Death penalty opponents regard the death penalty as inhumane and criticize it for its irreversibility. They argue also that capital punishment lacks deterrent effect, or has a brutalization effect, discriminates against minorities and the poor, and that it encourages a "culture of violence". There are many organizations worldwide, such as Amnesty International, and country-specific, such as the American Civil Liberties Union (ACLU), whose main purpose includes abolition of the death penalty.