Case Title: State v. Burch

Citation: 

Docket Number: 2019AP001404-CR

State: wisconsin

Court: Wisconsin Supreme Court

Date: 2021-06-29T00:00:00Z

Document:
2021 WI 68 
 
SUPREME COURT OF WISCONSIN 
 
 
 
 
 
CASE NO.: 
2019AP1404-CR 
 
 
 
COMPLETE TITLE: 
State of Wisconsin, 
          Plaintiff-Respondent, 
     v. 
George Steven Burch, 
          Defendant-Appellant. 
 
 
 
 
 
ON CERTIFICATION FROM THE COURT OF APPEALS 
 
 
OPINION FILED: 
June 29, 2021   
SUBMITTED ON BRIEFS: 
        
ORAL ARGUMENT: 
April 12, 2021   
 
 
SOURCE OF APPEAL: 
 
 
COURT: 
Circuit   
 
COUNTY: 
Brown   
 
JUDGE: 
John Zakowski   
 
 
 
JUSTICES: 
 
HAGEDORN, J., delivered the majority opinion of the Court, in 
which ZIEGLER, C.J, ROGGENSACK, and REBECCA GRASSL BRADLEY, JJ., 
joined, and in which DALLET and KAROFSKY, JJ., joined with 
respect to Parts I. and II.B.  REBECCA GRASSL BRADLEY, J., filed 
a concurring opinion.  DALLET, J., filed an opinion concurring 
in part and dissenting in part, in which KAROFSKY, J., joined 
and in which ANN WALSH BRADLEY, J., joined except for footnote 
1.  ANN WALSH BRADLEY, J., filed a dissenting opinion. 
NOT PARTICIPATING: 
    
 
 
 
ATTORNEYS: 
 
 
For the defendant-appellant, there were briefs filed by Ana 
L. Babcock and Babcock Law, LLC. There was an oral argument by 
Ana L. Babcock.  
 
For the plaintiff-respondent, there was a brief filed by 
Aaron R. O’Neil, assistant attorney general; with whom on the 
brief was Joshua L. Kaul, attorney general. There was an oral 
argument by Aaron R. O’Neil.  
 
 
2 
 
An amicus curiae brief was filed on behalf of Legal Action 
of Wisconsin, Inc. by Rebecca M. Donaldson, Milwaukee.  
 
 
 
 
 
2021 WI 68 
NOTICE 
This opinion is subject to further 
editing and modification.  The final 
version will appear in the bound 
volume of the official reports.   
No.   2019AP1404-CR 
(L.C. No. 
2016CF1309) 
STATE OF WISCONSIN  
 
 
   : 
IN SUPREME COURT 
 
 
State of Wisconsin, 
 
          Plaintiff-Respondent, 
 
     v. 
 
George Steven Burch, 
 
          Defendant-Appellant. 
 
FILED 
 
JUN 29, 2021 
 
Sheila T. Reiff 
Clerk of Supreme Court 
 
 
 
 
HAGEDORN, J., delivered the majority opinion of the Court, in 
which ZIEGLER, C.J, ROGGENSACK, and REBECCA GRASSL BRADLEY, JJ., 
joined, and in which DALLET and KAROFSKY, JJ., joined with 
respect to Parts I. and II.B.  REBECCA GRASSL BRADLEY, J., filed 
a concurring opinion.  DALLET, J., filed an opinion concurring 
in part and dissenting in part, in which KAROFSKY, J., joined 
and in which ANN WALSH BRADLEY, J., joined except for 
footnote 1.  ANN WALSH BRADLEY, J., filed a dissenting opinion. 
 
 
APPEAL from a judgment of the Circuit Court for Brown 
County.  Affirmed. 
 
¶1 
BRIAN HAGEDORN, J.   George Steven Burch appeals a 
judgment of conviction for first-degree intentional homicide on 
the 
grounds 
that 
two 
pre-trial 
evidentiary 
motions 
were 
incorrectly denied. 
No. 
2019AP1404-CR   
 
2 
 
¶2 
First, relying on the Fourth Amendment, Burch moved to 
suppress the admission of incriminating cell phone data.  This 
data was obtained via an unrelated criminal investigation and 
kept in a police database.  A different law enforcement agency 
investigating the homicide came upon this data and used it to 
connect Burch to the homicide.  Burch argues that the initial 
download of the data exceeded the scope of his consent, the data 
was unlawfully retained, and the subsequent accessing of the 
data violated his reasonable expectation of privacy.  We 
conclude that even if some constitutional defect attended either 
the initial download or subsequent accessing of the cell phone 
data, there was no law enforcement misconduct that would warrant 
exclusion of that data.  Therefore, we conclude the circuit 
court correctly denied Burch's motion to suppress that data. 
¶3 
Regarding the second pre-trial evidentiary motion, 
Burch asks us to reverse the circuit court's discretionary 
decision to admit evidence from a Fitbit device allegedly worn 
by the victim's boyfriend at the time of the homicide.  This 
evidence, Burch maintains, should have been accompanied by 
expert testimony and was insufficiently authenticated.  We agree 
with the State that the circuit court's decision to admit this 
evidence was not an erroneous exercise of discretion.  Burch's 
judgment of conviction is affirmed. 
 
I.  BACKGROUND 
¶4 
On May 20, 2016, Nicole VanderHeyden went to a bar 
with her boyfriend, Douglass Detrie.  The two became separated 
No. 
2019AP1404-CR   
 
3 
 
and, in the course of a subsequent phone call and text messages, 
got into an argument.  Detrie returned alone to their shared 
home.  The next day, VanderHeyden's body was discovered next to 
a nearby field.  Her blood-stained clothing was later found 
discarded alongside a freeway on-ramp, and some of her blood and 
hair were identified outside the house of VanderHeyden's 
neighbor.  The Brown County Sheriff's Office (the "Sheriff's 
Office") opened a homicide investigation that spanned the next 
several months.  Detrie was initially a suspect, but the focus 
of the investigation shifted away from Detrie in part because 
his Fitbit device logged only 12 steps during the hours of 
VanderHeyden's death.1 
¶5 
While the Sheriff's Office investigated VanderHeyden's 
homicide, 
the 
Green 
Bay 
Police 
Department 
(the 
"Police 
Department") undertook an unrelated investigation into three 
incidents involving the same vehicle——a stolen vehicle report, a 
vehicle fire, and a hit-and-run.  George Burch was a suspect in 
this 
investigation, 
and 
Police 
Department 
Officer 
Robert 
Bourdelais interviewed him on June 8, 2016.  Burch denied 
involvement and offered the alibi that he was at a bar that 
night and texting a woman who lived nearby.  As Officer 
Bourdelais testified, "I asked [Burch] if I could see the text 
messages between him and [the woman], if my lieutenant and I 
could take a look at his text messages."  Burch agreed.  Officer 
                                                 
1 Detrie wore a Fitbit Flex, a wrist-worn device that 
continuously tracks the wearer's steps and interfaces with the 
wearer's phone or computer. 
No. 
2019AP1404-CR   
 
4 
 
Bourdelais 
then 
explained 
that 
he 
preferred 
to 
download 
information off the phone because "it's a lot easier to do that 
than try to take a bunch of pictures and then have to scan those 
in."  "So I asked him if he would be willing to let me take his 
phone to this detective, download the information off the phone 
and then I'd bring the phone right back to him . . . and he said 
that would be fine." 
¶6 
Before Officer Bourdelais took the phone to be 
downloaded, Burch signed a consent form.  The form read:  "I 
George Stephen Burch . . . voluntarily give Det. Danielski, 
Officer Bourdelais or any assisting personnel permission to 
search my . . . Samsung cellphone."  Officer Bourdelais took the 
phone and the signed consent form to the certified forensic 
computer examiner for the Police Department.  The forensic 
expert performed a "physical extraction" of all the data on 
Burch's phone, brought the data into a readable format, and 
saved the extraction to the Police Department's long-term 
storage.  At a motion hearing, the forensic expert testified 
that this was consistent with the Police Department's standard 
practice. 
¶7 
Two months later, two Sheriff's Office detectives 
continuing the investigation of VanderHeyden's homicide matched 
a DNA sample from VanderHeyden's sock to Burch.  The detectives 
then searched their own department's records and the records of 
other local departments for prior police contacts with Burch.  
There they discovered the Police Department's file related to 
the three vehicle-related incidents.  The file included Burch's 
No. 
2019AP1404-CR   
 
5 
 
signed consent form and a copy of the data the Police Department 
extracted from Burch's phone during the search.  It also 
contained a narrative written by Officer Bourdelais which 
indicated Burch said Officer Bourdelais "could take his phone to 
the department to have the information on it downloaded."  
Nothing in the consent form, the narrative, or anything else in 
the file, indicated that Burch limited the scope of the data he 
consented to have downloaded from his phone. 
¶8 
The Sheriff's Office detectives reviewed the data 
downloaded from Burch's phone.  They noted that Burch's internet 
history 
included 
64 
viewings 
of 
news 
stories 
about 
VanderHeyden's death.  And they also discovered Burch had an 
email address associated with a Google account.  In light of 
this discovery, the Sheriff's Office detectives procured a 
search warrant to obtain the "Google Dashboard" information from 
Google corresponding to Burch's email address.  The data Google 
provided contained location information that placed Burch's 
phone at a bar VanderHeyden visited the night of her death, a 
location 
near 
VanderHeyden's 
residence, 
the 
place 
where 
VanderHeyden's 
body 
was 
found, 
and 
the 
on-ramp 
where 
VanderHeyden's discarded clothing was discovered. 
¶9 
Burch was arrested and charged with VanderHeyden's 
death.  He filed two pre-trial evidentiary motions relevant to 
this appeal. 
¶10 In one motion, Burch sought to suppress the data 
obtained from his cell phone for two reasons:  (1) the Police 
Department's extraction of the data exceeded the scope of 
No. 
2019AP1404-CR   
 
6 
 
Burch's consent by obtaining all the phone's data, rather than 
just the text messages; and (2) the Sheriff's Office unlawfully 
accessed the data in August 2016.  The circuit court2 denied 
Burch's motion.  It concluded that the conversation between 
Burch and Officer Bourdelais did not limit the scope of Burch's 
consent, and that "the sharing of such information, without 
first obtaining a warrant, is a common and long-understood 
practice between related departments." 
¶11 Burch also moved to exclude evidence related to 
Detrie's Fitbit device.  He argued the State must produce an 
expert to establish the reliability of the science underlying 
the Fitbit device's technology and that the State failed to 
sufficiently authenticate the records.  The circuit court 
disagreed and refused to exclude the Fitbit evidence related to 
step-counting.3 
¶12 Burch testified in his own defense at trial.  He 
denied killing VanderHeyden, but acknowledged he was with her 
the night she died.  According to Burch, he met VanderHeyden at 
a bar, and the two left together.  After parking near 
VanderHeyden's house, they became intimate.  That, Burch said, 
was the last thing he remembered before waking up on the ground 
with Detrie there, and VanderHeyden dead.  Burch told the jury 
that Detrie held him at gunpoint and instructed him to move 
                                                 
2 The Honorable John P. Zakowski of the Brown County Circuit 
Court presided. 
3 The circuit court granted Burch's motion in part, agreeing 
to exclude Fitbit evidence related to sleep-monitoring. 
No. 
2019AP1404-CR   
 
7 
 
VanderHeyden's body into his vehicle, drive to a field, and 
carry VanderHeyden's body into the ditch.  Only then did Burch 
escape by pushing Detrie, running back to his vehicle, and 
driving away.  Burch added that on his way home he noticed that 
articles of VanderHeyden's clothing were still in his vehicle 
and threw them out the window in a panic.  In the months that 
followed, Burch told no one this version of events, even as 
authorities sought the public's help in solving VanderHeyden's 
homicide. 
¶13 The 
jury 
found 
Burch 
guilty 
of 
first-degree 
intentional homicide, and the circuit court sentenced him to 
life in prison.  Burch appealed, challenging the circuit court's 
denial of his motion to suppress the cell phone data and his 
motion to exclude the Fitbit evidence.  The court of appeals 
certified the case to us, and we accepted the certification. 
 
II.  DISCUSSION 
A.  Cell Phone Data 
¶14 Burch asks us to reverse the circuit court's denial of 
his motion to suppress the cell phone data as contrary to the 
Fourth Amendment.  The Fourth Amendment protects the "right of 
the people to be secure in their persons, houses, papers, and 
effects, against unreasonable searches and seizures."  U.S. 
Const. amend. IV.  On review of a circuit court's denial of a 
suppression motion, we uphold the circuit court's findings of 
historical 
fact 
unless 
they 
are 
clearly 
erroneous, 
and 
independently apply constitutional principles to those facts.  
No. 
2019AP1404-CR   
 
8 
 
State v. Robinson, 2010 WI 80, ¶22, 327 Wis. 2d 302, 786 
N.W.2d 463. 
¶15 Before us, Burch argues the cell phone data was 
obtained in violation of the Fourth Amendment for three reasons:  
(1) the Police Department obtained the data without his consent; 
(2) the Police Department unlawfully retained the data after its 
investigation into the vehicle-related incidents had ended; and 
(3) the Sheriff's Office unlawfully accessed the data in the 
Police Department's records without a warrant.4  However, for the 
reasons that follow, regardless of whether the data was 
unlawfully obtained or accessed, we conclude suppression of the 
data is not warranted under the exclusionary rule.  See Herring 
v. United States, 555 U.S. 135, 139 (2009) (accepting the 
"assumption that there was a Fourth Amendment violation" and 
analyzing whether the exclusionary rule applied); see also State 
v. Kerr, 2018 WI 87, ¶¶20-24, 383 Wis. 2d 306, 913 N.W.2d 787. 
 
