State v. Daniel S. Iverson, 871 N.W.2d 661

Iverson was stopped by a Wisconsin State Patrol trooper in La Crosse after observing a cigarette butt ejected from Iverson's vehicle, which the trooper later used to justify a stop under Wis. Stat. § 287.81 (littering).
The trooper initially followed Iverson’s vehicle after it drifted within a lane and stopped at two flashing yellow lights with no traffic present, then observed the cigarette butt being discarded from the passenger side.
Iverson was cited for drunk driving offenses (Wis. Stat. § 346.63) but suppression was sought, arguing the stop was based solely on non-traffic civil forfeiture—littering—and not on reasonable suspicion or probable cause.
The circuit court granted suppression, concluding the littering statute is not a basis for a traffic stop and that the officer lacked valid authority to stop for that purpose.
The Wisconsin Court of Appeals affirmed on different grounds, holding that stopping for a civil forfeiture offense (littering) is not authorized without either traffic-related grounds or valid constitutional justification.
The supreme court reversed, holding that state troopers are statutorily empowered to stop to enforce § 287.81 and that a stop is generally reasonable when there is probable cause or reasonable suspicion of a littering violation; the cigarette butt violation was found to have probable cause.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Does discarding a cigarette butt onto a highway violate § 287.81?	Iverson: butt may not be 'solid waste' or littering.	Iverson: butt fits within 'other discarded materials' broadened by statute.	Yes, cigarette butt disposal violates § 287.81.
Does Wis. Stat. § 110.07 authorize a traffic stop to enforce § 287.81?	Iverson: stop lacks statutory authority as to littering.	Iverson: statute explicitly authorizes enforcement by state patrol.	Trooper had statutory authority to stop Iverson's vehicle.
May a state traffic patrol stop be based on probable cause or reasonable suspicion of a non-traffic civil forfeiture offense?	Iverson: no grounds to stop for non-traffic civil forfeiture alone.	Iverson: stop may be justified under totality of circumstances when grounds exist.	Yes; such a stop can be reasonable under the Fourth Amendment.
Was there probable cause to believe a § 287.81 violation occurred based on the observed cigarette butt?	Iverson: no basis to infer a violation from littering alone.	Iverson: observation provides probable cause to believe a violation occurred.	Yes; the officer had probable cause to believe a violation occurred.

State v. Popke, 317 Wis. 2d 118 (Wis. 2009) (articulates that a stop may be justified by reasonable suspicion of crime or traffic violation)
State v. Malone, 274 Wis. 2d 540 (Wis. 2004) (balancing public safety and personal security in stops)
Whren v. United States, 517 U.S. 806 (U.S. 1996) (pretextual stops permissible if based on an objective basis)
City of Milwaukee v. Nelson, 149 Wis. 2d 434 (Wis. 1989) (in presence requirement for certain ordinance violations; not controlling here but cited for context)
State v. Pallone, 236 Wis. 2d 162 (Wis. 2000) (arrests for civil forfeitures are not per se unconstitutional)