In an insanity defense, the defendant admits the action but asserts a lack of culpability based on mental illness. What Happens If I Plead Insanity?The insanity defense exists to make that distinction for people with a mental disability. An insanity plea or defense is not a loophole or escape from prison. In fact, most defendants found insane will spend their lives in a psychiatric hospital. Online legal forms are useful for frequent, basic, and necessary tasks. A defendant who intends to assert a defense of insanity at the time of the alleged offense must so notify an attorney for the government in writing. It's usually a contempt of court charge and will cost you considerably more than just having plead it out and doing 3 hours worth of drivers Ed.