2015 WI 79

SUPREME COURT OF WISCONSIN

CASE NO.: 2013AP1581-CR 

COMPLETE TITLE: State of Wisconsin, 

 Plaintiff-Respondent-Petitioner, 

 v. 

Richard E. Houghton, Jr., 

 Defendant-Appellant. 

REVIEW OF A DECISION OF THE COURT OF APPEALS 

(Reported at 354 Wis. 2d 623, 848 N.W.2d 904) 

(Ct. App. 2014 – Unpublished) 

OPINION FILED: July 14, 2015 

SUBMITTED ON BRIEFS: 

ORAL ARGUMENT: April 22, 2015 

SOURCE OF APPEAL: 

 COURT: Circuit 

 COUNTY: Walworth 

 JUDGE: John R. Race 

 

JUSTICES: 

 CONCURRED: 

 DISSENTED: ABRAHAMSON, BRADLEY, J.J., dissent. (Opinion 

Filed.) 

 NOT PARTICIPATING: 

 

ATTORNEYS: 

For the plaintiff-respondent-petitioner, the cause was 

argued by Tiffany M. Winter, assistant attorney general, with 

whom on the briefs was Brad D. Schimel, attorney general. 

For the defendant-appellant there was a brief by Andrew R. 

Walter, Elkhorn, and oral argument by Andrew R. Walter. 

An amicus curiae brief was filed by Hannah Schieber Jurss, 

assistant state public defender, with whom on the brief was 

Kelli S. Thompson, state public defender, on behalf of the 

Office of the State Public Defender. 
2015 WI 79

NOTICE

This opinion is subject to further 

editing and modification. The final 

version will appear in the bound 

volume of the official reports. 

No. 2013AP1581-CR 

(L.C. No. 2012CF187) 

STATE OF WISCONSIN : IN SUPREME COURT 

State of Wisconsin,

 Plaintiff-Respondent-Petitioner, 

 v. 

Richard E. Houghton, Jr., 

 Defendant-Appellant. 

FILED 

JUL 14, 2015 

Diane M. Fremgen 

Clerk of Supreme Court 

REVIEW of a decision of the Court of Appeals. Reversed. 

¶1 DAVID T. PROSSER, J. This is a review of an 

unpublished decision of the court of appeals,1 which reversed a 

judgment of conviction entered by the Walworth County Circuit 

Court2 against Richard E. Houghton, Jr. (Houghton). Houghton 

pled guilty to one count of possession of THC (greater than 200 

grams) with intent to deliver, following the circuit court's 

 

1 State v. Houghton, No. 2013AP1581-CR, unpublished slip op. 

(Wis. Ct. App. May 7, 2014). 

2 The Honorable John R. Race, Judge. 
No. 2013AP1581-CR 

2 

denial of Houghton's motion to suppress evidence obtained during 

the course of a traffic stop. 

¶2 This case presents questions related to the standard 

necessary for police to lawfully initiate a traffic stop. 

Specifically, we consider whether an officer's reasonable 

suspicion that a motorist is committing a traffic violation is 

always sufficient for the officer to stop the motorist, or 

whether some stops require probable cause. We also examine 

statutes related to the placement of objects in the front 

windshield of an automobile, and weigh the effect of recent 

developments in case law related to objectively reasonable 

mistakes of law made by law enforcement officers. 

¶3 Police Officer Jeff Price (Officer Price) pulled

Houghton over after Officer Price observed Houghton's vehicle 

traveling on a highway without a front license plate and with an 

air freshener and a GPS unit visible in the front windshield. 

Upon approaching the vehicle, Officer Price detected the odor of 

marijuana, which led him to conduct a search of Houghton's car. 

The search revealed approximately 240 grams of marijuana as well 

as various paraphernalia commonly used for packaging and 

distributing marijuana. 

¶4 Houghton argues that the stop was not an investigatory 

stop, and thus probable cause was required. Houghton contends 

that Officer Price lacked probable cause to stop Houghton's 

vehicle, making the subsequent search unlawful. The State 

counters that reasonable suspicion is sufficient for police 

officers to initiate any type of traffic stop, and that Officer 
No. 2013AP1581-CR 

3 

Price had reasonable suspicion to pull Houghton over for a 

violation of Wis. Stat. § 346.88(3)(b) (2011-12),3 "Obstruction 

of operator's view or driving mechanism." The State argues in 

the alternative that any mistake by Officer Price as to whether 

Houghton was operating his vehicle illegally was objectively 

reasonable, and that under the holding of the recent United 

States Supreme Court case of Heien v. North Carolina, 574 U.S. 

___, 135 S. Ct. 530 (2014), Officer Price had reasonable 

suspicion to stop Houghton's vehicle for the perceived 

violation. 

¶5 We hold that an officer's reasonable suspicion that a 

motorist is violating or has violated a traffic law is 

sufficient for the officer to initiate a stop of the offending 

vehicle. We also adopt the Supreme Court's holding in Heien 

that an officer's objectively reasonable mistake of law may form 

the basis for a finding of reasonable suspicion. 

¶6 In this case, we hold that Wis. Stat. § 346.88 does 

not create an absolute prohibition on any object being present 

in the front windshield of a vehicle. However, Officer Price's 

interpretation that the statute did create such a prohibition 

was objectively reasonable. Accordingly, Officer Price had 

reasonable suspicion to stop Houghton's vehicle, and it was not 

error for the circuit court to deny Houghton's motion to 

suppress. For these reasons, we reverse the court of appeals. 

 

3 All subsequent references to the Wisconsin Statutes are to 

the 2011-12 version unless otherwise indicated. 
No. 2013AP1581-CR 

4 

I. FACTUAL AND PROCEDURAL BACKGROUND 

¶7 At approximately 12:30 p.m. on April 16, 2012, Village 

of East Troy Police Officer Jeff Price was on duty in a marked 

squad car on the shoulder of Highway 20, facing east, near 

Townline Road in East Troy. Around that time, Officer Price saw 

a blue Ford Taurus traveling westbound on Highway 20. The car 

had no front license plate, and an air freshener suspended from 

the rearview mirror and a GPS unit were visible through the 

front windshield. Officer Price did a U-turn, activated his 

squad car's emergency lights, and pulled the Taurus over. 

¶8 Officer Price approached the Taurus and obtained

identification from the occupants. The car, which had a 

Michigan license plate attached to the back, was driven by the 

defendant, Richard E. Houghton, Jr., who is a resident of 

Michigan. In the front passenger seat of the car was James J. 

Taracek (Taracek), Houghton's step-brother and a resident of 

East Troy. After running a check on both Houghton and Taracek, 

Officer Price returned to the the Taurus, this time approaching 

the passenger side. As he approached, Officer Price smelled the 

odor of marijuana coming from the car. 

¶9 Officer Price searched the car and found the 

following: "two partially smoked marijuana cigarettes, a pack of 

zig-zag rolling paper, a piece of PVC tubing with a screen taped 

on one end, a large zip-lock bag containing green plant 

material, three smaller sandwich bags containing green plant 

material, a 150 count pack of sandwich bags, and an AMS digital 

scale with traces of green plant material on the weighing base." 
No. 2013AP1581-CR 

5 

The "green plant material" tested positive for 

Tetrahydrocannabinol (THC), the active ingredient in marijuana. 

The large "zip-lock" bag contained approximately 140 grams of 

marijuana, the three smaller sandwich bags each contained 

approximately 30 grams of marijuana, and the PVC tube contained 

approximately 9 grams of marijuana. 

