1

PRECEDENTIAL

UNITED STATES COURT OF APPEALS

FOR THE THIRD CIRCUIT

_____________

No. 12-2548

_____________

UNITED STATES OF AMERICA,

 Appellant

v.

HARRY KATZIN; MICHAEL KATZIN; MARK LOUIS 

KATZIN, SR. 

______________

APPEAL FROM THE 

UNITED STATES DISTRICT COURT 

FOR THE EASTERN DISTRICT OF PENNSYLVANIA

(D.C. Crim. Action No. 5:11-cr-00226)

District Judge: Honorable Gene E.K. Pratter

______________

Argued March 19, 2013

______________

Before: SMITH, GREENAWAY, JR., and VAN 

ANTWERPEN, Circuit Judges.
2

(Opinion Filed: October 22, 2013)

______________

Robert A. Zauzmer, Esq. [ARGUED]

Emily McKillip, Esq.

Zane D. Memeger, Esq.

Thomas M. Zaleski, Esq.

Office of United States Attorney

615 Chestnut Street Suite 1250

Philadelphia, PA 19106

Counsel for Appellant The United States of America

Thomas A. Dreyer, Esq. [ARGUED]

6 Dickinson Drive, Building 100

Chadds Ford, PA 19317-0000

Counsel for Appellee Harry Katzin

William A. DeStefano, Esq.

Stevens & Lee

1818 Market Street, 29th Floor

Philadelphia, PA 19103-0000

Counsel for Appellee Michael Katzin

Rocco C. Cipparone, Jr., Esq. [ARGUED]

205 Black Horse Pike

Haddon Heights, NJ 08035-0000

Counsel for Appellee Mark Louis Katzin, Sr.

Benjamin E. Wizner, Esq.

American Civil Liberties Union

National Security Project

125 Broad Street, 18th Floor
3

New York, NY 10004

Catherine N. Crump, Esq. [ARGUED]

Nathan Wessler, Esq.

American Civil Liberties Union

125 Broad Street, 17th Floor

New York, NY 10004

Counsel for Amicus Appellees the American Civil 

Liberties Union Foundation

Witold J. Walczak, Esq.

Sara J. Rose, Esq.

American Civil Liberties Union

313 Atwood Street

Pittsburgh, PA 15213-0000

Catherine N. Crump, Esq. [ARGUED]

American Civil Liberties Union

125 Broad Street, 17th Floor

New York, NY 10004

Counsel for Amicus Appellees the American Civil 

Liberties Union Foundation of Pennsylvania

Catherine N. Crump, Esq. [ARGUED]

American Civil Liberties Union

125 Broad Street, 17th Floor

New York, NY 10004

Hanni M. Fakhoury, Esq.

Marcia Hoffman, Esq.

Electronic Frontier Foundation

815 Eddy Street
4

San Francisco, CA 94109

Counsel for Amicus Appellees the Electronic Frontier 

Foundation

Peter Goldberger, Esq.

50 Rittenhouse Place

Ardmore, PA 19003

Catherine N. Crump, Esq. [ARGUED]

American Civil Liberties Union

125 Broad Street, 17th Floor

New York, NY 10004

Counsel for Amicus Appellee the National Association 

of Criminal Defense Lawyers

______________

OPINION

______________

GREENAWAY, JR., Circuit Judge.

This appeal stems from the Government‟s warrantless 

installation of a Global Positioning System device (a “GPS 

device” or “GPS tracker”) to track the movements of 

Appellee Harry Katzin‟s van. Harry Katzin, along with his 

brothers Mark and Michael (collectively, “Appellees”), 

claims that attaching the GPS device without a warrant 

violated the Fourth Amendment. The United States 

Government (“Appellant” or “Government”) argues that: (a) a 

warrant is not required to install a GPS device; (b) even if a 

warrant were required, the police were acting in good faith; 

and (c) in any case, Mark and Michael lack standing to 
5

contest admissibility of evidence recovered from Harry 

Katzin‟s van.

The instant case therefore calls upon us to decide two 

novel issues of Fourth Amendment law: First, we are asked 

to decide whether the police are required to obtain a warrant 

prior to attaching a GPS device to an individual‟s vehicle for 

purposes of monitoring the vehicle‟s movements (conduct a 

“GPS search”). If so, we are then asked to consider whether

the unconstitutionality of a warrantless GPS search may be 

excused for purposes of the exclusionary rule, where the 

police acted before the Supreme Court of the United States 

proclaimed that attaching a GPS device to a vehicle 

constituted a “search” under the Fourth Amendment. For the 

reasons discussed below, we hold that the police must obtain 

a warrant prior to a GPS search and that the conduct in this 

case cannot be excused on the basis of good faith. 

Furthermore, we hold that all three brothers had standing to 

suppress the evidence recovered from Harry Katzin‟s van. 

We therefore will affirm the District Court‟s decision to 

suppress all fruits of the unconstitutional GPS search.

I. FACTS AND PROCEDURAL HISTORY

Given that the issues in this matter touch upon several 

forms of electronic tracking devices, we feel it necessary —

in service of our forthcoming analysis — to embark on a brief 

discussion of the relevant technology before delving into the 

specific circumstances surrounding Appellees.
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A. Tracking Technology

This case concerns a “slap-on” GPS tracker, so called 

because it magnetically attaches to the exterior of a target 

vehicle, is battery operated, and thereby requires no electronic 

connection to the automobile. The tracker uses the Global 

Positioning System — a network of satellites originally 

developed by the military — to determine its own location 

with a high degree of specificity and then sends this data to a 

central server. This check-and-report process repeats every 

few minutes (depending on the tracker), thereby generating a 

highly accurate record of the tracker‟s whereabouts 

throughout its period of operation. The great benefit of such 

a system — apart from its accuracy — is that anyone with 

access to the central server can analyze or monitor the 

location data remotely. These aspects make GPS trackers 

particularly appealing in law enforcement contexts, where the 

police can attach a tracker to some vehicle or other asset and 

then remotely monitor its location and movement.

GPS technology must be distinguished from the more 

primitive tracking devices of yesteryear such as “beepers.” 

Beepers are nothing more than “radio transmitter[s], usually 

battery operated, which emit[] periodic signals that can be 

picked up by a radio receiver.” United States v. Knotts, 460 

U.S. 276, 277 (1983). In contrast to GPS trackers, beepers do 

not independently ascertain their location — they only 

broadcast a signal that the police can then follow via a 

corresponding receiver. Moreover, beeper signals are rangelimited: if the police move far enough away from the beeper, 

they will be unable to receive the signal that the unit 

broadcasts. At bottom, then, beepers are mere aids for police 

officers already performing surveillance of a target vehicle. 

Unlike GPS trackers, beepers require that the police expend 
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resources — time and manpower — to physically follow a 

target vehicle.

B. The Brothers Katzin

A spectre was haunting Delaware, Maryland, and New 

Jersey in 2009 and 2010 — the three states had been hit by a 

wave of pharmacy burglaries, many of which affected Rite 

Aid pharmacies. The method used in the various crimes was 

largely consistent: in many cases, the alarm systems for the 

pharmacies would be disabled by cutting the external phone 

lines. The local police approached the FBI for help 

(collectively, “the police”) and the hunt was on.

By mid-May 2010, a suspect emerged: a local 

electrician named Harry Katzin. Not only had he recently 

been caught burglarizing a Rite Aid pharmacy, but he and his 

brothers — Mark and Michael — had criminal histories that 

included arrests for burglary and theft. Over the course of the 

following months, the joint state and federal investigation 

began receiving reports of seeing Harry Katzin around Rite 

Aid pharmacies throughout the three states. For example, in 

late October 2010, local police in Pennsylvania encountered 

Harry Katzin crouching beside some bushes outside of a Rite 

Aid after responding to reports of suspicious activity. The 

police did not arrest him, but discovered the next day that the 

phone lines to the pharmacy had been cut. The next month, 

Harry Katzin, along with one of his brothers and one other 

individual, was approached by the police as he sat outside of 

a different Rite Aid in his Dodge Caravan. After Harry 

Katzin consented to a search, the police discovered electrical 

tools, gloves, and ski masks. Harry Katzin explained that 

these were tools of the electrician‟s trade and the police 

allowed the men to leave. The telephone lines to this Rite 
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Aid had also been cut. Soon thereafter, the police obtained 

footage of another recently burglarized Rite Aid showing that 

a vehicle similar to Harry Katzin‟s van had been parked 

outside for a long period of time. As the pieces began falling 

into place, the police proceeded with their next step: 

electronic tracking. The police knew that Harry Katzin 

regularly parked his van on a particular street in Philadelphia. 

Thus, in the early hours of a mid-December morning, after 

consulting with the United States Attorney‟s office, but 

without obtaining a warrant, the FBI affixed a “slap-on” GPS 

tracker to the exterior of Harry Katzin‟s van. 

