Statutory Defenses to Homicide in Wisconsin: What the Law Provide

Wisconsin's criminal code provides a number of statutory defenses that can acquit someone of a charge entirely or reduce the seriousness of the charge of Wisconsin homicide. Below is an overview of the principal statutory defenses for homicide in Wisconsin. Every case is different, and the best defense will depend on the facts of that case. 

If you or a loved one is facing a homicide charge, understanding statutory defenses can be as important as understanding the charges themselves. Learn more about Aaron Nelson and Nelson Defense Group's award-winning homicide attorneys

Wisconsin's self-defense law and statute is the most frequently invoked defense in homicide cases. Under § 939.48(1), a person may threaten or use force against another when they reasonably believe it is necessary to prevent or terminate an unlawful interference with their person. Deadly force — force intended or likely to cause death or great bodily harm — can only be used when the person reasonably believes it is necessary to prevent imminent death or great bodily harm to themselves.

Two words carry the weight of this statute: "reasonably believes." At trial, a jury evaluates the situation from the defendant's perspective at the moment force was used, asking whether a person of ordinary intelligence and prudence in the same circumstances would have held the same belief. The defendant does not have to be correct — a belief can be both mistaken and reasonable.

Section 939.48(4) extends the same privilege to the defense of third parties. A person may use force to protect someone else under the same conditions that would justify protecting themselves.

Critically, once a defendant properly raises self-defense with some supporting evidence, the burden shifts to the State to disprove it beyond a reasonable doubt. The defense does not have to prove the homicide was justified — the prosecution has to prove it was not.

In 2011, the Wisconsin Legislature enacted what is commonly called the castle doctrine. When an intruder unlawfully and forcibly enters (or is in the process of entering) a person's dwelling, motor vehicle, or place of business; and the person is present and knows or reasonably believes an unlawful, forcible entry is occurring; the law presumes that the person reasonably believed deadly force was necessary.

This presumption is powerful. In an ordinary self-defense case, the jury weighs the reasonableness of the defendant's belief. Under the castle doctrine, the court presumes it — and the statute expressly provides that the jury may not consider whether the person had an opportunity to flee or retreat before using force. 

The presumption does not apply in certain circumstances, such as when the person against whom force was used was a public safety officer performing official duties and identified as such, or when the defendant was engaged in criminal activity or using the dwelling, vehicle, or business to further criminal activity.

Wisconsin law recognizes that not every unjustified killing deserves the law's harshest condemnation. Section 940.01(2) sets out mitigating circumstances that reduce first-degree intentional homicide to second-degree intentional homicide — the difference between mandatory life imprisonment and a maximum term of 60 years. These affirmative defenses include:

Adequate provocation. Under §§ 939.44 and 940.01(2)(a), a homicide committed under the influence of adequate provocation is mitigated to second-degree intentional homicide. Provocation is "adequate" when it would cause complete lack of self-control in an ordinarily constituted person, and the defendant must actually have lacked self-control at the time. This is Wisconsin's version of what other states call "heat of passion."

Unnecessary defensive force — imperfect self-defense. Under § 940.01(2)(b), if the defendant actually believed deadly force was necessary to prevent imminent death or great bodily harm, but that belief (or the amount of force used) was unreasonable, the charge is mitigated to second-degree homicide. The defendant who honestly but wrongly perceives a deadly threat is not innocent, but neither is he guilty of first-degree homicide.

Prevention of a felony. Section 940.01(2)(c) mitigates a homicide committed because the defendant believed the force was necessary to prevent or terminate the commission of a felony, where that belief was unreasonable.

Once any of these mitigating circumstances is placed in issue by the trial evidence, the State must prove beyond a reasonable doubt that the mitigating circumstance did not exist in order to sustain a first-degree conviction. That burden allocation can be a significant opportunity in defense strategy.

Wisconsin recognizes coercion — acting under a threat by another person that causes a reasonable belief that the act is the only means of preventing imminent death or great bodily harm — and necessity — pressure from natural physical forces creating the same kind of reasonable belief. For most crimes, these are complete defenses. For homicide, the statutes treat them differently: coercion or necessity does not excuse an intentional killing outright, but it reduces first-degree intentional homicide to second-degree intentional homicide.

A person may use force reasonably believed necessary to prevent or terminate an unlawful interference with their property. But the statute is explicit that this privilege does not extend to force intended or likely to cause death or great bodily harm. Standing alone, defense of property will not justify a homicide — though in real cases, threats to property and threats to persons often arise together, and the facts may support a self-defense or castle doctrine theory instead.

Wisconsin's MDD defense is statutory. A defendant is not responsible for criminal conduct if, at the time of the offense, as a result of mental disease or defect, they lacked substantial capacity either to appreciate the wrongfulness of their conduct or to conform their conduct to the requirements of law. Wisconsin uses a unique bifurcated trial procedure: guilt is determined first, and the responsibility phase follows. Unlike self-defense, the defendant bears the burden on this defense, by the greater weight of the credible evidence. A successful Not Responsible by Reason of Mental Disease or Defect (NRRMDD) verdict results in commitment rather than acquittal and release, so the decision to pursue it is strategic.

Since the Legislature amended § 939.42 in 2014, voluntary intoxication is no longer a defense in Wisconsin, even to negate the intent element of first-degree intentional homicide. Involuntary intoxication — where the intoxicated condition was not self-induced — remains a defense if it rendered the defendant incapable of distinguishing right from wrong. An honest mistake of fact, under § 939.43, can be a defense where it negates a state of mind essential to the crime charged.

You may notice a pattern of words in these statutes like "reasonably believes," "imminent," "adequate," and "unlawful interference.” Whether a homicide charge ends in acquittal, mitigation, or conviction often comes down to how those words apply to each situation and to which side carries the burden of proof on each element. Building strategy starts early. Witness statements, forensic evidence, the defendant's own account, and expert testimony all shape whether a statutory defense gets to the jury at all.

If you are under investigation or have been charged in connection with a death, do not speak to law enforcement before speaking with an attorney. Hiring an attorney immediately gives your attorney time to catch up with the state’s investigation, often allowing them to protect you sooner and better. 

Nelson Defense Group is one of the leading criminal defense firms in Wisconsin. Lead Attorney Aaron Nelson has secured more Not Guilty verdicts on homicide cases than any other lawyer in the state. Our team of attorneys are experienced with Wisconsin law and know how to best tell your story. 

Contact our office for a confidential consultation today. Serious charges, require strategic defense.