¶10 In an information filed on June 5, 2012, Houghton was 

charged with one count of possession with intent to deliver THC 

(200 to 1000 grams), contrary to Wis. Stat. § 961.41(1m)(h)2. 

On July 31, Houghton filed a motion with the circuit court 

seeking suppression of the evidence obtained during the search 

of his vehicle. Houghton argued that the lack of a front 

license plate on his car and the items in his windshield were 

not violations of Wisconsin law. Houghton contended that 

"because no traffic violations occurred, [Officer Price] lacked 

the reasonable suspicion to justify a Terry stop."4 Therefore, 

Houghton argued, the stop violated his Fourth Amendment right 

against unreasonable search and seizure. 

¶11 The State answered Houghton's motion to suppress on 

October 16. The State argued that Officer Price had reasonable 

suspicion to stop Houghton for three observed violations: the 

 

4 Terry v. Ohio, 392 U.S. 1 (1968). 
No. 2013AP1581-CR 

6 

absence of a front license plate, the items in the front 

windshield, and a missing side mirror.5

¶12 The circuit court held a motion hearing on November 2, 

at which Officer Price testified briefly about his encounter 

with Houghton. At the end of the hearing, the circuit court 

denied the motion. The court was equivocal about whether the 

GPS unit and air freshener were statutory violations, noting 

that "there must be a zillion cars driving around with air 

fresheners and not very many of them would get stopped by the 

traffic officer. They've got better things to do." However, 

the court continued, "the princip[al] reason for the stop that 

creates this reasonable and articulable suspicion is the front 

license plate missing from a vehicle, missing on Wisconsin roads 

when Wisconsin requires two plates." 

¶13 After denial of his motion to suppress, Houghton pled 

guilty to the count as charged at a hearing on February 13, 

2013. As part of the plea agreement, the State recommended a 

two-year sentence consisting of one year of imprisonment and one 

year of extended supervision, imposed and stayed on the 

condition that Houghton complete two years of probation and pay 

a $500 fine plus costs. After a plea colloquy, the court 

 

5 Houghton's car was missing the mirror lens on the 

passenger side. However, Officer Price did not notice the lens 

was missing from the mirror housing until after he stopped 

Houghton. The State does not argue in this appeal that the 

missing mirror lens gave Officer Price reasonable suspicion to 

stop Houghton. 
No. 2013AP1581-CR 

7 

entered a judgment of conviction and accepted the sentence 

recommendation, allowing for the possibility that Houghton would 

serve probation in Michigan. 

¶14 Houghton appealed his conviction. On appeal, Houghton 

argued that the circuit court erred by denying his motion to 

suppress evidence. Houghton maintained his argument that 

Officer Price lacked reasonable suspicion to stop Houghton's 

vehicle. The State conceded that Officer Price made a mistake 

of law with regard to the license plate requirement. The State 

also conceded that under State v. Longcore, 226 Wis. 2d 1, 9, 

594 N.W.2d 412 (Ct. App. 1999), a mistake of law could not form 

the basis for a traffic stop. The State argued, however, that 

the items in the front windshield of Houghton's car gave Officer 

Price sufficient reason to pull Houghton over. 

¶15 In an unpublished per curiam decision, the court of 

appeals reversed the judgment of conviction and remanded the 

case to the circuit court. State v. Houghton, No. 2013AP1581-

CR, unpublished slip op. (Wis. Ct. App. May 7, 2014). The court 

provided little explanation for its ruling, noting that: 

the only objects near Houghton's front windshield were 

a standard-size, pine-tree-shaped air freshener 

hanging from the rearview mirror and a three-by-fiveinch GPS unit attached to the lower left-hand corner. 

On these facts, we are not persuaded that there was

probable cause to conclude that a violation of 

§ 346.88(3)(b) had occurred. 

Id. at 5. 

¶16 The court of appeals did acknowledge that the Supreme 

Court had recently granted certiorari in Heien v. North 
No. 2013AP1581-CR 

8 

Carolina, 749 S.E.2d 278 (N.C. 2013), which addressed whether a 

reasonable mistake of law could provide grounds for a traffic 

stop. Houghton, No. 2013AP1581-CR, at 4 n.3. The court noted 

that the decision in Heien could place the holding of Longcore 

in doubt, and "suppose[d] the State [could] petition the 

Wisconsin Supreme Court for review and then ask that the 

petition be held in abeyance pending the outcome in Heien." Id. 

¶17 The State petitioned this court for review and 

requested that we hold the petition in abeyance pending 

resolution of Heien. Following the release of the opinion in 

Heien, this court granted review on January 13, 2015. 

II. STANDARD OF REVIEW 

¶18 Whether reasonable suspicion or probable cause is 

necessary for a law enforcement officer to stop a vehicle is a 

question of law we review de novo. See State v. Kramer, 2001 WI 

132, ¶17, 248 Wis. 2d 1009, 637 N.W.2d 35. Whether a statute 

has been properly interpreted and applied also is a question of 

law we review de novo, but we do so "while benefitting from the 

analyses of the court of appeals and circuit court." 118th St. 

Kenosha, LLC v. DOT, 2014 WI 125, ¶19, 359 Wis. 2d 30, 41 

N.W.2d 486 (quoting 260 N. 12th St., LLC v. DOT, 2011 WI 103, 

¶39, 338 Wis. 2d 34, 808 N.W.2d 372). Finally, whether a 

defendant's constitutional rights were violated is a question of 

constitutional fact subject to a two-step standard of review. 

State v. Phillips, 218 Wis. 2d 180, 189, 577 N.W.2d 794 (1998). 

First, we uphold the circuit court's findings of historical fact 

unless they are clearly erroneous. State v. Williams, 2002 WI 
No. 2013AP1581-CR 

9 

94, ¶17, 255 Wis. 2d 1, 646 N.W.2d 834. Then, we review the 

circuit court's determination of the constitutional question de 

novo. Id. 

III. DISCUSSION 

¶19 We begin by reviewing the law relating to 

investigatory traffic stops, then examine the evolution of case 

law involving stops predicated on reasonable mistakes of law. 

We then turn to an analysis of the relevant statutes in this 

case and conclude by applying the relevant law to the facts. 

A. Probable Cause and Reasonable Suspicion 

¶20 Terry v. Ohio, 392 U.S. 1 (1968), is the seminal case 

on reasonable suspicion as justification for conducting 

investigatory stops. In Terry, the defendant was convicted of 

carrying a concealed weapon. Id. at 4. The arresting officer, 

a veteran detective with almost 40 years of experience, 

confronted Terry and his associates after observing them engage 

in a pattern of suspicious behavior. Id. at 5-7. After 

speaking to the men briefly, the detective grabbed Terry, spun 

him around, and performed a pat down search. Id. at 7. The 

search revealed a .38 caliber revolver in Terry's coat pocket. 

Id. Terry moved to suppress the evidence, arguing that the 

detective lacked probable cause to conduct the search. Id. at 

7-8. 

¶21 The Supreme Court affirmed Terry's conviction, holding 

that "a police officer may in appropriate circumstances and in 

an appropriate manner approach a person for purposes of 

investigating possibly criminal behavior even though there is no 
No. 2013AP1581-CR 

10 

probable cause to make an arrest." Id. at 22. In order to 

justify such a seizure, police must have reasonable suspicion 

that a crime or violation has been or will be committed; that 

is, "the police officer must be able to point to specific and 

articulable facts which, taken together with rational inferences 

from those facts, reasonably warrant that intrusion." Id. at 

21. This "reasonable suspicion" standard was understood to be a 

lower standard than probable cause. See id. at 35-36 (Douglas, 

J., dissenting). 

