The Act therefore provided for Irish citizenship for anyone born in the island of Ireland whether before or after independence.The only limitations to which were that anyone born in Northern Ireland was not automatically an Irish citizen but entitled to be an Irish citizen and, that a child of someone entitled to diplomatic immunity in the state would not become an Irish citizen.
Nonetheless, London continued to recognise Irish citizens as British subjects until the passing of the Ireland Act 1949, which recognised, as a distinct class of persons, "citizens of the Republic of Ireland".
Beginning in 1923, some new economic rights were created for Irish citizens.
With regard to Northern Ireland, despite the irredentist nature and rhetorical claims of articles 2 and 3 of the new constitution, the compatibility of Irish citizenship law with the state’s boundaries remained unaltered.
In 1956, the Irish parliament enacted the Irish Nationality and Citizenship Act 1956.
With the enactment of the Republic of Ireland Act in 1948, and the subsequent passage of the Ireland Act by the British government in 1949, the state’s constitutional independence was assured, facilitating the resolution of the unsatisfactory position from an Irish nationalist perspective whereby births in Northern Ireland were assimilated to "foreign" births.
The Irish government was explicit in its aim to amend this situation, seeking to extend citizenship as widely as possible to Northern Ireland, as well as to Irish emigrants and their descendents abroad.
This Act repealed the 1935 Act and remains, although heavily amended, the basis of Irish citizenship law.
This act, according to Ó Caoindealbháin, altered radically the treatment of Northern Ireland residents in Irish citizenship law.
The status of the Irish Free State as a dominion within the British Commonwealth was seen by the British authorities as meaning that a "citizen of the Irish Free State" was merely a member of the wider category of "British subject"; this interpretation could be supported by the wording of Article 3 of the Constitution, which stated that the privileges and obligations of Irish citizenship applied "within the limits of the jurisdiction of the Irish Free State".