Case Title: State v. Robert E. Post

Citation: 2007 WI 60

Docket Number: 2005AP002778-CR

State: wisconsin

Court: Wisconsin Supreme Court

Date: 2007-05-23T00:00:00Z

Document:
2007 WI 60 
 
SUPREME COURT OF WISCONSIN 
 
 
 
 
 
CASE NO.: 
2005AP2778-CR 
 
 
COMPLETE TITLE: 
 
 
State of Wisconsin, 
          Plaintiff-Respondent-Petitioner, 
     v. 
Robert E. Post, 
          Defendant-Appellant 
 
 
 
 
REVIEW OF A DECISION OF THE COURT OF APPEALS 
Reported at: 296 Wis. 2d 420, 722 N.W.2d 401 
(Ct. App. 2006—Unpublished) 
 
 
OPINION FILED: 
May 23, 2007   
SUBMITTED ON BRIEFS: 
        
ORAL ARGUMENT: 
February 14, 2007   
 
 
SOURCE OF APPEAL: 
 
 
COURT: 
Circuit   
 
COUNTY: 
Sauk   
 
JUDGE: 
Patrick Taggart 
 
 
 
JUSTICES: 
 
 
CONCURRED: 
        
 
CONCUR/DISSENT: 
ABRAHAMSON, C.J., concurs in part, dissents in 
part (opinion filed). 
 
DISSENTED: 
        
 
NOT PARTICIPATING:         
 
 
 
ATTORNEYS: 
 
For 
the 
plaintiff-respondent-petitioner 
the 
cause 
was 
argued by James M. Freimuth, assistant attorney general, with 
whom on the briefs was Peggy A. Lautenschlager, attorney 
general. 
 
For the defendant-appellant there was a brief filed by T. 
Christopher Kelly, and Kelly & Habermehl, S.C., Madison, and 
there was oral argument by T. Christopher Kelly. 
 
 
 
 
2007 WI 60
NOTICE 
This opinion is subject to further 
editing and modification.  The final 
version will appear in the bound 
volume of the official reports.   
No.  2005AP2778-CR  
(L.C. No. 
2004CF94) 
STATE OF WISCONSIN  
 
 
   : 
IN SUPREME COURT 
 
 
State of Wisconsin, 
 
          Plaintiff-Respondent-Petitioner, 
 
     v. 
 
Robert E. Post, 
 
          Defendant-Appellant. 
 
 
 
FILED 
 
MAY 23, 2007 
 
David R. Schanker 
Clerk of Supreme Court 
 
 
 
 
 
REVIEW of a decision of the Court of Appeals.  Reversed.   
 
¶1 
ANN WALSH BRADLEY, J.   The petitioner, State of 
Wisconsin, seeks review of an unpublished court of appeals 
decision 
reversing 
a 
judgment 
convicting 
Robert 
Post 
of 
operating 
a 
motor 
vehicle 
with 
a 
prohibited 
alcohol 
concentration, as a fifth offense.1 The State asserts that the 
court of appeals erred in concluding that Post's deviations 
within one lane of travel, with nothing more, failed to provide 
                                                 
1 See State v. Post, No. 2005AP2778-CR, unpublished slip 
op., (Wis. Ct. App. Aug. 10, 2006)(reversing judgment of circuit 
court for Sauk County, Patrick Taggart, Judge). 
No. 
2005AP2778-CR   
 
2 
 
the police officer with the reasonable suspicion to justify an 
investigative stop of the vehicle. The State, in essence, asks 
for a bright-line rule that repeated weaving within a single 
lane provides the reasonable suspicion necessary to justify a 
traffic stop. 
¶2 
We determine that weaving within a single traffic lane 
does not alone give rise to the reasonable suspicion necessary 
to conduct an investigative stop of a vehicle. However, we also 
determine that under the totality of the circumstances, the 
police officer did have reasonable suspicion in this case, and 
that the stop did not violate Post's constitutional right to be 
free from unreasonable searches and seizures. Accordingly, we 
reverse the court of appeals.  
I 
¶3 
In February 2004, Sauk Prairie police sergeant Josh 
Sherman, who had six years of experience as a police officer, 
was on routine patrol on Water Street in Sauk City. The 
northbound side of Water Street is approximately 22-24 feet wide 
from the yellow center line to the curb. It contains a traffic 
lane and parking lane. There is no line or marking delineating 
the traffic lane from the parking lane. The parking lane is 
bounded by the curb.  
¶4 
Sergeant Sherman testified that at approximately 9:30 
p.m., he was traveling southbound on Water Street and observed 
two cars traveling northbound. The second vehicle, a Chevrolet 
Cavalier driven by Post, was "canted" such that it was driving 
at least partially in the unmarked parking lane.  
No. 
2005AP2778-CR   
 
3 
 
¶5 
After the two cars passed, Sherman turned around to 
follow them. He did not lose site of the cars and caught up to 
them after six or seven blocks. While following the cars, 
Sherman observed Post's car traveling in a smooth "S-type" 
pattern. Sherman described the movement as "a smooth motion 
toward the right part of the parking lane and back toward the 
center line." He stated that Post's car moved approximately ten 
feet from right to left within the northbound lane, coming 
within 12 inches of the center line and to within six to eight 
feet of the curb. Post's car repeated the S-pattern several 
times over two blocks. The movement was neither erratic nor 
jerky, and the car did not come close to hitting any other 
vehicles or to hitting the curb at the edge of the parking lane. 
Sherman testified that the manner of Post's driving was a "clue 
that he may be intoxicated." 
¶6 
After being followed by Sherman for two blocks, both 
cars signaled and made a left turn onto a cross street. The 
first car turned into the oncoming traffic lane. The second car, 
driven by Post, made a proper turn. Sherman activated his 
emergency lights and both cars pulled over. 
¶7 
Relying on this court's decision in State v. Waldner, 
206 Wis. 2d 51, 556 N.W.2d 681 (1996), the circuit court 
determined that Sherman's testimony of "unusual driving" and 
"drifting even within one's own lane" provided the reasonable 
suspicion necessary to justify a traffic stop. The court of 
appeals reversed, concluding that slight deviations within a 
No. 
2005AP2778-CR   
 
