We frequently assume that full citizenship in a state should be available to all those who normally live and work in the country, as well as those who apply for citizenship. However, while many states may support the concept of universal and inclusive citizenship, each of them establishes criteria for granting citizenship. These would typically be enshrined in the country’s Constitution and laws.
States use their authority to keep undesirable visitors out.
Nonetheless, despite restrictions, including the construction of walls or fences, significant migration of peoples occurs around the world. People may be displaced as a result of wars, persecution, famine, or other factors. If no state will accept them and they are unable to return home, they either become stateless or refugees. They may be forced to live in camps or as undocumented migrants. Frequently, they are unable to legally work, educate their children, or acquire property. The magnitude of the problem has prompted the United Nations to appoint a High Commissioner for Refugees to assist them.