While the police do not appear to have set a time limit 

for using the GPS tracker, the device yielded the results they 

were after within several days. According to the tracker, 

Harry Katzin‟s van had left Philadelphia on the evening of 

December 15, 2010, and had traveled to the immediate 

vicinity of a Rite Aid in a neighboring town. Through use of 

the device, the police could see that the van had been driven 

around the town for several minutes before parking at a 

specific location for over two hours. That‟s when the FBI 

began to tighten the net. They alerted local police as to Harry

Katzin‟s whereabouts, but cautioned them not to approach too 

closely for fear of tipping off either Harry Katzin or any 

individual he may have been traveling with. When the FBI 

noticed that the van was once again on the move, the call 

came in: the van was to be taken.

While state troopers stopped Harry Katzin‟s van on a 

Pennsylvania highway, a squad of local police officers 

investigated the Rite Aid closest to where Harry Katzin‟s van

had been parked; they found that it had been burglarized and 

relayed this information to the troopers. Inside the van, 

troopers found Harry at the wheel, with Mark and Michael as 
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passengers. From outside of the van, the troopers could see 

merchandise and equipment from the burglarized Rite Aid, 

including pill bottles and Rite Aid storage bins. The police 

impounded the van and arrested the Katzin brothers.

All three brothers moved to suppress the evidence 

discovered in the van. The Government opposed the motions, 

arguing: (a) that a warrant was not required for use of the 

GPS device; (b) that the police had acted in good faith when 

installing the GPS device; and (c) that Mark and Michael

lacked standing to challenge the GPS search and therefore 

could not move to suppress any of the evidence. The District 

Court held in favor of the brothers and suppressed all of the 

evidence found in the van. United States v. Katzin, No. 11-

226, 2012 WL 1646894, *11 (E.D. Pa. May 9, 2012). This 

appeal followed.

II. JURISDICTION AND STANDARD OF REVIEW

The District Court had jurisdiction to hear this case

pursuant to 18 U.S.C. § 3231; our jurisdiction stems from 18 

U.S.C. § 3731. In reviewing a district court‟s ruling on a 

motion to suppress, “we review [the] court‟s factual findings 

for clear error, and we exercise de novo review over its 

application of the law to those factual findings.” United 

States v. Pavulak, 700 F.3d 651, 660 (3d Cir. 2012) (citing 

United States v. Coles, 437 F.3d 361, 365 (3d Cir. 2006)).

III. GPS SEARCHES AND THE WARRANT 

REQUIREMENT

The Fourth Amendment mandates that
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[t]he right of the people to be secure in their 

persons, houses, papers, and effects against 

unreasonable searches and seizures, shall not be 

violated, and no Warrant shall issue, but upon 

probable cause, 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. Prior to 1967, the Supreme Court of 

the United States interpreted this language generally to mean 

that the Fourth Amendment prevented the police from 

physically intruding upon an individual‟s private property for 

purposes of conducting a search (the physical intrusion 

theory). See United States v. Jones, 132 S. Ct. 945, 949-50

(2012); see also, e.g., Olmstead v. United States, 277 U.S. 

438 (1928) (upholding the warrantless wiretapping of a 

target‟s telephone lines primarily because “[t]here was no 

entry of the houses or offices of the defendants”), overruled 

in part by Katz v. United States, 389 U.S. 347 (1967).

1

 A 

 

1 We note that, at times, the Supreme Court has referred to 

this theory in the language of “trespass” rather than physical 

intrusion. Compare Jones, 132 S. Ct. at 949-50, with Florida 

v. Jardines, 133 S. Ct. 1409, 1414 (2013). As the law 

currently stands, we think the latter term — “physical 

intrusion” — is the more appropriate. See Jardines, 133 S. 

Ct. at 1420-21 (Alito, J., dissenting) (criticizing the Supreme 

Court‟s most recent application of the physical intrusion 

theory and noting that “trespass law provides no support for 

the Court‟s holding today”); Silverman v. United States, 365 

U.S. 505, 511 (1961) (“[W]e need not pause to consider 

whether or not there was a technical trespass under the local 
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change came in 1967 with the decision in Katz v. United 

States, which involved the warrantless wiretapping of a public 

phone booth. 389 U.S. 347. In Katz, the Court announced 

that the Fourth Amendment “protects people, not places,” id.

at 351, a principle that eventually became embodied in what 

Justice Harlan termed an individual‟s “reasonable expectation 

of privacy” (the privacy theory), id. at 360-61 (Harlan, J., 

concurring). In subsequent years, the privacy theory became 

the driving force behind Fourth Amendment jurisprudence,

while the physical intrusion theory lay dormant. See, e.g., 

United States v. Santillo, 507 F.2d 629, 632 (3d Cir. 1975) 

(noting that “the trespassory concepts [in early Fourth 

Amendment jurisprudence] . . . have since been discredited” 

(footnotes omitted) (citing Katz, 389 U.S. at 352-53)).

A. Beepers, GPS Devices, and the Fourth Amendment

It was in this context that courts began grappling with 

the constitutionality of using tracking devices. For purposes 

of our discussion, we begin with the Fifth Circuit‟s 1981 

decision in United States v. Michael, 645 F.2d 252 (5th Cir. 

1981) (en banc), which considered the warrantless use of a 

beeper for surveillance of a suspected drug manufacturer. In 

Michael, the court assumed that installation of the beeper on 

the exterior of a van constituted a search before holding that 

the DEA agents‟ conduct was constitutional since they acted 

based on reasonable suspicion. Id. at 256-59 (holding that 

defendant had “reduced” privacy expectations in the 

 

property law relating to party walls. Inherent Fourth 

Amendment rights are not inevitably measurable in terms of 

ancient niceties of tort or real property law.” (footnote 

omitted)).
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movement of his automobile and that the use of a beeper was 

minimally intrusive). A pair of dissenting opinions argued 

that, among other things, the DEA agents were required to 

obtain a warrant because they physically intruded upon the 

defendant‟s property (i.e., his car). See, e.g., id. at 260-70 

(Tate, J., dissenting).

Two years later, the Supreme Court took up the beeper 

issue, ultimately holding that concealing a beeper inside of a 

container that was then loaded onto a target‟s vehicle did not 

constitute a search, where the beeper‟s placement was 

accomplished with the container owner‟s consent. United 

States v. Knotts, 460 U.S. 276, 279-80, 285 (1983). In so 

doing, the Supreme Court explained that “[a] person traveling 

in an automobile on public thoroughfares has no reasonable 

expectation of privacy in his movements from one place to 

another.” Id. at 281. Nonetheless, the Court‟s ruling was not 

unequivocal, with the Majority cautioning that twenty-four

hour, “dragnet type law enforcement practices” could 

implicate “different constitutional principles.” Id. at 283-84.

The Supreme Court returned to beepers the following 

year when it decided United States v. Karo, 468 U.S. 705 

(1984), which centered on the DEA‟s use of a beeper to 

collect information regarding the whereabouts of objects 

inside a private residence. In Karo, the DEA had once again 

secreted a beeper inside of a container — also with the 

container owner‟s consent — and ensured that the container 

would be loaded into the target‟s vehicle. Id. at 708-09. The 

agents then used the beeper to track the vehicle to various 

locations and determined that the beeper-concealing container 

had been brought inside several residences (something that 

they could not verify with visual surveillance). Id. at 709-10. 

In holding that use of the beeper was unconstitutional under 
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those circumstances, the Court explained that, unlike in 

Knotts — where information was “voluntarily conveyed to 

anyone who wanted to look” — the information obtained by 

monitoring the beeper while inside a private residence gave 

the DEA information “that could not have been visually 

verified.” Id. at 715 (internal quotation marks omitted). In a 

partial dissent, Justice Stevens (joined by Justices Brennan 

and Marshall) argued that placing the beeper inside a 

container, which was then loaded into the target‟s vehicle, 

implicated both a “seizure and a search within the meaning of 

the Fourth Amendment.” Id. at 728 (Stevens, J., dissenting in 

part).

After the beeper-centered decisions in Michael, Knotts, 

and Karo, technological advances heralded the advent of a 

new electronic surveillance device: the GPS tracker. One of 

the first decisions to address the constitutionality of this new 

technology was United States v. McIver, 186 F.3d 1119 (9th 

Cir. 1999). In McIver, the Ninth Circuit rejected defendant‟s 

argument that installing a GPS device (along with a beeper) 

on the “undercarriage of [the defendant‟s automobile]” 

constituted a “seizure of the vehicle.” Id. at 1127 (“McIver 

did not present any evidence that the placement of the 

magnetized tracking devices deprived him of dominion and 

control of his [vehicle], nor did he demonstrate that the 

presence of these objects caused any damage to the electronic 

components of the vehicle.”). The court also concluded that, 

because McIver could demonstrate no reasonable expectation 

of privacy in the exposed undercarriage of his car, the use of 

the electronic devices did not constitute a search under the 

Fourth Amendment. Id. at 1126-27.

The Seventh Circuit followed suit in 2007, with Judge 

Posner explaining that attaching a GPS device to a target 
14

vehicle did not constitute a search because such a device 

merely substitutes for “following a car on a public street,” an 

activity that “is unequivocally not a search within the 

meaning of the [Fourth Amendment].” United States v. 

