When the World War II Allies began preparing the Nuremberg Trials to prosecute Axis war criminals, they faced the problem that the existing laws of armed conflict did not address crimes against one’s own nationals. The Nazis, for example, had arrested and deported millions of civilians to concentration camps where they were held without trial, abused, and executed. To address the war’s atrocities, the Nuremberg Charter for the first time codified crimes against humanity, that is, crimes which may have been committed before or during a war and against one’s own population. It included “murder, extermination, enslavement, deportation, and other inhumane acts done against any civilian population, or persecutions on political, racial, or religious grounds.”

In their verdicts, the Nuremberg judges repeatedly referred to “acts of imprisonment” as being among the crimes against humanity, and subsequently it has been recognized as such in customary law.

The statutes of the UN International Criminal Tribunals for Rwanda and the former Yugoslavia, established by the UN Security Council, both list imprisonment as a crime against humanity. The charter of the International Criminal Court of 1998, in an article approved by UN member-States without dissent, says that “imprisonment or other severe deprivation of physical liberty in violation of fundamental rules of international law,” if carried out as a widespread or systematic attack on any civilian population, is a crime against humanity.

(See unlawful confinement.)