1.  The Exclusionary Rule 
¶16 "When there has been an unlawful search, a common 
judicial remedy for the constitutional error is exclusion."  
State v. Dearborn, 2010 WI 84, ¶15, 327 Wis. 2d 252, 786 
                                                 
4 Burch forfeited his argument related to the Police 
Department's retention of the cell phone data by not raising 
that argument before the circuit court.  See State v. Huebner, 
2000 WI 59, ¶10, 235 Wis. 2d 486, 611 N.W. 2d 727.  His 
arguments regarding the initial download of the data and the 
subsequent accessing of the data are, however, properly before 
us. 
No. 
2019AP1404-CR   
 
9 
 
N.W.2d 97.  The exclusionary rule is a judicially-created, 
prudential doctrine designed to compel respect for the Fourth 
Amendment's constitutional guaranty.  Davis v. United States, 
564 U.S. 229, 236 (2011).  In recent years, the United States 
Supreme Court has significantly clarified the purpose and proper 
application of the exclusionary rule.  See id.; Herring, 555 
U.S. 135.  In Davis, the Supreme Court explained that prior 
cases suggested that the exclusionary rule "was a self-executing 
mandate implicit in the Fourth Amendment itself."  564 U.S. at 
237.  However, more recent cases have acknowledged that the 
exclusionary rule is not one of "reflexive" application, but is 
to be applied only after a "rigorous weighing of its costs and 
deterrence benefits."  Id. at 238.  Thus, in both Herring and 
Davis, the Court explained that to "trigger the exclusionary 
rule, police conduct must be sufficiently deliberate that 
exclusion can meaningfully deter it, and sufficiently culpable 
that such deterrence is worth the price paid by the justice 
system."  Herring, 555 U.S. at 144; see also Davis, 564 U.S. at 
240. 
¶17 The "sole purpose" of the exclusionary rule "is to 
deter future Fourth Amendment violations."  Davis, 564 U.S. at 
236-37.  Therefore, exclusion is warranted only where there is 
some present police misconduct, and where suppression will 
appreciably deter that type of misconduct in the future.  Id. at 
237.  The exclusionary rule applies only to police misconduct 
that can be "most efficaciously" deterred by exclusion.  Id. 
(quoting United States v. Calandra, 414 U.S. 338, 348 (1974)).  
No. 
2019AP1404-CR   
 
10 
 
Specifically, "the exclusionary rule serves to deter deliberate, 
reckless, or grossly negligent conduct, or in some circumstances 
recurring or systemic negligence."  Herring, 555 U.S. at 144.  
"But when the police act with an objectively reasonable good-
faith belief that their conduct is lawful, or when their conduct 
involves only simple, isolated negligence, the deterrence 
rationale loses much of its force, and exclusion cannot pay its 
way."  Davis, 564 U.S. at 238 (cleaned up). 
¶18 "Real deterrent value is a 'necessary condition for 
exclusion,' but it is not 'a sufficient' one."  Id. at 237 
(quoting Hudson v. Michigan, 547 U.S. 586, 596 (2006)).  In 
Davis, the Court explained that the "analysis must also account 
for the 'substantial social costs' generated by the rule."  Id. 
(quoting United States v. Leon, 468 U.S. 897, 907 (1984)).  It 
elaborated: 
Exclusion exacts a heavy toll on both the judicial 
system and society at large.  It almost always 
requires 
courts 
to 
ignore 
reliable, 
trustworthy 
evidence bearing on guilt or innocence.  And its 
bottom-line effect, in many cases, is to suppress the 
truth and set the criminal loose in the community 
without punishment.  Our cases hold that society must 
swallow this bitter pill when necessary, but only as a 
"last resort."  For exclusion to be appropriate, the 
deterrence benefits of suppression must outweigh its 
heavy costs. 
Id. (citations omitted). 
¶19 Applying this rationale, the Supreme Court in Herring 
held that a county's failure to update a computer database to 
reflect the recall of an arrest warrant was only negligent, and 
therefore was "not enough by itself to require 'the extreme 
No. 
2019AP1404-CR   
 
11 
 
sanction of exclusion.'"  555 U.S. at 140 (quoting Leon, 468 
U.S. at 916).  Similarly, in Davis, the Supreme Court refused to 
exclude evidence that was obtained via a search conducted in 
compliance with binding, but subsequently overruled, precedent.  
564 U.S. at 232.  Exclusion, it explained, was inappropriate 
because it "would do nothing to deter police misconduct."  Id. 
¶20 We have followed suit as well.  In Kerr, we explained 
that no police misconduct occurred when an officer conducted an 
arrest relying on dispatch's confirmation that the defendant had 
a warrant out for his arrest.  383 Wis. 2d 306, ¶22.  Exclusion 
was improper because "the officers' conduct [was] at most 
negligent, and isolated negligence is not 'misconduct' for 
purposes of the exclusionary rule."  Id. (citing Herring, 555 
U.S. at 146-47). 
¶21 Many more examples could be provided,5 but the 
principle 
is 
clear: 
 
unless 
evidence 
was 
obtained 
by 
sufficiently 
deliberate 
and 
sufficiently 
culpable 
police 
misconduct, "[r]esort to the massive remedy of suppressing 
                                                 
5 See, e.g., United States v. Leon, 468 U.S. 897, 916 (1984) 
(reasonable reliance on a warrant later held invalid); Illinois 
v. Krull, 480 U.S. 340, 342 (1987) (reasonable reliance on 
subsequently invalidated statutes); 
Arizona v. Evans, 514 
U.S. 1, 15-16 (1995) (reasonable reliance on arrest warrant 
information in a database maintained by judicial employees); 
State v. Ward, 2000 WI 3, ¶63, 231 Wis. 2d 723, 604 N.W.2d 517 
(reasonable reliance on settled law subsequently overruled); 
State v. Dearborn, 2010 WI 84, ¶44, 327 Wis. 2d 252, 786 
N.W.2d 97 (refusing to exclude evidence where doing so "would 
have absolutely no deterrent effect on officer misconduct"). 
No. 
2019AP1404-CR   
 
12 
 
evidence of guilt is unjustified."6  Hudson, 547 U.S. at 599.  
With these principles in mind, we turn to the facts at hand. 
 
2.  Application 
¶22 In this case, the Sheriff's Office detectives acted by 
the book.  After a DNA sample from VanderHeyden's sock matched 
Burch, officers checked the interdepartmental records already on 
file with the police.7  They discovered the two-month-old Police 
Department file documenting the investigation for the vehicle-
related incidents.  In it, they found and reviewed Burch's 
signed consent form and Officer Bourdelais' narrative further 
documenting Burch's consent.  The Sheriff's Office detectives 
observed that neither the consent form nor the narrative listed 
any limitations to the scope of consent.  And the officers 
reviewed the downloaded data, having every reason to think it 
was lawfully obtained with Burch's unqualified consent. 
¶23 Burch argues that the Sheriff's Office should have 
obtained a warrant before accessing the Police Department's 
                                                 
6 Failure to apply exclusion is usually described in our 
cases as the "good faith" exception to the exclusionary rule.  
See, e.g., Dearborn, 327 Wis. 2d 252, ¶4.  However, the United 
States 
Supreme 
Court 
has 
called 
the 
"good 
faith" 
label 
confusing.  Herring v. United States, 555 U.S. 135, 142 (2009).  
The Supreme Court's most recent cases do not use that phrase as 
a catchall for cases where exclusion is improper, and do not 
describe their conclusion that exclusion was inappropriate as 
applying a "good faith" exception.  See id. at 147-48; Davis v. 
United States, 564 U.S. 229, 249-50 (2011). 
7 Officers from both the Police Department and the Sheriff's 
Office testified that it is common police practice for agencies 
to share records with other agencies. 
No. 
2019AP1404-CR   
 
13 
 
data.  But no case from this court or the federal courts has 
suggested that accessing evidence previously obtained by a 
sister law enforcement agency is a new search triggering a 
renewed warrant requirement.8  Rather, the Sheriff's Office 
detectives reasonably relied on Burch's signed consent form and 
Officer Bourdelais' narrative to conclude that Burch consented 
to the download of the data.  They had no reason to think they 
were engaging in illegal activity by reviewing interdepartmental 
files and evidence.  Far from it.  Reliance on well-documented 
computer records, like the detectives did here, is something the 
Supreme Court has characterized as objectively reasonable police 
conduct.  Arizona v. Evans, 514 U.S. 1, 15-16 (1995).  Thus, 
there was no misconduct that would "render[] the evidence 
suppressible 
under 
the 
exclusionary 
rule." 
 
Kerr, 
383 
Wis. 2d 306, ¶22. 
¶24 Moreover, even if the Sheriff's Office's actions could 
be labeled as some kind of misconduct, nothing they did would 
rise beyond mere negligence.  See id., ¶22 (concluding that "to 
the extent that looking at a warrant before executing it may be 
                                                 
8 Justice Dallet's concurrence/dissent argues that courts 
should treat cell phone data collected by law enforcement 
differently than other types of evidence.  It acknowledges that 
the sharing of already-collected evidence without a warrant by 
sister law enforcement agencies is routine and unproblematic, 
but maintains a different kind of analysis should attend cell 
phone evidence.  We need not decide this question to conclude 
exclusion is not warranted in this case.  Justice Dallet's 
approach 
would 
break 
new 
ground 
in 
Fourth 
Amendment 
jurisprudence, and as such, the violation of her new proposed 
rule does not implicate the kind of gross or systemic law 
enforcement misconduct the exclusionary rule is meant to deter. 
No. 
2019AP1404-CR   
 
14 
 
best practice," failing to do so was "at most negligent"); 
Herring, 555 U.S. at 140 (holding that a county's failure to 
update a computer database was negligent and therefore "not 
enough by itself to require" exclusion).  And mere negligence 
does not warrant suppression.  Id. at 144-45. 
¶25 In addition, the societal cost of excluding the cell 
phone data would far outweigh any deterrence benefit that 
exclusion might provide.  See Dearborn, 327 Wis. 2d 252, ¶35.  
This is in part because there is nothing concerning under 
current Fourth Amendment doctrine with how the Sheriff's Office 
detectives 
conducted 
themselves. 
 
Even 
if 
the 
Police 
Department's initial download or retention gave cause for 
concern, it's not clear what behavior by the Sheriff's Office 
Burch would have this court seek to deter.9  Based on the 
arguments presented, Burch has given us no reason to deter law 
enforcement reliance on the computer records of other law 
enforcement agencies.  In this case, the societal cost of 
                                                 
9 Many of Burch's arguments focus on the conduct of the 
Police Department and the initial download of his cell phone 
data.  He argues that because the Police Department unlawfully 
obtained the data, any subsequent accessing of the data violated 
the 
Fourth 
Amendment 
because 
he 
retained 
a 
reasonable 
expectation of privacy in it.  But the conduct of the Police 
Department has little bearing on whether we should apply the 
exclusionary rule against the Sheriff's Office in this case.  
The Police Department's involvement in this case was limited to 
an investigation of unrelated crimes and was only fortuitously 
useful to the Sheriff's Office's investigation of VanderHeyden's 
homicide months later.  Exclusion therefore would not serve as a 
meaningful deterrent for the Police Department and is not 
warranted on that basis. 
No. 
2019AP1404-CR   
 
15 
 
exclusion would far outweigh the limited benefit——if any——its 
application could achieve. 
¶26 We conclude that suppression of Burch's cell phone 
data is not warranted under the exclusionary rule.  Regardless 
of whether a constitutional violation occurred, there was no 
police misconduct to trigger application of the exclusionary 
rule. 
 
B.  Fitbit Evidence 
¶27 Burch also appeals the circuit court's denial of his 
motion to exclude evidence associated with Detrie's Fitbit 
device.  Burch offers two arguments.  First, he argues the 
Fitbit evidence must be excluded because the State did not 
produce expert testimony to establish its reliability.  Second, 
he 
maintains 
the 
Fitbit 
evidence 
was 
insufficiently 
authenticated.10  We review these evidentiary rulings for an 
erroneous exercise of discretion.  State v. Nelis, 2007 WI 58, 
¶26, 300 Wis. 2d 415, 733 N.W.2d 619. 
 