Garcia, 474 F.3d 994, 997 (7th Cir. 2007). However, 

echoing the Supreme Court‟s concerns in Knotts, the Seventh 

Circuit warned that it might need to reevaluate its conclusion 

if faced with a case concerning use of GPS technology for 

mass surveillance. Id. at 998.

Three years later, the Ninth Circuit returned to the 

topic of GPS tracking, reaffirming its conclusion that 

attaching a GPS tracker to the undercarriage of a vehicle did 

not constitute a search. United States v. Pineda-Moreno, 591 

F.3d 1212, 1214-15 (9th Cir. 2010). The appellant filed a 

petition for rehearing en banc, and though the Ninth Circuit 

denied the petition, Chief Judge Kozinski issued a fiery 

dissent from the denial, accusing the Pineda-Moreno majority 

of being “inclined to refuse nothing” to the needs of law 

enforcement. United States v. Pineda-Moreno, 617 F.3d 

1120, 1121 (9th Cir. 2010) (Kozinski, C.J., dissenting). In his 

dissent, the Chief Judge noted that GPS devices “have little in 

common with the primitive devices in Knotts,” in part 

because, unlike GPS devices, beepers “still require[] at least 

one officer — and usually many more — to follow the 

suspect.” Id. at 1124. Thus, the dissent noted, while “[y]ou 

can preserve your anonymity from prying eyes, even in 

public, by traveling at night, through heavy traffic, in crowds, 

by using a circuitous route, disguising your appearance, 

passing in and out of buildings and being careful not to be 

followed,” there is “no hiding from the all-seeing network of 

GPS satellites that hover overhead, which never sleep, never 

blink, and never lose attention.” Id. at 1126.
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That same year, the Eighth Circuit became the third of 

our sister courts to say that attaching a GPS device to a target 

car was not a constitutional violation. United States v. 

Marquez, 605 F.3d 604, 609-10 (8th Cir. 2010). While the 

Marquez court based its ruling on standing grounds, it still 

announced — albeit in dicta — that “[w]hen electronic 

monitoring does not invade upon a legitimate expectation of 

privacy, no search has occurred.” Id. at 609 (“A person 

traveling via automobile on public streets has no reasonable 

expectation of privacy in his movements from one locale to 

another.” (citing Knotts, 460 U.S. at 281)).

Later that year, the D.C. Circuit split from our sisters, 

holding that attaching a GPS device to a defendant‟s vehicle 

constituted a search under the Fourth Amendment that 

required the police to obtain a warrant. United States v. 

Maynard, 615 F.3d 544 (D.C. Cir. 2010). In so doing, the 

court rejected the Knotts-based argument that a driver‟s 

movements are exposed to the public and therefore do not 

constitute information shielded by the Fourth Amendment. 

Id. at 560 (“[W]e hold the whole of a person‟s movements 

over the course of a month is not actually exposed to the 

public because the likelihood a stranger would observe all 

those movements is not just remote, it is essentially nil.”). At 

the same time, the court in Maynard rejected the applicability 

of the automobile exception to the warrant requirement, 

holding that while the exception “permits the police to search 

a car without a warrant if they have reason to believe it 

contains contraband[, it] . . . does not authorize them to install 

a tracking device on a car without the approval of a neutral 

magistrate.” Id. at 567. A year later, the Supreme Court 

granted certiorari, changing the name to United States v. 

Jones. 131 S. Ct. 3064 (2011).
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In reviewing the Maynard decision (now called Jones), 

the Supreme Court held that magnetically attaching a GPS 

device to a suspect‟s automobile constituted a search for 

purposes of the Fourth Amendment. Jones, 132 S. Ct. at 949. 

Rather than focusing on whether the owner of the vehicle had 

a reasonable expectation of privacy while driving the car over

public streets, the Court (with Justice Scalia writing for the 

majority) concluded that attaching a GPS device to a target 

car constituted a physical intrusion upon the vehicle owner‟s 

private property. Id. (“The Government physically occupied 

private property for the purpose of obtaining information. 

We have no doubt that such a physical intrusion would have 

been considered a „search‟ within the meaning of the Fourth 

Amendment when it was adopted.”).

Justice Alito concurred in the judgment, but did not 

join the majority‟s opinion. Id. at 957 (Alito, J., concurring). 

In his opinion — joined by Justices Ginsburg, Breyer, and 

Kagan — the appropriate Fourth Amendment analysis was 

the “reasonable expectation of privacy” inquiry under Katz. 

The outcome would be no different if the Court had applied 

Katz, the concurrence argued, because “society‟s expectation 

has been that law enforcement agents and others would not —

and indeed, in the main, simply could not — secretly monitor 

and catalogue every single movement of an individual‟s car 

for a very long period” of time. Id. at 964.

Justice Sotomayor, who joined the majority, also filed 

a concurrence. Id. at 954 (Sotomayor, J., concurring). And 

while she agreed with portions of Justice Alito‟s reasoning, 

she nonetheless rebuked the concurring Justices for 

potentially countermanding an “irreducible constitutional 

minimum: When the Government physically invades 

personal property to gather information, a search occurs.” Id.
17

at 955. Moreover, Justice Sotomayor argued that GPS 

devices present law-enforcement agencies with a low-cost, 

low-resource method of tracking citizens. As such, even 

short-term surveillance constituted an impermissible search 

under the Fourth Amendment. Id. at 955-57 (calling, also, for 

potentially reassessing the privacy interests individuals enjoy 

in information disclosed to third parties so as to account for 

the new realities of the digital age).

Among the issues that Jones left open, however, was 

whether warrantless use of GPS devices would be 

“reasonable — and thus lawful — under the Fourth 

Amendment [where] officers ha[ve] reasonable suspicion, and 

indeed probable cause” to execute such searches. Id. at 954

(citation and internal quotation marks omitted). The instant 

case squarely presents this very issue for our consideration.2 

 

2 At the time of this writing, we are not aware of — nor has 

either party brought to our attention — any decision by one of 

our sister circuits that directly and definitively resolves the 

matter. As our brethren in the First Circuit noted earlier this 

year:

Few courts (and no circuits that we know of) have grappled 

with the warrant question so far, largely because the searches 

at issue in recent cases occurred pre-Jones, allowing the 

government to argue, and a number of courts to find, that the 

good-faith exception [to the exclusionary rule] would apply 

even if the searches were unconstitutional.

United States v. Sparks, 711 F.3d 58, 62 (1st Cir. 2013). As 

we explain at greater length below, we do not believe that the 

good-faith exception applies in this case and consequently 

take on the warrant issue.
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We therefore turn now to a consideration of the Fourth 

Amendment‟s warrant requirement and the various — albeit 

circumscribed — exceptions thereto.

B. The Warrant Requirement and Its Exceptions

The Fourth Amendment does not protect individuals 

from all searches, just unreasonable ones. Indeed, as the 

Supreme Court has noted: “[T]he ultimate measure of the 

constitutionality of a governmental search is 

„reasonableness.‟” Vernonia Sch. Dist. 47J v. Acton, 515 

U.S. 646, 652 (1995). “[W]hether a particular search meets 

the reasonableness standard is judged by balancing its 

intrusion on the individual‟s Fourth Amendment interests 

against its promotion of legitimate governmental interests.” 

Id. at 652-53 (internal quotation marks omitted). Under this 

“general . . . approach,” courts look to the “totality of the 

circumstances” in performing this balancing test. United 

States v. Knights, 534 U.S. 112, 118 (2001) (internal 

quotation marks omitted).

More often than not, courts “strike this balance in 

favor of the procedures described by the Warrant Clause of 

the Fourth Amendment.” Skinner v. Ry. Labor Execs.’ Ass’n, 

489 U.S. 602, 619 (1989). Thus, “[i]t remains a cardinal 

principle that searches conducted outside the judicial process, 

without prior approval by judge or magistrate, are per se

unreasonable under the Fourth Amendment — subject only to 

a few specifically established and well-delineated 

exceptions.” United States v. Harrison, 689 F.3d 301, 306 

(3d Cir. 2012) (internal quotation marks omitted). This 

protection applies to both “„houses‟ and „effects,‟” barring the 

presence of some “„exceptional circumstances‟” that would 

permit an exception. See United States v. Jeffers, 342 U.S. 
19

48, 51 (1951) (quoting Johnson v. United States, 333 U.S. 10, 

14 (1948)).

