An unmarried father has begun his High Court action to have his two-year-old twin boys returned to him in Ireland in what is a potentially landmark case.
The man, known as Mr G, is taking the action against the mother of his sons who took the children to England in December of last year.
He is being represented by former minister for justice Michael McDowell.
Mr G is seeking the return of the children under the terms of the Hague Convention which covers child abduction.
The case is potentially significant as Mr G will have to prove that he had a right of custody to the children at the time of their removal from Ireland.
In order to do so, he will argue that unmarried fathers have the same rights as married fathers under the terms of the European Convention on Human Rights, which was incorporated into Irish law in December 2003, and that the convention makes no distinction between married and unmarried families.
The Irish courts have so far held that unmarried fathers have no explicit rights in relation to their children.
If Mr G is successful, his case could redefine the status of unmarried fathers in Irish law.
An unmarried father's only legal right to his children comes if he is appointed a legal guardian by the court or if the mother chooses to appoint him as a legal guardian.
The mother of Mr G's two children is likely to argue that she did not abduct the children out of the jurisdiction as Mr G is not their legal guardian under Irish law.
The case was taken to the High Court in London last month where Mr G sought the return of the children, but Mrs Justice Mary Hogg said it was not appropriate for her to make a ruling on something of constitutional importance in Ireland, and she referred it to the courts here.
The High Court action, which is scheduled to last two days, is being heard before Mr Justice Liam McKechnie, and is in camera, as are all cases of alleged child abduction.
An order is likely to be made on Friday, though Mr Justice McKechnie may decide to issue a written judgment on the case at a later date.
