## Facts

- Milwaukee City Ordinance 106-31(1)(a) prohibited loitering or prowling in an unusual place, time, or manner “under circumstances that warrant alarm for the safety of persons or property.”
- The ordinance listed nonexclusive factors relevant to “alarm” (including flight, refusal to identify oneself, and concealment) and, where feasible, required officers to give the person an opportunity to explain before arrest.
- Police officers observed Stefan Nelson outside a tavern in an area they described as high crime, greeting pedestrians and occupants of passing cars; officers did not observe any exchange of money or objects.
- When officers approached, Nelson twice retreated into the tavern; inside, he told officers he was doing “nothing.” A pat-down revealed no weapon.
- Officers arrested Nelson for violating the ordinance and transported him in a police van.
- A handgun was later found in the van; Nelson admitted it was his and that it had been stolen, leading to a separate charge for carrying a concealed weapon.
- In the concealed-weapon case, Nelson moved to suppress the gun and related statements, arguing the ordinance (and the statute authorizing arrest for ordinance violations) was unconstitutional, making the arrest unlawful.

## Issues

1. Whether Milwaukee City Ordinance 106-31(1)(a) was unconstitutionally vague.
2. Whether the ordinance was facially overbroad, including as applied to constitutionally protected activity.
3. Whether the ordinance and Wis. Stat. § 800.02(6) violated the Fourth Amendment and Wis. Const. art. I, § 11 by permitting arrest on less than probable cause.
4. Whether the City exceeded municipal authority by enacting an ordinance allegedly authorizing arrest on reasonable suspicion rather than probable cause.

## Decision

- The Wisconsin Supreme Court affirmed the court of appeals.
- The court held the ordinance was not unconstitutionally vague because it provided fair notice and sufficient standards to guide enforcement, focusing on conduct that warrants alarm for safety.
- The court held the ordinance was not facially overbroad because it targeted conduct related to safety risks, not protected expression, and included a safeguard requiring an opportunity to explain when feasible.
- The court held the ordinance and Wis. Stat. § 800.02(6) did not violate the Fourth Amendment or Wis. Const. art. I, § 11 because arrests under the ordinance must be supported by probable cause.
- The court held the City did not exceed municipal power because the ordinance, properly construed with governing constitutional limits, does not authorize arrest on less than probable cause.

## Legal Principles

- A criminal or quasi-criminal ordinance is void for vagueness only if it fails to give fair notice of prohibited conduct or lacks enforceable standards, creating an unacceptable risk of arbitrary enforcement.
- A loitering ordinance may survive vagueness review when it limits liability to conduct occurring under safety-threatening circumstances and provides contextual criteria to guide officer judgment.
- Facial overbreadth is not established where a law is directed at conduct rather than expression and does not substantially reach constitutionally protected activity.
- The Fourth Amendment and Wis. Const. art. I, § 11 require probable cause for a custodial arrest; a municipal ordinance cannot validly be applied to authorize arrest on a lesser standard.
- Statutes authorizing arrest for ordinance violations operate within constitutional constraints; arrests remain subject to the probable-cause requirement.

## Conclusion

The Wisconsin Supreme Court upheld Milwaukee’s loitering ordinance and the ordinance-arrest statute, construing the enforcement scheme to require probable cause and concluding the ordinance provided adequate standards and did not substantially burden protected activity.


City of Milwaukee v. Nelson, 149 Wis. 2d 434, 439 N.W.2d 562 (Wis. 1989)