Right to Self Determination
The Right to Self Determination is an important customary right, internationally recognised (including by the United Nations Charter). Generally, the Right applies to peoples being distinct by politics, culture, race, or religion, rather than to individuals. Self-determination refers to the right to form a body politic and for that people to decide the laws and culture that they wish to live under.
Individualists and secessionists argue that the Right to Self-Determination is the right to secede from any existing body politic and form their own. Theoretically this would include a body politic of just one person -- i.e. secession from all other people -- leading to the idea of individual anarchism.
The Montevideo Convention was a Treaty signed in 1933 by the Seventh International Conference of American States. The Treaty sets up the declarative theory of statehood providing that a state (recognised or unrecognised) is a state by virtue that it has the following attributes: Defined territory, Defined population, Government, and the Capacity to enter into relations with other states.