Wis. Stat. § 940.01
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). 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). 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). 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. 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). 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. 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. 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. 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. 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. An actor causes death if his or her conduct is a substantial factor in bringing about that result. A substantial factor need not be the sole cause of death for one to be held legally culpable. Whether an intervening act was negligent, intentional or legally wrongful is irrelevant. The state must still prove beyond a reasonable doubt that the defendant's acts were a substantial factor in producing the death. State v. Below, 2011 WI App 64, 333 Wis. 2d 690, 799 N.W.2d 95, 10-0798. Under the facts of this case, the court did not err in denying an intervening cause instruction. Even if the defendant could have established that the termination of the victim's life support was "wrongful" under Wisconsin law, that wrongful act would not break the chain of causation between the defendant's actions and victim's subsequent death. State v. Below, 2011 WI App 64, 333 Wis. 2d 690, 799 N.W.2d 95, 10-0798. Importance of clarity in law of homicide: The Wisconsin revision. Dickey, Schultz & Fullin. 1989 WLR 1323 (1989). State v. Camacho: The Judicial Creation of an Objective Element to Wisconsin's Law of Imperfect Self-defense Homicide. Leiser. 1995 WLR 742.