                                                 
10 Burch also argues that admission of the Fitbit evidence 
violates the Confrontation Clause of the Sixth Amendment to the 
United States Constitution.  Burch concedes, however, that his 
novel argument "does not neatly fit within the test set forth in 
Crawford v. Washington, 541 U.S. 36 (2004)," and that he raised 
the issue solely "to preserve for review before higher courts."  
Accordingly, we reject Burch's Confrontation Clause claim and do 
not address it further. 
No. 
2019AP1404-CR   
 
16 
 
1.  Expert Testimony 
¶28 We have held that that "the requirement of expert 
testimony is an extraordinary one" and should apply only "when 
the issues before the jury are 'unusually complex or esoteric.'"  
State v. Kandutsch, 2011 WI 78, ¶28, 336 Wis. 2d 478, 799 
N.W.2d 865 (quoting another source).  Before compelling expert 
testimony, 
"the 
circuit 
court 
must 
first 
find 
that 
the 
underlying issue is 'not within the realm of the ordinary 
experience of mankind.'"  Id. (quoting Cramer v. Theda Clark 
Mem'l Hosp., 45 Wis. 2d 147, 150, 172 N.W.2d 427 (1969)).  What 
falls within the "ordinary experience of mankind," meanwhile, 
turns on the circuit court's exercise of its discretion "on a 
case-by-case basis" to decide whether "the issue is outside the 
realm of lay comprehension" or within the "common knowledge" of 
"the average juror."  Id., ¶29. 
¶29 Burch argues that the Fitbit evidence was improperly 
admitted because the circuit court should have required expert 
testimony to establish the reliability of the science underlying 
Fitbit's technology.  He notes that the Fitbit device features 
"a 
three-axis 
accelerometer 
sensor 
that 
generates 
data 
representing the user's movements," but explains that his 
"greater concern is with how the device processes the data into 
a meaningful output, how that output is exchanged with a phone 
or computer, and how that evidence ultimately ended up in 
Fitbit's business records." 
¶30 In its written order rejecting Burch's argument that 
expert testimony was required, the circuit court explained that 
No. 
2019AP1404-CR   
 
17 
 
Fitbit's step counters have been in the marketplace since 2009, 
and 
the 
"principle 
idea 
behind 
pedometers . . . for 
a 
significantly longer period than that."  Many smartphones, the 
court added, "come equipped with a pedometer by default."  
Analogizing to a watch and a speedometer, the court noted that 
even though the average juror may not know "the exact mechanics" 
of 
a 
technology's 
"internal 
workings," 
the 
public 
may 
nevertheless "generally understand[] the principle of how it 
functions and accept[] its reliability."  Similarly, the court 
reasoned, a Fitbit's use of sophisticated hardware and software 
does not render it an "unusually complex or esoteric" technology 
because the average juror is nevertheless familiar with what a 
Fitbit does and how it is operated. 
¶31 This conclusion was reasonable and within the circuit 
court's discretionary authority.  The circuit court correctly 
interpreted the standard for requiring expert testimony and 
reasonably applied that standard to the Fitbit evidence before 
it.  Given the widespread availability of Fitbits and other 
similar wireless step-counting devices in today's consumer 
marketplace, the circuit court reasonably concluded Detrie's 
Fitbit was not so "unusually complex or esoteric" that the jury 
needed an expert to understand it.11  The circuit court's 
                                                 
11 To the extent Burch now argues that the Fitbit is outside 
the realm of lay comprehension because it is an "internet of 
things" device, we are unpersuaded.  Wireless technology is 
nothing new.  It is entirely within the "ordinary experience of 
mankind" to use a Bluetooth or Wi-Fi connection to transfer data 
from one device to another. 
No. 
2019AP1404-CR   
 
18 
 
conclusion that expert testimony was not required under these 
circumstances was within the circuit court's discretion.12 
 
2.  Authentication 
¶32 Wisconsin Stat. § 909.01 (2019-20)13 sets out the 
evidentiary standard for authentication:  "The requirements of 
authentication or identification as a condition precedent to 
admissibility are satisfied by evidence sufficient to support a 
finding that the matter in question is what its proponent 
claims."  Simply put, authentication requires that a circuit 
court conclude, within its discretion, that the finder of fact 
could reasonably determine that the evidence sought to be 
admitted is what its proponent says it is.  Id.; State v. Smith, 
2005 WI 104, ¶¶31-33, 283 Wis. 2d 57, 699 N.W.2d 508.  In this 
case, that means the State's authentication obligation is to 
present sufficient evidence to support a finding that the 
records produced by the State are in fact Fitbit's records 
associated with Detrie's Fitbit device. 
¶33 Notably, Burch does not actually disagree that the 
State's 
records 
are 
accurate 
copies 
of 
Fitbit's 
records 
associated with Detrie's Fitbit device.  Instead, he focuses his 
challenge on whether the State properly authenticated "the 
                                                 
12 Of course, opposing counsel may attack the reliability of 
admitted evidence.  T.A.T. v. R.E.B., 144 Wis. 2d 638, 652-53, 
425 N.W.2d 404 (1988). 
13 All subsequent references to the Wisconsin Statutes are 
to the 2019-20 version unless otherwise indicated. 
No. 
2019AP1404-CR   
 
19 
 
information within those records."  Specifically, he argues that 
"the State failed to show that the Fitbit device reliably and 
accurately registered Detrie's steps that evening, and that that 
data was reliably and accurately transmitted to Fitbit's 
business records without manipulation." 
¶34 Burch's argument reaches beyond the threshold question 
authentication presents.  The circuit court's authentication 
obligation is simply to determine whether a fact-finder could 
reasonably conclude evidence is what its proponent claims it to 
be.  Wis. Stat. § 909.01.  The circuit court did so here by 
reviewing the Fitbit records and the affidavit of "a duly 
authorized custodian of Fitbit's records" averring that the 
records "are true and correct copies of Fitbit's customer data 
records," and then concluding the data was self-authenticating 
under Wis. Stat. § 909.02(12).14  The circuit court's obligation 
is not to scrutinize every line of data within a given record 
and decide whether each line is an accurate representation of 
the facts.  Rather, once the circuit court concludes the fact-
finder could find that the records are what their proponent 
claims them to be, the credibility and weight ascribed to those 
                                                 
14 More precisely, the circuit court held that the records 
were self-authenticating as certified records of regularly 
conducted activity.  See Wis. Stat. § 909.02(12).  Burch has 
not, either before the circuit court or this court, challenged 
the statements in the affidavit from Fitbit certifying that the 
records 
it 
provided 
are 
accurate 
copies 
of 
its 
records 
associated with Detrie's Fitbit device. 
No. 
2019AP1404-CR   
 
20 
 
records are questions left to the finder of fact.15  State v. 
Roberson, 2019 WI 102, ¶25, 389 Wis. 2d 190, 935 N.W.2d 813.  
The circuit court's conclusion that the Fitbit records were 
sufficiently authenticated therefore was within its discretion. 
 
III.  CONCLUSION 
¶35 Burch's appeal of his conviction for first-degree 
intentional homicide challenged the denial of two pre-trial 
evidentiary orders.  We uphold both orders, and therefore affirm 
the judgment of conviction.  Burch's cell phone data was 
properly admitted because, even if there was some constitutional 
defect in how it was obtained or retained, exclusion would be an 
improper remedy.  The circuit court also permissibly exercised 
its discretion in admitting the Fitbit evidence; no expert was 
required and the State sufficiently authenticated the records 
from Fitbit. 
By the Court.——The judgment of the circuit court is 
affirmed. 
                                                 
15 Here, too, opposing counsel can attack the reliability of 
admitted evidence.  See T.A.T., 144 Wis. 2d at 652-53. 
No.  2019AP1404-CR.rgb 
 
1 
 
¶36 REBECCA GRASSL BRADLEY, J.   (concurring).  I join the 
majority opinion in full.  Because there are no controlling 
cases interpreting the Fourth Amendment to prohibit the second 
search of Burch's cellphone by the Brown County Sheriff's Office 
(Sheriff's Office), the exclusionary rule does not apply and 
suppression of the evidence obtained from that search would be 
improper.1  I write separately to discuss the application of the 
Fourth Amendment to warrantless second searches of smartphones 
without consent. 
¶37 Under the original meaning of the Fourth Amendment, 
law enforcement generally will need a warrant to search the 
contents of a smartphone, absent an exception to the warrant 
requirement.  The consent-to-search exception, which the State 
argues authorized law enforcement to conduct a second search of 
Burch's smartphone data, does not extend to a second search of a 
smartphone by a different law enforcement agency investigating 
an entirely separate crime.  "Modern cell phones are not just 
another technological convenience.  With all they contain and 
all they may reveal, they hold for many Americans 'the privacies 
of life.'"  Riley v. California, 573 U.S. 373, 403 (2014) 
(quoting Boyd v. United States, 116 U.S. 616, 630 (1886)).  The 
Fourth Amendment secures "'the privacies of life' against 
'arbitrary power,'" and embodies the "central aim of the 
Framers . . . 'to place obstacles in the way of a too permeating 
                                                 
1 I also agree with the majority that the circuit court did 
not erroneously exercise its discretion by admitting evidence 
from Douglass Detrie's Fitbit device. 
No.  2019AP1404-CR.rgb 
 
2 
 
police surveillance.'"  Carpenter v. United States, 138 S. Ct. 
2206, 2214 (2018) (quoted sources omitted). 
¶38 The contents of smartphones constitute "papers" and 
"effects" secured by the Fourth Amendment, giving each of those 
categories their historical meanings and bearing in mind that "a 
cell phone search would typically expose to the government far 
more than the most exhaustive search of a house."  Riley, 573 
U.S. at 396.  Accordingly, law enforcement generally must get a 
warrant before searching a cell phone.  Id. at 403.  Because 
Burch's consent to search covered only the Green Bay Police 
Department's initial search of his smartphone for evidence 
related to a hit-and-run investigation, a warrant should have 
been procured before the Sheriff's Office searched Burch's 
smartphone data as part of an unrelated murder investigation.  
Because neither this court nor the United States Supreme Court 
has decided this novel issue, the Sheriff's Office committed no 
misconduct in searching Burch's cell phone and the circuit court 
properly admitted the evidence obtained from the search.  
Accordingly, I respectfully concur. 
I 
¶39 In June 2016, a few weeks after Nicole VanderHeyden's 
murder and the ensuing investigation by the Sheriff's Office, 
the Green Bay Police Department (Police Department) began 
investigating an entirely unrelated crime:  an auto theft that 
resulted in a hit-and-run incident.2  The stolen car belonged to 
Burch's roommate, and law enforcement identified Burch as a 
                                                 
2 The vehicle was also lit on fire. 
No.  2019AP1404-CR.rgb 
 
3 
 
person of interest because he had last driven the car.  Officer 
Robert Bourdelais of the Police Department interviewed Burch 
about the hit and run.  Burch denied any involvement, but 
informed Officer Bourdelais that, on the night of the hit and 
run, he was texting a woman who lived one block away from the 
location of the accident.  Burch stated that he did not go to 
the woman's house on the night of the incident, and never made 
arrangements to go to her house.  According to Officer 
Bourdelais' testimony, he and Burch had the following exchange: 
I asked him if I could see the text messages between 
him and [the woman], if my lieutenant and I could take 
a look at his text messages.  He said that we 
could . . . .  I [then] asked him if he would be 
willing to let me take his phone to this detective, 
download the information off the phone and then I'd 
bring the phone right back to him, probably take a 
half an hour and he said that would be fine. 
¶40 The attorney eliciting Officer Bourdelais' testimony 
inquired:  "When you asked [Burch] about downloading the 
information off of his phone, did you specifically limit the 
information to the text messages when you were talking to him?"  
Officer Bourdelais responded: 
No, I didn't.  Initially, when I had asked him, hey, 
do you mind if we take a look at those text messages, 
I refer to them as text messages because he said he 
was texting [the woman] back and forth, but from my 
experience 
as 
a 
police 
officer 
I 
know 
people 
communicate [by] phone calls, text messages, texting 
apps like WhatsApp, MINE, Facebook Messenger, things 
like that.  So that's the information, I wanted 
information to corroborate that whatever conversation 
he had with [the woman] or communication he had 
supported his claims that he never went over to her 
house or made arrangements to go over to her house. 
No.  2019AP1404-CR.rgb 
 
4 
 
¶41 Following the exchange between Burch and Officer 
Bourdelais, Burch signed a consent form which read as follows:  
"I, George Stephen Burch, . . . voluntarily give Det. Danielski, 
Officer Bourdelais, or any assisting personnel permission to 
search my . . . Samsung cellphone."  Subsequently, at the 
instruction of Officer Bourdelais, a Police Department forensic 
examiner downloaded all of the data from Burch's cellphone into 
the Police Department records database.  The forensic examiner 
then converted the data into a readable format, and tabbed the 
data into categories such as text messages, images, and internet 
history.  At the homicide trial, the forensic examiner testified 
that the Police Department retains smartphone data for an 
indefinite amount of time, noting that "[e]ver since [she] [has] 
been employed with [the Police Department], [they] have saved 
all extractions for long-term storage for as far back as [she] 
[has] been employed," which was roughly two years at the time of 
trial. 
¶42 In August 2016 (two months after Burch consented to 
the search of his phone for the hit-and-run investigation), the 
Sheriff's Office identified Burch as a person of interest in the  
investigation into the murder of VanderHeyden based upon a DNA 
match on VanderHeyden's socks.  Relying on databases shared 
between 
the 
Sheriff's 
Office 
and 
other 
local 
entities, 
detectives from the Sheriff's Office discovered that the Police 
Department had prior contact with Burch while investigating the 
unrelated hit-and-run incident.  After the detectives learned 
that the Police Department had extracted all of Burch's 
No.  2019AP1404-CR.rgb 
 
5 
 
smartphone data in June 2016, they procured a copy of the data 
from the Police Department and searched its contents "for 
anything in the timeframe of the night of [the murder] into the 
[following] morning, whether it be calls, texts, internet 
history, any kind of location data available from that device."  
The detectives did not obtain a warrant for this search.  In 
reviewing the data, the detectives discovered that, shortly 
after the murder, Burch repeatedly searched for news articles 
about the murder using his internet browser. 
¶43 Additionally, during their warrantless search of the 
smartphone's contents, the detectives learned that Burch had a 
Google email account (Gmail).  The detectives were aware that 
Gmail addresses are associated with a Google Dashboard, which 
tracks an individual's location based upon GPS, Wi-Fi, and 
cellphone tower data.  The detectives procured a search warrant 
to obtain Google Dashboard information from Google.  The 
location data placed Burch's smartphone at various critical 
places on the night of the murder, including the location of 
VanderHeyden's body and the on-ramp where her discarded clothing 
was discovered. 
¶44 Burch was arrested and charged with first-degree 
intentional homicide.  In a pre-trial motion, Burch moved to 
suppress the evidence obtained by the Sheriff's Office from the 
warrantless search of his smartphone data.3  Burch argued that 
the Sheriff's Office "violated the Fourth Amendment when [it] 
                                                 
3 Burch also filed a motion to exclude evidence related to 
Detrie's Fitbit device, which the circuit court denied. 
No.  2019AP1404-CR.rgb 
 
6 
 
searched the phone data initially seized by [the Police 
Department]."  Specifically, Burch contended that the Sheriff's 
Office "blew past Mr. Burch's scope of consent, and likewise, 
obliterated any Fourth Amendment warrant exceptions."  The 
circuit court denied Burch's suppression motion, and the State 
introduced at trial the evidence obtained from the smartphone.  
The jury convicted Burch of first-degree intentional homicide.  
Burch appealed the circuit court's decision to admit the 
evidence procured by the Sheriff's Office from its search of his 
smartphone data.  The court of appeals certified Burch's Fourth 
Amendment 
challenge 
to 
this 
court, 
and 
we 
accepted 
certification. 
II 
¶45 The Fourth Amendment 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, and no 
Warrants 
shall 
issue, 
but 
upon 
probable 
cause, 
supported by Oath or affirmation, and particularly 
describing the place to be searched, and the persons 
or things to be seized. 
U.S. Const. amend. IV.  "The first clause outlaws promiscuous 
search and seizure, even as the second clarifies precisely what 
will be required for a particularized warrant to be valid."  
Laura K. Donohue, The Original Fourth Amendment, 83 U. Chi. L. 
Rev. 1181, 1193 (2016); State v. Pinder, 2018 WI 106, ¶¶48-51, 
384 Wis. 2d 416, 919 N.W.2d 568.  As understood at the time the 
Fourth Amendment was ratified, "[t]he government could not 
violate the right against search and seizure of one's person, 
house, papers, or effects absent either a felony arrest or a 
No.  2019AP1404-CR.rgb 
 
7 
 
warrant meeting the requirements detailed in the second clause."  
Donohue, supra, at 1193. 
¶46 As the United States Supreme Court has repeatedly 
held, "the ultimate touchstone of the Fourth Amendment is 
'reasonableness.'"  Brigham City v. Stuart, 547 U.S. 398, 403 
(2006).  "[W]hether an individual has a reasonable expectation 
of 
privacy 
in 
avoiding 
the 
method 
of 
search 
and 
a reasonable expectation of privacy in the place searched are 
the 
questions 
that 
drive 
a 
court's 
examination 
of 
the 
reasonableness of the search."  State v. Brereton, 2013 WI 17, 
¶32, 345 Wis. 2d 563, 826 N.W.2d 369.  "The general rule is that 
searches and seizures conducted without a warrant are not 
reasonable." 
 
