Contrary to a very popular misconception, in Nazi Germany interment itself was legal as it was authorized by the infamous “Reichstag Fire Decree” which was issued by German President Paul von Hindenburg February 28th, 1933 – on the next day after the Reichstag Fire and abolished the habeas corpus and thus made it possible for both Kripo and Gestapo to indefinitely keep any individual in custody (i.e. in an internment camp).
After this decree was issued, the detained no longer had the right to report his or her detention to a court and request that the court order the custodian of the person, usually a prison official, to bring the prisoner to court, to determine whether the detention is lawful. Thus making internment without trial de-facto legal.
However, the treatment of KL inmates was very much illegal, because they were beaten, tortured (physically and emotionally), undernourished (by the end of the war to the point of starvation) and otherwise mistreated. And sometimes even murdered (which in official reports was typically disguised as suicides or accidents)
Worse, just about every KL had a resident killer – typhoid, which in large KL killed thousands (if not tens of thousands) of inmates. Consequently, KL officers were guilty of at least criminally negligent mass manslaughter/homicide.
However, officers in some KL (Buchenwald, Auschwitz, Dachau, Mauthausen, Gusen, Flossenbürg, Neuengamme, Ravensbrück, Groß-Rosen and some others) were guilty of not just manslaughter, but of a very much premeditated mass murder. Capital murder. Murder one. Others were guilty of conspiracy to commit murder, felony murder or accessory to murder.
This mass murder was in many ways similar to Nazi euthanasia campaign (Aktion T4) that I will cover in appropriate detail in one of the next sections. It had a similar name (Action 14f13 which I will cover below) and used a very similar process and the facilities (including gas chambers) in the same killing centers – Bernburg, Sonnenstein and Hartheim.
Another heinous crime was sexual slavery. Women from the Ravensbrück c Auschwitz camps (the KL component of the latter) were forced to work in brothels established by the SS for camp inmates. These institutions were used mostly by camp Kapos (supervisors/administrators), “prisoner functionaries” and (of course) the criminal element.
“All of the above” was illegal because neither Weimar Constitution (in force during all 12 years of the Third Reich) nor any laws passed by Nazi government allowed KL officers to abuse, beat and torture (let alone murder) inmates.
This fact made it possible for the Allies to prosecute, try, and convict dozens male and female KL officers and guards. For example, out of 45 defendants at the Belsen trial 11 were sentenced to death, three were sentenced to 15 years in jail, five to 10 years, three to 1 to 5 years and ten (more than one in five) were acquitted.