4 
 
single travel lane do not give rise to a reasonable suspicion 
that a driver is intoxicated.  
II 
¶8 
In this case we examine whether a traffic stop 
violated Post's constitutional rights because it was not based 
on reasonable suspicion. The question of whether a traffic stop 
is reasonable is a question of constitutional fact. State v. 
Knapp, 2005 WI 127, ¶19, 285 Wis. 2d 86, 700 N.W.2d 899. A 
question of constitutional fact is a mixed question of law and 
fact to which we apply a two-step standard of review. State v. 
Martwick, 2000 WI 5, ¶16, 231 Wis. 2d 801, 604 N.W.2d 552. We 
review the circuit court's findings of historical fact under the 
clearly erroneous standard, and we review independently the 
application of those facts to constitutional principles. Id.; 
State v. Payano-Roman, 2006 WI 47, ¶16, 290 Wis. 2d 380, 714 
N.W.2d 548. 
III 
¶9 
This court has never addressed the question of whether 
a vehicle's weaving within a single lane, without more, provides 
the reasonable suspicion necessary to justify an investigatory 
stop of that vehicle. We begin our analysis of this question by 
reviewing the principles underlying investigatory stops. 
¶10 The Fourth Amendment to the United States Constitution 
provides that "[t]he right of the people to be secure in their 
persons . . . against unreasonable searches and seizures, shall 
not be violated, and no Warrants shall issue, but upon probable 
No. 
2005AP2778-CR   
 
5 
 
cause . . . ."2 In Terry v. Ohio, the U.S. Supreme Court allowed 
that, although investigative stops are seizures within the 
meaning of the Fourth Amendment, in some circumstances police 
officers may conduct such stops even where there is no probable 
cause to make an arrest. 392 U.S. 1, 22 (1968). Such a stop must 
be 
based 
on 
more 
than 
an 
officer's 
"inchoate 
and 
unparticularized suspicion or 'hunch.'" Id. at 27. Rather, the 
officer "must be able to point to specific and articulable facts 
which, taken together with rational inferences from those facts, 
reasonably warrant" the intrusion of the stop. Id. at 21.  
¶11 This 
court 
adopted 
the 
Terry 
standard 
for 
investigative stops in State v. Chambers. 55 Wis. 2d 289, 294, 
198 N.W.2d 377 (1972). The Wisconsin legislature codified the 
standard 
in 
Wis. Stat. § 968.24(2005-06).3 
In 
interpreting 
                                                 
2 The State frames this question in terms of both the Fourth 
Amendment 
and 
Article 
I, 
Section 
11 
of 
the 
Wisconsin 
Constitution, which states: "The right of the people to be 
secure in their persons, houses, papers, and effects against 
unreasonable searches and seizures shall not be violated; and no 
warrant shall issue but upon probable cause . . . ." This court 
has 
in 
large 
part 
interpreted 
the 
protections 
against 
unreasonable searches and seizures afforded by the state and 
federal constitutions coextensively. See State v. Knapp, 2005 WI 
127, ¶59, 285 Wis. 2d 86, 700 N.W.2d 899; State v. Williams, 
2001 WI 21, ¶18, 241 Wis. 2d 631, 623 N.W.2d 106. However, the 
state provisions may provide greater protections. State v. 
Eason, 2001 WI 98, ¶63, n.30, n.31, 245 Wis.2d 206, 629 N.W.2d 
625; see also  Michigan v. Long, 463 U.S. 1032, 1041 (1983)("It 
is fundamental that state courts be left free and unfettered by 
us in interpreting their state constitutions."). 
3 Wis. Stat. § 968.24 provides: 
Temporary questioning without arrest. After having 
identified himself or herself as a law enforcement 
officer, a law enforcement officer may stop a person 
No. 
2005AP2778-CR   
 
6 
 
§ 968.24 we apply Terry and cases following Terry. State v. 
Williamson, 113 Wis. 2d 389, 399-400, 335 N.W.2d 814 (1983).  
¶12 Investigative 
traffic 
stops 
are 
subject 
to 
the 
constitutional 
reasonableness 
requirement. 
Whren 
v. 
United 
States, 517 U.S. 806, 809-10 (1996); State v. Rutzinski, 2001 WI 
22, ¶14, 241 Wis. 2d 729, 623 N.W.2d 516. The burden of 
establishing that an investigative stop is reasonable falls on 
the state. State v. Taylor, 60 Wis. 2d 506, 519, 210 N.W.2d 873 
(1973). 
¶13 The determination of reasonableness is a common sense 
test. The crucial question is whether the facts of the case 
would warrant a reasonable police officer, in light of his or 
her training and experience, to suspect that the individual has 
committed, was committing, or is about to commit a crime. State 
v. Anderson, 155 Wis. 2d 77, 83-84, 454 N.W.2d 763 (1990). This 
common sense approach balances the interests of the State in 
detecting, preventing, and investigating crime and the rights of 
individuals to be free from unreasonable intrusions. Waldner, 
206 Wis. 2d at 56; Rutzinski, 241 Wis. 2d 729, ¶15; State v. 
                                                                                                                                                             
in a public place for a reasonable period of time when 
the officer reasonably suspects that such a person is 
committing, is about to commit or has committed a 
crime, and may demand the name and address of the 
person and an explanation of the person's conduct. 
Such detention and temporary questioning shall be 
conducted in the vicinity of where the person was 
stopped. 
All subsequent references to the Wisconsin Statutes are to the 
2005-06 version unless otherwise indicated. 
No. 
2005AP2778-CR   
 
