not guilty by reason of insanity

1

: a plea by a criminal defendant who intends to raise an insanity defense

—used in jurisdictions that require such a plea in order for an insanity defense to be presented

2

: a verdict rendered by a jury in a criminal case that finds that the defendant was insane at the time of committing the crime as determined by application of the test for insanity used in the jurisdiction compare guilty but mentally ill

Note: A verdict of not guilty by reason of insanity usually results in the commitment of the defendant to a mental institution. Such a verdict, however, may allow the defendant to be released, sometimes into the custody or care of another (as a family member).