Northern Ireland law
Northern Ireland law refers to the legal system of statute and common law operating in Northern Ireland since the partition of Ireland established Northern Ireland as a separate jurisdiction within the United Kingdom in 1921.
For the purposes of private international law the United Kingdom is divided into three distinct legal jurisdictions:Northern Ireland is a common law jurisdiction. Although its common law is similar to that in England and Wales, and partially derives from the same sources, there are some important differences in law and procedure between Northern Ireland and England and Wales. While influenced by English law, the Northern Ireland legal system is distinctive for a number of reasons: it has roots in Irish common law prior to Irish independence in 1921; following Irish independence, Northern Ireland became a devolved jurisdiction within the United Kingdom.
Ireland
In December 1921, the Anglo-Irish Treaty was concluded between the British government and representatives of the Second Dáil. It gave Ireland complete independence in its home affairs and practical independence for foreign policy, but an opt-out clause allowed Northern Ireland to remain within the United Kingdom, which it immediately exercised as expected. Additionally, Members of the Free State Parliament were required to swear an oath of allegiance to the Constitution of the Irish Free State and make a statement of faithfulness to the King. Disagreements over these provisions led to a split in the nationalist movement and a subsequent Irish Civil War between the new government of the Irish Free State and those opposed to the treaty, led by Éamon de Valera. The civil war officially ended in May 1923 when de Valera issued a cease-fire order.