The deportation into a concentration camp happened without any legal basis. The "Notverordnung zum Schutz von Volk und Reich" ("Emergency Decree to Protect People and Reich"), dated from January 4, 1934, allowed police officials in Germany to impose "Protective Custody" without trial and limitation in order to "fight subversive efforts". Usually, a written order called "Schutzhaftbefehl" would be issued by the Gestapo headquarter and the RSHA in Berlin, but this only applied to German citizens.

The structure of NS-persecution aimed at the elimination of "hostile groups", beside political opponents and possible enemies of the people primarily Jews. After 1936, persecution was enlarged against "Antisocials", Witnesses of Jehova, homosexuals, Gypsies and Jews.

Since 1942, the Jews were undoubtedly the largest group of concentration camp prisoners.

The steady growth of tasks within the camp administration required the cooperation of inmates. A system of controlled "Häftlingsselbstverwaltung" ("Prisoner's self Administration") was built up after the "Führer" principle (principle of totalitarian leadership) - "Lagerältester" (camp senior), "Blockältester" (block senior), Capo (a prisoner in charge of a commando or work squad). Thus developed a hierarchy which was very similar to the SS-structure. The SS tried to mobilize criminal prisoners as "Funktionshäftling" (prisoner occupying a prominent position) which caused conflicts with the political prisoners. In Auschwitz, the policital prisoners were able to displace criminals from their functions. The SS assigned functions and special positions and thus developed a classification of prisoners:


The biggest part of those, who were killed in Auschwitz, were Jews, followed by Russian prisoners of war and Gypsies who had been deported after the so-called "Auschwitz-Erlaß" of January 29, 1943.