The Statute of Establishment was a Act of Parliament by the United Kingdom. It was the major legislation that led to the independence of full Irish independence.
It allowed countries to edit laws made by Britain before they gained semi-independence. This meant any colony could now declare independence. Soon the Ireland parliament passed the Irish Liberalism Act 1932 which used this law and deemed Ireland a republic. It also laid down that Northern Ireland could become part of the south if they wanted to. The North had forcefully become part of the UK and wanted to stay with the south. They joined the south on the 1 June 1931. The Old Republic of Ireland was abolished and a new government had already began forming