A 1988 treaty demarcates the boundary of the
exclusive economic zones across the
continental shelf from the south Irish Sea southwest to the
Celtic Sea.
Waters around Northern Ireland The exact division of territorial waters between Northern Ireland and
Southern Ireland ('Southern Ireland' being coterminous with the territory of the modern-day Irish state) was a matter of some controversy from the outset. The Government of Ireland Act 1920 did not explicitly address the position of territorial waters although Section 11(4) provided that neither Southern Ireland nor Northern Ireland would have any competence to make laws in respect of "Lighthouses, buoys, or beacons (except so far as they can consistently with any general Act of the Parliament of the United Kingdom be constructed or maintained by a local harbour authority)". When the territory that initially was Southern Ireland ultimately became a separate self-governing dominion outside the United Kingdom known as the
Irish Free State, the status of the territorial waters naturally took on a significance it had not had before. Northern Ireland's Unionists were conscious of this matter from an early stage. They were keen to put it beyond doubt that the territorial waters around Northern Ireland would not belong to the Irish Free State. In this regard,
James Craig, the
Prime Minister of Northern Ireland put the following question in the British House of Commons on 27 November 1922 (the month before the establishment of the Irish Free State): In response the Attorney General, Sir
Douglas Hogg, said that "I have considered the question, and I have given an opinion that that is so [i.e. the territorial waters do go with the counties]". However, this interpretation that the territorial waters went with the counties was later disputed by Irish governments. On 29 February 1972, the then Taoiseach,
Jack Lynch, summarised the Irish position during a
Dáil debate on the legal status of
HMS Maidstone, a
prison ship which was moored in
Belfast Harbour at the time: A particular dispute arose between the Government of the Irish Free State of the one part and the Northern Ireland and UK governments of the other part over territorial waters in
Lough Foyle. Lough Foyle lies between
County Londonderry in Northern Ireland and
County Donegal in the then Irish Free State. A court case in the Free State in 1923 relating to fishing rights in Lough Foyle held that the Free State's territorial waters ran right up to the shore of County Londonderry. For as long as both states remain members of the EU (and thus the
Common Fisheries Policy), the territorial waters are not disputed in practice between the two states. Their respective
exclusive economic zones (EEZs) begin beyond their territorial waters and the boundary between them was agreed in 2014. but the precise
maritime boundary between Ireland and the United Kingdom concerning Lough Foyle (and similarly
Carlingford Lough) remains disputed in principle. As recently as 2005, when asked to list those areas of EU member states where border definition is in dispute, a British Government minister responding for the
Secretary of State for Foreign and Commonwealth Affairs stated: During Dáil debates on the Carlingford Fisheries Bill, a contributor to the debate stated that he welcomed "the Bill's aim of defining the area of jurisdiction over the Foyle". However, the Irish Foyle and Carlingford Fisheries Act 2007 does not mention this issue; neither does the virtually identical British "Foyle and Carlingford Fisheries (Northern Ireland) Order 2007": each merely refers to "the Commission's waters". The UK's
Foreign and Commonwealth Office underlined its view in 2009: A corresponding statement was made by Conor Lenihan, then an Irish Government Minister: ==Identification==