We therefore begin with the following observation: 

under the physical intrusion theory of the Fourth Amendment, 

the police actions in this case — i.e., physical entry upon and 

occupation of an individual‟s house or effects for purposes of 

ongoing GPS tracking — are highly disconcerting. In 

Silverman v. United States, 365 U.S. 505 (1961), the police, 

acting without a warrant, had surreptitiously driven a “spike 

mic” (a long spike capable of picking up sound) through the 

wall of a neighboring house and into the heating duct of the 

defendant‟s home. Id. at 506-07. The Court proclaimed this 

to be “beyond the pale of even those decisions in which a 

closely divided Court has held that eavesdropping 

accomplished by other than electronic means did not amount 

to an invasion of Fourth Amendment rights.” Id. at 509-10; 

id. at 511-12 (“This Court has never held that a federal officer 

may without warrant and without consent physically entrench 

into a man‟s office or home, there secretly observe or listen, 

and relate at the man‟s subsequent criminal trial what was 

seen or heard.” (emphasis added)). While the Fourth 

Amendment recognizes a difference between the invasion of 

a “store, dwelling house, or other structure . . . of which a . . . 

warrant readily may be obtained and a search of a ship, motor 

boat, wagon, or automobile . . . where it is not practicable to 

secure a warrant,” that difference, on its own, still mandates 

that a warrantless search of a car be based on probable cause 

— and, even then, only in a highly circumscribed universe of 

cases. Carroll v. United States, 267 U.S. 132, 153 (1925).3

 

3 We address the “automobile exception,” first recognized in 

Carroll, in greater detail below.
20

We thus have no hesitation in holding that the police 

must obtain a warrant prior to attaching a GPS device on a 

vehicle, thereby undertaking a search that the Supreme Court 

has compared to “a constable‟s concealing himself in the 

target‟s coach in order to track its movements.” Jones, 132 S. 

Ct. at 950 n.3. In the following section, therefore, we analyze 

whether any additional considerations weigh in favor of 

finding warrantless GPS searches to be reasonable.

1. Valid, Warrantless Searches Based on Less than 

Probable Cause

The Government first argues that the warrantless use 

of a GPS device in this case constitutes a reasonable search 

because the police action was based on reasonable suspicion.4 

In service of this argument, the Government posits that 

“[s]ince Terry v. Ohio, 392 U.S. 1 (1968), the Court has 

identified various law enforcement actions that qualify as 

Fourth Amendment searches or seizures, but that may 

nevertheless be conducted without a warrant or probable 

cause.” (Appellant Br. at 23.) This is true. The Government 

cites to three general categories of cases that permit 

warrantless searches based on less than probable cause: 

“special needs” cases, decisions addressing circumstances in 

which individuals have lessened privacy interests, and the 

progeny of Terry v. Ohio. We consider each category in turn 

and find that none apply to the instant matter.

 

4 We assume, without deciding, that the police had reasonable 

suspicion for purposes of our analysis.
21

a. The “Special Needs” Cases

As the Supreme Court has explained: “We have 

recognized exceptions to th[e Warrant Clause] when special 

needs, beyond the normal need for law enforcement, make the 

warrant and probable-cause requirement impracticable.” 

Skinner, 489 U.S. at 619-20 (internal quotation marks 

omitted) (collecting cases). Thus, so long as the “primary 

purpose” is not to “uncover evidence of ordinary criminal 

wrongdoing,” City of Indianapolis v. Edmond, 531 U.S. 32, 

42 (2000), courts should “balance the governmental and 

privacy interests to assess the practicality of the warrant and 

probable-cause requirements in the particular context,” 

Skinner, 489 U.S. at 619. See also United States v. Ward, 131 

F.3d 335, 342 (3d Cir. 1997). Such “special needs” cases, 

many of which permit searches without any particularized 

suspicion, constitute a “closely guarded category” of Fourth 

Amendment jurisprudence. Ferguson v. City of Charleston, 

532 U.S. 67, 77 (2001) (internal quotation marks omitted). 

In the instant case, the reasoning behind the “special 

needs” doctrine is inapposite. The Government cannot 

articulate a particularized interest, other than a generalized

interest in law enforcement. Indeed, the Government 

contends that if officers are required to obtain a warrant and 

have probable cause prior to executing a GPS search, 

“officers could not use GPS devices to gather information to 

establish probable cause, which is often the most productive 

use of such devices.” (Appellant Br. at 27 (emphasis added).) 

This statement — which wags the dog rather vigorously —

runs headlong into Ferguson‟s admonition that, to qualify for 

a “special needs” exception, the primary purpose of a search 

cannot be to “generate evidence for law enforcement 

purposes.” 532 U.S. at 83 (emphasis omitted); Edmond, 531 
22

U.S. at 48 (finding that a search did not qualify under the 

“special needs” doctrine where the “primary purpose of the 

[search] is ultimately indistinguishable from the general 

interest in crime control”).5

b. Cases of Diminished Privacy Expectations

Still, the “special needs” cases are not the only 

decisions to permit warrantless searches based on less than 

probable cause. The Government also cites a number of cases 

that address situations where the targets of a search enjoyed a 

lower expectation of privacy.6 See, e.g., United States v. 

 

5

The Government contends that requiring a warrant prior to 

GPS searches would “seriously impede the government‟s 

ability to investigate drug trafficking, terrorism, and other 

crimes.” (Appellant Br. at 27.) We fail to see how such a 

conclusory assertion suffices to except GPS searches from the 

requirements of the Fourth Amendment‟s Warrant Clause. 

Doubtless, we are aware of the dangers posed by terrorism 

and comparably reprehensible criminal activity. However, 

we would work a great disservice by permitting the word 

“terrorism” (in the absence of any other information or 

circumstance) to act as a skeleton key to the liberties 

guaranteed under the Constitution.

6

The seemingly paradoxical exercise of analyzing a search 

based on physical intrusion under the rubric of privacy 

expectations does not escape our notice. Still, as the Supreme 

Court noted in Jones: “The Katz reasonable-expectation-ofprivacy test has been added to, not substituted for, the 

common-law trespassory test.” Jones, 132 S. Ct. at 952. 

Moreover, we note that even before Katz, the Supreme Court 

was balancing the “need for effective law enforcement 
23

Knights, 534 U.S. 112, 121 (2001) (“When an officer has 

reasonable suspicion that a probationer subject to a search 

condition is engaged in criminal activity, there is enough 

likelihood that criminal conduct is occurring that an intrusion 

on the probationer‟s significantly diminished privacy interests 

is reasonable.”). We do not think such reasoning is 

applicable to this case.

The police executed a GPS search against an 

individual — Harry Katzin — who, at least when the police 

attached the GPS device, enjoyed the full breadth of privacy 

interests owed to him under the Constitution. That the search 

was executed on a car is, likewise, unpersuasive. While the 

Supreme Court has acknowledged that individuals enjoy a 

lowered expectation of privacy in their cars, United States v. 

Chadwick, 433 U.S. 1, 12 (1977), abrogated by California v. 

Acevedo, 500 U.S. 565 (1991), absent circumstances that are 

not present in this case, the police must still have probable 

cause, Acevedo, 500 U.S. at 579-80.

c. Terry and Its Progeny

In no small part, the Government argues that the 

warrantless use of slap-on GPS devices is permissible based 

on reasonable suspicion under the principles of Terry v. Ohio, 

392 U.S. 1. In Terry, the Supreme Court held that a police 

officer could “stop” an individual on the street for questioning 

 

against the right of privacy” in considering whether a 

particular situation constituted an exception to the Fourth 

Amendment‟s warrant requirement. Johnson, 333 U.S. at 14-

15 (considering warrantless searches based on probable 

cause).
24

and then “frisk” him to ascertain whether the individual was 

carrying weapons. Terry, 392 U.S. at 22-27. More 

specifically, the Court held that a warrantless search — the 

stop — was permissible when based on less than probable 

cause if the “police officer observes unusual conduct which 

leads him reasonably to conclude in light of his experience 

that criminal activity may be afoot.” Id. at 30. As for the 

search — the frisk — the Court explained that a search was 

permitted when the officer reasonably believed that “the 

person[] with whom he is dealing may be armed and 

presently dangerous . . . and where nothing in the initial 

stages of the encounter serves to dispel his reasonable fear for 

his own or others‟ safety.” Id. Such a search, given that it is 

performed without probable cause, “must be limited to that 

which is necessary for the discovery of weapons which might 

be used to harm the officer or others nearby, and may 

realistically be characterized as something less than a „full‟ 

search.” Id. at 26. The Terry framework has since expanded 

to include situations where, for example, an automobile has 

been stopped. See, e.g., Michigan v. Long, 463 U.S. 1032 

(1983); Pennsylvania v. Mimms, 434 U.S. 106 (1977); United 

States v. Yamba, 506 F.3d 251 (3d Cir. 2007).

We find Terry and its progeny to be inapposite in this 

situation. While the frisk in Terry involved a pat-down of an 

individual, that search was limited to a specific instance in 

time (and limited to ascertaining whether the individual was 

armed or otherwise posed a danger to officer safety). A GPS 

search, in contrast, is an ongoing, vastly broader endeavor.7 

 

7

The Government argues that “[a] Terry search is the 

paradigmatic example of a law enforcement action, absent 

„special needs‟ . . . , in which the balancing of law 
25

Cf. Berger v. New York, 388 U.S. 41, 59 (1967) (noting that 

“eavesdropping for a two-month period is the equivalent of a 

series of intrusions, searches, and seizures”). Over the course 

of the GPS tracker‟s operation, the device can “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.” 