¶22 In Berkemer v. McCarty, 468 U.S. 420 (1984), the Court 

extended the reasoning underlying Terry to include traffic 

stops, holding that a police officer "who lacks probable cause 

but whose 'observations lead him reasonably to suspect' that a 

particular person has committed, is committing, or is about to 

commit" a violation may conduct a traffic stop in order to 

"'investigate the circumstances that provoke suspicion.'" See 

id. at 439 (citation omitted). In other words, while probable 

cause is enough to justify a traffic stop, probable cause is not 

indispensable to justify a traffic stop. Rather, police 

officers who reasonably suspect an individual is breaking the 

law are permitted to conduct a traffic stop "to try to obtain 

information confirming or dispelling the officer's suspicions." 

Id. 

¶23 Twelve years after Berkemer, the Supreme Court

decided Whren v. United States, 517 U.S. 806 (1996). In Whren, 

the Court addressed whether temporarily detaining "a motorist 

who the police have probable cause to believe has committed a 
No. 2013AP1581-CR 

11 

civil traffic violation is inconsistent with the Fourth 

Amendment's prohibition against unreasonable seizures unless a 

reasonable officer would have been motivated to stop the car by 

a desire to enforce the traffic laws." Id. at 808.

¶24 On June 10, 1993, D.C. Metro Police officers were 

patrolling an area of the city known for drug activity. Id. 

The officers grew suspicious of a vehicle with temporary plates 

and "youthful occupants" after seeing the driver of the vehicle 

"looking down into the lap of the passenger at his right." Id. 

The officers stopped the vehicle after observing it driving 

erratically, and upon approaching the vehicle, they observed 

Whren in possession of crack cocaine. Id. at 809. Whren was 

arrested and charged with multiple drug violations. Id. Prior 

to trial, the defense moved to suppress the evidence on the 

theory that the officers' "ground for approaching the vehicle——

to give the driver a warning concerning the traffic violation——

was pretextual." Id. at 809. 

¶25 In an opinion by Justice Scalia, a unanimous Court 

held that the brief detention of a motorist who police have 

probable cause to believe has violated a traffic law is not an 

unreasonable search or seizure within the meaning of the Fourth 

Amendment, even if the officer would not have initiated the stop 

without some additional law enforcement objective. Id. at 808, 

818-19. In other words, pretextual traffic stops——stops 

designed to investigate violations not related to the observed 

violation——are not per se unreasonable under the Fourth 

Amendment. 
No. 2013AP1581-CR 

12 

¶26 Since Whren, some have sought deeper meaning in the 

Court's assertion that, "As a general matter, the decision to 

stop an automobile is reasonable where the police have probable 

cause to believe that a traffic violation has occurred." Id. at 

810 (emphasis added). Some courts interpreted Whren to mean 

that probable cause——not reasonable suspicion——is required for a 

traffic stop to be reasonable. See United States v. DelfinColina, 464 F.3d 392, 396 (3d Cir. 2006) (discussing the 

uncertainty raised by Whren). 

¶27 The existence of multiple standards necessary to 

justify traffic stops in Wisconsin was implied in State v. 

Gaulrapp, 207 Wis. 2d 600, 558 N.W.2d 696 (Ct. App. 1996). In 

Gaulrapp, the court of appeals stated that a "traffic stop is 

generally reasonable if the officers have probable cause to 

believe that a traffic violation has occurred, or have grounds 

to reasonably suspect a violation has been or will be 

committed." Id. at 605 (citations omitted). This dual-standard 

analysis continued in Longcore when the court of appeals noted 

that the officer "did not act upon a suspicion that warranted 

further investigation, but on his observation of a violation 

being committed in his presence," thus requiring the officer's 

observations to meet the probable cause standard. Longcore, 226 

Wis. 2d at 8-9 (footnote omitted). 

¶28 Houghton urges this court to hold that this dual 

standard is correct——that an investigative stop may be based on 

reasonable suspicion, but a stop for an observed violation must 

be based on probable cause. He argues that our decision in 
No. 2013AP1581-CR 

13 

State v. Popke, 2009 WI 37, ¶11, 317 Wis. 2d 118, 765 

N.W.2d 569, recognized this distinction by citing Gaulrapp 

multiple times, and that stare decisis dictates that we adhere 

to it. Houghton also argues that this dual standard provides 

proper protection to citizens' Fourth Amendment rights. 

¶29 It is undisputed that traffic stops must be reasonable 

under the circumstances. Gaulrapp, 207 Wis. 2d at 605. It is 

also widely accepted that traffic stops may be justified by 

either probable cause or reasonable suspicion. Popke, 317 

Wis. 2d 118, ¶23. The question here is whether this "either/or" 

principle means that reasonable suspicion will always suffice to 

initiate a traffic stop, or whether the nature of certain types 

of stops requires that a higher standard be met in those stops. 

¶30 We conclude that reasonable suspicion that a traffic 

law has been or is being violated is sufficient to justify all 

traffic stops.6 The prevailing case law instructs that this is 

so. See, e.g., Delfin-Colina, 464 F.3d at 396 ("the Second, 

Sixth, Eighth, Ninth, Tenth and Eleventh Circuits have all 

construed Whren to require only that the police have reasonable 

suspicion to believe that a traffic law has been broken.") 

(internal quotation marks omitted) (citation omitted). See also 

Berkemer, 468 U.S. at 439 ("the usual traffic stop is more 

analogous to a so-called 'Terry stop' than to a formal arrest"); 

 

6 In at least some circumstances, reasonable suspicion that 

a non-traffic-related law has been broken may also justify a 

traffic stop. Cf. State v. Harris, 206 Wis. 2d 243, 258-61, 557 

N.W.2d 245 (1996). 
No. 2013AP1581-CR 

14 

United States v. Ruiz, 785 F.3d 1134, 1141 (7th Cir. 2015); 

United States v. Lopez-Soto, 205 F.3d 1101, 1104-05 (9th Cir. 

2000) (collecting cases). As the Supreme Court has noted, 

"detention of a motorist pursuant to a traffic stop is 

presumptively temporary and brief." Berkemer, 468 U.S. at 437. 

When weighed against the public interest in safe roads, we are 

satisfied that the "temporary and brief" detention of a traffic 

stop is an "appropriate manner" in which a police officer may 

"approach a person for purposes of investigating possibly 

criminal behavior even though there is no probable cause to make 

an arrest." Terry, 392 U.S. at 22. 

B. Reasonable Mistakes of Law 

¶31 At issue in this case is whether a seizure predicated 

by an objectively reasonable mistake of law violates 

constitutional protections against unreasonable searches and 

seizures. The Fourth Amendment to the United States 

Constitution and Article I, Section 11 of the Wisconsin 

Constitution provide these protections.7 The "[t]emporary 

detention of individuals during the stop of an automobile by the 

police, even if only for a brief period and for a limited 

 

7 The Fourth Amendment to the United States Constitution 

provides: "The right of the people to be secure in their 

persons, houses, papers, and effects, against unreasonable 

searches and seizures, shall not be violated . . . ." U.S. 

Const. amend. IV. Article I, Section 11 of the Wisconsin 

Constitution uses identical language. See Wis. Const. Art. I, 

§ 11. We have historically read these provisions as 

coextensive. State v. Artic, 2010 WI 83, ¶28, 327 Wis. 2d 392, 

786 N.W.2d 430. 
No. 2013AP1581-CR 

15 

purpose, constitutes a 'seizure' of 'persons' within the 

meaning" of the Fourth Amendment. Whren, 517 U.S. at 809-10. 

