Mental Health and Insanity Defense Lawyer Milwaukee, Wisconsin

A mental disability or mental impairment can play an important role in how a case is evaluated, but it doesn’t automatically remove responsibility. The court looks at whether the criminal defendant was criminally responsible for the alleged act at the time it was committed. [Wis JI-Criminal 605] Wisconsin law follows the American Law Institute standard from the Model Penal Code. [Wis. Stat. § 971.15] Under this standard, a person may be considered legally not responsible if a serious mental illness or mental disorder left them lacking substantial capacity to understand their actions or control their behavior. This is a legal standard, not just a medical concept, so expert testimony has to translate clinical diagnoses like those in the DSM-5 into terms the court and jury can apply. [Wis. Stat. § 971.16(5)]

Wisconsin doesn’t use the traditional M’Naghten rule, the Durham rule, or the irresistible impulse test on their own. [National Institute of Justice] Instead, it follows the American Law Institute standard, which is considered a more balanced approach. This legal standard asks whether the defendant, due to a mental disease or defect, lacked substantial capacity to either understand the wrongfulness of the act or conform their behavior to the law. [Wis. Stat. § 971.15] The M’Naghten test focuses on knowing right from wrong, and most states still use either M’Naghten or the ALI standard today. Wisconsin’s approach also considers a person’s ability to control their actions, reflecting elements of both older tests.

A verdict of not guilty by reason of insanity doesn’t mean someone walks free. Instead, they’re typically committed to institutional care or placed on conditional release, and courts periodically review the person’s mental status to decide whether they remain a danger before considering further release. [Wis. Stat. § 971.17(3)] This means the person is still held accountable for the act, but in a way that focuses on treatment rather than punishment. In many cases, this commitment can last as long as, or even longer than, a traditional prison sentence would have, because the length depends on mental condition and progress rather than the charge. The U.S. Supreme Court addressed this directly in Jones v. United States, holding that the Constitution doesn’t require release just because someone has been committed longer than they could have been imprisoned if convicted.

The insanity criminal defense is an affirmative defense, meaning the burden is on the defendant and their attorney to prove it, rather than on the state to disprove it. [Wis. Stat. § 971.15(3)] This requires showing, through credible evidence, that a qualifying mental condition left the person lacking substantial capacity to control or understand their conduct. [Wis. Stat. § 971.15(2)] Courts require strong proof, including psychiatric testimony, partly to preserve the deterrent effect the law is meant to maintain. Partly because of that, research shows the insanity defense is raised in roughly one percent of felony cases nationally, and succeeds in only about a quarter of those. [Callahan et al., National Library of Medicine] Simply being mentally ill isn’t enough, because the condition must directly affect the person’s ability to understand or control the wrongful conduct.

Wisconsin doesn’t use the traditional M’Naghten rule, the Durham rule, or the irresistible impulse test on their own. [National Institute of Justice] Instead, it follows the American Law Institute standard, which is considered a more balanced approach. This legal standard asks whether the defendant, due to a mental disease or defect, lacked substantial capacity to either understand the wrongfulness of the act or conform their behavior to the law. [Wis. Stat. § 971.15] The M’Naghten test focuses on knowing right from wrong, and most states still use either M’Naghten or the ALI standard today. Wisconsin’s approach also considers a person’s ability to control their actions, reflecting elements of both older tests.