Legal Memorandum: Possible Consequences of Defendant's Insanity (NGI) Plea in WI

Issue: If a defendant is found not guilty by reason of insanity (NGI) under Wisconsin law, what are the possible consequences to the defendant?

Wis. Stat. § 971.06(1)(d) provides that “[a] defendant charged with a criminal offense may plead . . . not guilty by reason of mental disease or defect.” The Wisconsin Supreme Court recently summarized the requirements for the defense:

A criminal defendant may raise an affirmative defense of not guilty by reason of mental disease or defect, also known as an “insanity” or “NGI” defense. Wis. Stat. § 971.15. The defendant bears the burden of establishing the defense “to a reasonable certainty by the greater weight of the credible evidence.” Wis. Stat. § 971.15(3). Wisconsin Stat. § 971.15(1) provides that the defendant may establish an insanity defense by demonstrating that he lacked substantial capacity either to (1) appreciate the wrongfulness of his conduct, or (2) conform his conduct to the requirements of the law.

State v. Anderson, 851 N.W.2d 760, 765 (Wis. 2014). See Wis. Stat. § 971.15.

Generally, under current Wisconsin practice, where a defendant pleads not guilty and not guilty by reason of mental disease or defect, there is a two-part—or “bifurcated”—procedure. State v. Magett, 850 N.W.2d 42, 53 (Wis. 2014). The Magett court explained:

A bifurcated criminal trial consists of two phases: (1) the guilt phase; and (2) the responsibility phase. When a criminal defendant pleads not guilty and not guilty by reason of mental disease or defect, the jury hears evidence relating to the defendant’s guilt in the first phase of the trial, and if the jury finds the defendant guilty, the trial proceeds to the second phase. Wis. Stat. § […]

margin-left:1.0in;margin-bottom:.0001pt;text-align:justify’>