Secession is the act of a region or group leaving the country it belongs to. It can be negotiated and peaceful, as with the Czech and Slovak split in 1993, or contested and violent. Most national constitutions do not provide a right to secede, and international law treats a state’s territorial integrity as a core principle.
Debates over secession usually set a region’s right to self-determination against the country’s right to remain whole. Examples range from the American Civil War, which began when Southern states tried to secede, to Scotland’s 2014 independence referendum and Catalonia’s contested 2017 referendum.