7 
 
Guzy, 
139 
Wis. 2d 663, 
679, 
407 
N.W.2d 548 
(1987). 
The 
reasonableness of a stop is determined based on the totality of 
the facts and circumstances. State v. Williams, 2001 WI 21, ¶22, 
241 Wis. 2d 631, 623 N.W.2d 106; Guzy, 139 Wis. 2d at 679. 
¶14 The 
State 
contends 
that 
Sergeant 
Sherman 
had 
reasonable suspicion to stop Post. It advocates the view that 
repeated weaving of a motor vehicle within a single lane (absent 
an 
obvious 
innocent 
explanation) 
provides 
the 
reasonable 
suspicion to make an investigatory stop. While we agree that the 
facts of the case give rise to a reasonable suspicion that Post 
was driving while intoxicated and that the investigative stop 
was reasonable, we reject the bright-line rule that repeated 
weaving within a single lane alone gives rise to reasonable 
suspicion. Rather, our determination is based on the totality of 
the circumstances, in accord with Wisconsin jurisprudence.  
¶15 In 
Waldner, 
this 
court 
addressed 
the 
issue 
of 
investigative stops based on reasonable suspicion that a person 
is driving while intoxicated. There, a police officer observed 
the defendant's car traveling at a slow speed. The car stopped 
at an intersection that had no stop sign or traffic light, 
turned onto a cross-street, and accelerated "at a high rate of 
speed" (though not exceeding the speed limit). 206 Wis. 2d at 
53. The officer then observed the car pull into a legal parking 
space, where the defendant opened the car door and poured what 
appeared to be "a mixture of liquid and ice" from a plastic 
glass onto the roadway. Id. When the officer pulled near the 
defendant and identified himself, the defendant began to walk 
No. 
2005AP2778-CR   
 
8 
 
away, at which point the officer made an investigative stop of 
the defendant. Id. at 53-54.  
¶16 The defendant in Waldner argued that the stop was 
unreasonable on the ground that it was based upon the officer's 
inchoate hunch, and not on a reasonable suspicion. This court 
determined that the search was based on a reasonable suspicion. 
It noted that the stop was based on a number of specific, 
articulable facts, including the car's varying speeds and 
stopping at an intersection without a stoplight or sign, and the 
driver's pouring out a cup of liquid and ice. The court 
recognized that each of these facts alone would be insufficient 
to provide reasonable suspicion. However, it explained that 
cumulatively they were sufficient to support an inference that 
the driver was intoxicated:  
Any one of these facts, standing alone, might well be 
insufficient. But that is not the test we apply. We 
look to the totality of the facts taken together. The 
building blocks of fact accumulate. And as they 
accumulate, reasonable inferences about the cumulative 
effect can be drawn. In essence, a point is reached 
where the sum of the whole is greater than the sum of 
its individual parts. That is what we have here. 
Id. at 58. 
¶17 Thus, the court's determination was based on the 
totality of circumstances rather than on any particular fact. 
Considered as a whole they constituted reasonable suspicion. Id. 
at 60-61. 
¶18 The State's view that repeated weaving within a single 
lane alone gives an experienced police officer reasonable 
No. 
2005AP2778-CR   
 
9 
 
suspicion to make an investigatory stop therefore conflicts with 
the approach articulated in Waldner. The State asks for a 
bright-line rule, where this court has consistently maintained 
that the determination of reasonable suspicion is based upon the 
totality of the circumstances. State v. Kyles, 2004 WI 15, ¶49, 
269 Wis. 2d 1, 675 N.W.2d 449; Williams, 241 Wis. 2d 631, ¶22; 
State v. Richardson, 156 Wis. 2d 128, 139-40, 456 N.W.2d 830 
(1990); Guzy, 139 Wis. 2d at 679; see also Alabama v. White, 496 
U.S. 325, 330 (1990)(adopting a totality of circumstances test 
for determining reasonable suspicion based on anonymous tips).  
¶19 Further, the State's proffered bright-line rule is 
problematic because movements that may be characterized as 
"repeated weaving within a single lane" may, under the totality 
of the circumstances, fail to give rise to reasonable suspicion. 
This may be the case, for example, where the "weaving" is 
minimal or happens very few times over a great distance.4 Courts 
in a number of other jurisdictions have concluded that weaving 
within a single lane can be insignificant enough that it does 
not give rise to reasonable suspicion.5 In such cases, weaving 
                                                 
4 This is, in effect, the rule articulated by the court of 
appeals. Post, unpublished slip op., ¶4. As we note below, 
however, the conclusion that Post's deviations were "slight" is 
not in accord with the circuit court's rendition of the facts. 
5 Warrick v. Comm'r of Pub. Safety, 374 N.W.2d 585, 585-86 
(Minn. Ct. App. 1985)("subtle" weaving within lane insufficient 
to support reasonable suspicion); Salter v. North Dakota Dept. 
of 
Transp., 
505 
N.W.2d 111, 
112-113 
(N.D. 
1993)(weaving 
described as "slight movement back and forth" insufficient to 
support reasonable suspicion); State v. Binette, 33 S.W.3d 215, 
220 (Tenn. 2000)(multiple lateral movements which were "not 
pronounced" insufficient to support reasonable suspicion).  
No. 
2005AP2778-CR   
 
