Not Guilty by Reason of Insanity

I’ve heard it before: “sure she was insane . . . riiiiight” [eye roll]. The insanity defense, more accurately, the defense of Not Guilty by Reason of Mental Illness, is often caricatured and ridiculed.

The defense is rarely raised in Minnesota and even more-rarely is it successful.  It is estimated  that  approximately 1% of criminal defense cases raise mental illness as a defense.  Of those roughly 25% succeed.  So, one quarter of one percent of criminal defendants succeed with a mental illness defense.

The Standard

Most states in the United States, including Minnesota, use the M’Naghten standard for determining whether someone is criminally liable for his or her actions if a mental health  defense is raised.  The standard is named after Daniel M’Naghten who attempted in 1843 to assassinate British Prime Minister Robert Peel and was found not criminally liable for his actions because he was operating under a mental illness (defect) such that he did not know his actions were wrong.

In Minnesota, the standard is codified in statute (Minn. Stat. §611.026) which states that a “person shall not be excused from criminal liability except upon proof that at the time of committing the alleged criminal act the person was laboring under such a defect of reason . . . as not to know the nature of the act, or that it was wrong.”

The Procedure

Rule 20 Evaluation

When a defense lawyer tells the judge and prosecutor that he intends to raise a mental illness, the procedures in Rule 20.02  take over.  (Note, this blog is specifically about whether someone is mentally ill such that she is not liable for her illegal conduct.  Whether someone is competent to stand trial is a different matter altogether.) At that point, the judge will order a licensed psychologist to conduct an evaluation of the defendant’s mental health.  In Hennepin County, the Department of Psychological Services employs licensed forensic psychologists who perform these evaluations and submits them to the defense counsel, prosecutor, and judge.  This is the point at which 99% of the cases fail to reach the mental defect standard and get referred back to the regular course of prosecution.  However, if the psychologist does find that the defendant “was laboring under such a defect of reason as not to know the nature of wrongfulness of his or her criminal behavior,” the criminal matter will be treated under the standards set forth under Rule 20.02.


Typically, the parties (prosecution and defense) will agree to submit the case to the judge on stipulated findings.  This means that the parties will agree to tell the judge what happened at the time the offense was committed and will submit their psychological evaluations for the judge to consider.  If the judge finds the defendant was laboring under a mental illness such as not to know that her actions were wrong, the Rule requires that a defendant be civilly committed.

Civil Commitment

As one recent client put it, the consequence of being found Not Guilty by Reason of Mental Illness is that you have  to then deal with the consequences of being found mentally ill.

If the defendant is already under a civil commitment order, the judge must order the commitment continued and, in the case of a felony or gross misdemeanor, that the court and the prosecutor be informed when the commitment is to end.

If the defendant is not under a civil commitment order the court must order that a civil commitment proceeding begin.  In all cases, the court and the prosecutor have a right to participate in the civil commitment proceedings as a party – that is, to present their argument why a commitment should be longer or shorter, whether it should require institutionalization, and what restrictions should be placed on the mentally ill person.  The court and prosecutor must also be informed when the commitment is due to end and to oppose the termination of commitment if they wish.

Findings that a person is not criminally liable for her conduct because she was mentally ill at the time, mentally ill in a specific way such that she did not know the nature of her actions was legally wrong, are exceedingly rare.  The person is usually operating under delusions or hallucinations.

I recently had a client found not guilty by reason of insanity.  Call me at (612) 310-7398 for a free initial consultation.


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