It appears that Wisconsin, unlike some US states, considers self-defense to be a "negative" defense, and once "some evidence" has been presented tending to establish self defense, the state has the burden of proving otherwise beyond a reasonable doubt. See State v. Stietz, 2017 WI 58, 369 Wis. 2d 222, 880 N.W.2d 182, 14-2701 and State v. Langlois, 2018 WI 73, 382 Wis. 2d 414, 913 N.W.2d 812, 16-140 quoted below. However State v. Head, 2002 WI 99, 255 Wis. 2d 194, 648 N.W.2d 413, 99-3071. and State v. Austin, 2013 WI App 96, 349 Wis. 2d 744, 836 N.W.2d 833, 12-0011 (also quoted below) seem to impose more of a burden on the defendant.
In Paragraph 1 of State v. Langlois, 2018 WI 73, teh Wisconsin Court of Appeals wrote:
The court properly instructed the jury that the
State had the burden of disproving self-defense beyond a reasonable doubt.
US Rules in General
In this matter the law varies in different US states. For the defendant to assert an affirmative defense, the defense must at least present sufficient evidence tending to establish the defense to raise the issue. In some states the prosecution then has the burden of proving beyond a reasonable doubt that the defense does not apply. In some states the defense has the burden of establishing the defense by a preponderance of the evidence, or in some cases by clear and convincing evidence (a standard between preponderance and "beyond a reasonable doubt).
But self-defense is often treated differently than other affirmative defenses in this regard. In the University of Pennsylvania Law Review and American Law Register vol 61 it is stated on page 268 that in Minnesota the state must establish beyond a reasonable doubt that self-defense does not apply, while in North Carolina and ohio the burden rests on the defense. (This may be out of date, but shows that there has been variation.)
The Nolo page "Burdens of Proof in Criminal Cases" states:
Some states may require defendants to prove self-defense by a "preponderance of the evidence," while others require them to simply raise a plausible basis for it, and the prosecution to disprove it beyond a reasonable doubt.
In Martin v. Ohio, 480 U.S. 228 (1987) the Justia Syllabus reads:
Under the Ohio Revised Code (Code), the burden of proving the elements of a criminal offense is upon the prosecution, but, for an affirmative defense, the burden of proof by a preponderance of the evidence is placed on the accused. Self-defense is an affirmative defense under Ohio law, and therefore must be proved by the defendant. ... both the Ohio Court of Appeals and Supreme Court affirmed the conviction, rejecting petitioner's Due Process Clause challenge, which was based on the charge's placing on her the self-defense burden of proof. In reaching its decision, the State Supreme Court relied on Patterson v. New York, 432 U. S. 197.
Martin v. Ohio was cited as good law in Montana v. Egelhoff, 518 U.S. 37 (1996) Justice O'Connorwroe, referring to Martin
In other words, the State's right to shift the burden of proving an affirmative defense did not include the power to prevent the defendant from attempting to prove self-defense in an effort to cast doubt on the State's case.
In "Federal Burden-Of-Proof Rule In Self-Defense Claims " by Lawrence K. Furbish, Assistant Director, Office of Legal Research) it is stated that:
In federal court the prosecution has the burden of disproving self-defense, once the claim has been properly raised. This rule does not appear in either Title 18 of the federal statutes or the Rules of Criminal Procedure but is established by common law. (In the federal system many of the defenses, such as duress, entrapment, and self-defense, are common law defenses.) The federal standard is that once a defendant meets the initial burden of producing sufficient evidence for the judge to give a jury instruction on self-defense, the burden shifts to the government to disprove the defense beyond a reasonable doubt. (See United States v. Thomas, 34 F.3d 44,47 (2d Cir. 1994).)
Wis Code section 939.48 (Self-defense and defense of others) provides:
(1) A person is privileged to threaten or intentionally use force against another for the purpose of preventing or terminating what the person reasonably believes to be an unlawful interference with his or her person by such other person. The actor may intentionally use only such force or threat thereof as the actor reasonably believes is necessary to prevent or terminate the interference. The actor may not intentionally use force which is intended or likely to cause death or great bodily harm unless the actor reasonably believes that such force is necessary to prevent imminent death or great bodily harm to himself or herself.
(2) (a) A person who engages in unlawful conduct of a type likely to provoke others to attack him or her and thereby does provoke an attack is not entitled to claim the privilege of self-defense against such attack, except when the attack which ensues is of a type causing the person engaging in the unlawful conduct to reasonably believe that he or she is in imminent danger of death or great bodily harm. In such a case, the person engaging in the unlawful conduct is privileged to act in self-defense, but the person is not privileged to resort to the use of force intended or likely to cause death to the person's assailant unless the person reasonably believes he or she has exhausted every other reasonable means to escape from or otherwise avoid death or great bodily harm at the hands of his or her assailant.
(2) (b) The privilege lost by provocation may be regained if the actor in good faith withdraws from the fight and gives adequate notice thereof to his or her assailant.
(2) (c) A person who provokes an attack, whether by lawful or unlawful conduct, with intent to use such an attack as an excuse to cause death or great bodily harm to his or her assailant is not entitled to claim the privilege of self-defense. \
(3) The privilege of self-defense extends not only to the intentional infliction of harm upon a real or apparent wrongdoer, but also to the unintended infliction of harm upon a 3rd person, except that if the unintended infliction of harm amounts to the crime of first-degree or 2nd-degree reckless homicide, homicide by negligent handling of dangerous weapon, explosives or fire, first-degree or 2nd-degree reckless injury or injury by negligent handling of dangerous weapon, explosives or fire, the actor is liable for whichever one of those crimes is committed.
In the "History" part of the above section the following caselaw is quotes (along with other quotes):
- 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).
- A defendant asserting perfect self-defense against a charge of 1st-degree murder must meet 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 that the force used was necessary to prevent imminent death or great bodily harm. A defendant asserting the defense of unnecessary defensive force s. 940.01 (2) (b) to a charge of 1st-degree murder is not required to satisfy the objective threshold showing. State v. Head, 2002 WI 99, 255 Wis. 2d 194, 648 N.W.2d 413, 99-3071.
- When a defendant successfully makes self-defense an issue, the jury must be instructed as to the state's burden of proof regarding the nature of the crime, even if the defense is a negative defense. Wisconsin JI-Criminal 801 informs the jury that it “should consider the evidence relating to self-defense in deciding whether the defendant's conduct created an unreasonable risk to another. If the defendant was acting lawfully in self-defense, [his] conduct did not create an unreasonable risk to another." This instruction implies that the defendant must satisfy the jury that the defendant was acting in self-defense and removes the burden of proof from the state to show that the defendant was engaged in criminally reckless conduct. State v. Austin, 2013 WI App 96, 349 Wis. 2d 744, 836 N.W.2d 833, 12-0011.
- Wisconsin law establishes a low bar that the accused must surmount to be entitled to a jury instruction on the privilege of self-defense. The accused need produce only “some evidence" in support of the privilege of self-defense. State v. Stietz, 2017 WI 58, 369 Wis. 2d 222, 880 N.W.2d 182, 14-2701.
- The jury instruction for self-defense in this case was not erroneous. The circuit court gave the jury a general instruction on the state's burden to establish guilt beyond a reasonable doubt. Because self-defense is a negative defense, the state disproves self-defense beyond a reasonable doubt if the state proves the elements of the crime beyond a reasonable doubt, specifically criminal negligence. Therefore, the jury was aware that the state had to prove criminal negligence—the element that self-defense would negate—beyond a reasonable doubt. State v. Langlois, 2018 WI 73, 382 Wis. 2d 414, 913 N.W.2d 812, 16-1409.