10 
 
within a single lane would not alone warrant a reasonable police 
officer to suspect that the individual has committed, was 
committing, or is about to commit a crime.  
¶20 In addition, the rule that weaving within a single 
lane may alone give rise to reasonable suspicion fails to strike 
the 
appropriate 
balance 
between 
the 
State's 
interest 
in 
detecting, 
preventing, 
and 
investigating 
crime 
with 
the 
individual's 
interest 
in 
being 
free 
from 
unreasonable 
intrusions. "[R]epeated weaving within a single lane" is a 
malleable enough standard that it can be interpreted to cover 
much innocent conduct.  In U.S. v. Lyons, a police officer made 
an investigatory stop after having seen the defendant's vehicle 
weave three to four times within a single lane. 7 F.3d 973, 974 
(10th Cir. 1993). The court recognized "the universality of 
drivers' 'weaving' in their lanes." Id. at 976. It therefore 
cautioned that allowing weaving to justify a vehicle stop may 
subject many innocent people to an investigation. "Indeed, if 
failure to follow a perfect vector down the highway or keeping 
one's eyes on the road were sufficient reasons to suspect a 
person of driving while impaired, a substantial portion of the 
public would be subject each day to an invasion of their 
privacy." Id.; United States v. Colin, 314 F.3d 439, 446 (9th 
Cir. 2002).  
¶21 Because the standard proffered by the State can be 
interpreted to cover conduct that many innocent drivers commit, 
it may subject a substantial portion of the public to invasions 
of their privacy. It is in effect no standard at all. Adopting 
No. 
2005AP2778-CR   
 
11 
 
it here would allow essentially unfettered discretion and permit 
the arbitrary invasions of privacy by government officials 
addressed by the Fourth Amendment and Article I, Section 11. 
Delaware v. Prouse, 440 U.S. 648, 661 (1979); Brown v. Texas, 
443 U.S. 47, 52 (1979); State v. Sykes, 2005 WI 48, ¶13, 279 
Wis. 2d 742, 695 N.W.2d 277; Waldner, 206 Wis. 2d at 57; Guzy, 
139 Wis. 2d at 672.6 
¶22 Like the State, Post offers a bright-line rule for 
determining reasonable suspicion. He argues that movements 
within a lane can give rise to the reasonable suspicion 
                                                 
6 The State contends that "the individual privacy interest 
implicated in a traffic stop for possible drunk driving pales by 
comparison" to the interest in preventing drunk driving, citing 
the case of Michigan Dept. of State Police v. Sitz. 496 U.S. 
444, 451-55 (1990). Sitz is inapt in this context. That case 
involved vehicle stops at sobriety check-points where every 
passing car was briefly detained while the drivers were checked 
for signs of intoxication. Id. at 447. Because every car was 
stopped, there was no individualized suspicion. However, the 
officers in Sitz were not in the position of exercising 
discretion in determining which vehicles they detained for 
initial examination. This contrasts with situations like the one 
in the present case, where patrol officers must exercise 
discretion. 
We are also skeptical of the State's interpretation of the 
Supreme Court's assessment of the magnitude of investigatory 
stops for drunk driving. Relying on Sitz, the State asserts that 
an investigatory traffic stop "is a minimal intrusion on 
individual privacy." The State compares the intrusion of the 
stop in the present case to the magnitude of the check-point 
stops in Sitz. However, the Sitz court determined that the 
intrusions of check-point stops were minimal in contrast to 
roving patrol type stops of the sort at issue here. 496 U.S. at 
453. The State's claim that Sitz supports the view that roving 
patrol stops are minimally intrusive appears to turn that case 
on its head.  
No. 
2005AP2778-CR   
 
12 
 
necessary to justify an investigative stop only where the 
movements are erratic, unsafe, or illegal.7 We reject this 
bright-line rule as well. 
¶23 Post's claim that lateral movements must be erratic, 
unsafe, or illegal in order to generate reasonable suspicion is 
belied by our decision in Waldner. In that case, the defendant 
drove slowly, paused at an intersection without a stoplight or 
sign, accelerated quickly, and poured liquid and ice from a cup. 
206 Wis. 2d at 53. The Waldner court based its conclusion that 
there 
was 
reasonable 
suspicion 
on 
the 
totality 
of 
the 
circumstances, not on an intermediate determination that the 
defendant's driving was erratic or unsafe. Moreover, even if one 
were to interpret the driving in Waldner as erratic or unsafe, 
there is no reason to conclude that those actions were any more 
erratic or unsafe than Post's weaving in the present case. 
¶24 Further, it is clear that driving need not be illegal 
in order to give rise to reasonable suspicion. As the Waldner 
court observed, requiring reasonable suspicion to be based upon 
an observation of unlawful conduct would allow investigatory 
stops only when there was probable cause to make an arrest. Id. 
                                                 
7 Post also contends that his vehicle's movement was 
"drifting" 
rather 
than 
"weaving," 
and 
that 
"weaving" 
is 
characterized by being erratic. Because his vehicle's "drifting" 
was neither erratic nor unsafe, he argues that it cannot give 
rise to reasonable suspicion. We do not see anything to be 
gained by distinguishing or parsing "weaving" from "drifting." 
What matters here is whether the vehicle's movements, considered 
with the totality of the circumstances, give rise to a 
reasonable suspicion that Post was driving while intoxicated. 
No. 
2005AP2778-CR   
 
13 
 
at 59. Such a requirement would run counter to the law set forth 
in Terry, where an officer's investigative stop was based on 
activity that standing alone fell short of the probable cause 
necessary to make an arrest. Waldner, 206 Wis. 2d at 59 (citing 
State v. Jackson, 147 Wis. 2d 824, 835, 434 N.W.2d 386 (1989)); 
see Terry, 392 U.S. at 22-23. We therefore determine that a 
driver's actions need not be erratic, unsafe, or illegal to give 
rise to reasonable suspicion. 
¶25 Cases from other jurisdictions support our view that 
reasonable suspicion does not require erratic, unsafe, or 
illegal driving, as Post maintains. They also support our view 
that reasonable suspicion does not follow automatically from 
repeated weaving within a single lane, as the State advocates. 
Certainly courts in other jurisdictions have found reasonable 
suspicion where vehicles weave erratically.8 However, courts also 
point to other factors, such as pronounced or prolonged weaving9 
                                                 
