940.01 Annotation The affirmative defenses specified in sub. (2) were formerly treated in s. 940.05. This caused confusion because they seemed to be elements of manslaughter rather than defenses to first-degree murder. Sub. (2) specifies only those affirmative defenses which mitigate an intentional homicide from first to 2nd degree. Other affirmative defenses are a defense to 2nd-degree intentional homicide also, such as self-defense, i.e., when both beliefs specified in sub. (2) (b) are reasonable. Section 939.48.

940.01 Annotation The prosecution is required to prove only that the defendant's acts were a substantial factor in the victim's death; not the sole cause. State v. Block, 170 Wis. 2d 676, 489 N.W.2d 715 (Ct. App. 1992).

940.01 Annotation The trial court must apply an objective reasonable view of the evidence test to determine whether under sub. (3) a mitigating affirmative defense "has been placed in issue" before submitting the issue to the jury. In Interest of Shawn B. N. 173 Wis. 2d 343, 497 N.W.2d 141 (Ct. App. 1992).

940.01 Annotation Imperfect self-defense contains an initial threshold element requiring a reasonable belief that the defendant was terminating an unlawful interference with his or her person. State v. Camacho, 176 Wis. 2d 860, 501 N.W.2d 380 (1993).

940.01 Annotation Sub. (1) (a) cannot be applied against a mother for actions taken against a fetus while pregnant as the applicable definition of human being under s. 939.22 (16) is limited to one who is born alive. Sub. (1) (b) does not apply because s. 939.75 (2) (b) excludes from its application actions by a pregnant woman. State v. Deborah J.Z. 228 Wis. 2d 468, 596 N.W.2d 490 (Ct. App. 1999), 96-2797.

940.01 Annotation Barring psychiatric or psychological opinion testimony on the defendant's capacity to form an intent to kill is constitutional. Haas v. Abrahamson, 910 F. 2d 384 (1990) citing Steele v. State, 97 Wis. 2d 72, 294 N.W.2d 2 (1980).

940.01 Annotation A privilege for excusable homicide by accident or misfortune is incorporated in s. 939.45 (6). Accident is a defense that negatives intent. If a person kills another by accident, the killing could not have been intentional. Accident must be disproved beyond a reasonable doubt when a defendant raises it as a defense. When the state proves intent to kill beyond a reasonable doubt, it necessarily disproves accident. State v. Watkins, 2002 WI 101, 255 Wis. 2d 265, 647 N.W.2d 244, 00-0064.

940.01 Annotation A defendant may demonstrate that he or she was acting lawfully, a necessary element of an accident defense, by showing that he or she was acting in lawful self-defense. Although intentionally pointing a firearm at another constitutes a violation of s. 941.20, under s. 939.48 (1) a person is privileged to point a gun at another person in self-defense if the person reasonably believes that the threat of force is necessary to prevent or terminate what he or she reasonably believes to be an unlawful interference. State v. Watkins, 2002 WI 101, 255 Wis. 2d 265, 647 N.W.2d 244, 00-0064.

940.01 Annotation A defendant seeking a jury instruction on perfect self-defense to a charge of first-degree intentional homicide must satisfy an objective threshold showing that he or she reasonably believed that he or she was preventing or terminating an unlawful interference with his or her person and reasonably believed that the force used was necessary to prevent imminent death or great bodily harm. A defendant seeking a jury instruction on unnecessary defensive force under sub. (2) (b) to a charge of first-degree intentional homicide is not required to satisfy the objective threshold. State v. Head, 2002 WI 99, 255 Wis. 2d 194, 648 N.W.2d 413, 99-3071.

940.01 Annotation A defendant who claims self-defense to a charge of first-degree intentional homicide may use evidence of a victim's violent character and past acts of violence to show a satisfactory factual basis that he or she actually believed he or she was in imminent danger of death or great bodily harm and actually believed that the force used was necessary to defend himself or herself, even if both beliefs were unreasonable. State v. Head, 2002 WI 99, 255 Wis. 2d 194, 648 N.W.2d 413, 99-3071.

940.01 Annotation The common law "year-and-a-day rule" that no homicide is committed unless the victim dies within a year and a day after the injury is inflicted is abrogated, with prospective application only. State v. Picotte, 2003 WI 42, 261 Wis. 2d 249, 661 N.W.2d 381, 01-3063.

940.01 Annotation Importance of clarity in law of homicide: The Wisconsin revision. Dickey, Schultz & Fullin. 1989 WLR 1323 (1989).

940.01 Annotation State v. Camacho: The Judicial Creation of an Objective Element to Wisconsin's Law of Imperfect Self-defense Homicide. Leiser. 1995 WLR 742.