Sometimes a defendant commits a crime without being truly responsible for his or her actions. Illinois recognizes this concept as the insanity defense. There are, however, many misconceptions about how it works.

Legal insanity does not mean just any type of mental illness or inexplicable behavior. A serial killer’s actions sound insane, but the killer can still appreciate what they are doing is wrong and have the capacity, if not the desire, to conform their conduct to the law.

Legal insanity does not mean diminished capacity, a defense no longer used in Illinois. The fact you committed the crime when you were too drunk to think straight will not excuse your conduct.

Illinois law does recognize the verdict of guilty but mentally ill, where your judgment was impaired by mental illness, but you still knew what you did was wrong. This verdict, however, does not relieve you from punishment.

Under the Illinois Insanity statute, a person is not criminally responsible for their acts if at the time, as a result of mental disease or mental defect, he or she lacked substantial capacity to appreciate the criminality of his or her conduct. (See Insanity.)

Insanity does not mean a person is innocent. In fact, the state must prove you guilty of all elements of the crime beyond a reasonable doubt. Then you must prove your legal insanity by clear and convincing evidence.

Because the defendant must prove insanity, it is critical to present the most compelling evidence possible. A criminal law attorney who is experienced in this defense knows that a credible doctor’s testimony can make or break a case. Your acquaintances may testify about how they saw you immediately before or after the crime, but their testimony is no substitute for an expert’s.

The court will pronounce you guilty of the offense before finding you “not guilty by reason of insanity.” The benefit of such a verdict is that you will likely avoid prison. You can instead be committed to a mental hospital until you are considered well enough to be released.

If you have questions about this or another related Illinois criminal or traffic matter, please contact Matt Keenan at 847-568-0160 or email

(Besides Skokie, Matt Keenan also serves the communities of Arlington Heights, Chicago, Deerfield, Des Plaines, Evanston, Glenview, Morton Grove, Mount Prospect, Niles, Northbrook, Park Ridge, Rolling Meadows, Wilmette and Winnetka.).

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