8 People v. Greco, 783 N.E.2d 201, 206 (Ill. App. Ct. 2003); 
State v. Dorendorf, 359 N.W.2d 115, 117 (N.D. 1984)("erratic" 
weaving sufficient to justify investigative stop); Neal v. 
Commonwealth, 498 S.E.2d 422, 423 (Va. Ct. App. 1998)("erratic 
driving" sufficient to justify investigative stop).  
9 People v. Perez, 221 Cal. Rptr. 776, 776 (Cal. App. Dep't 
Super. Ct. 1977)("pronounced weaving" over three-quarters of a 
mile sufficient for reasonable suspicion); Roberts v. State, 732 
So.2d 1127, 1128 (Fla. Dist. Ct. App. 1999)("significant" side-
to-side weaving sufficient for reasonable suspicion); State v. 
Thomte, 413 N.W.2d 916, 917 (Neb. 1987)("sharp" weave followed 
by another weave sufficient for reasonable suspicion); State v. 
Bailey, 624 P.2d 663, 664 (Or. Ct. App. 1981)(continuous weaving 
that took place over "substantial distance" sufficient to 
justify investigative stop). 
No. 
2005AP2778-CR   
 
14 
 
or other suspicious aspects of driving,10 as supporting a finding 
of reasonable suspicion. 
¶26 Thus, we adopt neither the bright-line rule proffered 
by the State that weaving within a single lane may alone give 
rise to reasonable suspicion, nor the bright-line rule advocated 
by Post that weaving within a single lane must be erratic, 
unsafe, or illegal to give rise to reasonable suspicion. Rather, 
we maintain the well-established principle that reviewing courts 
must determine whether there was reasonable suspicion for an 
investigative stop based on the totality of the circumstances.  
¶27 Having concluded that the determination of whether 
weaving within a single lane gives rise to reasonable suspicion 
requires an examination of the totality of the circumstances, we 
turn to the particular facts of this case. The question we must 
answer is whether the State has shown that there were "specific 
and articulable facts which, taken together with rational 
inferences from those facts, reasonably warrant" the intrusion 
of the stop. Terry, 392 U.S. at 21. While we acknowledge that 
this case presents a close call, we determine that the movements 
do warrant the stop. 
                                                 
10 United States v. Banks, 971 F. Supp. 992, 993 (E.D. Va. 
1997)(weaving combined with driving 5-7 miles per hour under the 
speed limit and slower than other cars on the road sufficient 
for reasonable suspicion); Veal v. State, 614 S.E.2d 143, 145 
(Ga. Ct. App. 2005)(weaving combined with driving 25 miles per 
hour in a 55-mile-per-hour zone sufficient for reasonable 
suspicion); State v. Jones, 386 S.E.2d 217, 219 (N.C. Ct. App. 
1989)(weaving combined with driving 45 miles per hour in a 65-
mile-per-hour zone sufficient for reasonable suspicion).  
No. 
2005AP2778-CR   
 
15 
 
¶28 As in Waldner, the police officer in the present case 
did not observe any actions that constituted traffic violations 
or which, considered in isolation, provided reasonable suspicion 
that criminal activity was afoot. However, when considered in 
conjunction with all of the facts and circumstances of the case, 
Post's driving provided Sherman with reasonable suspicion to 
believe that Post was driving while intoxicated. 
¶29 The court of appeals concluded that Post's movements 
amount to "slight deviations within one lane of travel" and 
therefore are not sufficient for reasonable suspicion. However, 
the court of appeals' account is not in accord with the circuit 
court's rendition. Although the circuit court did not detail the 
measurements upon which it relied, it does state that Post's 
vehicle appeared to be "moving between the roadway centerline 
and parking lane." Moving between the roadway centerline and 
parking lane is not slight deviation within one's own lane. The 
circuit court also incorporated by reference Sherman's testimony 
regarding Post's "drifting and unusual driving." Our read of 
Sherman's testimony does not support the view that Post's 
weaving constituted only slight deviation within one lane. 
¶30 When Sergeant Sherman first observed the two vehicles, 
he described Post's vehicle as being "canted" into the parking 
lane. He explained that this meant that Post "[w]asn't traveling 
in 
the 
designated 
traveling 
lane." 
After 
this 
initial 
observation, Sherman turned around to follow the vehicles. He 
testified that this was when he observed Post's weaving.  
No. 
2005AP2778-CR   
 
16 
 
Q: [W]ith respect to [Post's vehicle], what did you 
observe concerning the driving conduct?  
A: 
The 
vehicle 
continued 
to 
travel 
northbound, 
traveling in an S type manner, from the parking lane 
to the yellow center line. 
Q: You say an S type manner. What do you mean?  
A: The motion that the vehicle was making wasn't 
jerky. It was a smooth motion toward the right part of 
the parking lane and back towards the center line.  
Q: Using the driver's side front door tire as your 
point of reference, how far did the vehicle go from 
right to left within that lane? 
A: Approximately ten feet.  
Q: How many times did it do that?  
A: 
I 
don't 
have 
a 
specific 
number 
of 
times. 
Approximately two blocks worth.  
¶31 Sergeant Sherman testified that driving in such an S-
type manner contrasted with most driving behavior:  
Q: Did that strike you as being unusual driving 
conduct?  
A: Yes.  
Q: Why was that?  
A: Most vehicles travel straight down the road near 
the center line.  
Q: Was the first car . . . also traveling in that same 
manner?  
A: Not at that time, no. 
¶32 Further, Sherman described Post's S-type driving as 
covering both the traveling lane and the parking lane:  
Q: Do you know approximately how wide the lane is on 
Water Street?  
No. 
2005AP2778-CR   
 
