The Civil Guard is the oldest law enforcement agency in Spain and is one of two national police forces. As a national gendarmerie force, it is military in nature and is responsible for civil policing under the authority of both the Ministry of the Interior and the Ministry of Defence. The role of the Ministry of Defence is limited except in times of war when the Ministry has exclusive authority. The corps is colloquially known as the benemérita. In annual surveys, it generally ranks as the national institution most valued by Spaniards, closely followed by other law enforcement agencies and the armed forces.

A gendarmerie is a military force with law enforcement duties among the civilian population. The term gendarme is derived from the medieval French expression gens d'armes, which translates to "men-at-arms". In France and some Francophone nations, the gendarmerie is a branch of the armed forces that is responsible for internal security in parts of the territory, with additional duties as military police for the armed forces. It was introduced to several other Western European countries during the Napoleonic conquests. In the mid-twentieth century, a number of former French mandates and colonial possessions adopted a gendarmerie after independence. A similar concept exists in Eastern Europe in the form of Internal Troops, which are present in many countries of the former Soviet Union and its former allied countries.