Jones, 132 S. Ct. at 955 (Sotomayor, J., concurring).8

 

enforcement interests and privacy rights yields a standard less 

than probable cause.” (Appellant Br. at 33.) This is 

incorrect. While the Court found that the “stop” was 

permissible despite merely serving a “legitimate investigative 

function,” that same rationale did not apply to the “frisk.” 

Terry, 392 U.S. at 22-24. Rather, the Court explicitly noted, 

in evaluating the search of an individual‟s person, that it was 

“now concerned with more than the governmental interest in 

investigating crime.” Id. at 23 (emphasis added). 

Specifically, the Terry court looked to the “more immediate 

interest of the police officer in taking steps to assure himself 

that the person with whom he is dealing is not armed with a 

weapon that could unexpectedly and fatally be used against 

him.” Id. The police, in attaching a GPS device to a car, are 

not looking for weapons and generally are not attempting to 

safeguard anyone‟s immediate safety — they are attempting 

to investigate crime.

8

The Government also seems to suggest that our evaluation 

should turn on how long the GPS unit remained attached to 

Harry Katzin‟s van. (Appellant Br. at 25.) It is unclear, 

however, whether such a test would prove workable. It is not 

apparent whether, pursuant to such a test, the government 

would need to know how long a GPS search would last or 
26

Ultimately, we disagree with the Government‟s 

arguments advocating a “reasonable suspicion” standard. 

While the interests the police wished to further in this case are 

certainly important, the same interests arise in every

investigation where the police have a potential suspect. We 

are hard pressed to say, therefore, that the police can —

without warrant or probable cause — embark on a lengthy 

program of remote electronic surveillance that requires almost 

no law enforcement resources and physically intrudes upon 

an ordinary citizen‟s private property. Consequently, we hold

that — absent some highly specific circumstances not present 

in this case — the police cannot justify a warrantless GPS 

search with reasonable suspicion alone.9

 

whether they could, upon reaching some threshold duration, 

request a warrant from the courts for further GPS 

surveillance. We need not definitively resolve this question 

now, however. In this case, it was only by dint of 

coincidence that the GPS surveillance lasted for a mere 

handful of days.

9

In support of its position, the Government points to the 

Eighth Circuit‟s decision in Marquez and the Fifth Circuit‟s 

decision in Michael. In Marquez, the court suggested that 

“[w]hen electronic monitoring does not invade upon a 

legitimate expectation of privacy, no search has occurred.” 

605 F.3d at 610 (“[W]hen police have reasonable suspicion 

that a particular vehicle is transporting drugs, a warrant is not 

required when, while the vehicle is parked in a public place, 

they install a non-invasive GPS tracking device on it for a 

reasonable period of time.”). In Michael, the Fifth Circuit 

explained that the “reduced” expectation of privacy with 

respect to the movement of an automobile and the 
27

 

nonintrusive nature of the procedure permitted DEA agents to 

install a beeper on the defendant‟s car. 645 F.2d at 257-58 

(“The actual installation of the beeper was much less intrusive 

than the typical stop and frisk. Michael . . . was not detained 

or questioned; he suffered no indignity; nothing from the 

interior of the van was seized or searched; indeed, nothing 

even from the van‟s exterior was removed.” (footnote 

omitted)).

The Government‟s reliance is misplaced. Both Michael and 

Marquez were decided prior to Jones, and thus did not have 

the benefit of: (a) the Court‟s reliance on the pre-Katz

trespass theory of the Fourth Amendment or (b) Justice 

Sotomayor‟s concurrence. Moreover, both cases are 

inapposite: In Marquez, the court found that the defendant 

lacked standing to challenge the use of the GPS device and 

therefore never reached the question of whether such use 

constituted an unreasonable search. 605 F.3d at 609. The 

Eighth Circuit‟s discussion of reasonable suspicion is 

therefore dicta, coming only while the court was musing on 

what would happen “[e]ven if [the defendant] had standing.” 

Id. In Michael, the Fifth Circuit focused on a beeper —

which is markedly different from a GPS device — and its 

decision is therefore distinguishable. 645 F.2d 256-59. 

Additionally, both decisions run up against the holding in 

Maynard, where the D.C. Circuit explained that warrantless 

installation of a GPS device by the police was per se

unreasonable under the Fourth Amendment. 615 F.3d at 566-

67.
28

2. Valid, Warrantless Searches Based on Probable 

Cause

As an alternative, the Government suggests that 

warrantless GPS searches can be constitutional if the police 

have probable cause, pointing principally to a line of cases 

addressing the “automobile exception” to the warrant 

requirement.10 We do not agree.11

 

10 We note that a warrantless search based on probable cause 

is also reasonable in the presence of certain “exigent 

circumstances” that “make the needs of law enforcement so 

compelling that [a] warrantless search is objectively 

reasonable under the Fourth Amendment.” Kentucky v. King, 

131 S. Ct. 1849, 1856 (2011) (internal quotation marks 

omitted). Such exigent circumstances include, but are not 

limited to, “hot pursuit of a suspected felon, the possibility 

that evidence may be removed or destroyed, and danger to the 

lives of officers or others.” United States v. Coles, 437 F.3d 

361, 366 (3d Cir. 2006) (“In these limited situations, the need 

for effective law enforcement trumps the right of privacy and 

the requirement of a search warrant, thereby excusing an 

otherwise unconstitutional intrusion.” (footnote omitted)). In 

this case, we perceive (and the Government points to) no 

exigency that would have justified the police in immediately 

searching Harry Katzin‟s van. We do not discount, therefore, 

the possibility that under highly specific circumstances —

such as where life is on the line, say — the police can justify 

undertaking a warrantless GPS search based on probable 

cause.

11 Here we also assume, without deciding, that the police had 

probable cause for purposes of our analysis.
29

Generally speaking, a warrantless search is not 

rendered reasonable merely because probable cause existed 

that would have justified the issuance of a warrant. See Vale 

v. Louisiana, 399 U.S. 30, 34 (1970); see also Johnson, 333 

U.S. at 14 (“Any assumption that evidence sufficient to 

support a magistrate‟s disinterested determination to issue a 

search warrant will justify the officers in making a search 

without a warrant would reduce the Amendment to a nullity 

and leave the people‟s homes secure only in the discretion of 

police officers.”). However, under the “automobile 

exception,” we permit “warrantless searches of any part of a 

vehicle that may conceal evidence . . . where there is probable 

cause to believe that the vehicle contains evidence of a 

crime.” United States v. McGlory, 968 F.2d 309, 343 (3d Cir. 

1992) (internal quotation marks omitted); see also United 

States v. Ross, 456 U.S. 798, 825 (1982) (“If probable cause 

justifies the search . . . , it justifies the search of every part of 

the vehicle and its contents that may conceal the object of the 

search.”); United States v. Burton, 288 F.3d 91, 100 (3d Cir. 

2002) (holding that warrantless searches of an automobile are 

permitted if “probable cause exists to believe it contains 

contraband” (internal quotation marks omitted)). That said, 

the Supreme Court has recognized that “[t]he word 

„automobile‟ is not a talisman in whose presence the Fourth 

Amendment fades away and disappears.” Coolidge v. New 

Hampshire, 403 U.S. 443, 461-62 (1971) (discussing the 

automobile exception in the context of exigent 

circumstances).12 Indeed, the automobile exception does not 

 

12 The automobile exception began as part of the “exigent 

circumstances” jurisprudence. Carroll, 267 U.S. at 153 

(noting that the Fourth Amendment made a distinction for 

searches of automobiles since “it is not practicable to secure a 
30

validate all warrantless automobile searches, but instead is 

“unquestionably [a] specifically established and well 

delineated” exception. Ross, 456 U.S. at 824 (internal 

quotation marks omitted). Thus, “„[t]he scope of a 

warrantless search of an automobile . . . is defined by the 

object of the search and the places in which there is probable 

cause to believe that it may be found.‟” Acevedo, 500 U.S. at 

579-80 (quoting United States v. Ross, 456 U.S. 798, 824 

(1982)).

We hold that the automobile exception is inapplicable 

here. The key distinction in this case is the type of search at 

issue. While the Supreme Court has stated that the 

automobile exception permits a search that is “no broader and 

no narrower than a magistrate could legitimately authorize by 

warrant,” Ross, 456 U.S. at 825, the search is still limited to a 

 

warrant, because the vehicle can be quickly moved out of the 

locality or jurisdiction in which the warrant must be sought”). 

Later cases expanded on this rationale, adding further 

justification for why the police need not obtain a search 

warrant for the car. Most significantly, after the Katz

decision had given precedential imprimatur to the language of 

“privacy,” the Court explained in United States v. Chadwick, 

that “„[o]ne has a lesser expectation of privacy in a motor 

vehicle because its function is transportation and it seldom 

serves as one‟s residence or as the repository of personal 

effects.‟” 433 U.S. at 12 (quoting Cardwell v. Lewis, 417 

U.S. 583, 590 (1974)). Finally, the Supreme Court severed 

the connection between the automobile exception and exigent 

circumstances, holding that the exception “has no separate 

exigency requirement” at all. Maryland v. Dyson, 527 U.S. 