See also Popke, 317 Wis. 2d 118, ¶11. 

¶32 In the past, Wisconsin courts have held that a seizure 

predicated on a police officer's mistake of law is invalid under 

the Fourth Amendment. See State v. Brown, 2014 WI 69, ¶22, 355 

Wis. 2d 668, 850 N.W.2d 66; Longcore, 226 Wis. 2d at 3-4. 

However, the Supreme Court's recent decision in Heien is at odds 

with these holdings. 

¶33 A brief review of the relevant case law is useful to 

provide context for our decision. 

¶34 In 1999, the court of appeals issued its opinion in 

Longcore. Longcore involved police officer Kevin Larson, who 

became suspicious of a vehicle when he observed it leaving the 

parking lot of several closed businesses at about 2:00 a.m. 

Longcore, 226 Wis. 2d at 4. Officer Larson also observed that 

the rear passenger window of the vehicle was missing and had 

been replaced with a plastic sheet. Id. Officer Larson 

believed the plastic sheet violated Wis. Stat. § 347.43(1), 

which required that safety glass be properly equipped in all 

cars manufactured after 1935. Id. After pulling the car over, 

Officer Larson discovered that the driver of the car, Michael 

Longcore, was operating with a suspended license. Id. at 3. 

¶35 The circuit court concluded that the stop was valid, 

reasoning, "[T]he officer believed a traffic regulation was 

being violated, the regulation is ambiguous, the officer's 

interpretation was reasonable and therefore his suspicion that 
No. 2013AP1581-CR 

16 

the law was violated was reasonable." Id. at 5. However, the 

court of appeals reversed the circuit court. The court of 

appeals stated: 

If the facts would support a violation only under a

legal misinterpretation, no violation has occurred,

and thus by definition there can be no probable cause 

that a violation has occurred. We conclude that when 

an officer relates the facts to a specific offense, it 

must indeed be an offense; a lawful stop cannot be 

predicated upon a mistake of law. 

Id. at 9. 

¶36 Longcore was affirmed by this court in a per curiam 

opinion after the court divided 3-3 on whether to affirm or 

reverse the court of appeals. State v. Longcore, 2000 WI 23, 

233 Wis. 2d 278, 607 N.W.2d 620. 

¶37 This court was confronted with a similar scenario 14 

years later in Brown. On the night of July 3, 2010, Antonio 

Brown and a friend attended a barbeque together. Brown, 355 

Wis. 2d 668, ¶8. After the barbeque, the friend drove Brown 

home in Brown's car because Brown was too intoxicated to drive 

himself. Id. The two were stopped by Milwaukee police officers 

William Feely and Michael Wawrzonek, who believed that an unlit 

bulb in the car's tail lamp violated Wis. Stat. § 347.13(1). 

Id., ¶¶2, 7. The officers eventually conducted a search of the 

vehicle, which revealed a firearm under the front seat. Id., 

¶7. 

¶38 Brown sought to suppress the evidence, arguing that 

the stop of his car was unconstitutional and the subsequent 

search was therefore invalid. See id., ¶12. The court of 
No. 2013AP1581-CR 

17 

appeals held that the police lacked probable cause or reasonable 

suspicion to stop Brown's vehicle, and because there was no 

probable cause or reasonable suspicion to support the stop, the 

evidence from the search should have been suppressed. Id., 

¶¶14-16. 

¶39 This court affirmed the court of appeals. The 

majority opinion noted that prior holdings provided "if the 

officers' interpretation of the law were incorrect . . . the 

stop would be unconstitutional because a lawful stop cannot be 

predicated upon a mistake of law." Id., ¶22 (citing Longcore, 

226 Wis. 2d at 9). In examining the relevant statutes, the 

court determined that Wis. Stat. § 347.13(1) did not require 

every single light bulb in a vehicle's tail lights to work. 

Id., ¶3. Rather, the statute required only that the tail lights 

"be in proper working condition" and visible from 500 feet away 

in the dark. Id. Thus, "[b]ecause having one unlit bulb on the 

back of a vehicle does not on its own violate the statutory 

requirements for tail lamps, the State . . . failed to show that 

the officers had probable cause to believe that a traffic 

violation had occurred." Id., ¶38. 

¶40 In dissent, Justice Roggensack——joined by Justice 

Ziegler——argued that a search based on a reasonable mistake of 

law is constitutional. Id., ¶91 (Roggensack, J., dissenting). 

Specifically, an officer's mistake of law is reasonable if a 

statute is "ambiguous or unclear so that an objectively 

reasonable officer could form a reasonable belief that a 

violation was occurring, even when it was not." Id. 
No. 2013AP1581-CR 

18 

¶41 Shortly after Brown, the Supreme Court also considered 

the issue of a seizure premised on a police officer's mistake of 

law. On the morning of April 29, 2009, a police sergeant began 

to follow a vehicle after noticing that the driver looked "very 

stiff and nervous." Heien, 135 S. Ct. at 534. When the vehicle 

braked, the sergeant noticed that one of the vehicle's brake 

lights was not working and he stopped the vehicle. Id. While 

issuing a written warning for the broken brake light, the 

sergeant became suspicious of the behavior of the occupants and 

their conflicting answers to questions he asked. Id. The 

sergeant asked for and received consent to search the vehicle, 

whereupon he discovered a bag containing cocaine. Id. Heien 

was arrested and charged with attempted trafficking in cocaine. 

Id. at 535-36. 

¶42 As it turned out, having only one functioning brake 

light is not a violation of law in North Carolina. Id. at 536. 

Thus, on appeal, the Supreme Court had to determine whether the 

sergeant's mistake of law nevertheless could have provided "the 

reasonable suspicion necessary to uphold the seizure under the 

Fourth Amendment." Id. at 534. 

¶43 The Court began its decision by noting that under the 

Fourth Amendment: 

a search or seizure may be permissible even though the 

justification for the action includes a reasonable 

factual mistake. An officer might, for example, stop 

a motorist for traveling alone in a high-occupancy 

vehicle lane, only to discover upon approaching the

car that two children are slumped over asleep in the 
No. 2013AP1581-CR 

19 

back seat. The driver has not violated the law, but 

neither has the officer violated the Fourth Amendment. 

Id. 

¶44 The Court held that an objectively reasonable mistake 

of law could give rise to reasonable suspicion. "Because the 

officer's mistake about the brake-light law was reasonable, the 

stop . . . was lawful under the Fourth Amendment." Id. In 

support of this holding, the Court noted, "To be reasonable is 

not to be perfect, and so the Fourth Amendment allows for some 

mistakes on the part of government officials, giving them fair 

leeway for enforcing the law in the community's protection." 

Id. at 536. 

¶45 The Court further explained: 

Reasonable suspicion arises from the combination of an 

officer's understanding of the facts and his 

understanding of the relevant law. The officer may be 

reasonably mistaken on either ground. Whether the 

facts turn out to be not what was thought, or the law 

turns out to be not what was thought, the result is

the same: the facts are outside the scope of the law. 

There is no reason, under the text of the Fourth 

Amendment or our precedents, why this same result 

should be acceptable when reached by way of a 

reasonable mistake of fact, but not when reached by

way of a similarly reasonable mistake of law. 

Id. 

¶46 Thus, under Heien, a seizure predicated on reasonable 

suspicion based on a law enforcement officer's objectively 

reasonable mistake of law is not a violation of an individual's 

Fourth Amendment rights. This holding, however, stands in stark 

contrast to the precedents established in Longcore and Brown. 

