A unilateral declaration of independence (UDI) or unilateral secession is a formal process leading to the establishment of a new state by a subnational entity which declares itself independent and sovereign without a formal agreement with the state from which it is seceding. The term was first used when Rhodesia declared independence in 1965 from the United Kingdom (UK) without an agreement with the UK.Douglas George Anglin. Zambian Crisis Behaviour: Confronting Rhodesia's Unilateral Declaration of Independence, 1965–1966. McGill-Queens, 1994.

Examples

Prominent examples of a unilateral declaration of independence other than Rhodesia's UDI in 1965 include that of the United States in 1776,Don H. Doyle. Secession as an International Phenomenon: From America's Civil War to Contemporary Separatist Movements. University of Georgia Press, 2010. the Irish Declaration of Independence of 1919 by a revolutionary parliament, Katanga's declaration of independence by Moise Tshombe in July 1960, the attempted secession of Biafra from Nigeria in 1967, the Proclamation of Bangladeshi Independence from Pakistan in 1970, the secession of the Turkish Republic of Northern Cyprus from Cyprus in 1983, the Palestinian Declaration of Independence in 1988, and that of the Republic of Kosovo in 2008.United Nations. Index to Proceedings of the General Assembly 2008/2009: Subject Index. New York City, USA: United Nations, 2010. Pp. 138. During the dissolution of the Soviet Union, many of its republics declared their independence unilaterally without agreement and were thus not recognised as legitimate by the Soviet central government.

During the breakup of Yugoslavia, the government of the United States asked the governments of Croatia and Slovenia to drop their UDI plans because of the threat of major war erupting in the Balkans because of it, and threatened that it would oppose both countries' UDIs on the basis of the Helsinki Final Act if they did so. However, four days later both Slovenia and Croatia announced their UDIs from Yugoslavia.Florian Bieber, Džemal Sokolović. Reconstructing multiethnic societies: the case of Bosnia-Herzegovina. Ashgate, 2001. Pp. 41.

Date Declared state Parent state International recognition Notes 1776 Great Britain 1777 Great Britain Vermont signed a separate armistice with Britain in 1781 before the surrender of Cornwallis at Yorktown. Effective retroactive recognition by the United States was granted in 1791 when Vermont became the 14th state. 1813 No other nation besides Venezuela, itself an unrecognised government at the time, recognised the independence of Cundinamarca. The nation was later incorporated by military force into the United Provinces of New Granada in 1814. 1813 No other nation besides Venezuela, itself an unrecognised government at the time, recognised the independence of New Granada. The nation would later join together with Venezuela to form the Republic of Colombia. 1816 Became the Argentine Confederation in 1831. Recognised by Spain in 1859. 1819 Initially recognised by the United States (1822), the United Kingdom (1825), the Netherlands (1829) and various other Hispanic American nations between 1822 and 1831. Recognised by Spain in 1881. 1821 Intervention by France, Russia, and the United Kingdom in favour of Greece in the Greek War of Independence secured its independence in 1832. 1830 Recognized by major European powers following the London Conference of 20 December 1830. 1860-1861 Reconquered by the United States 1898 Spain Conquered by the United States; became independent in 1946 by the Treaty of Manila. 1903 1905 1912 1917 Recognized after White victory in the Finnish Civil War 1918 Recognized after victory in the Estonian War of Independence 1918 Recognized after victory in the Latvian War of Independence 1918 Recognized after victory in the Lithuanian Wars of Independence 1919 Became the Irish Free State upon the ratification of the Anglo-Irish Treaty. 1920 1921 1921 Mirdita Recognized only by Greece 1922 Unilateral grant of independence by the British government 1931 1931 Spanish sovereignty remained unchanged 1938 1941 Ukraine 1945 1960 Breakaway Congolese province, secession forcibly ended by the United Nations Operation in the Congo in 1963. 1965 Self-governing British colony, unilaterally declared itself independent as Rhodesia in 1965, renamed Zimbabwe Rhodesia and returned to British control in 1979, then gained international recognition as Zimbabwe in 1980. 1967 Returned as a British Crown Colony in 1969. 1967 Recognized by five countries. Present-day Nigeria 1971 1971 1973 1975 North Solomons Present-day Autonomous Region of Bougainville, Papua New Guinea 1975 Cabinda Present-day Angola 1975 Shortly following the declaration of independence, the territory was invaded and annexed by Indonesia. A referendum in 1999 led to eventual independence in 2002. 1983 Cyprus Still claimed by Cyprus, and recognized as such by all UN member-states except for Turkey, which recognizes Northern Cyprus instead. 1988 Claims territories occupied by Israel since 1967Israeli–Palestinian conflict and peace process still ongoingSee: International recognition of the State of Palestine 1988 West Papua 1990 After the failed 1991 Soviet coup attempt, the Soviet Union recognized Latvia's independence.1990 After the failed 1991 Soviet coup attempt, the Soviet Union recognized Lithuania's independence.1990 1990 Incorporated into Uzbekistan in 1993.1991 1991 Still claimed by Somalia. Recognized by Israel since 2026. 1991 Set off Croatian War of Independence 1991 Set off Ten-Day War 1991 Present-day Chechnya, part of Russia. Retroactively recognized by Ukraine in 2022 1991 Still claimed by Moldova, recognized by 2 partially unrecognised breakaway states South Ossetia and Abkhazia (+ the former Nagorno-Karabakh Republic). 1991 Recognized by 3 partially unrecognised breakaway states South Ossetia, Abkhazia and Transnistria between 1991 and 2023. Incorporated back into Azerbaijan as aftermath of Second Nagorno-Karabakh War and 2023 Azerbaijani offensive in Nagorno-Karabakh. 1991 Still claimed by Georgia. Recognized by 5 UN member-states.1992 Set off Bosnian War 1999 Still claimed by Georgia. Recognized by 5 UN member-states. 2008 Still claimed by SerbiaA United Nations General Assembly (UNGA) resolution adopted on 8 October 2008 backed the request of Serbia to seek an International Court of Justice advisory opinion on Kosovo's declaration of independence.Backing Request by Serbia, General Assembly Decides to Seek International Court of Justice Ruling on Legality of Kosovo's Independence, United Nations, 8 October 2008 On 22 July 2010, the ICJ ruled that the declaration of independence of Kosovo "did not violate any applicable rule of international law", because its authors, who were "representatives of the people of Kosovo", were not bound by the Constitutional Framework (promulgated by UNMIK) or by UNSCR 1244 that is addressed only to United Nations member states and organs of the United Nations.Accordance with international law of the unilateral declaration of independence in respect of Kosovo, Nspm.rs, 22 July 2010Accordance with international law of the unilateral declaration of independence in respect of Kosovo , International Court of Justice, 22 July 2010See: International recognition of Kosovo 2014 Annexed by Russia; still claimed by Ukraine. Recognized only by 7 UN member states. 2014 Annexed by Russia; still claimed by Ukraine. Recognized only by 8 UN member states. 2017 Spanish sovereignty remained unchanged

Legal aspects The International Court of Justice, in a 2010 advisory opinion, declared that unilateral declarations of independence were not illegal under international law.

See also Declaration of independence Decolonization Helsinki Accords (also known as the Helsinki Final Act) International law International relations List of sovereign states by date of formation Secession United Nations

References