465, 466 (1999).
31

discreet moment in time. For example, the exception permits 

the police to enter upon and search a vehicle to ascertain 

whether it indeed contains the evidence that they suspect is 

inside. Thus, assuming — as we said we would — that the 

police had probable cause to believe that Harry Katzin‟s van 

contained some form of contraband, they would have been 

justified in entering “any part of [the] vehicle that may 

conceal evidence.” McGlory, 968 F.2d 343 (emphasis 

added). Attaching and monitoring a GPS tracker is different: 

It creates a continuous police presence for the purpose of 

discovering evidence that may come into existence and/or be 

placed within the vehicle at some point in the future.

It is no argument, then, to say that a GPS search 

presents the type of circumstances that usually trigger the 

automobile exception. It does not. While the police are still 

physically intruding into a target vehicle for evidencegathering purposes, a GPS search extends the police intrusion 

well past the time it would normally take officers to enter a 

target vehicle and locate, extract, or examine the then-existing 

evidence.

13 For similar reasons, the case in favor of applying 

the automobile exception fares no better if we look to the 

 

13 We recognize that the Supreme Court has sanctioned 

warrantless searches under the automobile exception that, for 

example, have occurred some time after the police first 

impounded a vehicle. See, e.g., United States v. Johns, 469 

U.S. 478, 485-88 (1985). We think this to be of no moment 

for our purposes. In cases such as Johns the search at issue 

still occurs at a specific point in time and is specifically 

limited in its scope to “places in which there is probable cause 

to believe that [contraband] may be found.” Id. at 485-86

(internal quotation marks omitted).
32

“ready mobility” of the target vehicle. Burton, 288 F.3d at 

100 (“[T]he „ready mobility‟ of automobiles permits their 

search based only on probable cause.”); see also Maryland v. 

Dyson, 527 U.S. 465, 467 (1999) (noting that “the automobile 

does not have a separate exigency requirement,” partly 

because vehicles are “readily mobile”). Simply put: attaching 

and monitoring a GPS tracker does not serve the purposes 

animating the automobile exception. As has already been 

said: the automobile exception permits the police to intrude 

into a vehicle to retrieve or examine then-existing evidence. 

A GPS search does not deal with existing evidence, but with 

future evidence that the police suspect could come into being. 

That is a worthy goal, to be sure, but it cannot absolve law 

enforcement personnel of the warrant requirement. As the 

Government points out, the Supreme Court‟s automobile 

exception decisions are “„based on the practicalities of the 

situations presented.‟” (Appellant Br. at 40 (quoting Ross, 

456 U.S. at 807 n.9).) However, the Government seems to 

overlook that the power to create an ongoing, near-invisible 

police presence via a GPS tracker skews the “realistic 

appraisal of the . . . protection that a contrary rule would 

provide” from the “relatively minor” to the decidedly major. 

(Id. (discussing protection for “privacy interests”).)

Additionally, we think that the “pervasive regulation 

of vehicles capable of traveling on the public roadways” is of 

no moment for purposes of the instant case. California v. 

Carney, 471 U.S. 386, 392 (1985). True, such pervasive 

regulation gave rise to the understanding that an individual is 

“accorded less privacy in [his] automobile[].” Id. Indeed, 

this principle animated the Supreme Court‟s statement that 

“[e]ven in cases where an automobile was not immediately 

mobile, the lesser expectation of privacy resulting from its 
33

use as a readily mobile vehicle justified application of the 

vehicular exception.” Id. at 391. Nevertheless, we still hold 

that a GPS search is sufficiently different from the type of 

search sanctioned by the automobile exception jurisprudence 

— and that, as a consequence, even the extensive scheme of 

regulation now affecting motorists does not permit the 

government to dispense with asking for permission from a 

neutral magistrate when seeking to physically intrude upon a 

target vehicle for longer than is necessary to locate, remove, 

and/or verify the presence of already-existing evidence of 

criminal wrongdoing. Cf. Delaware v. Prouse, 440 U.S. 648, 

662-63 (1979) (noting, in the context of Terry stops, that 

“[w]ere the individual subject to unfettered governmental 

intrusion every time he entered an automobile, the security 

guaranteed by the Fourth Amendment would be seriously 

circumscribed”).14

 

14 The Government also points to New York v. Class, 475 U.S. 

106 (1986), for the proposition that a warrantless, minimally 

intrusive search of a vehicle is permitted where the police 

have probable cause. (Appellant Br. at 37). In Class, the 

police had stopped a car for various traffic violations. After 

the driver exited the vehicle of his own accord, an officer 

approached the vehicle in order to copy the VIN number on 

the dashboard. Finding his view obscured, the officer reached 

into the car to move some papers and, in the process, 

observed the handle of a gun. Inevitable results followed. 

Class, 475 U.S. at 107-09. A brief look at the underlying 

reasoning of Class, however, demonstrates that it is 

inapposite: the Court reasoned that the brief search served 

several important government needs beyond a basic interest 

in law enforcement, including “the governmental interest in 
34

Ultimately, in executing a GPS search, the police were 

not attempting to recover or ascertain the presence of 

evidence already present in Harry Katzin‟s vehicle. If they 

were, the automobile exception would have sanctioned their 

search in so far as it allowed them to enter Harry Katzin‟s van 

and retrieve and/or verify the presence or absence of the 

sought-after evidence. It would not (and, indeed, did not) 

permit them to leave behind an ever-watchful electronic 

sentinel in order to collect future evidence. Were we to hold 

otherwise, we would unduly expand the scope of the

automobile exception well past its “specifically established 

and well delineated” contours, Ross, 456 U.S. at 824, 

permitting the police to intrude indefinitely upon a target 

vehicle based solely on the prospect that it will, in the future, 

contain some contraband or be used during the commission of 

a crime. 

For these reasons we hold that the warrantless search 

in this case was not justifiable based solely on reasonable 

suspicion or probable cause, was thereby unreasonable, and 

consequently violated the Fourth Amendment.

IV. The Exclusionary Rule & the Good Faith Exception

Having held that the police were required to obtain a 

warrant prior to executing their GPS search of Harry Katzin‟s 

van, we now consider whether the evidence uncovered as a 

 

highway safety” and a “concern for the officers‟ safety.” Id.

at 118. Here, neither of the interests is directly served. 

Accord Jones, 132 S. Ct. at 952 (holding that Class is 

inapplicable to GPS searches because “attaching [a] device to 

the [car]” may have resulted in a different outcome).
35

result of their unconstitutional actions should be suppressed. 

We hold that it should.

A. Exclusionary Rule Jurisprudence

While the Fourth Amendment protects the “right of the 

people to be secure in their persons, houses, papers, and 

effects, against unreasonable searches and seizures[, it] says 

nothing about suppressing evidence obtained in violation of 

this command.” Davis v. United States, 131 S. Ct. 2419, 

2426 (2011) (internal quotation marks omitted). 

Nevertheless, to “compel respect for the constitutional 

guaranty,” the Supreme Court created the exclusionary rule. 

Elkins v. United States, 364 U.S. 206, 217 (1960). The rule 

mandates that evidence obtained in violation of the Fourth 

Amendment should not be available at trial. Herring v. 

United States, 555 U.S. 135, 139 (2009). However, “that a 

Fourth Amendment violation occurred . . . does not 

necessarily mean that the exclusionary rule applies.” Id. at 

140. 

As the Supreme Court has made plain, “exclusion has 

always been our last resort, not our first impulse.” Id.

(internal quotation marks omitted). To that end, the Supreme 

Court has recognized the existence of a “good faith” 

exception to the exclusionary rule in cases where the police 

“act[ed] with an objectively reasonable good-faith belief that 

their conduct [was] lawful.” Davis, 131 S. Ct. at 2427 

(internal quotation marks omitted).15 More specifically, the 

 

15 As the Supreme Court noted in Herring, “good faith 

exception” is somewhat of a misnomer. 555 U.S. at 142. The 

inquiry is not subjective at all, but instead looks to an 

officer‟s “objectively reasonable reliance.” Id. Nonetheless, 
36

Supreme Court has held this exception to cover situations 

where law enforcement personnel have acted in objectively 

reasonable reliance on some seemingly immutable authority 

or information that justifies their course of action. See Davis, 

131 S. Ct. 2419 (later-reversed binding appellate precedent); 

Herring, 555 U.S. 135 (undiscovered error in policemaintained database); Arizona v. Evans, 514 U.S. 1 (1995) 

(undiscovered error in court-maintained database); Illinois v. 

Krull, 480 U.S. 340 (1987) (subsequently overturned statute); 

United States v. Leon, 468 U.S. 897 (1984) (later-invalidated 

warrant).

To determine whether a particular situation is covered 

under this good faith exception, the Supreme Court has 

directed courts to consider whether exclusion would serve “to 

deter future Fourth Amendment violations.” Davis, 131 S. 