We therefore must determine which rule controls. 
No. 2013AP1581-CR 

20 

¶47 The majority opinion in Brown noted that the parties 

in that case agreed that a traffic stop predicated on a mistake 

of law was unconstitutional. Brown, 355 Wis. 2d 668, ¶22. This 

agreement between the parties was based on their common 

understanding that Longcore was the settled and accepted law of 

Wisconsin. Id. As noted above, the court of appeals in 

Longcore "conclude[d] that when an officer relates the facts to 

a specific offense, it must indeed be an offense; a lawful stop 

cannot be predicated upon a mistake of law." Longcore, 226 

Wis. 2d at 9. However, the court of appeals provided no 

authority for this proposition. 

¶48 The majority opinion in Brown also cited to a number 

of federal circuit courts that have held that a mistake of law 

cannot provide the basis for a traffic stop. Brown, 355 

Wis. 2d 668, ¶23. While those cases undoubtedly provided 

persuasive authority at the time Brown was decided, the Supreme 

Court's decision in Heien abrogated those cases which were based 

on the Fourth Amendment, as the Supreme Court has the final say 

on the meaning of the Fourth Amendment. 

¶49 Of course, it is uncontested that a state's 

constitution may provide citizens with protections beyond those 

afforded by the United States Constitution. However, we have 

traditionally understood the Wisconsin Constitution's provision 

on search and seizure to be coextensive with the Fourth 

Amendment. State v. Artic, 2010 WI 83, ¶28, 327 Wis. 2d 392, 

786 N.W.2d 430. 
No. 2013AP1581-CR 

21 

¶50 "Where . . . the language of the provision in the 

state constitution is 'virtually identical' to that of the 

federal provision . . . , Wisconsin courts have normally 

construed the state constitution consistent with the United 

States Supreme Court's construction of the federal 

constitution." State v. Agnello, 226 Wis. 2d 164, 180-81, 593 

N.W.2d 427 (1999) (citing State v. Tompkins, 144 Wis. 2d 116, 

133, 423 N.W.2d 823 (1988)). Here, the relevant portions of the 

federal and state constitutions are "virtually identical." 

Compare U.S. Const. amend. IV with Wis. Const. art. I, § 11. 

Accordingly, our standard practice dictates that we interpret 

the search and seizure provision of the Wisconsin Constitution 

consistently with the search and seizure provision of the United 

States Constitution. 

¶51 We are sensitive to the fact that Brown was decided 

only one year ago. It is unusual for this court to overrule a 

holding after such a short period of time. However, it would be 

equally unusual for this court to ignore a holding of the 

Supreme Court that interprets a provision of the United States 

Constitution virtually identical to a provision in the Wisconsin 

Constitution. 

¶52 Accordingly, we hold that an objectively reasonable 

mistake of law by a police officer can form the basis for 

reasonable suspicion to conduct a traffic stop. All Wisconsin 

cases holding otherwise are hereby overruled to the extent they 

conflict with this holding. 

C. Pertinent Statutes 
No. 2013AP1581-CR 

22 

¶53 Before analyzing the case at hand, we consider the 

statutes that formed the basis for Officer Price's stop of 

Houghton. For Officer Price's interpretation of these statutes 

to be "objectively reasonable," we must first consider their 

meaning. 

¶54 Our purpose in interpreting a statute is to "determine 

what the statute means so that it may be given its full, proper, 

and intended effect." State ex rel. Kalal v. Circuit Ct. for 

Dane Cnty., 2004 WI 58, ¶44, 271 Wis. 2d 633, 681 N.W.2d 110. 

To do this, we begin with the language of the statute, giving 

words their "common, ordinary, and accepted meaning"; technical 

words are given their technical or special definitional meaning. 

Id., ¶45. We then consider that language in light of the 

statute's structure and context as well as in "relation to the 

language of surrounding or closely-related statutes . . . to 

avoid absurd or unreasonable results." Id., ¶46. See Force ex 

rel. Welcenbach v. Am. Family Mut. Ins. Co., 2014 WI 82, ¶30, 

356 Wis. 2d 582, 850 N.W.2d 866. A statute's "context" includes 

its statutory history, which "encompasses previously enacted and 

repealed provisions of [the] statute." Richards v. Badger Mut. 

Ins. Co., 2008 WI 52, ¶22, 309 Wis. 2d 541, 749 N.W.2d 581. 

¶55 "If this process of analysis yields a plain, clear 

statutory meaning . . . the statute is applied according to this 

ascertainment of its meaning." Kalal, 271 Wis. 2d 633, ¶46 

(quoting Bruno v. Milwaukee Cnty., 2003 WI 28, ¶20, 260 

Wis. 2d 633, 660 N.W.2d 656). However, if the meaning of the 

statute is unclear after examining the statute's language, we 
No. 2013AP1581-CR 

23 

will consult extrinsic sources, including items of legislative 

history, to resolve any ambiguities. Id., ¶50. 

¶56 The Wisconsin Statutes contain a tremendous number of 

provisions directed toward safety on the roadway. At the fore 

in this case are statutory sections related to Wisconsin's 

unobstructed windshield requirement, set forth in Wis. Stat. 

§ 346.88, that motorists have a clear view of the roadway when 

operating a vehicle. At issue in this case are subsections 

346.88(3)(a) and (3)(b). These sections provide: 

(3)(a) No person shall drive any motor vehicle 

with any sign, poster or other nontransparent material 

upon the front windshield, front side wings, side 

windows in the driver's compartment or rear window of 

such vehicle other than a certificate or other sticker 

issued by order of a governmental agency. Such 

permitted sticker shall not cover more than 15 square 

inches of glass surface and shall be placed in the 

lower left-hand corner of the windshield; the left 

corner being on the driver's left when seated behind 

the wheel. 

(b) No person shall drive any motor vehicle upon 

a highway with any object so placed or suspended in or 

upon the vehicle so as to obstruct the driver's clear 

view through the front windshield. 

¶57 The first thing we note about these provisions is that 

each provision has a slightly different character. Subsection 

(3)(a) appears to be an absolute prohibition on the placement of 

"any sign, poster or other nontransparent material upon the 

front windshield, front side wings, side windows in the driver's 

compartment or rear window of" a vehicle, with a small exception 

for government certificates or stickers. Subsection (3)(b), on 

the other hand, forbids the placement of all items if they would 
No. 2013AP1581-CR 

24 

"obstruct the driver's clear view through the front windshield." 

In other words, subsection (3)(a) appears to be a strict 

prohibition on a narrow group of items, while subsection (3)(b) 

is a slightly more forgiving prohibition that applies to all 

items. 

¶58 The State urges this court to adopt a reading of these 

subsections that a driver may have nothing attached to or 

suspended from the front windshield——including the rearview 

mirror——except those items specifically exempted in subsection 

(3)(a). The State made clear at oral argument that this 

prohibition would apply to oil change stickers and rosaries as 

well as standard pine-tree-shaped air fresheners.8

¶59 We note that the interpretation of these subsections 

is a close case. In truth, however, we are unpersuaded that the 

purpose of subsections (3)(a) and (3)(b) is to create an 

absolute prohibition on any items being attached to or suspended 

from a vehicle's front windshield or rearview mirror. 