State 
v. 
Randall, 
2019 
WI 
80, 
¶10, 
387 
Wis. 2d 744, 930 N.W.2d 223.  However, there are a number of 
exceptions to the warrant requirement.  See Riley, 573 U.S. at 
382 ("In the absence of a warrant, a search is reasonable only 
if it falls within a specific exception to the warrant 
requirement.").  "One of the exceptions to the warrant rule is 
that 
an 
individual's 
consent 
to 
search 
satisfies 
the 
constitutional 'reasonableness' requirement."  Randall, 387 
Wis. 2d 744, ¶10; see also Birchfield v. North Dakota, 136 S. 
Ct. 2160, 2185 (2016) ("It is well established that a search is 
reasonable when the subject consents[.]").  "If a search is 
premised on an individual's consent, it must cease immediately 
upon revocation of that consent," and an individual "may of 
course delimit as she chooses the scope of the search to which 
No.  2019AP1404-CR.rgb 
 
8 
 
she 
consents." 
 
Randall, 
387 
Wis. 2d 744, 
¶10 
(internal 
alterations and citations omitted). 
¶47 Just a few years ago, the United States Supreme Court 
addressed the Fourth Amendment's application to a modern 
phenomenon:  the proliferation of smartphones and their ever-
increasing capacity to store mass amounts of data.  The Court 
held that law enforcement generally must obtain a warrant before 
conducting a search of smartphone data.  Specifically, the Riley 
Court clarified that "[its] holding . . . is not that the 
information on a cell phone is immune from search," but "instead 
that a warrant is generally required before such a search, even 
when a cell phone is seized incident to arrest."4  Riley, 573 
U.S. at 401.  In reaching this holding, the Court recognized the 
"pervasiveness that characterizes cell phones" and how "[c]ell 
phones differ in both a quantitative and a qualitative sense 
from other objects."  Id. at 393, 395.  "The possible intrusion 
on privacy is not physically limited in the same way [as other 
objects] when it comes to cell phones."  Id. at 394.  "An 
internet search and browsing history, for example, can be found 
on an internet-enabled phone and could reveal an individual's 
private 
interests 
or 
concerns," 
and 
"historic 
location 
                                                 
4 Although 
Riley involved the search-incident-to-arrest 
exception to the Fourth Amendment warrant requirement, the 
principles it espouses apply more broadly.  See Riley v. 
California, 573 U.S. 373, 386 (2014) ("[O]fficers must generally 
secure a warrant before conducting such a search [of a cell 
phone]."); see also People v. Hughes, 958 N.W.2d 98, 108 (Mich. 
2020) ("In Riley v. California, the Supreme Court of the United 
States held that officers must generally obtain a warrant before 
conducting a search of cell-phone data."). 
No.  2019AP1404-CR.rgb 
 
9 
 
information" 
could 
allow 
law 
enforcement 
to 
"reconstruct 
someone's specific movements down to the minute."  Id. at 395-
96. 
¶48 The United States Supreme Court fully understood that 
its decision "[would] have an impact on the ability of law 
enforcement to combat crime."  Id. at 401.  After all, "[c]ell 
phones have become important tools in facilitating coordination 
and communication" for individuals committing crimes and "can 
provide 
valuable 
incriminating 
information 
about 
dangerous 
criminals."  Id.  But "[p]rivacy comes at a cost."  Id.  And the 
Fourth Amendment is designed to safeguard the people's security 
against unreasonable government intrusion.  Riley recognizes 
that the Fourth Amendment safeguards this right by generally 
requiring law enforcement to procure a warrant before searching 
a smartphone. 
¶49 A warrant requirement for searches of smartphone data 
comports with the original meaning of the Fourth Amendment.  The 
Framers, "after consulting the lessons of history, designed our 
Constitution to place obstacles in the way of a too permeating 
police surveillance, which they seemed to think was a greater 
danger to a free people than the escape of some criminals from 
punishment."  United States v. Di Re, 332 U.S. 581, 595 (1948).  
In 
particular, 
"the 
Fourth 
Amendment 
was 
the 
founding 
generation's response to the reviled 'general warrants' and 
'writs of assistance' of the colonial era, which allowed British 
officers to rummage through homes in an unrestrained search for 
evidence of criminal activity.  Opposition to such searches was 
No.  2019AP1404-CR.rgb 
 
10 
 
in fact one of the driving forces behind the Revolution itself."  
Riley, 573 U.S. at 403.  "Indeed, the character of that threat 
implicates the central concern underlying the Fourth Amendment——
the concern about giving police officers unbridled discretion to 
rummage at will among a person's private effects."  Arizona v. 
Gant, 556 U.S. 332, 345 (2009).  For the Framers, it was 
absolutely necessary to ensure "the government not be allowed 
free 
rein 
to 
search 
for 
potential 
evidence 
of 
criminal 
wrongdoing."  Donohue, supra, at 1194. 
¶50  The Framers designed the Fourth Amendment to protect 
the people from government overreach.  Described as the "very 
essence of constitutional liberty and security," the Fourth 
Amendment applies to "all invasions on the part of the 
government and its employes of the sanctity of a man's home and 
the privacies of life."  Boyd, 116 U.S. at 630.  "It is not the 
breaking of [one's] doors, and the rummaging of his drawers, 
that constitutes the . . . offense; but it is the invasion of 
his infeasible right of personal security, personal liberty, and 
private property[.]"  Id.  With this understanding in mind, 
"[t]he Supreme Court has . . . confirmed that the basic purpose 
of the Fourth Amendment 'is to safeguard the privacy and 
security 
of 
individuals 
against 
arbitrary 
invasions 
by 
governmental officials'"——that is, "to secure 'the privacies of 
life' against 'arbitrary power.'"  Matthew DeVoy Jones, Cell 
Phones are Orwell's Telescreen: The Need for Fourth Amendment 
Protection in Real-Time Cell Phone Location Information, 67 
No.  2019AP1404-CR.rgb 
 
11 
 
Clev. St. L. Rev. 523, 533 (2019) (quoting Carpenter, 138 S. Ct. 
at 2213-14). 
¶51 The Fourth Amendment specifically recognizes the right 
of people to be secure in their "persons, houses, papers, and 
effects."  U.S. Const. amend. IV; see United States v. Jones, 
565 U.S. 400, 406 (2012) ("[F]or most of our history the Fourth 
Amendment was understood to embody a particular concern for 
government trespass upon the areas ('persons, house, papers, and 
effects') it enumerates.").  Much modern analysis of the Fourth 
Amendment has centered upon the primacy of protecting "houses."  
See Payton v. New York, 445 U.S. 573, 589 (1980) ("The Fourth 
Amendment protects the individual's privacy in a variety of 
settings.  In none is the zone of privacy more clearly defined 
than when bounded by the unambiguous physical dimensions of an 
individual's home[.]").  However, as the Riley Court explained, 
smartphones implicate privacy interests more compelling than 
even those associated with the home.  "A cell phone search would 
typically expose to the government far more than the most 
exhaustive search of a house:  A phone not only contains in 
digital form many sensitive records previously found in the 
home; it also contains a broad array of private information 
never found in a home in any form[.]"  Riley, 573 U.S. at 396-
97. 
¶52 Given the nature of its contents, a smartphone is not 
just another personal item; it is a device that holds many 
modern "privacies of life"——an area that receives acute and 
particularized protection from government interference under the 
No.  2019AP1404-CR.rgb 
 
12 
 
Fourth Amendment.  See Boyd, 116 U.S. at 630.  Governmental 
searches of smartphones invade "the indefeasible right of 
personal security, personal liberty, and private property," 
which Americans hold "sacred."  Id.  Permitting law enforcement 
to rummage through the data residing in smartphones without a 
warrant would "allow[] free rein to search for potential 
evidence of criminal wrongdoing," which the Fourth Amendment 
prohibits.  With respect to smartphone data, as in the home, 
"all details are intimate details, because the entire area is 
held safe from prying government eyes."  See Kyllo v. United 
States, 533 U.S. 27, 37 (2001). 
¶53 The Fourth Amendment includes both "papers" and 
"effects" among the four enumerated categories protected from 
unreasonable searches.  The contents of smartphones constitute 
"papers" within the original understanding of the Fourth 
Amendment.  "Historically, private papers, including documents 
and pamphlets that challenged governmental power, served as a 
central point of contestation in the Founding era."  Andrew 
Guthrie Ferguson, The "Smart" Fourth Amendment, 102 Cornell L. 
Rev. 547, 595-96 (2017).  The Fourth Amendment's protection of 
"papers" "reflect[s] the importance of freedom of thought, 
expression, and communication."  Id.  According to Lord Camden 
in his seminal decision in Entick v. Carrington, "papers are 
often the dearest property a man can have."  19 How. St. Tr. 
1029 (C.P. 1765). 
¶54 The 
Framers' 
inclusion 
of 
"papers" 
within 
the 
protections of the Fourth Amendment was motivated in part by the 
No.  2019AP1404-CR.rgb 
 
13 
 
case of John Wilkes, "who was targeted for writing mocking 
articles about King George III" and had his papers seized by 
investigating officers.  Ferguson, supra, at 596 (citation 
omitted).  "The Wilkes controversy . . . directly influenced the 
[F]ramers of the Fourth Amendment.  The English search and 
seizure cases received extensive publicity in England and in 
America, and the Wilkes case was the subject of as much 
notoriety and comment in the colonies as it was in Britain."  
Eric Schnapper, Unreasonable Searches and Seizures of Papers, 71 
Va. L. Rev. 869, 912-13 (1985).  "Wilkes' cause generated many 
supporters among American colonists, some of whom became key 
figures in the framing of the Constitution."  Id. at 913.  Based 
upon Wilkes' case, "[p]rotecting private papers . . . became a 
central rallying cry in the creation of constitutional liberty," 
receiving 
explicit 
protection 
under 
the 
United 
States 
Constitution.  Ferguson, supra, at 596. 
¶55 Today, the people's "papers" largely exist in digital 
form.  "E-mails, texts, and other social media communication 
have replaced letter writing."  Id. at 599.  Additionally, 
calendars, notes, health information, photographs, restaurant 
and hotel reservations, airline flights, shopping and browsing 
histories, as well as banking transactions all reside in (or are 
accessible from) smartphones, forming a digital diary of one's 
life, accessible from a single source.  Given the breadth and 
detail of this information, "individuals have expectations of 
privacy in their digital papers."  Id. at 600.  From the 
Framers' outrage over the search of Wilkes' papers to the 
No.  2019AP1404-CR.rgb 
 
14 
 
Court's 
concern 
regarding 
the 
search 
of 
David 
Riley's 
smartphone, the overarching aim "has always been the protection 
of ideas embodied in those papers"——not whether the papers are 
in physical or digital form.  Id. at 613. 
¶56 Some portion of the contents of smartphones, as well 
as the devices themselves, also constitute "effects," which 
"have historically been understood to mean personal property——
the objects we possess."  Id. at 578 (citing Dictionarium 
Brittanicum (Nathan Baily ed., 1730) (defining "effects" as "the 
goods of a merchant, tradesman") and Noah Webster, First Edition 
of an American Dictionary of the English Language (1828) 
(defining "effects" as "goods; moveables; personal estate")).  
"The 
early 
American 
understanding 
distinguished 
personal 
property from real property," and "personal property meant 
physical belongings"——items which were "obviously prized by the 
Founders" and accordingly received Fourth Amendment protection.  
Id.  Founding-era history "demonstrates that effects were 
specifically included in the constitutional text [not only] 
because of the harms to privacy and dignity that could be 
incurred in their inspection, but also because of the risk of 
mishandling or damage generally associated with interferences 
with personal property."  Maureen E. Brady, The Lost "Effects" 
of 
the 
Fourth 
Amendment: 
 
Giving 
Personal 
Property 
Due 
Protection, 125 Yale L.J. 946, 987 (2016).  Founding-era sources 
suggest the Framers understood "[p]ersonal property [to] give[] 
its owner a right to exclude others from possessing, using, and 
interfering with the effect"——and most of all to "protect[] 
No.  2019AP1404-CR.rgb 
 
