won their High Court case against the State over the refusal of the Registrar General to change her mother's name on her birth certificate.

The woman, a Romanian national who has five Irish born children, recorded the wrong name on her first child's birth certificate.

President of the High Court Mr Justice Nicholas Kearns ruled in favour of the girl and her mother.

He said they had a legitimate interest in ensuring accurate details were on a birth certificate.

Mr Justice Kearns also said no clear or coherent explanation was provided for the five-year delay by the State in giving the woman a decision.

He said it was "far from clear" why the delay occurred.

Maria Caldaras, who cannot read or write, was living in Limerick 13 years ago, but now lives in Dundalk.

She grew up in a Roma encampment, where she was known by a nickname.

When she moved to Ireland she was given the wrong birth certificate, believing it to be her own.

Three years later, she discovered her real name and received her correct birth certificate.

She had all her official documentation changed.

However, the Registrar of Births refused to change the name on the birth certificate of her first-born, Sara Stancu.

Her four other children, who were born after the discovery, have their mother's correct name on their birth certificates.

At the High Court last week, lawyers for the woman and her daughter said the Registrar had misinterpreted his powers by refusing to change the name on the birth certificate.

Senior Counsel Garrett Simons said Mrs Caldaras had been forced to wait for five years for a decision, which was ultimately a refusal to change her daughter's birth certificate.

The case was first taken when she had difficulty obtaining a passport for Sara.

The fact that a passport had now been secured did not alter the fact that her rights under the Constitution and European law were being infringed by the refusal, he said.

It also had implications for her daughter's education, as questions had recently been raised about the name on the birth certificate, the court was told.

Mr Simons said the Chief Registrar had refused to accept there had been an error of fact when the birth was registered.

He said both parent and child had a right to have the correct identity of the parent recorded on the birth certificate.

This right was recognised under the Constitution, the European Convention on Human Rights and the EU Charter.

Counsel for the State Eugene Regan said the case was grounded on the issue of a passport, which had since been issued, so it was therefore moot.

He said there was no action or interference by the State in the identity of the child, whose name and surname was correctly recorded.

A birth certificate was intended to be a snapshot of the situation at the time.

He said that Mrs Caldaras had chosen to use another name at the time of her daughter's birth when there were two possible names in use.

Mr Justice Kearns said the Registrar General had fallen into error in holding there must have been an error on his part for the register to be altered.

The Registrar General was also mistaken in his submission that the issue before the court was moot because a passport had been obtained.