¶60 Subsection (3)(a) creates an absolute prohibition on 

"any sign, poster or other nontransparent material upon the 

 

8 "Little Trees" air fresheners have been sold in the United 

States since the mid-1950s. The air fresheners were created by 

German-Jewish chemist Julius Samaan, who fled the Nazis for 

North America before developing his product. The Car-Freshener 

Corporation of Watertown, New York, now offers Little Trees air 

fresheners in some 60 scents. Car-Freshener Corporation's 

president claims the company has sold "billions" of air 

fresheners in its history. See generally Hilary Greenbaum and 

Dana Rubenstein, Who Made That? (Little Trees), New York Times 

Magazine, 19 (Mar. 4, 2012). 
No. 2013AP1581-CR 

25 

front windshield . . . ." By contrast, another provision of the 

same statute, subsection (4), states: "The windshield, side 

wings and side and rear windows of a motor vehicle shall be kept 

reasonably clean at all times." (Emphasis added.) We see no 

reason why the legislature would choose to ban oil change 

stickers, often no more than one or two square inches in size 

and placed in a top corner of a windshield, but require that 

same area of a windshield be only "reasonably" clean.9 Instead, 

we interpret subsection (3)(a) to prohibit the attachment of 

"sign[s], poster[s]," and other items of a similar nature to the 

 

9 At the motion hearing, the circuit court briefly examined 

Officer Price about the area of the windshield that is within 

reach of the wipers. The court noted that "manufacturers 

determine the area, that is the area that's critical for the 

operation of a motor vehicle as determined by the 

manufacturers." The court asked Officer Price whether it would 

be reasonable to define an obstruction as something that 

obstructs the area within the extent of wiper coverage. 

Officer Price did not specifically answer the question, but 

the question itself raises its own interesting questions. For 

example, what if the area of the windshield beyond the range of 

the wipers is entirely covered with snow? Under the State's 

argument, the presence of the snow may not be a violation. 

However, if the driver were to stop and clean the entire 

windshield——thereby exposing a one-inch by two-inch oil change 

sticker——the driver may then be subject to a ticket, even though 

the driver's view would be significantly less obstructed than it 

would have been had the driver not cleaned away the snow. 
No. 2013AP1581-CR 

26 

front windshield of a motor vehicle.10 See State v. Engler, 80 

Wis. 2d 402, 408-09, 259 N.W.2d 97 (1977) ("The doctrine of 

ejusdem generis . . . provides that when a general word is used 

in a statute, either preceded or followed by specific words in 

an enumeration, the general word is construed to embrace 

something similar to the specific word."). 

¶61 Unlike subsection (3)(a), subsection (3)(b) applies to 

"any object" in or on a vehicle. However, an object is 

prohibited only if it "obstruct[s] the driver's clear view 

through the front windshield." The key term in this provision——

"obstruct"——is not defined by the statutory scheme. As such, we 

give the term its "common, ordinary, and accepted meaning." 

Kalal, 271 Wis. 2d 633, ¶45. 

¶62 Black's Law Dictionary defines "obstruct" as "To block 

or stop up . . . to close up or close off, esp. by 

obstacle . . . . To make difficult or impossible; to keep from 

happening; hinder . . . . To cut off a line of vision; to shut 

out . . . ." Black's Law Dictionary 1246 (10th ed. 2014) 

 

10 At oral argument, the State was asked about the legality 

of a plastic I-Pass prepaid toll collection transponder attached 

to a front windshield. The State postulated that an I-Pass 

transponder would be exempt from Wis. Stat. § 346.88(3)(a) for 

two reasons: because it can be affixed behind the rearview 

mirror, and because it is issued by a government agency. 

However, subsection (3)(a) exempts only certificates and 

stickers issued by a government agency, and makes no exemption 

for any otherwise-prohibited item that is placed behind the 

rearview mirror. Thus, we fail to see how the State's strict 

reading of the statute would not also outlaw the use of an IPass transponder. 
No. 2013AP1581-CR 

27 

(emphasis added). This definition suggests that an object needs 

to have more than a de minimus effect on the driver's vision to 

be considered an "obstruction" of a driver's clear view. 

¶63 Although there appears to be no published case law 

directly on point, Walker v. Baker, 13 Wis. 2d 637, 109 

N.W.2d 499 (1961), indirectly supports this position. Walker 

was a tort case in which the defendant, Baker, was found liable 

for Walker's injuries incurred in an automobile accident. At 

trial, the circuit court denied Baker's request to include a 

jury instruction for plaintiff's negligence related to Walker's 

possibly "obstructed view through his windshield." Id. at 643-

44. This court noted: 

While there is testimony that Walker had a pair 

of plastic dice suspended over his windshield, there 

is no evidence that this interfered with his vision, 

and it would be pure speculation on the part of the

jury so to find. The trial court properly refused to 

submit the requested instruction as to this aspect of 

the case. 

Id. at 644. 

¶64 It seems likely that, had Walker's "plastic dice 

suspended over his windshield" been a violation of Wis. Stat. 

§ 346.88,11 a jury instruction would have been in order. 

¶65 Given the above, we conclude that Wis. Stat. 

§ 346.88(3)(b)——which requires that an object "obstruct" a 

 

11 Wisconsin Stat. § 346.88 has not changed since there was 

a comprehensive revision of the motor vehicle code in 1957. See 

Chapter 260, Laws of 1957. In fact, much of the language in 

§ 346.88 is unchanged since 1929. See §§ 85.35(1) and (3), 1929 

Statutes. 
No. 2013AP1581-CR 

28 

driver's clear view to be a violation——does not mean that every 

object in a driver's clear view is a violation. Rather, we 

interpret subsection (3)(b) as requiring a material obstruction—

—even if minor——in order to be considered a violation of the 

statute. 

D. Analysis 

¶66 Having concluded both that reasonable suspicion can 

form the basis for any traffic stop and that an officer can form 

reasonable suspicion to initiate a traffic stop based on an 

objectively reasonable mistake of law, and having addressed the 

statutory sections at issue in this case, we turn to the 

ultimate question of whether Officer Price's initiation of a 

traffic stop against Houghton violated Houghton's constitutional 

rights. 

¶67 The State contends that Officer Price's stop of

Houghton was not based on a mistake of law because the presence 

of the GPS unit and air freshener in Houghton's front windshield 

was indeed a violation of Wis. Stat. § 346.88. The State argues 

in the alternative that any mistake of law by Officer Price as 

to whether those items violated the statute was objectively 

reasonable. Houghton counters that it was not objectively 

reasonable for Officer Price to interpret the statute as 

carrying an absolute prohibition on all items in the front 

windshield, pointing to Justice Kagan's concurrence in Heien—— 

joined by Justice Ginsburg——in which she stated that 

objectively reasonable mistakes of law are "exceedingly rare." 

Heien, 135 S. Ct. at 541 (Kagan, J., concurring). 
No. 2013AP1581-CR 

29 

¶68 Justice Kagan's concurrence also expanded on what 

could constitute an objectively reasonable mistake of law: 

A court tasked with deciding whether an officer's 

mistake of law can support a seizure thus faces a 

straightforward question of statutory construction. 

If the statute is genuinely ambiguous, such that 

overturning the officer's judgment requires hard 

interpretive work, then the officer has made a 

reasonable mistake. But if not, not. As the 

Solicitor General made the point at oral argument, the 

statute must pose a "really difficult" or "very hard 

question of statutory interpretation." 

Id. 

¶69 Justice Kagan noted that the difference between a 

"stop lamp" and a "rear lamp" in the North Carolina statute 

offered "conflicting signals" as to how the statute should be 

interpreted. Id. at 541-42. She concluded that the sergeant's 

interpretation of the statute was objectively reasonable because 

the sergeant's "judgment, although overturned, had much to 

recommend it." Id. at 542. 

