If a person in Germany does not have a valid residence permit, she or he can be forced to leave the country. If one does not comply with this obligation and there is, by judicial assessment, a risk that one might elude the authorities, one is taken into detention. This way, the obligation to leave the country is compelled by force. Detention is thus not the result of a crime, but is considered a »civil confinement«. This means that the fundamental right to freedom can be bypassed on the basis of ensuring the deportation alone.
In the federal state of Hesse, due to a regulation that started in the 1960s, immigration detention was carried out in police prisons or, in exceptional cases only, in correctional facilities. Accordingly, the police prison Klapperfeld was used for immigration detention until its closure in 2002. In July 2014, a verdict of the European Court of Justice ruled that detention can no longer take place in police prisons or correctional facilities, but has to be implemented in designated facilities.
In the Klapperfeld cells, the inscriptions left by the detainees reflect the changing migration patterns and massive political transformations, particularly in the period from the 1980s until 2002. For example: The languages of the inscriptions mirror the migration movements during and after the collapse of the Soviet Union and the war in former Yugoslavia, the so-called »asylum compromise« in 1992 and the accompanying drastic restrictions of the fundamental right to seek asylum in the Federal Republic of Germany, as well as the development of repressive and restrictive migration policies by the European Union. At the same time, free movement of EU citizens was established by European law. Along these legal and political changes, the institution of immigration detention served as an important instrument of a policy of deterrence and seclusion. However, at different times it was aimed at different groups of people. For example, nowadays most authors of the numerous Polish or Romanian inscriptions are EU citizens and have freedom of movement in all member countries.
The emergence of immigration detention in Germany dates back to well before the foundation of the Federal German Republic. Already in 1919 immigration detention was practiced in Bavaria. The legal origins are rooted in the »Aliens Police Regulation« of 1938, which introduced immigration detention into the Nazi judicature. This legislation remained valid until 1965, when it was replaced by the new »Aliens Act«. The regulations remained the same in character, though the maximum duration of detention was extended to twelve months. Since 2005, immigration detention is regulated in § 62 of the »Residence Act«.
Until 1990, immigration detention was rarely enforced. Detention gained importance as part of the »asylum compromise« of 1992 in Germany. Already in 1990, the maximum duration of detention regulated in the federal »Aliens Act« had been extended to 18 months. In 1992, compelling grounds for detention were introduced by § 57 of the »Aliens Act«, meaning that detention is obligatory under certain circumstances. In the course of this development a steep increase in deportation numbers could be found nationwide: The Initiative gegen Abschiebung [»initiative against deportation«] reported that about 700 people were detained in 1992; this number rose to 2,800 in 1994.
Furthermore, the »Asylum Procedure Act« regulates that people aged 16 and older are treated as adults with the according asylum procedures. As a consequence, minors can be put into detention. The Klapperfeld prison was no exception to this rule: According to an article in the newspaper Abendpost/Nachtausgabe in 1984, a 16-year-old teenager was detained in Klapperfeld for at least four months before being deported.
The significance of Frankfurt, and thus also Klapperfeld prison, can be assigned to the strategic role of the Frankfurt airport as the main detention hub in Germany, followed by the airports of Berlin and Munich. For this reason, Klapperfeld has been used as an intermediate station for detainees from other federal states, ensuring a fast deportation from Frankfurt. For many people in detention, Klapperfeld was the last station before being deported from Germany. As can be inferred from some of the inscriptions, detention and deportation were also used as additional sanctions after a prison sentence was served in another prison. Some detainees were transferred from Klapperfeld to other detention or refugee centres. This was done for various reasons; for example, when the required documents for a definite deportation were missing. Immigration detainees are charged with the full costs of their detention and deportation, which have to be paid before re-entering Germany.
Even today, thousands of people are deported from Frankfurt airport every year. According to the federal government, 2,863 people were deported from Frankfurt airport in 2020. This number does not include an unknown proportion of the 2,953 intra-European »transfers« under the Dublin Regulation.