geneva leaders spain industrialize northeastern region catalonia say regional population vote independence ballot central government constitutional court say illegal push catalan independence appear find much support international law much successful precedent look achieve independent statehood law practice matter international law become state recognize state say anna stilz professor politics princeton university decline comment catalan case say several accept scenarios group people claim right rule independently country right self-determination conventionally think extend internal minorities within state conventionally think apply colonize people people subject overseas colonization people subject apartheid government people military occupation idea self-determination popularize u.s. president woodrow wilson century ago response ideas russian revolutionary vladimir lenin hard-coded u.n. charter establish unite nations 1945. subsequent u.n. agreements clarify interference state although colonies non-self-governing territories distinct status right self-determination hard fast rule many countries recognition require state recognize taiwan universally recognize state still function independently china purpose supporters independent state palestine achieve breakthrough u.n. general assembly recognize non-member observer state 2012 give ticket join international body interpol countries crucially israel unite state recognize struggle operate independently 1933 montevideo convention set four criteria statehood function government fix population control territory capacity enter relations state tick box enough entity like somaliland currency territory government recognize state stilz say u.n. membership also irrelevant statehood switzerland u.n. member 2002 nobody think less state since break-up soviet union 1991 several new countries arise years war former yugoslavia south sudan east timor international community approve referendums self-determination hop cement peace decades bloodshed shadow yugoslavia war ensure czechoslovakia divorce trigger slovak independence party regional elections peaceful opinion poll show majority side would prefer stay together separatists scotland quebec hold referendums years political campaign vote go independence regions grant great autonomy undermine case independence referendums internationally recognize russian-backed claim crimea leave ukraine last month vote iraqi kurdistan kosovo unilaterally declare secession 2008 serbia go court try stop international court justice rule international law contain applicable prohibition declaration independence although one dissent judge say create dangerous precedent refiled version story remove reference margin victories par 16 factbox passport catalonia achieve independence