15 
 
privacy interests with respect to the property."  Id. at 993-94 
(discussing founding-era sources, including William Blackstone's 
Commentaries 
and 
Lord 
Camden's 
judgment 
in 
Entick 
v. 
Carrington). 
¶57 Although "'effects' has captured rather less of the 
[United States] Supreme Court's attention" than "papers" and 
"houses," when the Court has addressed the topic, "property 
considerations loom large."  Laura K. Donohue, The Fourth 
Amendment in a Digital World, 71 N.Y.U. Ann. Surv. Am. L. 553, 
679 (2017).  For example, in United States v. Jones, the United 
States Supreme Court held that law enforcement's installation of 
a GPS device on an individual's vehicle to monitor the vehicle's 
movements constituted a "search" under the Fourth Amendment, 
deeming it "beyond dispute" that a vehicle is an "effect" within 
the meaning of the Fourth Amendment.  565 U.S. 400, 404 (2012).  
The Court emphasized the government's "physical intrusion" of 
the "effect" at issue.  Id. at 411.  The Court did not focus on 
the physical attachment of the GPS device to the effect but 
rather 
the 
device's 
capture 
of 
sensitive 
and 
private 
information, "relay[ing] more than 2,000 pages of data over [a] 
4-week period."  Id. at 403; see also Ferguson, supra, at 606 
("[In Jones] the real harm was exposing the revealing personal 
data about the effect (car).").  That is, in Jones the Fourth 
Amendment analysis turned on the "capturing of data trails" of 
the owner and "invad[ing] the informational security of the 
effect."  Ferguson, supra, at 606.  The Court's reasoning in 
Jones applies no less to smartphones and the data they hold, 
No.  2019AP1404-CR.rgb 
 
16 
 
supporting the characterization of smartphones as "effects" 
entitled to constitutional protection from unreasonable searches 
and seizures. 
III 
¶58 Having 
established 
a 
historical 
basis 
for 
the 
application of the Fourth Amendment's warrant requirement to 
smartphones and their data, it is necessary to address the 
application of the consent exception to the warrant requirement 
within the context of the facts of Burch's case.  It is well-
established that "[o]ne of the exceptions to the warrant rule is 
that 
an 
individual's 
consent 
to 
search 
satisfies 
the 
constitutional 'reasonableness' requirement."  Randall, 387 
Wis. 2d 744, ¶10; see also Birchfield, 136 S. Ct. at 2185.  
Burch gave consent for the Police Department to download and 
search his smartphone and its data as part of the investigation 
of the hit-and-run incident in June 2016.  According to his 
testimony, Officer Bourdelais asked Burch if "[he] could see the 
text messages between him and [the woman]" on the night of the 
hit-and-run incident.  Officer Bourdelais then asked Burch if he 
could 
"take 
his 
phone 
to 
this 
detective, 
download 
the 
information off the phone" and then bring it right back to 
Burch.  Burch agreed to all requests in this exchange and signed 
a consent form saying he "voluntarily give[s] Det. Danielski, 
Officer Bourdelais, or any assisting personnel permission to 
search [his] . . . Samsung cellphone."  Burch permitted Officer 
Bourdelais 
"or 
any 
assisting 
personnel" 
to 
download 
his 
smartphone's data and search for evidence of the hit-and-run 
No.  2019AP1404-CR.rgb 
 
17 
 
incident.  Burch's consent encompassed the Police Department's 
investigation of a particular crime.  The Constitution permitted 
this search.  Schneckloth v. Bustamonte, 412 U.S. 218, 222 
(1973) ("[A] search conducted pursuant to a valid consent is 
constitutionally permissible."). 
¶59 Two months later, a different law enforcement agency——
the Sheriff's Office——searched Burch's smartphone data while 
investigating an entirely separate crime.  This search went 
beyond the scope of Burch's consent.  Officer Bourdelais 
questioned Burch in June 2016 regarding the hit-and-run incident 
only, 
and 
obtained 
Burch's 
consent 
to 
download 
Burch's 
smartphone data "[to] corroborate that whatever conversation 
[Burch] had with [the woman] . . . supported his claims that he 
never went over to her house" the night of the hit and run.  The 
consent form did not include any language authorizing a second 
search by a separate law enforcement agency for a different 
crime.  The form authorized only Officer Bourdelais, the 
forensic 
examiner 
(Det. 
Danielski), 
and 
their 
assisting 
personnel to view the smartphone's contents.  Any search beyond 
the scope of Burch's consent would require a warrant. 
¶60 The State argues that this court's decision in State 
v. Betterley, 191 Wis. 2d 406, 529 N.W.2d 216 (1995), allows law 
enforcement to take a "second look" at smartphone data that was 
previously searched.  That case does not apply to searches of 
cell phone data.  In Betterley, officers at the St. Croix County 
Jail seized a ring from the defendant during an inventory 
search.  Id. at 414.  Later that day, a New Richmond police 
No.  2019AP1404-CR.rgb 
 
18 
 
officer asked to see the ring, believing it was evidence that 
the defendant had committed insurance fraud.  Id. at 415.  The 
New Richmond police officer retained the ring as evidence 
without obtaining a warrant.  Id.  This court held that "the 
permissible extent of the second look [at evidence] is defined 
by what the police could have lawfully done without violating 
the defendant's reasonable expectations of privacy during the 
first search, even if they did not do it at that time."  Id. at 
418.  Because the defendant had a diminished expectation in 
privacy in the ring after forfeiting it during the first search, 
the second look at the ring was permissible, so long as it was 
"no more intrusive" than the first search.  Id. 
¶61 Betterley does not apply to cell phone data retrieved 
pursuant to the owner's consent.  Betterley involved an 
inventory search of an item, not the consent-to-search exception 
to the warrant requirement.  Unlike searches conducted with 
consent, inventory searches are "administrative by nature, not 
an investigation motivated by a search for evidence."  State v. 
Weber, 163 Wis. 2d 116, 132, 471 N.W.2d 187 (1991).  More 
importantly, physical items such as rings are qualitatively 
different than searches of smartphone data.  Examination of a 
ring reveals nothing more than the physically observable item 
itself, while smartphones contain——and conceal——the "privacies 
of life," which generally are not viewable by others at a 
glance.  For this reason, smartphones "differ in both a 
quantitative and a qualitative sense from other objects."  
Riley, 573 U.S. at 393.  "[I]t is no exaggeration to say that 
No.  2019AP1404-CR.rgb 
 
19 
 
many of the more than 90% of American adults who own a cell 
phone keep on their person a digital record of nearly every 
aspect of their lives——from the mundane to the intimate.  
Allowing the police to scrutinize such records on a routine 
basis is quite different from allowing them to search a personal 
item or two in the occasional case."   Id. at 395.  Certainly, 
"the possible intrusion on privacy is not physically limited in 
the same way [as other objects] when it comes to cell phones."  
Id. at 394.  Accordingly, Betterley does not inform the Fourth 
Amendment analysis governing searches of cell phone data. 
¶62 Even if "a Fourth Amendment violation has occurred," 
however, it "does not mean the exclusionary rule applies," 
particularly because "exclusion [of evidence] is the last 
resort."  State v. Dearborn, 2010 WI 84, ¶35, 327 Wis. 2d 252, 
786 N.W.2d 97.  "To trigger the exclusionary rule, police 
misconduct must be sufficiently deliberate that exclusion can 
meaningfully deter it, and sufficiently culpable that such 
deterrence is worth the price paid by the justice system."  Id., 
¶36 (quoted source omitted).  For the reasons stated in the 
majority opinion, there was no misconduct by the Sheriff's 
Office.  Neither this court nor the United States Supreme Court 
has declared that second searches of cell phone data by separate 
law enforcement agencies require a warrant.  Accordingly, 
suppression of the evidence obtained during the Sheriff's 
Office's second search would be inappropriate and I respectfully 
concur. 
No.  2019AP1404-CR.rgb 
 
20 
 
* * * 
¶63 "The great end, for which men entered into society, 
was to secure their property."  Entick v. Carrington, 19 How. 
St. Tr. 1029 (C.P. 1765) (Lord Camden presiding).  "Property 
must be secured, or liberty cannot exist."  Discourses on 
Davila, in 6 The Works of John Adams 280 (C. Adams ed. 1851).  
"The Fourth Amendment imposes limits on search-and-seizure 
powers in order to prevent arbitrary and oppressive interference 
by enforcement officials with the privacy and personal security 
of individuals."  United States v. Martinez-Fuerte, 428 U.S. 
543, 554 (1976).  Because smartphones contain the "privacies of 
life," law enforcement generally needs a warrant to search the 
data they hold unless an exception to the warrant requirement 
applies. 
No.  2019AP1404-CR.rfd 
 
1 
¶64 REBECCA 
FRANK 
DALLET, 
J.   (concurring 
in 
part, 
dissenting in part).  Under the Fourth Amendment, when the 
police want to search a person's private information, they 
generally need a warrant.  The Brown County Sheriff's Office 
searched George Steven Burch's private cell phone data without 
obtaining a warrant, assuming that Burch's consent for another 
agency to download his phone's data for a wholly separate 
investigation obviated its Fourth Amendment duty to do so.  It 
did not.  The Sheriff's Office's warrantless search of Burch's 
cell phone data violated the Fourth Amendment, and the evidence 
obtained from that unlawful search should be suppressed.  The 
majority 
opinion's 
contrary 
holding 
ignores 
the 
novel 
constitutional 
problems 
presented 
by 
private 
cell 
phone 
information, is inconsistent with the Fourth Amendment's text, 
and undermines the exclusionary remedy for Fourth Amendment 
violations.  I therefore respectfully dissent from that part of 
the majority opinion.1 
I.  BACKGROUND 
¶65 A 
Green 
Bay 
Police 
Department 
(GBPD) 
officer 
interviewed Burch while investigating crimes involving the car 
Burch would borrow for work.  Burch denied his involvement but 
acknowledged that he was text messaging a friend that night who 
lived near the scene.  When the officer asked Burch if he and 
his lieutenant could see those text messages, Burch verbally 
consented.  After the officer explained that it was easier to 
                                                 
1 I join Parts I. and II.B. of the majority opinion because 
I agree that the circuit court permissibly admitted evidence 
regarding a Fitbit device. 
No.  2019AP1404-CR.rfd 
 
2 
download 
"the 
information" 
from 
the 
phone 
than 
to 
take 
screenshots, Burch verbally consented to allowing the officer to 
take his phone to a GBPD detective for that purpose.2  The 
officer then presented Burch with a standardized written consent 
form.  The form contained the heading "City of Green Bay Police 
Department" and indicated that Burch "voluntarily" gave a named 
GBPD officer, a named GBPD detective, as well as any "assisting 
personnel," "permission to search" his "Samsung Cellphone."  
Burch signed the form.  The officer testified that he requested 
only 
"text 
messages, 
phone 
calls, 
Facebook 
posts, 
and 
photographs taken any time after 11:00 p.m." the night of the 
accident; yet, to access that information, the GBPD downloaded 
the entire contents of Burch's phone. 
¶66 Two 
months 
later, 
the 
Sheriff's 
Office 
was 
investigating a homicide that had occurred a few weeks before 
the crimes being investigated by the GBPD.  It matched Burch's 
DNA to DNA collected from the victim's body, her socks, and a 
cord believed to be used in her murder.  The Sheriff's Office 
                                                 
2 At trial, the officer testified that by "the information," 
he meant any communications between Burch and his friend that 
would corroborate Burch's alibi: 
Initially, when I had asked [Burch], hey, do you mind 
if we take a look at those text messages, I refer to 
them as text messages because he said he was texting 
[his friend] back and forth, but from my experience as 
a police officer I know people communicate phone 
calls, text messages, texting apps like WhatsApp, 
MINE, Facebook Messenger, things like that.  So that's 
the information, I wanted information to corroborate 
that whatever conversation he had with [his friend] or 
communication he had supported his claims that he 
never went over to [the victim's] house or made 
arrangements to go over to her house. 
No.  2019AP1404-CR.rfd 
 
3 
also discovered that the GBPD had retained the full data 
extraction from Burch's cell phone.  After reviewing the GBPD's 
files and seeing Burch's signed consent form, the Sheriff's 
Office searched that data without first obtaining a warrant.  
The search led the Sheriff's Office to Burch's internet search 
history and his Google email account.  The internet history 
revealed that Burch had viewed online stories about the victim's 
disappearance 64 times.  The email account allowed the Sheriff's 
Office to issue Google a subpoena for Burch's Google Dashboard 
records, which included his location data from the night of the 
murder.  The location data placed Burch's cell phone near the 
victim's residence and the field where her body was discovered 
around the time of the victim's death. 
II.  ANALYSIS 
¶67 The Fourth Amendment inquiry here is two-fold.  The 
first 
consideration 
is 
whether 
the 
Sheriff's 
Office's 
warrantless search of the GBPD's download of Burch's data was 
unreasonable.  If so, it violated the Fourth Amendment, and the 
question becomes whether excluding the unlawfully obtained 
evidence would sufficiently deter the same police conduct in the 
future.  These questions involve a mixed standard of review, 
under which we uphold the circuit court's findings of historical 
fact unless they are clearly erroneous, but we review de novo 
the application of constitutional principles to those facts.  
See State v. Blackman, 2017 WI 77, ¶25, 377 Wis. 2d 339, 898 
N.W.2d 774. 
No.  2019AP1404-CR.rfd 
 