¶70 Here, we conclude that Officer Price's interpretation 

of Wis. Stat. § 346.88——that the statute prohibited the 

placement of any object in the front windshield——was objectively 

reasonable. That the statute has never been interpreted before 
No. 2013AP1581-CR 

30 

weighs in favor of this decision.12 See id. at 540 (majority 

opinion) ("This 'stop lamp' provision, moreover, had never been 

previously construed by North Carolina's appellate courts."). 

Our conclusion that the analysis of the statute is a close call 

also advances this conclusion. See id. at 542 (Kagan, J., 

concurring) ("The critical point is that the statute poses a 

quite difficult question of interpretation . . . ."). 

¶71 Because "a reasonable judge could agree with the 

officer's view" in this case, id. at 541, we hold that Officer 

Price's mistake of law was objectively reasonable, and that the 

stop of Houghton's vehicle therefore was not unlawful. 

¶72 We turn briefly to the issue of Houghton's "missing" 

front license plate. Although the State concedes that Officer 

Price's interpretation of the license plate statute was not 

objectively reasonable, we choose to address this issue to 

 

12 We note that some unpublished Wisconsin cases have found 

reasonable suspicion or probable cause of a violation of 

subsection (3)(b) based on items hanging from a rearview mirror. 

E.g., State v. Currie, No. 2011AP322-CR, unpublished slip op., 

¶2 (Wis. Ct. App. Jul. 19, 2011) ("a very large air freshener"); 

State v. Jury, No. 2010AP622-CR, unpublished slip op., ¶7 (Wis. 

Ct. App. Sept. 1, 2010) (necklace visible "from a distance of 

200 feet"); State v. Avery, No. 2001AP1995-CR, ¶4 (Wis. Ct. App. 

Feb. 13, 2002) ("a bunch of stuff hanging from the rearview 

mirror"). We cite these cases not for any persuasive authority, 

but merely to show that the issue of windshield obstruction does 

arise in Wisconsin from time to time. 

In any event, none of these cases suggest either way 

whether subsection (3)(b) is an absolute prohibition on all 

items placed in a front windshield. 
No. 2013AP1581-CR 

31 

provide guidance in future cases and because it was the basis of 

the circuit court's decision. 

¶73 It is clear that Wis. Stat. § 341.15 requires a

vehicle to display a front license plate only when two license 

plates are issued for that vehicle. Officer Price's belief that 

Houghton was violating the statute by not having a front plate 

was not a reasonable mistake of law to the extent that it 

implies that all vehicles must display a front license plate. 

¶74 An officer who observes a vehicle driving without a 

front license plate may have no way of knowing whether that 

vehicle is required to display a front plate. Whether a vehicle 

is indeed required to display a front plate is both a question 

of law and a question of fact——the operative fact being whether 

the vehicle was issued two plates. Thus, it could perhaps be 

argued that a stop based on the lack of a front plate when the 

vehicle was issued only one plate is based on a mistake of fact 

rather than a mistake of law. 

¶75 Because searches and seizures can be based on mistakes 

of fact, see Illinois v. Rodriguez, 497 U.S. 177, 183-86 (1990); 

State v. Reierson, No. 2010AP596-CR, unpublished slip op., ¶1 

(Wis. Ct. App. Apr. 28, 2011), we confront the question of 

whether the lack of a front license plate, without more, may 

give rise to reasonable suspicion to conduct a traffic stop. To 

answer this question in the affirmative, we would have to hold 

that it is reasonable for a police officer in Wisconsin to 

believe that, if a vehicle is operating on a Wisconsin road, it 

must have been issued two license plates. 
No. 2013AP1581-CR 

32 

¶76 Such a belief would usually be unreasonable. 

Wisconsin borders four other states, and residents from those 

and many other states pass through Wisconsin on a regular basis. 

That most vehicles on Wisconsin roads might be registered in 

Wisconsin and most vehicles registered in Wisconsin might be 

issued two plates is not enough to conclude that a stop of a 

vehicle solely because it lacks a front license plate passes 

constitutional muster. 

¶77 On the other hand, if an officer observes some indicia 

that a vehicle without a front license plate is from Wisconsin, 

then the officer may indeed have reasonable suspicion to stop 

the vehicle. Perhaps the most common indication would be a 

Wisconsin plate attached to the rear of the vehicle in question. 

However, other things may clue an officer in to a vehicle's 

origins as well——for example, markings indicating an affiliation 

with a local business. 

¶78 Here, however, there was no initial indication that 

Houghton's vehicle was from Wisconsin. Once Officer Price was 

behind Houghton's vehicle, it would have become apparent from 

the rear plate that the vehicle was registered in Michigan. 

Thus, to the extent that Officer Price may have believed that 

Houghton was violating the law by not having a front license 

plate displayed, we hold that belief was neither a reasonable 

mistake of law nor a reasonable mistake of fact. 

IV. CONCLUSION 

¶79 We hold that an officer's reasonable suspicion that a 

motorist is violating or has violated a traffic law is 
No. 2013AP1581-CR 

33 

sufficient for the officer to initiate a stop of the offending 

vehicle. We also adopt the Supreme Court's holding in Heien 

that an officer's objectively reasonable mistake of law may form 

the basis for a finding of reasonable suspicion. 

¶80 In this case, we hold that Wis. Stat. § 346.88 does 

not create an absolute prohibition on any object being present 

in the front windshield of a vehicle. However, Officer Price's 

interpretation that the statute did create such a prohibition 

was objectively reasonable. Accordingly, Officer Price had 

reasonable suspicion to stop Houghton's vehicle, and it was not 

error for the circuit court to deny Houghton's motion to 

suppress. For these reasons, we reverse the court of appeals. 

By the Court.—The decision of the court of appeals is 

reversed. 
No. 2013AP1581-CR.ssa 

1 

¶81 SHIRLEY S. ABRAHAMSON, J. (dissenting). The 

majority opinion reverses the decision of the court of appeals 

and affirms the defendant's conviction. The conviction was 

based on a denial of the defendant's motion to suppress evidence 

obtained from a traffic stop. The traffic stop was predicated 

on a law enforcement officer's mistake of law, which the 

majority opinion deems "objectively reasonable."1

¶82 By declaring for the first time that reasonable

suspicion for a traffic stop can rest on a law enforcement 

officer's objectively reasonable mistake of law, the majority 

opinion adopts a new interpretation of Article I, Section 11 of 

the Wisconsin Constitution. It does so solely in order to 

remain in lockstep with the United States Supreme Court's 

interpretation of the Fourth Amendment.2

¶83 The majority opinion overturns not only the court of 

appeals decision in the instant case but also two prior 

decisions: State v. Brown, 2014 WI 69, 355 Wis. 2d 668, 850 

N.W.2d 66, and State v. Longcore, 226 Wis. 2d 1, 594 N.W.2d 412 

(Ct. App. 1999). What happened to precedent and stare decisis? 

¶84 I would adhere to precedent, reaffirm Brown and

Longcore, and affirm the court of appeals decision in the 

instant case. 

 

1 Majority op., ¶71. 

2 Majority op., ¶¶46-52. 
No. 2013AP1581-CR.ssa 

2 

¶85 In Brown, an opinion released just last year, this 

court held that reasonable suspicion for a traffic stop cannot 

rest on a law enforcement officer's mistake of law.3 After Brown 

was decided, the United States Supreme Court held in Heien v. 

