Law enforcement in Germany is constitutionally vested solely with the states, which is one of the main features of the German political system.
Policing has always been a responsibility of the German states even after 1871 when the country was unified. The 1919 constitution of the Weimar Republic did provide for the possibility of creating a national police force, should the necessity arise, but it was only in the Nazi era that state police forces were unified under central control and a national police force created (Reichssicherheitshauptamt or RSHA). The police became a tool of the centralized state and the Nazi party. Following the defeat of 1945, Germany was divided; in 1949 the three western zones were turned into the Federal Republic of Germany (West Germany), the Soviet zone became the German Democratic Republic (East Germany). Each country pursued a different path concerning law enforcement.
In light of the gross misuse of power by the centralized Nazi state, the new constitution of West Germany provided for a strict separation of powers, placing law enforcement firmly in the hands of the states. The only policing allowed at the federal level was border control (Bundesgrenzschutz, including the coast guard) controlled by the Ministry of the Interior and originally organized along paramilitary lines, the Federal Criminal Police Office. Since 2005, Germany's borders became largely open because of the European Union, and the Bundesgrenzschutz was renamed the Bundespolizei (Federal Police), which is still limited to rail traffic, airports, ports, and several other special duties.
East Germany created a centralized police force under the Ministry of the Interior, the paramilitary Volkspolizei (literally "People's Police"). It also established a border police force (Grenztruppen der DDR), initially an independent force, later integrated into the army and then reorganized as an independent military organization.