4 
A.  The Sheriff's Office's Warrantless Search Was Unreasonable. 
¶68 The Fourth Amendment to the United States Constitution 
prohibits the government from conducting "unreasonable" searches 
of a person, a person's home, or her "effects": 
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 
warrants shall issue, but upon probable cause . . . . 
The Amendment seeks to secure "the privacies of life" against 
such unreasonable searches by placing "obstacles in the way of a 
too permeating police surveillance."  See Carpenter v. United 
States, 585 U.S. ___, 138 S. Ct. 2206, 2214 (2018).  Police 
surveillance amounts to a "search," for purposes of the Fourth 
Amendment, when it collects information in which the person has 
a reasonable expectation of privacy.  E.g., id. at 2213-14. 
¶69 To protect one's reasonable expectation of privacy, 
the text of the Fourth Amendment communicates a "strong 
preference for searches conducted pursuant to a warrant."  See 
Illinois v. Gates, 462 U.S. 213, 236 (1983); U.S. Const. 
amnd. IV.  Indeed, a warrantless search is per se unreasonable, 
see Schneckloth v. Bustamonte, 412 U.S. 218, 219 (1973), and 
presumptively violates the Fourth Amendment, see State v. 
Tate, 2014 WI 89, ¶27, 357 Wis. 2d 172, 849 N.W.2d 798.  That 
presumption is overcome only when the warrantless search falls 
under one of the "few specifically established and well-
delineated exceptions."  State v. Coffee, 2020 WI 53, ¶24, 391 
Wis. 2d 831, 943 N.W.2d 845. 
¶70 Consent is one such exception.  State v. Hogan, 2015 
WI 76, ¶55, 364 Wis. 2d 167, 868 N.W.2d 124.  As with any 
No.  2019AP1404-CR.rfd 
 
5 
exception to the warrant requirement, consent is "jealously and 
carefully drawn," and must be "confined in scope" and "strictly 
circumscribed."  See Jones v. United States, 357 U.S. 493, 499 
(1958); Terry v. Ohio, 392 U.S. 1, 25-26, 29 (1968).  Consent to 
a 
particular 
search 
must 
therefore 
be 
"unequivocal 
and 
specific."  State v. Reed, 2018 WI 109, ¶8, 384 Wis. 2d 469, 920 
N.W.2d 56.  Even absent express limits, the scope of consent is 
neither "boundless" nor "perpetual."  See State v. Douglas, 123 
Wis. 2d 13, 
21-22, 
365 
N.W.2d 580 
(1985) 
(lead 
opinion).  
Rather, its scope is determined objectively as "the typical 
reasonable person [would] have understood" it from "the exchange 
between the officer and the suspect."  Florida v. Jimeno, 500 
U.S. 248, 251 (1991).  When the police rely on consent as their 
justification for not getting a warrant, the State carries the 
burden to demonstrate by clear and convincing evidence that the 
search remained within the scope of that consent.  See Reed, 384 
Wis. 2d 469, ¶58; Douglas, 123 Wis. 2d at 22 (explaining that a 
warrantless 
search 
exceeding 
the 
scope 
of 
consent 
is 
unreasonable). 
¶71 The lawfulness of the Sheriff's Office's search 
therefore turns on two sub-questions:  (1) although he consented 
to 
specific 
GBPD 
personnel 
downloading 
his 
cell 
phone 
information, did Burch maintain a reasonable expectation of 
privacy in that information such that the Sheriff's Office 
review of it was a Fourth Amendment search; and, if so, (2) did 
the Sheriff's Office act unreasonably by searching the GBPD's 
download of Burch's cell phone data without a warrant, in light 
of Burch's consent to the GBPD? 
No.  2019AP1404-CR.rfd 
 
6 
1.  Burch Maintained a Reasonable Expectation of Privacy in the 
GBPD's Download of His Cell Phone Data. 
¶72 In the Fourth Amendment context, the United States 
Supreme Court has clearly expressed that cell phone data is in 
an evidence class of its own because it "implicate[s] privacy 
concerns far beyond those implicated by the search of" other 
physical belongings.  Riley v. California, 573 U.S. 373, 393 
(2014).  Cell phones are unique in that they are almost always 
with 
us 
and 
they 
store 
"vast 
quantities 
of 
personal 
information."  Id. at 386.  Thus, by carrying cell phones, 
people carry with them "a digital record of nearly every aspect 
of their lives——from the mundane to the intimate."  Id. at 395.  
That digital record may include a person's internet "search and 
browsing history" and "[h]istoric location information," see id. 
at 395-96, allowing someone with access to that information to 
"generate[] a precise, comprehensive record of a person's public 
movements that reflects a wealth of detail about her familial, 
political, professional, religious, and sexual associations," 
see 
United 
States 
v. 
Jones, 
565 
U.S. 400, 
415 
(2012) 
(Sotomayor, J., 
concurring). 
 
Although 
traditionally 
most 
private information was kept in one's home, advances in digital 
technology have shifted that paradigm such that searching a 
personal cell phone "would typically expose to the government 
far more than the most exhaustive search of a house."  
Riley, 573 U.S. at 396-97.  Accordingly, people have a unique 
and heightened expectation of privacy in their cell phone data 
that demands commensurate Fourth Amendment protection.  See id. 
at 386, 393; People v. Hughes, 958 N.W.2d 98, 112 (Mich. 2020) 
No.  2019AP1404-CR.rfd 
 
7 
("Riley distinguished cell-phone data from other items . . . in 
terms of the privacy interests at stake."). 
¶73 The unique privacy expectation in cell phone data 
informs why Burch's consent to the GBPD does not relieve the 
Sheriff's Office of its obligation to get a warrant for its own 
review.  Burch's consent, as "the typical reasonable person 
[would] have understood" it, had the "expressed object" of the 
GBPD reviewing messages to verify his alibi for the GBPD's 
investigation.  See Jimeno, 500 U.S. at 251.  The GBPD officer's 
report explained that Burch "consented to Lt. Allen and I [two 
GBPD officers] looking at the text messages between him and 
[Burch's acquaintance] last night and also indicated I could 
take his phone to the department to have the information on it 
downloaded."  Burch's signed consent form is also specific to 
the "City of Green Bay Police Department" and indicated that 
Burch gave certain members of the GBPD permission to search his 
phone.  Critically absent from the report or the consent form is 
any mention of any other law enforcement agency, the possibility 
of the GBPD sharing the entirety of the downloaded data, or even 
that Burch was consenting to the GBPD retaining indefinitely all 
of his phone's information.  Cf. Douglas, 123 Wis. 2d at 21-22. 
No.  2019AP1404-CR.rfd 
 
8 
¶74 Burch's consent was therefore limited to the GBPD for 
the GBPD's investigation.3  See Terry, 392 U.S. at 25-26, 29 
(requiring courts to interpret warrant exceptions as "confined 
in scope" and "strictly circumscribed").  With respect to other 
agencies and their investigations, Burch maintained a reasonable 
expectation of privacy in the data downloaded by the GBPD but 
unrelated to its investigation, including his internet search 
history and Google email account.  See Carpenter, 138 S. Ct. 
at 2217 (holding that, because of cell phone data's "unique 
nature," a person "maintains a legitimate expectation of 
privacy" in the data even after consensually giving it to 
another party for a limited purpose); Hughes, 958 N.W.2d at 111 
(concluding that the lawful seizure and search of certain cell 
phone 
information 
does 
not 
"extinguish[] 
that 
otherwise 
reasonable expectation of privacy in the entirety" of that 
information).  Consequently, the Sheriff's Office's subsequent 
review of Burch's data invaded Burch's reasonable expectation of 
privacy such that it was a search under the Fourth Amendment. 
2.  The Sheriff's Office Acted Unreasonably in Searching the 
GBPD's Download of Burch's Cell Phone Data. 
¶75 The Sheriff's Office decided that no warrant was 
required for its search after determining that Burch's consent 
                                                 
3 The circuit court's determination that Burch placed no 
parameters on the scope of his consent is suspect given that his 
conversation with the GBPD about his phone was strictly limited 
to his text messages.  The categorical uniqueness of private 
cell phone data requires circuit courts to take seriously the 
admonition that exceptions to the warrant requirement like 
consent be interpreted as "confined in scope" and "strictly 
circumscribed."  See Riley v. California, 573 U.S. 373, 382, 393 
(2014); Terry v. Ohio, 392 U.S. 1, 25-26, 29 (1968). 
No.  2019AP1404-CR.rfd 
 
9 
to the GBPD extended to the Sheriff's Office.  But as discussed 
above, Burch's "unequivocal and specific" consent extended only 
to certain members of the GBPD, and only so they could review 
his text messages to confirm his alibi.  See Reed, 384 
Wis. 2d 469, ¶8.  Burch did not consent to all of the 
information 
on 
his 
phone 
being 
available 
to 
other 
law 
enforcement agencies for some later, unrelated investigation.  
And the Sheriff's Office did not independently get Burch's 
consent to search his cell phone information. 
¶76 Given those facts, no reasonable person in Burch's 
position would have understood that his consent to the GBPD was 
an open invitation for any other law enforcement agency to 
search his private information whenever it wanted to and without 
a warrant.  Therefore, the consent exception to the Fourth 
Amendment's warrant requirement does not apply to the Sheriff's 
Office's subsequent warrantless search of Burch's private cell 
phone data for an unrelated investigation.  That search was 
unreasonable and violated the Fourth Amendment. 
B.  Evidence of Burch's Google Location Data and His Internet 
Search History Should Be Suppressed. 
¶77 Having concluded that the Sheriff's Office's search 
violated the Fourth Amendment, the next question is whether the 
exclusionary rule applies; that is, whether excluding, or 
suppressing, the unlawfully obtained evidence would sufficiently 
deter the same police conduct in the future.  Here, Burch's 
Google location data and his internet search history should be 
excluded because if they are not, other law enforcement agencies 
are likely to repeat the Sheriff's Office's unconstitutional 
No.  2019AP1404-CR.rfd 
 
10 
search of downloaded cell phone data, especially given the 
ubiquity of cell phones and the increasing prevalence of 
personal digital data in criminal investigations. 
¶78 The 
exclusionary 
rule——that 
evidence 
obtained 
in 
violation of the Fourth Amendment be excluded from trial——
ensures that the Fourth Amendment's right to be free from 
unreasonable searches remains one "of substance rather than mere 
tinsel."  Hoyer v. State, 180 Wis. 407, 415, 193 N.W. 89 (1923).  
By excluding otherwise relevant evidence, "[t]he exclusionary 
rule generally serves to 'deter deliberate, reckless, or grossly 
negligent conduct, or in some circumstances recurring or 
systemic negligence.'"  Blackman, 377 Wis. 2d 339, ¶68 (quoting 
Herring v. United States, 555 U.S. 135, 150-51 (2009)).  The 
rule thus incentivizes "the law enforcement profession as a 
whole" to conduct itself "in accord with the Fourth Amendment."  
Gates, 462 U.S. at 261 n.15 (White, J., concurring in the 
judgment). 
¶79 Given that critical function, the United States 
Supreme Court has permitted deviation from the exclusionary rule 
only when the deterrent value of excluding the evidence is 
"marginal" or "nonexistent" and outweighed by the social cost of 
doing 
so. 
 
See, 
e.g., 
United 
States 
v. 
Leon, 
468 
U.S. 897, 913-17, 922 (1984).  Such is the case when there is no 
police misconduct to deter or when the police misconduct is 
"isolated," "nonrecurring," and "attenuated."  See id. at 922; 
Herring, 555 U.S. at 137, 144.  For example, excluding 
unlawfully obtained evidence is inappropriate if the police 
acted in objectively reasonable reliance on either a facially 
No.  2019AP1404-CR.rfd 
 
11 
valid warrant properly issued by a neutral, detached magistrate; 
an apparently constitutional statute; or a binding appellate 
precedent.  See Leon, 468 U.S. 897 (warrants);4 Illinois v. 
Krull, 
480 
U.S. 
340 
(1987) 
(statutes); 
Davis 
v. 
United 
States, 564 U.S. 229, 239-41 (2011) (appellate precedents).  
Likewise, exclusion is inappropriate when an arresting officer 
acts in objectively reasonable reliance on either a judicial or 
police employees' infrequent clerical mistake.  See Arizona v. 
Evans, 
514 
U.S. 1, 14-16 
(1995) 
(court 
clerk 
made 
a 
recordkeeping error regarding outstanding arrest warrants only 
once "every three or four years"); Herring, 555 U.S. at 144-47 
(police employees' clerical error in warrant database had never 
happened before).  The common thread through each of these cases 
is that the fault lies with someone who is not directly engaged 
in the "competitive enterprise of ferreting out crime"; who has 
"no stake in the outcome of particular prosecutions."  See 
Evans, 514 U.S. at 15. 
¶80 Conversely, 
the 
exclusionary 
rule 
applies 
when 
evidence is unlawfully obtained due to an error made by law 
enforcement.  See Leon, 468 U.S. at 923.  For instance, evidence 
should be suppressed when law enforcement secures evidence based 
on a facially deficient warrant, or when a warrant is issued 
based on an officer knowingly or recklessly stating a falsehood 
in the warrant affidavit.  See id.  The same goes for when 
police exceed a valid warrant's authority when executing it.  
See id.  As for the police relying on statutory authority, the 
                                                 
4 See also Massachusetts v. Sheppard, 468 U.S. 981, 988-91 
(1984). 
No.  2019AP1404-CR.rfd 
 
12 
exclusionary 
rule 
still 
applies 
when 
police 
officers 
misinterpret and "act outside the scope" of a statute and when a 
reasonable officer would have known either that the law in 
question is unconstitutional or that the conduct authorized by 
the statute violates other clearly established law.  Krull, 480 
U.S. at 355, 360 n.17.  Indeed, the rule applies even to 
unlawfully 
negligent 
police 
conduct 
when 
the 
conduct 
is 
"recurring or systemic."  E.g., Herring, 555 U.S. at 144. 
¶81 The exclusionary rule applies in this case because it 
was the Sheriff's Office's conduct that rendered unlawful its 
search of Burch's cell phone, not some detached third party's.  
There 
was 
no 
statute 
or 
judicial 
precedent 
condoning 
a 
warrantless search of another agency's download of a person's 
private cell phone data.  Instead, the Sheriff's Office judged 
for itself, incorrectly, that the Fourth Amendment's warrant 
requirement did not apply to Burch's cell phone data.  The 
unlawful conduct here——not obtaining a warrant to search Burch's 
private cell phone data——is solely attributable to the Sheriff's 
Office's detectives.  And because those detectives are directly 
engaged in the "competitive enterprise of ferreting out crime," 
the exclusionary rule should apply.  See Evans, 514 U.S. at 15. 
¶82 Applying the rule is also justified because the record 
demonstrates that warrantless searches of private cell phone 
information are commonplace, and therefore likely to recur.  
Officers from both the GBPD and the Sheriff's Office confirmed 
that it is "very common" for agencies to share "full downloads" 
of private cell phones with other agencies without first 
obtaining a warrant, adding that their agencies "regularly" do 
No.  2019AP1404-CR.rfd 
 
13 
so.  This widespread neglect of the Fourth Amendment's warrant 
requirement is just the kind of "systemic negligence" the 
exclusionary rule is designed to correct.  See Herring, 555 U.S. 
at 144.  The exclusionary rule thus squarely applies here. 
¶83 The State's counterarguments are unavailing.  Its 
contention that the Sheriff's Office reasonably relied upon its 
own determination regarding the scope of Burch's consent misses 
the point.  It is not up to the police to determine the contours 
of an exception to a constitutional requirement restricting 
their own conduct.  See Leon, 468 U.S. at 959 (Brennan, J., 
dissenting) (presciently lamenting that exceptions to the 
exclusionary rule would not stay "confined" but instead be 
wrongfully extended "to situations in which the police have 
conducted a warrantless search solely on the basis of their own 
judgment"). 
 