17 
 
A: I would say 22 to 24 feet.  
Q: How close did the vehicle come to the center line?  
A: At times, within 12 inches.  
 . . . . 
Q: How close did the vehicle come to the curb on the 
right side?  
A: Within approximately 6 to 8 feet.  
¶33 After initially stating that he did not have an 
estimate of how many times Post's vehicle weaved, on cross-
examination Sherman stated that Post's vehicle weaved "several" 
or "a few" times:  
Q: [You] [d]on't have any estimate at all? 
A: Several times within the two blocks. 
Q: Could it be a few times?  
A: I'm sorry? 
Q: Could it be a few times?  
A: Again, our words could be the same, a few and 
several.  
¶34 Post contends that his car "didn't change its position 
very much at all." He bases this claim on a selective reading of 
Sergeant Sherman's testimony at the suppression hearing. Sherman 
testified that the northbound side of Water Street was "22 to 
24" feet wide, that Post's vehicle came within one foot of the 
center line, and to within "approximately six to eight feet" of 
the curb, and that Post's vehicle was about eight feet wide. 
Post picks out only the favorable parts of Sherman's estimates. 
For example, he asserts that northbound Water Street is 22 feet 
No. 
2005AP2778-CR   
 
18 
 
wide (i.e., the low end of Sherman's estimate) and that his 
vehicle "was never closer to the curb than eight feet" (i.e., 
the high end of Sherman's estimate). Thus, subtracting the width 
of the car (which Sherman testified he was estimating at 
"[p]robably eight feet" wide),11 the distance from the center 
line, and the distance from the curb, Post calculates that his 
car weaved only five feet from side-to-side. 
¶35 However, Post's calculations fail to account for the 
whole 
of 
Sergeant 
Sherman's 
testimony. 
Sherman 
estimated 
northbound Water Street to be 22 to 24 feet wide and that Post's 
vehicle came to within six to eight feet of the curb. Thus, even 
taking his estimate that the vehicle was eight feet wide at face 
value, Sherman's testimony indicates that Post's weave was 
between five feet and nine feet, based on his individual 
estimates of distances. Sherman further testified that Post's 
vehicle moved laterally ten feet. 
¶36 However, the width of Post's weaving is not the only 
specific, articulable fact in the case. It is noteworthy that 
the single lane here, described as between 22 and 24 feet, is 
                                                 
11 At oral argument, Post's counsel was questioned about the 
accuracy of the estimate the Chevy Cavalier was "[p]robably 
eight feet" wide. We note that this appears to greatly 
overestimate 
the 
width 
of 
Post's 
car. 
When 
Sherman 
was 
questioned at the suppression hearing regarding his estimate, he 
repeatedly 
noted 
that 
this 
estimate 
was 
"approximate." 
Nevertheless, this estimate of "probably eight feet" is the only 
description of the width of the Cavalier that is reflected in 
the record. 
No. 
2005AP2778-CR   
 
19 
 
approximately twice as wide as the standard single lane.12 Post's 
vehicle moved in a discernible S-type pattern within that single 
lane, and it repeated that S-type pattern several (or "a few") 
times for two blocks. When Sherman first observed Post's 
vehicle, it was "canted into the parking lane" and "wasn't in 
the designated traffic lane." Finally, we note that the incident 
took place at 9:30 at night. While this is not as significant as 
when poor driving takes place at or around "bar time," it does 
lend some further credence to Sherman's suspicion that Post was 
driving while intoxicated.13 
                                                 
12 As a point of reference, the Wisconsin Department of 
Transportation's Facilities Development Manual describes the 
desirable lane width for urban roadways as 10 to 12 feet, 
depending on volume. Chapter 11, Section 20, Subject 1, Figure 
1, available at https://trust.dot.state.wi.us/static/standards/ 
fdm/11/11-20-1.pdf (updated April 26, 2007).  Similarly, the 
minimum design standards for county trunk highways call for 10- 
to 12-foot lanes. Wis. Admin. Code § Trans. 205.03(2)(2006). The 
minimum design standards for improvements to existing town roads 
call for 9- to 12-foot lanes. Wis. Admin. Code § Trans. 
204.03(1)(2006). See Wis. Stat. § 902.03(1)(b). 
13 Relying on this court's decision in State v. Seibel, 163 
Wis. 2d 164, 471 N.W.2d 226 (1991), the State contends that 
because Post appeared to be traveling in tandem with the car in 
front of him, the fact that the front car made a turn into the 
wrong traffic lane supports the inference that Post was driving 
while intoxicated. This argument is not compelling. In Seibel, 
it was undisputed that the motorcycle driver was traveling with 
companions from whom the strong odor of intoxicants emanated. 
Id. at 181. Here, it is not established that the cars were 
traveling in tandem, and the evidence that the driver of the 
first car was intoxicated is scant. Moreover, as the court noted 
in Seibel, "ordinarily, the mere fact that the defendant's 
friends were drinking would not constitute evidence of the 
defendant's drinking." Id. at 182. Finally, we are wary of a 
rule that would allow the actions of one car to justify 
investigative stops of other cars because of their proximity to 
the first car.  
No. 
2005AP2778-CR   
 
20 
 
¶37 When viewed in isolation, the individual facts that 
Post was weaving across the travel and parking lanes, that the 
weaving created a discernible S-type pattern, that Post's 
vehicle was canted into the parking lane, and that the incident 
took place at night may not be sufficient to warrant a 
reasonable officer to suspect that Post was driving while 
intoxicated. As this court stated in Waldner, "[a]ny one of 
these facts, standing alone, might well be insufficient." 206 
Wis. 2d at 58. However, such facts accumulate, and "as they 
accumulate, reasonable inferences about the cumulative effect 
can be drawn." Id. We determine, under the totality of the 
circumstances, that Sherman presented specific and articulable 
facts, which taken together with rational inferences from those 
facts, give rise to the reasonable suspicion necessary for an 
investigative stop. Accordingly, the stop did not violate Post's 
constitutional right to be free from unreasonable searches and 
seizures.  
IV 
¶38 In sum, we determine that weaving within a single 
traffic lane does not alone give rise to the reasonable 
suspicion necessary to conduct an investigative stop of a 
vehicle. However, we also determine that under the totality of 
the circumstances, the police officer did have reasonable 
suspicion in this case, and that the stop did not violate Post's 
constitutional right to be free from unreasonable searches and 
seizures. Accordingly, we reverse the court of appeals.  
No. 
2005AP2778-CR   
 
21 
 
By the Court.—The decision of the court of appeals is 
reversed. 
 
