Gesetz zur Verhütung erbkranken Nachwuchses
Action T4 was a programme of systematic murder of the physically and mentally handicapped and patients in psychiatric hospitals that took place mainly from 1939 to 1941, and continued until the end of the war. Initially the victims were shot by the "Einsatzgruppen" and others; gas chambers and gas vans using carbon monoxide were used by early 1940. Under the Law for the Prevention of Hereditarily Diseased Offspring, enacted on 14 July 1933, over 400,000 individuals underwent compulsory sterilisation. Over half were those considered mentally deficient, which included not only people who scored poorly on intelligence tests, but those who deviated from expected standards of behaviour regarding thrift, sexual behaviour, and cleanliness. Most of the victims came from disadvantaged groups such as prostitutes, the poor, the homeless, and criminals. Other groups persecuted and killed included Jehovah's Witnesses, homosexuals, social misfits, and members of the political and religious opposition.