Moreover, 
because 
the 
police 
may 
encounter 
circumstances that are on the margins of the law regarding 
warrant exceptions——as is the case here——police officers are 
required to "err on the side of constitutional behavior" and get 
a warrant.5  See United States v. Johnson, 457 U.S. 537, 561 
                                                 
5 The State erroneously argues that the Sheriff's Office's 
search is akin to law enforcement's ability to take a "second 
look" at physical evidence inventoried during a jail intake or 
that it already lawfully seized.  See State v. Betterley, 191 
Wis. 2d 406, 418, 529 N.W.2d 216 (1995); State v. Riedel, 2003 
WI App 18, ¶16, 259 Wis. 2d 921, 656 N.W.2d 789.  But as the 
United States Supreme Court explained in Riley, "cell phones, as 
a 
category, 
implicate 
privacy 
concerns 
far 
beyond 
those 
implicated" by physical objects.  573 U.S. at 393.  And because 
a "search of the information on a cell phone bears little 
resemblance" to other types of searches, the rationales for 
other searches do not extend to cell phone information.  See id. 
at 386.  Therefore, the State's arguments fail.  See People v. 
Hughes, 958 N.W.2d 98, 111-15 (Mich. 2020). 
No.  2019AP1404-CR.rfd 
 
14 
(1982); Blackman, 377 Wis. 2d 339, ¶53 (warrantless searches 
executed outside any "clearly delineated" warrant exception are 
"per se unreasonable" and "unlawful").  The Sheriff's Office's 
erroneous determination that Burch's consent extended to the 
Sheriff's Office is no justification for failing to get a 
warrant. 
¶84 Nor is the Sheriff's Office relieved of its Fourth 
Amendment duty to get a warrant simply because law enforcement 
agencies "regularly" share this type of information.  The 
pervasiveness of this practice is no defense to the exclusionary 
rule; it is the reason to apply it.  See Herring, 555 U.S. 
at 144 (exclusion applies when unreasonable police conduct is 
"recurring" or "systemic").  The same goes for the majority's 
characterization of the Sheriff's Office's conduct as "by the 
book."  Majority op., ¶22.  If following "the book" leads to 
violations of the Fourth Amendment, then the exclusionary rule's 
deterrent value is at its peak.  Excluding evidence obtained by 
following such an unlawful and widespread policy provides 
significant societal value by both specifically deterring 
continued adherence to an unconstitutional practice and more 
broadly incentivizing police agencies to adopt policies in line 
with the Fourth Amendment.6  See Wayne R. LaFave, 1 Search & 
Seizure § 1.3(i) (6th ed. 2020).  This is especially true when 
                                                 
6 The State counters that because the Sheriff's Office may 
have had access to Burch's Google email account and internet 
search history via a lawful, independent source, that evidence 
should 
not 
be 
excluded. 
 
See 
State 
v. 
Carroll, 
2010 
WI 8, ¶¶44-45, 322 Wis. 2d 299, 778 N.W.2d 1.  But the State has 
forfeited that argument by failing to raise it below.  See State 
v. Counihan, 2020 WI 12, ¶25, 390 Wis. 2d 172, 938 N.W.2d 530. 
No.  2019AP1404-CR.rfd 
 
15 
the Constitution already provides law enforcement with a simple 
solution for how to lawfully obtain cell phone data:  get a 
warrant.  See Riley, 573 U.S. at 403. 
C.  The Majority Opinion Has No Support in Fourth Amendment 
Jurisprudence. 
¶85 The majority opinion offers a contrary analysis that 
ignores the novel constitutional problems presented by cell 
phone data, is inconsistent with the Fourth Amendment's text, 
and undermines the exclusionary remedy. 
¶86 The majority opinion's analysis reveals a lack of 
appreciation for the fundamental differences between digital 
cell phone data and more "traditional," non-digital evidence 
that law enforcement might share with other agencies.  The 
Fourth Amendment treats cell phone data differently because it 
often contains nearly all the "privacies of [a person's] life," 
such that "any extension" of Fourth Amendment principles "to 
digital data has to rest on its own bottom."  See Riley, 573 
U.S. at 393, 403 (quoting another source); Carpenter, 138 S. Ct. 
at 2219 (explaining that Fourth Amendment jurisprudence must 
account for the "seismic shifts in digital technology").  
Accordingly, it is a grave analytical error to "mechanically 
apply[]" to cell phone data Fourth Amendment rationales that 
were developed without such invasive technologies in mind.  
Carpenter, 138 S. Ct. at 2219; see also Riley, 573 U.S. 
at 400-01 (rejecting the argument that the police can search 
cell phone data under the same rationale that allows them to 
obtain "the same information from a pre-digital counterpart").  
Or, as the United States Supreme Court put it, treating cell 
No.  2019AP1404-CR.rfd 
 
16 
phone data the same as its non-digital analogues "is like saying 
a ride on horseback is materially indistinguishable from a 
flight to the moon.  Both are ways of getting from point A to 
point B, but little else justifies lumping them together."  
Riley, 573 U.S. at 393.  The majority opinion, however, is 
content to toss a saddle on a spaceship and call it a horse.  
Nowhere does the majority opinion account for Burch's special 
privacy interest in his cell phone data, leaving a tremendous 
hole in its exclusionary rule analysis. 
¶87 More troubling is the majority's disregard for the 
Fourth Amendment's text.  It is bedrock Fourth Amendment law 
that search warrants are generally required and that a search 
without a warrant is per se unlawful.  See, e.g., City of 
Ontario v. Quon, 560 U.S. 746, 760 (2010); Blackman, 377 
Wis. 2d 339, ¶53.  The majority's assertion that "there is 
nothing concerning under current Fourth Amendment doctrine with 
how the Sheriff's Office detectives conducted themselves" 
shockingly discards this well-settled principle.  Indeed, the 
majority opinion fails to even mention the presumption that 
warrantless searches violate the Fourth Amendment. 
¶88 But worse than mere silence, the majority's refusal to 
apply the exclusionary rule flips this presumption on its head.  
According to the majority, if "no case from this court or the 
federal courts" directs the police to get a warrant, then the 
police act "reasonably" in not getting a warrant.  Majority 
op., ¶23.  The majority appears to create a new prerequisite for 
applying the exclusionary rule, holding that it applies only if 
a court has previously declared that the police conduct at issue 
No.  2019AP1404-CR.rfd 
 
17 
is unconstitutional.  Imposing this hurdle undermines the 
exclusionary remedy for Fourth Amendment violations and is 
directly contrary to both our and the United States Supreme 
Court's Fourth Amendment jurisprudence. 
¶89 All of which makes inexcusable the majority opinion's 
refusal to address the constitutionality of the Sheriff's 
Office's search.  Despite law enforcement's admittedly "very 
common" practice of sharing with other agencies entire downloads 
of private cell phone data, that recurring Fourth Amendment 
violation will continue with impunity unless and until the court 
engages with the specific Fourth Amendment issue raised by 
private cell phone information.  By skipping straight to whether 
the exclusionary rule applies, the majority opinion deprives 
aggrieved defendants——and future courts——of the very prior 
precedent now necessary to remedy law enforcement's continued 
unconstitutional conduct: 
Forgoing a knotty constitutional inquiry makes for 
easier sledding, no doubt.  But the inexorable result 
is 
"constitutional 
stagnation"——fewer 
courts 
establishing law at all, much less clearly doing 
so, . . . [creating a] Catch-22.  [Defendants] must 
produce precedent even as fewer courts are producing 
precedent.  Important constitutional questions go 
unanswered precisely because no one's answered them 
before.  Courts then rely on that judicial silence to 
conclude there's no equivalent case law on the 
books. . . . If 
courts 
leapfrog 
the 
underlying 
constitutional merits in cases raising novel issues 
like digital privacy, then constitutional clarity——
matter-of-fact guidance about what the Constitution 
requires——remains 
exasperatingly 
elusive.  
Result:  gauzy 
constitutional 
guardrails 
as 
technological innovation outpaces legal adaptation. 
Zadeh 
v. 
Robinson, 
928 
F.3d 457, 
479-80 
(5th 
Cir. 2019) 
(Willet, J., concurring), cert. denied, 141 S. Ct. 110 (2020).  
No.  2019AP1404-CR.rfd 
 
18 
Together with its new prior-precedent requirement, the majority 
opinion's 
avoidance 
of 
the 
Fourth 
Amendment 
issues 
here 
perpetuates a cycle of diminished police accountability and 
courts' unwillingness to address it. 
¶90 Given that the Fourth Amendment law specific to cell 
phone data is undeveloped, this court should be providing "clear 
guidance 
to 
law 
enforcement 
through 
categorical 
rules."  
Riley, 573 U.S. at 398; see also Michigan v. Summers, 452 
U.S. 692, 705 n.19 (1981) (explaining that clear "workable" 
rules are necessary so that difficult Fourth Amendment questions 
are not resolved in an "ad hoc, case-by-case fashion by 
individual police officers") (quoting another source)).  If a 
law enforcement agency wishes to search a person's private 
information, such as cell phone data, and the person did not 
consent to that agency's search, the agency must get a warrant. 
III.  CONCLUSION 
¶91 The Sheriff's Office should have obtained a warrant to 
search Burch's private cell phone data.  Because it did not, the 
evidence it found as a result of that search should be 
suppressed.  The majority's refusal to apply the exclusionary 
rule is incompatible with our Fourth Amendment jurisprudence and 
perverts the long-standing bedrock requirement that police 
obtain a warrant to search private information.  I therefore 
respectfully dissent from that part of the majority opinion. 
¶92 I am authorized to state that Justice JILL J. KAROFSKY 
joins this opinion and that Justice ANN WALSH BRADLEY joins this 
opinion except for footnote 1. 
No.  2019AP1404-CR.rfd 
 
19 
 
No.  2019AP1404-CR.awb 
 
1 
 
¶93 ANN WALSH BRADLEY, J.   (dissenting).  Ubiquitous use 
does not mean the average wearer of a Fitbit knows how it works.  
Nor does ubiquitous use indicate reliability sufficient to be 
admissible in a court of law. 
¶94 An average jury member would likely know what a Fitbit 
is and what it does.  Of course, as relevant here, it counts the 
wearer's steps.  But that isn't the question.  In determining 
whether expert testimony is required, the relevant inquiry is 
how a Fitbit counts the wearer's steps and then ultimately, 
whether it does so with sufficient reliability. 
¶95 How 
does 
it 
work? 
 