 
No.  2005AP2778-CR.ssa 
 
1 
 
 
¶39 SHIRLEY S. ABRAHAMSON, C.J.   (concurring in part and 
dissenting in part).  The State presented the following issue of 
law for this court to decide: Does the drifting or weaving of a 
motor vehicle within a single traffic lane several (or a few) 
times over two blocks give an experienced patrol officer 
reasonable suspicion to make an investigatory stop for possible 
drunk driving?  The State seeks an affirmative answer and a per 
se rule that repeated drifting or weaving within a single lane 
alone, absent any obvious innocent explanation for the drifting 
or weaving, justifies a traffic stop.  The majority opinion 
answers with a resounding "no."  
I 
¶40 I agree with the majority opinion that the court 
should not adopt a bright-line rule declaring that the drifting 
or weaving of a vehicle within a single lane alone gives rise to 
the reasonable suspicion necessary for a law enforcement officer 
to conduct an investigative stop of that vehicle.  Majority op., 
¶2.1  I agree with the majority that adopting the State's 
standard would "allow essentially unfettered discretion and 
permit 
the 
arbitrary 
invasions 
of 
privacy 
by 
government 
officials addressed by the Fourth Amendment and Article I, 
Section 11."  Majority op., ¶21.   
                                                 
1 Thus the majority and I agree with the court of appeals 
that the movement of a car in a single lane, without more, does 
not give a law enforcement officer reasonable suspicion that the 
driver was violating a law that would justify a traffic stop.  
The court of appeals reversed the judgment and remanded the 
cause for further proceedings.    
No.  2005AP2778-CR.ssa 
 
2 
 
¶41 I also agree with the majority opinion that the 
constitutionality of the stop of Robert Post's vehicle must be 
judged under the totality of the circumstances test.  In short, 
the "determination [of reasonable suspicion] is based on the 
totality of the circumstances, in accordance with Wisconsin 
jurisprudence."  Majority op., ¶14.  
¶42 This case is not just about Robert Post.  This is an 
important case because the rule of law announced by the court 
today applies with equal force to all who drive.  "Were the 
individual subject to unfettered governmental intrusion every 
time he entered an automobile, the security guaranteed by the 
Fourth Amendment would be seriously circumscribed."2   
¶43 A traffic stop is a "major interference in the lives 
of the [vehicle's] occupants."  Coolidge v. New Hampshire, 403 
U.S. 443, 479 (1971).  Significant interests are at stake when 
determining the permissibility of a traffic stop.  An invasion 
of privacy occurs every time a law enforcement officer stops a 
car, regardless of the motivation for the stop.  "The Fourth and 
Fourteenth Amendments are implicated . . . because stopping an 
automobile and detaining its occupants constitute a 'seizure' 
within the meaning of those Amendments, even though the purpose 
of the stop is limited and the resulting detention quite brief."3  
Traffic 
stops 
"interfere 
with 
freedom 
of 
movement, 
are 
inconvenient, 
and 
consume 
time," 
and 
they 
"may 
create 
                                                 
2 Delaware v. Prouse, 440 U.S. 648, 662-63 (1979). 
3 Id. at 653. 
No.  2005AP2778-CR.ssa 
 
3 
 
substantial anxiety" for those detained.4  Moreover, a traffic 
stop provides law enforcement officers with an opportunity for 
further intrusion on the driver and passengers. 
II 
¶44 I disagree with the majority opinion's application of 
the totality of circumstances standard in the instant case.   
¶45 The standard by which this court reviews a circuit 
court or court of appeals decision on the constitutionality of a 
stop is well established.  A reviewing court accepts the circuit 
court's findings of historical fact unless they are clearly 
erroneous, but determines the application of constitutional 
principles to those facts independently of the circuit court and 
court of appeals, but benefiting from their analyses.  Majority 
op., ¶8.   
¶46 The majority opinion is not faithful to this standard 
of review:  The majority opinion engages in its own fact-finding 
and ignores relevant facts in setting forth the totality of the 
circumstances in the instant case.  
¶47 The circuit court made no findings of fact; it issued 
a 
brief 
memorandum 
decision 
describing 
some 
facts. 
The 
memorandum decision describes Post's car as appearing to be 
"canted"5 or moving between the roadway centerline and the 
                                                 
4 Id. at 657. 
5 When asked at the suppression hearing, "What do you mean 
by that [word "cant"]?", the officer explained he meant that 
Post's vehicle "[w]asn't traveling in the designated traveling 
lane, traveling closer into the parking lane." 
No.  2005AP2778-CR.ssa 
 
4 
 
parking lane, drifting with no sudden, jerky, or violent 
movement.   
¶48 The circuit court did not apply the totality of 
circumstances test. Rather, the circuit court decided in its 
memorandum decision, as a matter of law, that "based on the 
training and experience of Officer Sherman, drifting even within 
one's own lane gives a suspicion that the driver may have been 
intoxicated."        
¶49 The majority opinion mines the testimony of the law 
enforcement officer, who was the only witness to testify, when 
exploring the totality of the circumstances.  The officer, at 
various times in his testimony, characterized Post's car as 
having "drifted," "canted," and traveled in an "S type manner" 
in a "smooth motion" from the unmarked parking lane to a foot 
from the center lane dividing the two lanes of traffic.  The 
officer testified that Post's car "did not drift more than 5 
feet."  The officer also testified that the width of Post's 
vehicle was eight feet and further estimated that the single 
traffic lane, which included unmarked space for parking, was 
approximately 22-24 feet wide. 
¶50 The majority opinion questions the accuracy of the 
officer's estimate of the width of Post's vehicle as eight feet 
but nonetheless accepts it and the other estimates provided by 
the officer as valid measurements.  Majority op., ¶34 n.11.  The 
majority opinion then goes outside the record to show that the 
officer's estimate of the width of the parking and driving area 
No.  2005AP2778-CR.ssa 
 
