All of the countries, with the exception of Sweden, provide an insanity defense for criminal defendants. All formulations of the defense focus on whether the defendant was mentally ill at the time of the alleged offense, but they vary greatly on what, if any, other elements are required in an insanity defense. Some countries, such as the United Kingdom, consider mental illness to be a criminal defense only if such illness results in specified psychological impairment. Other countries, such as France, apparently consider the mere presence of mental illness a sufficient basis for excusing a defendant, without regard to any incapacitating consequences of mental illness. Moreover, the United States and the European countries also have systems of involuntary civil commitment for persons found not guilty by reason of insanity. In the United States, the mentally ill person can be committed involuntarily under the police power or the parens patriae power of the state. The European systems of involuntary confinement range from Switzerland's broad parens patriae power over the mentally ill to Hungary's emphasis on the police power to prevent harm. Compared to the United States, the European nations barely address the political, philosophical, and moral issues related to personal responsibility and individual autonomy, issues which underlie the insanity defense. Included are 45 references.