A 
Fitbit 
device 
uses 
a 
microelectronic triaxial accelerometer to capture a person's 
body motion in three-dimensional space and record related data.  
This motion data is then analyzed by utilizing proprietary 
algorithms to surmise patterns and thus to identify daily steps 
taken.   
¶96 Is it sufficiently reliable to be admitted as evidence 
in court?  I don't know.  But, I do know that the answer does 
not lie in its ubiquitous use. 
¶97 I also know that absent expert testimony there is 
insufficient foundation in this record for the majority to 
determine, in essence, that a presumption of accuracy and 
reliability attends the underlying technology of a Fitbit.  The 
error of such a presumption is made manifest by reference to an 
overarching 
analysis 
of 
67 
studies 
on 
Fitbit 
accuracy 
disseminated 
by 
the 
National 
Center 
for 
Biotechnology 
Information (NCBI), under the auspices of the U.S. National 
No.  2019AP1404-CR.awb 
 
2 
 
Institutes of Health (NIH).  The researchers found that Fitbit 
devices were "likely to meet acceptable accuracy for step count 
approximately half the time."  Lynne M. Feehan, et al., Accuracy 
of Fitbit Devices:  Systematic Review and Narrative Syntheses of 
Quantitative 
Data, 
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6107736/ (2018). 
¶98 In citing this study, I neither endorse nor disclaim 
its conclusions.  It suggests, however, when a compilation of 
studies indicates acceptable accuracy is met only "half the 
time," 
that 
something 
may 
be 
amiss 
with 
the 
majority's 
presumption of accuracy and reliability. 
¶99 Expert 
testimony 
is 
required 
when 
matters 
are 
presented that are "unusually complex."  White v. Leeder, 149 
Wis. 2d 948, 960, 440 N.W.2d 557 (1989).  Movement measured by a 
"microelectronic 
triaxial 
accelerometer" 
and 
analyzed 
by 
proprietary algorithms certainly fits that bill. 
¶100 In my view, the technology underlying a Fitbit is not 
within the ordinary experience of an average jury member.  
Fitbits and other wearable devices may be ubiquitous, but it 
does not follow from this premise that the technology underlying 
their use is not "unusually complex."   
¶101 Expert 
testimony 
assists 
the 
trier 
of 
fact 
to 
understand the evidence and to determine a fact in issue.  The 
accuracy of the number of steps recorded on Douglass Detrie's 
Fitbit is certainly a fact in issue.  Thus, expert testimony 
should have been required to assist the jury in understanding 
the technology and assessing its reliability. 
No.  2019AP1404-CR.awb 
 
3 
 
¶102 Invoking a deferential standard, it is not unusual for 
an appellate court to do only a cursory analysis of an 
evidentiary issue.  But this is not the usual case and a more 
nuanced analysis is required. 
¶103 This case presents a groundbreaking question.  To my 
knowledge, this is the first appellate court decision in the 
country to conclude that Fitbit step-counting evidence is 
admissible absent expert testimony explaining how the device 
works.  The parties have not cited, and I have not found, any 
case making such a proclamation.  The majority's analysis 
provides a slim reed upon which to support such a novel 
determination.   
¶104 Rather than allowing evaluation of the question, the 
majority cuts off the debate.  It essentially rubber stamps the 
circuit 
court's 
erroneous 
analysis 
and 
declares 
Fitbit's 
technology to be simple enough to be presented as evidence 
without 
the 
benefit 
of 
an 
expert 
witness 
or 
further 
consideration of its reliability. 
¶105 Although I join Justice Dallet's dissent, concluding 
that the search of Burch's cell phone at issue violated his 
Fourth Amendment rights and that the good faith exception to the 
warrant requirement does not apply, I do not join footnote 1 
that concurs with the majority's analysis of the Fitbit 
evidence.  Because I conclude that the circuit court erroneously 
admitted the Fitbit evidence without an expert witness to 
establish the reliability of the science underlying the Fitbit 
technology, I respectfully dissent. 
No.  2019AP1404-CR.awb 
 
4 
 
I 
¶106 I briefly recount the facts that are relevant to the 
issue on which I write:  the admission of the Fitbit evidence. 
¶107 As the majority opinion sets forth, the initial 
suspect in the crime at issue here was Douglass Detrie, the 
victim's 
boyfriend. 
 
Majority 
op., 
¶4. 
 
However, 
the 
investigation shifted after police learned that Detrie's Fitbit 
device had recorded only 12 steps during the time the homicide 
was committed.  Burch was ultimately arrested and charged. 
¶108 The 
State 
sought 
to 
present 
evidence 
regarding 
Detrie's Fitbit, and Burch moved to exclude it.  Id., ¶11.  As 
relevant here, Burch contended that the State must present 
expert testimony to establish the reliability of the science 
behind the Fitbit device.  Id.1   
¶109 The circuit court granted Burch's motion in part and 
denied it in part.  Specifically, the circuit court excluded 
Fitbit evidence related to sleep monitoring, but it allowed the 
admission of the step-counting data without the testimony of an 
expert regarding the science underlying the Fitbit technology.  
Id., ¶11 & n.3.   
¶110 In the circuit court's estimation, a Fitbit is more 
akin to an electronic monitoring device (which does not require 
expert testimony, see State v. Kandutsch, 2011 WI 78, 336 
                                                 
1 Burch made several additional arguments, including an 
assertion that Fitbit's records were not properly authenticated, 
which he renews on appeal.  Because I determine that expert 
testimony was necessary to admit the evidence in question, I do 
not reach Burch's arguments regarding authentication. 
No.  2019AP1404-CR.awb 
 
5 
 
Wis. 2d 478, 799 N.W.2d 865) than to a preliminary breath test 
(which requires expert testimony, see State v. Doerr, 229 
Wis. 2d 616, 599 N.W.2d 897 (Ct. App. 1999)).  Similarly, the 
circuit court distinguished Fitbit data from DNA, fingerprint 
analysis, blood alcohol content tests, tool mark evidence and 
accident reconstruction because "few people encounter those 
things in their everyday life."   
¶111 Comparing a Fitbit to an electronic monitoring device, 
the circuit court stated that a Fitbit is "passively worn by a 
person," and the device collects data "based on that person's 
movements, which is then transmitted and recorded.  There is no 
active manipulation by the wearer to achieve the results; the 
results are simply a record of the wearer's movements, i.e., 
their location or the number of steps they took."  Thus, in the 
circuit court's view "the step-counting feature of the Fitbit 
Flex, like the [electronic monitoring device], is not so 
unusually complex or esoteric that the jury will require the aid 
of expert testimony to interpret the information." 
¶112 At trial, because it was not required to provide an 
expert to introduce the data from Detrie's Fitbit, the State 
relied upon the testimony of Tyler Behling, a computer forensic 
crime analyst with the Brown County Sheriff's Office.  Although 
Behling claimed to have knowledge of how a Fitbit works "on a 
high level," he did not know the answer when asked how a Fitbit 
and a Bluetooth device send information from one to the other, 
how Fitbit stores its data, whether Fitbit data can be edited, 
No.  2019AP1404-CR.awb 
 
6 
 
whether the device would register steps while it is not being 
worn, or what a Fitbit's error rate is. 
¶113 Despite the dearth of technical testimony regarding 
how a Fitbit actually works, the majority now affirms the 
circuit court's determination.  It concludes that "[g]iven the 
widespread availability of Fitbits and other similar wireless 
step-counting devices in today's consumer marketplace, the 
circuit court reasonably concluded Detrie's Fitbit was not so 
'unusually complex or esoteric' that the jury needed an expert 
to understand it."  Majority op., ¶31. 
II 
¶114 It has long been the law that expert testimony is 
required when a matter involves "special knowledge or skill or 
experience on subjects which are not within the realm of the 
ordinary experience of mankind, and which require special 
learning, study and experience."  Cramer v. Theda Clark Mem'l 
Hosp., 45 Wis. 2d 147, 150, 172 N.W.2d 427 (1969).  "The 
requirement of expert testimony is an extraordinary one," and 
should be applied "only when unusually complex or esoteric 
issues are before the jury."  White, 149 Wis. 2d at 960.  
¶115 "In 
considering 
what 
constitutes 
the 
'ordinary 
experience of mankind'——i.e. the average juror——courts have not 
tailored this standard to the lowest common denominator.  
Rather, courts attempt to evaluate, on a case-by-case basis, 
whether expert testimony is required because the issue is 
outside the realm of lay comprehension."  Kandutsch, 336 
Wis. 2d 478, ¶29. 
No.  2019AP1404-CR.awb 
 
7 
 
¶116 The circuit court here determined that the technology 
underlying 
a 
Fitbit 
is 
not 
outside 
the 
realm 
of 
lay 
comprehension.  It compared a Fitbit to a watch in that "the 
public generally understands the principle of how it functions 
and accepts its reliability without knowing the exact mechanics 
of its internal workings."  Further, it determined that a Fitbit 
is not subject to "active manipulation by the wearer to achieve 
the results; the results are simply a record of the wearer's 
movements, i.e., their location or the number of steps they 
took." 
¶117 But the expert testimony standards do not rest on 
ubiquity.  Instead, they rest on the complexity of the subject 
matter.  Although many members of the jury may have been wearing 
Fitbits or similar devices, such a fact would not inform the 
question of whether those jury members understand how a Fitbit 
works or whether the technology is reliable. 
¶118 What does the average person really know about how a 
Fitbit works, much less its reliability?  As one study described 
it, "Fitbit devices use a microelectronic triaxial accelerometer 
to capture body motion in 3-dimensional space, with these motion 
data analyzed using proprietary algorithms to identify patterns 
of motion to identify daily steps taken, energy expenditure, 
sleep, distance covered, and time spent in different intensity 
of activities."  Feehan, et al., supra.  According to the 
majority, the average juror would understand, without expert 
No.  2019AP1404-CR.awb 
 
8 
 
testimony, 
not 
only 
what 
a 
"microelectronic 
triaxial 
accelerometer" is, but how it works.  Really?2   
¶119 If the State had presented an expert, that expert 
would have had to meet the requirements for expert testimony 
established by the United States Supreme Court in Daubert.3  
Pursuant to the Daubert standard, as codified in Wis. Stat. 
§ 907.02(1),4 the circuit court must act as a gatekeeper and make 
a threshold determination that the testimony is reliable in 
order for it to be presented at trial.  State v. Dobbs, 2020 WI 
64, ¶43, 392 Wis. 2d 505, 945 N.W.2d 609.  By not requiring the 
State to present an expert, the circuit court and the majority 
allow the State to skirt this initial reliability determination. 
¶120 There are various ways in which threshold reliability 
can be demonstrated.  See 7 Daniel D. Blinka, Wisconsin Practice 
Series:  Wisconsin Evidence § 702.402 (4th ed. 2020).  There may 
                                                 
2 Further, the intricacies of Fitbit's technology are 
"proprietary," setting up an additional roadblock to the jury's 
full knowledge and full understanding of how the device works.  
See State v. Loomis, 2016 WI 68, ¶66, 371 Wis. 2d 235, 881 
N.W.2d 749 (explaining that "proprietary nature" has been 
invoked to prevent disclosure of certain information). 
3 Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579 (1993). 
4 Wisconsin Stat. § 907.02(1) provides: 
If 
scientific, 
technical, 
or 
other 
specialized 
knowledge will assist the trier of fact to understand 
the evidence or to determine a fact in issue, a 
witness qualified as an expert by knowledge, skill, 
experience, 
training, 
or 
education, 
may 
testify 
thereto in the form of an opinion or otherwise, if the 
testimony is based upon sufficient facts or data, the 
testimony is the product of reliable principles and 
methods, and the witness has applied the principles 
and methods reliably to the facts of the case. 
No.  2019AP1404-CR.awb 
 
9 
 
be a statute indicating that certain tests or methods are 
admissible.  See, e.g., Wis. Stat. § 885.235 (addressing 
chemical 
tests 
for 
intoxication). 
 
There 
is 
no 
statute 
addressing Fitbit evidence. 
¶121 We can also look to court precedent which has already 
determined certain principles to be reliable.  See, e.g., State 
v. 
Hanson, 
85 
Wis. 2d 233, 
244, 
270 
N.W.2d 212 
(1978) 
(discussing the reliability of the underlying principles of 
speed radar detection that employs the Doppler effect).  The 
reliability of Fitbit's step counting capability is a novel 
issue, so there is no precedent on point. 
¶122 Stipulations 
or 
judicial 
notice 
may 
also 
be 
appropriate when a fact is "capable of accurate and ready 
determination by resort to sources whose accuracy cannot 
reasonably be questioned."  Wis. Stat. § 902.01(2)(b).  Again, 
these do not fit the present scenario——the reason we are here is 
because the parties do not agree and Burch reasonably questions 
the accuracy of Fitbit's step count. 
¶123 Finally, if none of the above proves to be an 
acceptable avenue to demonstrate the accuracy and reliability of 
the scientific principles sufficient to be accorded a prima 
facie presumption, expert testimony is necessary to explain the 
underlying scientific principles and to demonstrate their 
reliability.  Here, no expert was presented.   
¶124 The evidentiary process requires that the scientific 
principles be presented to the court before the evidence is 
determined to be reliable.  In a court of law, process matters.  
No.  2019AP1404-CR.awb 
 
10 
 
Without 
fulfilling 
one 
of 
these 
avenues, 
the 
threshold 
reliability determination cannot be made. 
¶125 And what of Fitbit's reliability?  Such reliability 
can depend on a number of factors, such as whether the user has 
self-manipulated the data, if the Fitbit is temporarily removed, 
where on the body the device is worn, or the type of physical 
activity in which the wearer is engaged.  Feehan, et al., supra; 
Katherine E. Vinez, The Admissibility of Data Collected from 
Wearable Devices, 4 Stetson J. Advoc. & L. 1, 16 (2017).  In a 
comprehensive aggregation of 67 different studies, researchers 
found that "[c]onsistent evidence indicated that Fitbit devices 
were 
likely 
to 
meet 
acceptable 
accuracy 
for 
step 
count 
approximately half the time."  Feehan, et al., supra.  Yet in 
the view of the majority and of the circuit court, an expert is 
not necessary to establish the reliability of Detrie's step 
count——the Fitbit evidence can go before the jury with no 
technical or scientific explanation. 
¶126 Indeed, questions arise about the reliability of 
wearable devices despite their widespread acceptance.  See 
Vinez, supra, at 16.  If reliability questions exist, where 
better than the circuit court to present the case for and 
against such reliability?  Instead of remanding to the circuit 
court for evaluation of the question, the majority curtly 
No.  2019AP1404-CR.awb 
 
11 
 
declares Fitbit's technology to be simple enough to be put 
before a jury without the benefit of an expert.5   
¶127 When new and popular devices emerge, courts should be 
wary of blindly accepting the data they produce without a 
thorough examination of the underlying technology.  "Machines 
warrant no blind faith, and whatever trust they receive must be 
earned through the crucible of the rules of evidence."  Brian 
Sites, Machines Ascendant:  Robots and the Rules of Evidence, 3 
Geo. L. Tech. Rev. 1, 1-2 (2018).  In many cases, such an 
examination will require an expert.  In my view, this is such a 
case. 
¶128 Rather than break new ground as does the majority, I 
would proceed with caution.  Basing the necessity of expert 
testimony on ubiquity rather than complexity sets a dangerous 
path. 
¶129 For the foregoing reasons, I respectfully dissent. 
                                                 
5 See Nicole Chauriye, Wearable Devices as Admissible 
Evidence:  Technology is Killing our Opportunities to Lie, 24 
Cath. U. J. L. & Tech. 495, 517 (2016) (arguing that "the trier 
of fact would greatly benefit from mandated expert testimony to 
explain the accuracy and details of the data recorded by the 
wearable technology").  
No.  2019AP1404-CR.awb 
 
 
 
1