Psychiatric imprisonment is involuntary imprisonment of people on the grounds that they are considered psychiatrically insane. In many countries, people behaving in such a way considered insane by a local judge can be put into a mental institution without trial. Critics argue that an open society based on freedom and personal responsibility has no room for treatment of this nature.
It is part of both the criminal justice and hospital systems in most countries and often has an ambiguous relationship to these.
Dr. Thomas Szasz argued that while these practices may have begun as an alternative to punishment, specifically retributive justice, in the U.S.A. they had become by the 1960s a means of defining mere differences as illnesses. This view has become much more prevalent and is today common among even the psychiatric profession, which views itself in a harm reduction role, and feels that psychiatric imprisonment is a legacy system that has no longer any clear moral justification.