North Carolina, 135 S. Ct. 530 (2014), that under the Fourth 

Amendment, a law enforcement officer's reasonable mistake of law 

can support reasonable suspicion for a traffic stop. 

¶86 The majority opinion in the instant case does an 

about-face, adopting the United States Supreme Court's 

interpretation of the Fourth Amendment in Heien as the correct 

interpretation of the Wisconsin Constitution. 

¶87 The drafters of the Wisconsin Constitution could have 

simply said "ditto" and incorporated the federal Bill of Rights 

into the Wisconsin Constitution. But they did not. Instead, 

they adopted a separate and distinct Wisconsin Declaration of 

Rights. 

¶88 In the instant case and many like it, this court is 

doing what the drafters of the Wisconsin Constitution did not 

do, namely adopting the federal Bill of Rights. More 

specifically, by adopting wholesale the United States Supreme 

Court's interpretation of the federal Bill of Rights as the 

proper interpretation of Wisconsin's Declaration of Rights, this 

court is in effect replacing Wisconsin's Declaration of Rights 

with its federal counterpart. This court is not taking 

 

3 State v. Brown, 2014 WI 69, ¶¶22-25, 355 Wis. 2d 668, 850 

N.W.2d 66. 
No. 2013AP1581-CR.ssa 

3 

seriously the Justices' oath of office to support the Wisconsin 

Constitution. 

¶89 Heien is binding on this court only insofar as the 

federal constitution is concerned. It is not binding with 

regard to the state constitution. This court need not and 

should not automatically adopt the United States Supreme Court's 

interpretation of the Fourth Amendment as the proper 

interpretation of Article I, Section 11 of the Wisconsin 

Constitution. 

¶90 In Brown, this court set forth three primary reasons 

for its determination that reasonable suspicion cannot rest on a 

law enforcement officer's mistake of law: 

1. Wisconsin precedent so stated. In State v. Longcore, 

226 Wis. 2d 1, 9, 594 N.W.2d 412 (Ct. App. 1999), the 

court of appeals declared that "a lawful [traffic] 

stop cannot be predicated upon a mistake of law." 

2. Other jurisdictions were in accord. A substantial 

majority of both the federal circuit courts and the

state courts that had addressed the issue had 

concluded that a law enforcement officer's mistake of 

law cannot support reasonable suspicion or probable

cause for a traffic stop.4

3. Holding that a law enforcement officer's mistake of 

law could support lawful traffic stops would defeat

the purpose of the exclusionary rule. More 

 

4 Brown, 355 Wis. 2d 668, ¶¶23, 25. See also Heien v. North 

Carolina, 135 S.Ct. 530, 544 (2014) (Sotomayor, J., dissenting). 
No. 2013AP1581-CR.ssa 

4 

specifically, declining to exclude evidence that was 

gathered from a traffic stop premised on a law 

enforcement officer's erroneous view of the law 

"would remove the incentive for police to make 

certain that they properly understand the law that 

they are entrusted to enforce and obey."5

¶91 These considerations remain persuasive and convince me 

to adhere to Brown. A law enforcement officer's reasonable 

mistake of law cannot, in my view, render a traffic stop 

reasonable in the eyes of the Wisconsin Constitution. 

¶92 My position is supported by several cogent points that 

Justice Sotomayor makes in her dissent in Heien: 

1. An inquiry into the reasonableness of officers' 

understanding of the law breaks with longstanding 

federal and state court precedent.6

2. The notion that the law is definite and knowable sits 

at the foundation of our legal system. Yet, Heien 

gives those who enforce the law leeway in 

interpreting and understanding it.7

 

5 Brown, 355 Wis. 2d 668, ¶24 (internal quotation marks 

omitted). 

6 Heien, 135 S. Ct. at 542-43 (Sotomayor, J., dissenting). 

7 Id. at 543 (Sotomayor, J., dissenting). 

Heien purports to rest on the concept of reasonableness, 

the touchstone of the Fourth Amendment. However, as Justice 

Sotomayor's dissent explains, 

this broad statement simply sets the standard a court 

is to apply when it conducts its inquiry into whether 

the Fourth Amendment has been violated. It does not 

(continued) 
No. 2013AP1581-CR.ssa 

5 

3. Heien "further erod[es] the Fourth Amendment's 

protection of civil liberties in a context," namely

traffic stops, "where that protection has already 

been worn down."8 

4. Heien is a significant expansion of officers' 

authority and leads one to wonder "how a citizen 

seeking to be law-abiding and to structure his or her 

behavior to avoid these invasive, frightening, and 

humiliating encounters could do so."9

5. Because traffic stops can be annoying, frightening 

and humiliating, they have consequences for 

 

define the categories of inputs that courts are to 

consider when assessing the reasonableness of a search 

or seizure, each of which must be independently 

justified. What this case requires us to decide is 

whether a police officer's understanding of the law is 

an input into the reasonableness inquiry, or whether 

this inquiry instead takes the law as a given and 

assesses an officer's understanding of the facts 

against a fixed legal yardstick. 

Id. at 542. 

8 Heien, 135 S. Ct. at 543 (Sotomayor, J., dissenting). 

For discussion of the "wearing down" of the protections of 

the Fourth Amendment in Wisconsin courts, see Alan Ball, How 

Effective are Fourth-Amendment Arguments in the Wisconsin 

Supreme Court?, SCOWstats, June 22, 2015, 

http://www.scowstats.com/2015/06/22/how-effective-are-fourthamendment-arguments-in-the-wisconsin-supreme-court/ (last 

visited June 30, 2015) (reviewing decisions of the Wisconsin 

Supreme Court and concluding that the current judicial climate 

is inhospitable to Fourth Amendment arguments). 

9 Heien, 135 S. Ct. at 544 (Sotomayor, J., dissenting). 
No. 2013AP1581-CR.ssa 

6 

individuals and communities "and for their 

relationships with the police . . . ."10

6. Law enforcement officers have not been unduly 

hampered in the exercise of their duties by the rule 

that their mistakes of law are not considered as part 

of the Fourth Amendment reasonableness inquiry.11

7. There is scarcely any law that does not admit of some 

ingenious doubt.12 A decision interpreting a law will 

not immunize the law from further interpretation. 

Interpretation of the law constitutes a substantial

portion of court business. 

¶93 These considerations apply with equal force in the 

context of the Wisconsin Constitution. Both precedent and 

policy compel me to conclude that a traffic stop premised on a 

law enforcement officer's mistake of law is unreasonable and 

thus unlawful under Article I, Section 11 of the Wisconsin 

Constitution. 

¶94 Accordingly, the traffic stop at issue in the instant 

case, which was premised on a law enforcement officer's mistake 

 

10 Heien, 135 S. Ct. at 544 (Sotomayor, J., dissenting). 

11 Id. 

12 Id. Justice Kagan authored a concurrence in Heien

explaining that an officer has made a reasonable mistake of law 

only when the statute in question is "genuinely ambiguous," 

"requires hard interpretive work," and "poses a quite difficult 

question." Heien, 135 S. Ct. at 541-42 (Kagan, J., concurring). 

I do not think the mistake of law at issue in the instant case 

falls within this exacting interpretation of what constitutes a 

reasonable mistake of law. 
No. 2013AP1581-CR.ssa 

7 

of law, was unlawful. The defendant's motion to suppress the 

evidence obtained from the unlawful traffic stop should have 

been granted, and the defendant's conviction should be reversed. 

¶95 For the reasons set forth, I dissent. 

¶96 I am authorized to state that Justice ANN WALSH

BRADLEY joins this opinion. 
No. 2013AP1581-CR.ssa 

1