5 
 
makes the width of the parking and driving area twice as wide as 
a "standard" single lane.  Majority op., ¶36.    
¶51 The 
majority 
opinion 
then 
performs 
its 
own 
calculations of the "S" pattern on the basis of the officer's 
testimony of the dimensions of the roadway and car, and finds 
that Post's weaving was "between five feet and nine feet."  
Majority op., ¶35.  The officer never made this calculation.   
¶52 Even more problematic, the majority opinion appears to 
treat what the officer described as Post's car "canting" in the 
parking lane as a separate factor from Post's car weaving and 
making a S-shaped maneuver.  According to the majority opinion, 
under the totality of the circumstances, we are presented not 
only with a vehicle in a wide single lane drifting, but also a 
vehicle traveling in an S-type pattern and "canting" into the 
parking area.6  The record is clear, however, that the officer 
was describing Post's driving in three different ways.  The 
officer was not testifying that Post's car performed three 
different maneuvers. 
¶53 The majority opinion is correct that nothing is to be 
gained from parsing "weaving" from "drifting."7  I would add that 
nothing is to be gained from parsing "drifting," "weaving" 
"canting," and an "S-shaped movement" in the present case.  The 
issue here is whether "the vehicle's movements, considered with 
                                                 
6 Majority op., ¶37. 
7 Majority op., ¶22 n.7. 
No.  2005AP2778-CR.ssa 
 
6 
 
the totality of the circumstances, give rise to a reasonable 
suspicion that Post was driving while intoxicated."8 
¶54 So what is the totality of circumstances upon which 
the majority relies?  Here are the circumstances:  The officer 
estimated the single lane as approximately 22-24 feet wide 
because it also included an unmarked parking lane (in which no 
cars were parked and in which Post could lawfully drive); Post's 
car, according to the officer's testimony, drifted no more than 
5 feet within this wide single lane (although the majority 
opinion calculates the drift could have been up to 9 feet); and 
it was 9:30 p.m.   
¶55 The majority opinion concedes that 9:30 p.m. is not as 
significant as bar closing time, but still concludes that "it 
does lend some further credence to [the officer's] suspicion 
that Post was driving while intoxicated."  Majority op., ¶36.  
Not surprisingly, the majority opinion is unable to explain how 
or why driving at 9:30 p.m. (in contrast to any other time) 
lends any credence to the suspicion of drunk driving.   
¶56 In contrast, the majority opinion ignores, without 
explanation, other salient factors in examining the totality of 
the circumstances: Post maintained the legal speed limit.  There 
was no indication that Post was traveling at an unsafe or 
unusual speed or was traveling either too fast or too slow for 
conditions.  Post never came close to striking another vehicle.  
Post properly signaled before making a left turn at an 
intersection.  Post successfully navigated a left-hand turn even 
                                                 
8 Id. 
No.  2005AP2778-CR.ssa 
 
7 
 
though the car immediately in front of him turned too sharply, 
into the oncoming traffic lane.  Post did not commit any 
violation of any traffic law.     
¶57 When considering whether reasonable suspicion exists, 
a court must consider all the circumstances.  Yet, the majority 
opinion omits many factors under its application of the totality 
of the circumstances standard.  
¶58 This case, like all stops for reasonable suspicion, 
turns on the details.  Yet the parties did not create a careful 
record of the facts at the suppression hearing.  They were too 
focused on the legal issue whether, as a matter of law, 
deviation within a single lane of traffic justifies a traffic 
stop.  Judge Richard Posner's comment in a recent case in which 
the parties failed to present concrete facts to support their 
respective 
positions 
fits 
the 
present 
case: 
"This 
case 
illustrates the curious and deplorable aversion of many lawyers 
to visual evidence and exact measurements (feet, inches, pounds, 
etc.) 
even 
when 
vastly 
more 
informative 
than 
a 
verbal 
description."9     
¶59 The majority opinion concedes that this is a close 
case.10  Because the parties and circuit court did not view this 
case from the perspective of the totality of the circumstances 
and did not provide the circuit court or this court with an 
adequate record to determine the totality of the circumstances, 
                                                 
9 Coffey v. N.E. Ill. Reg'l Commuter R.R. Corp., 479 F.3d 
472, 478 (7th Cir. 2007). 
10 Majority op., ¶27. 
No.  2005AP2778-CR.ssa 
 
8 
 
I would remand the case so that the parties can make an 
appropriate record. 
III 
¶60 We are all relieved that the officer stopped Post 
before his drunk driving could harm anyone, and all of us rely 
on law enforcement officers to stop drunk drivers.  A person who 
drives under the influence places not just his or her life at 
risk but also the life of any person who is in the same place at 
the same time as the intoxicated driver. 
¶61 This case is a hard case because it is difficult for a 
court to declare a stop unconstitutional when the stop revealed 
that the driver was, in fact, operating a motor vehicle while 
under the influence.  It is especially hard to cut Post any 
slack because this was the fifth time (not counting any times 
Post drove while intoxicated but evaded detection) that Post 
drank his alcoholic beverages, picked up his car keys, and 
brazenly and illegally got into the driver's seat.       
¶62 But as United States Supreme Court Justice Antonin 
Scalia has wisely explained: "[T]here is nothing new in the 
realization that the Constitution sometimes insulates the 
criminality of a few in order to protect the privacy of us 
all."11 
¶63 For the reasons set forth, I would remand the cause to 
the circuit court for an evidentiary suppression hearing to 
determine the facts surrounding the stop and to determine 
whether they justified an investigative stop.   
                                                 
11 Arizona v. Hicks, 480 U.S. 321, 329 (1987). 
No.  2005AP2778-CR.ssa 
 
9 
 
 
 
 
No.  2005AP2778-CR.ssa 
 
 
 
1