Issuing a visa derives from the sovereign authority of the State. Visa policy is composed of a group of parameters set by national legislation (Constitution, laws, regulations and decrees), thereby allowing the administration to determine which foreigners can be admitted to enter and stay on a temporary basis on its territory. It is a social phenomenon because it reacts and interacts with the entire social system of the State. It will respond to the social, economic, political, educational and ethical sub-systems. For example, during periods of war or social conflicts, visa policy has acted as an effective instrument to stop the immigration of a certain type of population. On the other hand, in times of high economic growth, in order to avoid labor shortages to sustain this growth, visa policy can allow for the immigration of foreigners on flexible terms than those impose when the economy is contracting.
This group of parameters, based on objective and sometimes subjective terms, allows regulating the entry of foreign nationals into the territory of the State. It has two manifestations: It acts permission that the state grants to a specific individual, while at the same time acting as a restriction through filtering people that are considered as a potential threat to public interest.