The Insanity Defense in Minnesota (Not Guilty by Reason of Mental Illness)

The Minnesota Standard: M'Naghten

Minnesota uses the traditional M'Naghten test, codified in Minn. Stat. § 611.026. Under it, a person is not criminally responsible if, at the time of the act, they were laboring under such a defect of reason, from mental illness or deficiency, as not to know either:

• the nature of the act; or
• that the act was wrong.

This is a cognitive test — it focuses on what the person knew. Minnesota has deliberately not adopted broader standards used in some states, such as the "irresistible impulse" test or the Model Penal Code's "substantial capacity" test.

What this means for you: Mental illness alone is not enough. Many people with serious psychiatric conditions — even those who were psychotic at the time — will not meet this strict standard, because the question is specifically whether the illness prevented them from knowing the nature or wrongfulness of the act.

For how FASD, cognitive impairment, and mental-health issues can specifically bear on intent, competency, statements, mitigation, and defense strategy, see FASD and mental health in criminal defense.

"Diminished Capacity" Is Not a Separate Defense Here

Unlike some states, Minnesota does not recognize "diminished capacity" or "diminished responsibility" as a way to reduce a charge. A defendant is generally presumed to have a normally functioning mind, and ordinarily can't introduce psychiatric evidence simply to argue they couldn't form intent or premeditate. The main avenue for mental-state evidence is the insanity defense itself.

But the Evidence Allowed Is Broader Than the Standard

There's an important nuance. Even though the legal standard is the narrow cognitive M'Naghten test, the Minnesota Supreme Court (in State v. Rawland) held that the evidence a jury may hear is broader. Courts should "freely receive" evidence so the fact-finder can consider the "whole person" — including evidence touching on the defendant's ability to control behavior — even though the ultimate question still comes back to whether they knew the nature of the act or that it was wrong.

You Have to Prove It — by a Preponderance

The insanity defense is an affirmative defense: the defendant bears the burden of proving it by a preponderance of the evidence (more likely than not). This is different from the prosecution's burden on guilt, which is always proof beyond a reasonable doubt. Courts have held that placing this burden on the defendant does not violate due process.

Raising the Defense: Notice and Examination

• Notice: A defendant who intends to rely on a mental-illness defense must give notice, so the issue can be properly prepared and evaluated.
• Examination: The court can order a mental examination of the defendant on the question of the defense.
• Refusal to be examined: A defendant who raises the defense but refuses to cooperate with a court-ordered examination may face consequences, including limits on presenting their own mental-state evidence.

The Bifurcated Trial

When the insanity defense is raised, Minnesota generally uses a two-phase ("bifurcated") trial:

1. Guilt phase: The jury first decides whether the prosecution has proven the elements of the crime beyond a reasonable doubt — without regard to the mental-illness defense.
2. Mental-illness phase: If the defendant is found to have committed the act, the trial moves to the insanity question, where the defendant must prove the defense by a preponderance of the evidence.

The fact-finder is not bound by expert testimony on sanity — psychiatric opinions are evidence to weigh, but the jury (or judge) decides.

What Happens After a Verdict of Not Guilty by Reason of Mental Illness

This is the most misunderstood part. A successful insanity defense does not mean the person simply walks free. A verdict of not guilty by reason of mental illness typically leads to civil commitment proceedings, and the person may be committed to a secure treatment facility — potentially for a long time, depending on whether they continue to meet the legal criteria for commitment. In practice, the period of confinement can equal or exceed what a criminal sentence might have been.

What this means for you: The insanity defense is not an "easy way out." It trades a criminal conviction for a commitment process that can result in lengthy confinement in a treatment setting. Whether to raise it is a serious strategic decision.

Misdemeanor Cases

There are streamlined procedures for handling the mental-illness defense in misdemeanor cases, which proceed somewhat differently from the full bifurcated felony process.

Insanity vs. Competency: The Key Difference

• Insanity defense — looks backward at mental state at the time of the offense; if successful, results in a verdict of not guilty by reason of mental illness (and usually commitment).
• Competency to stand trial — looks at the person's ability right now to understand the case and assist counsel; if lacking, the case is suspended (and possibly dismissed) while competency attainment is pursued.

A person can be competent to stand trial but still have a valid insanity defense — or be incompetent now with no insanity defense at all. They are independent questions.

Key Terms

• M'Naghten test: Minnesota's cognitive insanity standard — not knowing the nature of the act or that it was wrong.
• Affirmative defense: A defense the defendant must prove (here, by a preponderance of the evidence).
• Bifurcated trial: A two-phase trial separating guilt from the mental-illness question.
• Not guilty by reason of mental illness: The verdict that typically leads to civil commitment.