There was also the question of partition, which pre-dated the Treaty but which was copper-fastened by it. In theory, Northern Ireland was included under the terms of the Treaty but under Article 12 was, given the option to opt out within a month. (See Irish Free State Constitution Act 1922) Thus for three days from midnight on 6 December 1922 the newly established Irish Free State, in theory included all of the island of Ireland (including Northern Ireland). However, in practice, Northern Ireland was already a functioning autonomous area by this time and it formally left the Irish Free State on 8 December 1922.