Engaging in unlawful conduct does not completely preclude a claim of self-defense under Wisconsin law

...but it does raise the bar in some circumstances:

• Criminal conduct by the defendant removes the presumption that "force was necessary to prevent imminent death or great bodily harm" when defending against unlawful forced entry to one's own property.
• A much higher burden on use of force is imposed if engaging in unlawful conduct that is "of a type likely to provoke others to attack him or her and thereby does provoke an attack."
• Anyone intentionally provoking an attack by any means, lawful or unlawful, "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 self-defense at all.

Section 939.48 of Wisconsin law governs the standards for self-defense.

939.48(1) sets out the general standard:

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.

939.48(1m)(ar) provides presumptions in favor of the defendant and no duty to retreat when defending against unlawful entry to one's own property (an implementation of the castle doctrine), but those presumptions are removed by 939.48(1m)(b)1. if (among other things), "[t]he actor was engaged in a criminal activity."

More relevant to a case that occurred outside is 939.48(2), which lays out how provocation affects a claim of self-defense:

(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.

(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.

(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.