Ct. at 2426; see also Leon, 468 U.S. at 918 (“If exclusion of 

evidence obtained pursuant to a subsequently invalidated 

warrant is to have any deterrent effect, . . . it must alter the 

behavior of individual law enforcement officers or the 

policies of their departments.”). Thus, in analyzing whether 

the good faith exception applies, the Court balances “the 

benefits of the rule‟s deterrent effects against the costs of 

exclusion, which include „letting guilty and possibly 

dangerous defendants go free.‟” United States v. Tracey, 597 

F.3d 140, 151 (3d Cir. 2010) (quoting Herring, 555 U.S. at 

141).

When considering the benefits gained from deterrence, 

we must necessarily consider the nature and culpability of the 

 

because the Supreme Court (and our own decisions) use the 

terms interchangeably, we do so as well.
37

police conduct at issue. As the Supreme Court has explained, 

“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; Davis, 131 S. Ct. at 2429 

(cautioning courts not to discourage “the officer from doing 

his duty” (alteration and internal quotation marks omitted)). 

Thus, “we apply the rule when police conduct is „deliberate, 

reckless, or grossly negligent,‟ or when it will deter „recurring 

or systemic negligence.‟” Tracey, 597 F.3d at 151 (quoting 

Herring, 555 U.S. at 144). On the other hand, isolated or 

attenuated acts of negligence do not warrant the rule‟s 

application. Id.

In light of these principles, the Government argues that 

the police conduct at issue in this case does not rise to the 

level of culpability necessary for the exclusionary rule to 

apply and that, as a consequence, the balancing test outlined 

in Herring and Davis militates in favor of applying the good 

faith exception. In service of its argument, the Government 

urges that the police acted with an objectively reasonable 

good faith belief that their conduct was constitutional because 

“[b]efore Jones, every court of appeals to consider the 

question[, with the exception of one,] had concluded that, in 

light of the Supreme Court‟s decision in [Knotts], police did 

not need to obtain a warrant to install a GPS tracking device 

on the exterior of a vehicle or to use that device to monitor 

the vehicle‟s movements on public roads.” (Appellant Br. at 

48-49.) Indeed, the Government posits that this “consensus” 

among our sister circuits, coupled with the “guidance in 

Knotts and Katz,” absolves law enforcement personnel for 

purposes of the exclusionary rule. (Id. at 50, 55 n.21; Oral 

Argument Tr. at 23.) We find the Government‟s position 
38

unpersuasive and therefore hold that the good faith exception 

does not apply here. 

B. Reliance on Beeper Cases

The Government posits that law enforcement 

personnel acted in good faith because they relied on, among 

other things, the Supreme Court‟s “guidance” from Knotts

that using an electronic tracking device does not violate the 

Fourth Amendment. (Appellant Br. at 55 n.21.) Indeed, the 

Government observes that the reasoning from Knotts

underpins the decision of “every court of appeals to consider” 

GPS tracking (save the D.C. Circuit). (Id. at 48-49.) We first 

ask ourselves, therefore, whether the Knotts decision — along 

with its sibling case, Karo — qualifies as binding precedent 

under Davis v. United States, wherein the Supreme Court held 

that the good faith exception covers police officers acting in 

reliance on later-invalidated binding appellate precedent. 131 

S. Ct. 2419. As the forthcoming discussion demonstrates, we 

find that the explicit holding from Davis is inapposite because 

Knotts and Karo are both distinguishable given (1) the lack of 

a physical intrusion in those cases, (2) the placement by 

police of the beepers inside containers, and (3) the marked 

technological differences between beepers and GPS trackers.

In Davis, the police had executed a search of the 

defendant‟s car subsequent to his arrest. At the time of the 

search, prevailing Supreme Court and Eleventh Circuit 

precedent held that the police could lawfully search a 

suspect‟s car incident to his arrest. See New York v. Belton, 

453 U.S. 454 (1981); United States v. Gonzalez, 71 F.3d 819 

(11th Cir. 1996). The defendant unsuccessfully challenged 

the search. While the defendant‟s appeal was pending, the 

Supreme Court limited Belton, effectively restricting the areas 
39

of the car that the police were allowed to search after a 

suspect‟s arrest. See Arizona v. Gant, 556 U.S. 332 (2009). 

In deciding Davis, the Supreme Court reasoned that 

“[r]esponsible law-enforcement officers will take care to learn 

what is required of them under Fourth Amendment precedent 

and will conform their conduct to these rules.” 131 S. Ct. at 

2429 (internal quotation marks omitted). According to the 

Court, the police in Davis merely behaved as “reasonable 

officer[s] would and should act.” Id. (internal quotation 

marks omitted). Consequently, the Court found that “[t]he 

deterrent effect of exclusion in such a case can only be to 

discourage the officer from do[ing] his duty,” which was not 

“the kind of deterrence the exclusionary rule seeks to foster.” 

Id. (internal quotation marks omitted). Ultimately, therefore, 

the Court deemed that the police in Davis were covered by 

the good faith exception to the exclusionary rule and evidence 

recovered pursuant to the search was not suppressed. Id.

Of great significance to the instant case is the fact that

in Davis the police relied on binding appellate precedent that 

“specifically authorize[d the] particular police practice.” Id.

at 2429 (first emphasis added). Indeed, as Justice Sotomayor 

noted in her concurrence, Davis did not “present the markedly 

different question whether the exclusionary rule applies when 

the law governing the constitutionality of a particular search 

is unsettled.” Id. at 2435 (Sotomayor, J., concurring).16 By 

 

16 We also note that the Eleventh Circuit‟s opinion in Davis

was explicit on this point: “[We refuse] to apply the 

exclusionary rule when the police have reasonably relied on 

clear and well-settled precedent. We stress, however, that 

our precedent on a given point must be unequivocal before 

we will suspend the exclusionary rule‟s operation.” United 
40

its plain terms, therefore, the express holding in Davis is 

inapposite to this case because Knotts and Karo do not 

qualify as appropriate binding appellate precedent: Neither 

case involved a physical trespass onto the target vehicle; in 

both cases the police placed the beeper inside of a container 

which was then loaded into the target vehicle by the driver 

(all with the container owner‟s permission). See Karo, 468 

U.S. at 708; Knotts, 460 U.S. at 278. Additionally, both Karo

and Knotts addressed the use of beepers, which — as we have 

already explained — are markedly different from GPS 

trackers. See Maynard, 615 F.3d at 556-57.

Davis extends good faith protection only to acts that 

are explicitly sanctioned by clear and well-settled precedent, 

and neither Knotts nor Karo sanction the type of intrusion at 

issue in this case. Consequently, we hold that law 

enforcement‟s reliance on the beeper cases, standing on its 

own, cannot sufficiently insulates the GPS search in this case 

from the exclusionary rule.

 

States v. Davis, 598 F.3d 1259, 1266 (11th Cir. 2010) 

(citations omitted) (emphasis added); see also United States v. 

Buford, 632 F.3d 264, 276 n.9 (6th Cir. 2011) (“Like the 

Eleventh Circuit, we also „stress, however, that our precedent 

on a given point must be unequivocal before we will suspend 

the exclusionary rule‟s operation.‟” (quoting Davis, 598 F.3d 

at 1266)); United States v. McCane, 573 F.3d 1037, 1045 n.6 

(10th Cir. 2009) (finding that the good faith exception applied 

because “Tenth Circuit jurisprudence supporting the search 

was settled. Thus, there was no risk that law enforcement 

officers would engage in the type of complex legal research 

and analysis better left to the judiciary and members of the

bar”).
41

C. Reliance on Out-of-Circuit GPS Cases

We therefore consider the Government‟s contention 

that the good faith exception applies because the police acted 

in objectively reasonable reliance on out-of-circuit precedent 

sanctioning warrantless GPS surveillance. (Appellant Br. at 

15-16 (“Before [Jones], all but one of the courts of appeals to 

have addressed the issue had approved the warrantless 

installation and monitoring of a GPS device on a vehicle. . . . 

[T]he agents‟ reliance on this body of case law was 

objectively reasonable . . . .”).) And while the Government 

relies, in no small part, on the reasoning in Davis for support, 

we think that reading Davis so broadly would strain its 

reasoning, to say nothing of its holding.

17

 

17 We note that the majority in Davis itself suggested that its 

holding is inapplicable to the situation presented in this case. 

While explaining that its ruling will not deter defendants from 

challenging existing Fourth Amendment doctrine, the 

Supreme Court noted:

This Court reviews criminal convictions from 12 Federal 

Courts of Appeals, 50 state courts of last resort, and the 

District of Columbia Court of Appeals. If one or even many 

of these courts uphold a particular type of search or seizure, 

defendants in jurisdictions in which the question remains 

open will still have an undiminished incentive to litigate the 

issue. This Court can then grant certiorari, and the 

development of Fourth Amendment law will in no way be 

stunted.
42

The Davis decision hinged on the understanding that 

“[r]esponsible law-enforcement officers will take care to learn 

what is required of them under Fourth Amendment precedent 

and will conform their conduct to these rules.” Id. (internal 

quotation marks omitted). At the most basic level, then, the 

applicable body of “Fourth Amendment precedent” to which 

the responsible officer must conform consists of those 

decisions that are binding on the officer‟s jurisdiction. 

