The 1933 Montevideo Convention in its Art. 1 enumerates the criteria for statehood, which are a permanent population, a defined territory, a government and the capacity to enter into relations with other States. However, during its existence a State might increase or decrease in territory, its population oscillate and the capacity to enter into relations with other States vary. As Worster points out, the criteria for statehood is contentious and practice has not been consistent in international law. Although it is taken for granted that the Montevideo requirements should be met, there is ample evidence demonstrating that opportunism also plays an important role on the establishment and recognition of States.