Although cases invoking the insanity defense often receive much media attention, the defense is actually not raised very often. Virtually all studies conclude that the insanity defense is raised in less than 1 percent of felony cases, and is successful in only a fraction of those1.
Is pleading insanity successful?
Defendants offer an insanity defense in less than 1% of all felony cases, and are successful only about one-quarter of the time. ... Few offenders "fake" insanity; most defendants who plead insanity have a long history of mental illness and prior hospitalizations.
What happens if you plead insanity?
This definition of legal insanity is known as the “McNaghten (sometimes spelled M'Naghten or McNaughten) rule.” You can plead not guilty by reason of insanity at your arraignment hearing.