Accord Hudson v. Michigan, 547 U.S. 586, 599 (2006) 

(noting that officers are expected to learn and abide by “what 

is required of them” by courts having jurisdiction over them).

Thus, as already stated, the Court in Davis recognized 

that the good faith exception applies to situations where the 

police “conducted a search in objectively reasonable reliance 

on binding appellate precedent,” 131 S. Ct. at 2434, because 

“[t]he deterrent effect . . . in such a case can only be to 

discourage the officer from do[ing] his duty,” which was not 

“the kind of deterrence the exclusionary rule seeks to foster,” 

id. at 2429 (internal quotation marks omitted). The same 

cannot be said where the law is unsettled in a particular 

jurisdiction, even where persuasive authority may exist in the 

form of decisions by other circuit courts.

Indeed, extending the rationale from Davis to cover

reliance on out-of-circuit precedent would turn this principle 

on its head: Though our first and last word on the matter is 

that warrantless GPS searches are unconstitutional, in effect 

the Government argues that our sister circuits‟ decisions 

 

Davis, 131 S. Ct. at 2433 (emphasis added) (footnote 

omitted). Thus, the Court in Davis recognized that its holding 

was limited to jurisdictions where the law was clearly settled.
43

should control whether the evidence is excluded. This rule 

would eviscerate the notion that clear and well-settled 

precedent should control and thus contradicts the basic 

principles of stare decisis. We respect our sister circuits, but 

their decisions cannot dictate our conclusions. As such, any 

law enforcement officer who acts primarily in reliance on the 

Fourth Amendment proclamations of our sister circuits does 

so at his own peril for purposes of the exclusionary rule.

This is particularly true where, as in this case, our 

sister circuits are split on the relevant issue. The GPS search 

of Harry Katzin‟s van occurred in late 2010. By that time, 

four of our sister circuits — the Seventh, Eighth, Ninth, and 

D.C. Circuits — had addressed GPS surveillance. Of those, 

three circuits had held that GPS surveillance either did not 

constitute a search or, even if it did, that the police did not 

require a warrant. See McIver, 186 F.3d 1119; Garcia, 474 

F.3d 994; Pineda-Moreno, 591 F.3d 1212; Marquez, 605 F.3d 

604.

At the same time, the D.C. Circuit had held in United 

States v. Maynard (which became Jones on appeal to the 

Supreme Court) that GPS surveillance did constitute a search 

and that the police did require a warrant. Maynard, 615 F.3d 

544. At bottom, then, the Government seems to argue that 

reliance on a majority of a minority of our sister circuits is 

sufficient to escape the exclusionary rule. This cannot be. 

Although we find it commendable that law enforcement 

personnel would take the time to pore over out-of-circuit 

decisions relating to police procedures, it is not their duty for 

purposes of the exclusionary rule to parse and weigh the 

decisions of our sister circuits in an attempt to predict what 
44

this Court (or even the Supreme Court) would say if faced 

with a similar case.18

 

18 The Government urges that our analysis in United States v. 

Duka, 671 F.3d 329, 347 (3d Cir. 2011) (addressing evidence 

obtained in a search pursuant to the Foreign Intelligent 

Surveillance Act (FISA)), supports the proposition that the 

reasoning from Davis is not limited to binding precedent. 

(Appellant Br. at 61-62 (“[The] insistence on binding 

authority does not accord with this Court‟s approach 

following Davis. . . . [Duka] undermines the district court‟s 

position that reliance on non-binding case law . . . is per se 

unreasonable.”).) This is not correct. Not only was the good 

faith discussion in Duka based on a different Supreme Court 

decision — Krull, which addressed objectively reasonable 

reliance on a later-invalidated statute — but the entire 

discussion of the good faith exception is dicta. See Duka, 671 

F.3d at 346 (discussing the “good faith” exception only after 

noting that “[w]e are confident that FISA‟s „significant 

purpose‟ test satisfies the Fourth Amendment”). Moreover, 

the Government‟s argument seems to hinge on a footnote that 

contains the opinion‟s lone citation to Davis. In that footnote, 

this Court stated that “[t]he objective reasonableness of the 

officers‟ reliance on the statute in this case is further bolstered 

by the fact that the particular provision at issue has been 

reviewed and declared constitutional by several courts, going 

as far back as 2002.” Id. at 347 n.12 (collecting cases). Since 

none of these “several courts” are the Third Circuit, the 

Government argues, Duka demonstrates our willingness to 

apply the rationale from Davis to non-binding authority. We 

think this makes a mountain out of a molehill: this single 
45

Moreover, we cannot burden district courts with the 

type of case-by-case assessment that the Government‟s 

position would require. Unlike the archetypal situations in 

Leon or Davis, finding that the good faith exception applies in 

this case would, of necessity, require courts ruling on 

suppression motions to discern what amounts to sufficient 

out-of-circuit authority for purposes of an objectively 

reasonable good faith belief. Thus, district courts would need 

to consider how many circuits had addressed the police 

practice in question, what each one had said, whether the 

statements were mere dicta, and myriad other factors. Such 

an approach has no limiting principle and defies rational 

application. Surely police reliance on a single out-of-circuit 

decision could not support good faith, but what about two? If 

the circuits split two-to-one, that would present yet another 

problem. And what if our sister courts had all ruled in nearunanimity on a point, with one stalwart (perhaps, highly 

persuasive) holdout? Is the presence of good faith to be 

decided with an abacus or does the strength of each court‟s 

argument bear consideration? Because we foresee that it 

could lead to a sprawling, amorphous, and self-contradicting 

doctrine, we decline to adopt the Government‟s position and 

hold that reliance on out-of-circuit precedent (even where 

there is a so-called “consensus”) cannot, in and of itself, 

support application of the good faith exception.19

 

reference to Davis comes in dicta, in a footnote, as part of a 

“cf.” citation.

19 To see just how unwieldy the analysis could be, we need 

look no further than the Government‟s own arguments in this 

case. At oral argument, the Government attempted to 

minimize the significance of Maynard, suggesting that this 
46

D. Exclusion based on Culpability and Deterrence

Up to this point we have considered only whether 

reliance by law enforcement personnel on out-of-circuit or 

distinguishable authority, by itself, suffices for purposes of 

the good faith exception. Per the previous discussion, we 

hold that such reliance is insufficient to support a per se 

finding of good faith.20 The Supreme Court in Herring and 

 

single decision had come too late in the process and was, 

ultimately, distinguishable. Such arguments would be 

disastrously disruptive to lower courts if we were to hold that 

reliance on out-of-circuit authority could, by itself, suffice for 

purposes of the good faith exception. How up-to-date must 

law enforcement be regarding the state of relevant legal 

principles? What if a decision were issued but either (a) was 

late in being added to a reporter/electronic database or (b) did 

not get sufficiently wide-spread exposure to bring it to the 

attention of police departments half-way across the country? 

Not only would district courts be forced to tally the 

authorities on either side of an issue like so many chit marks, 

but they would also have to decide whether decisions had 

come too late, or were perhaps too obscure.

20 We note that some of our sister circuits have ruled 

otherwise, holding that, per Davis, pre-Jones warrantless GPS 

searches qualify for protection under the good faith exception. 

See United States v. Sparks, 711 F.3d 58 (1st Cir. 2013); 

United States v. Andres, 703 F.3d 828 (5th Cir. 2013); United 

States v. Pineda-Moreno, 688 F.3d 1087 (9th Cir. 2012). 

These cases, however, do not deter us from our conclusion.

To begin with, all three courts relied on binding precedent 

within their own circuits. The Ninth Circuit noted that the 
47

 

police could rely on, among other things, McIver for the 

proposition that “placing an electronic tracking device on the 

undercarriage of a car was neither a search nor a seizure 

under the Fourth Amendment.” Pineda-Moreno, 688 F.3d at 

1090. The Fifth Circuit, which devoted a single paragraph to 

the discussion, based its conclusion on the presence of 

Michael, and its holding that “„reasonable suspicion is 

adequate to support warrantless beeper installation‟ on a 

suspect‟s vehicle parked in a public space.” Andres, 703 F.3d 

at 835 (quoting Michael, 645 F.2d at 257). Finally, the First 

Circuit based its decision to apply the good faith exception on 

the presence of “clear and apposite” authority, including a 

First Circuit decision that found “„the lessened expectancy of 

privacy associated with motor vehicles justifies the use of 

beepers without a warrant to track vehicles . . . only if the 

officers have probable cause at the time.‟” Sparks, 711 F.3d 

at 65 (quoting United States v. Moore, 562 F.2d 106, 112-13 

(1st Cir. 1977)). At the same time, however, the First Circuit 

was far from certain that out-of-circuit precedent could 

support a finding of good faith, noting that “the two appellate 

courts to consider the question since Davis have read Davis to 

require reliance on the case law of the jurisdiction.” Id. at 63-

64 & 63 n.2 (internal quotation marks omitted).

Moreover, both the First and Fifth Circuits based their good 

faith exception determinations on cases dealing with beepers, 

with the First Circuit in Sparks going so far as to hold that 

Knotts was sufficiently “clear and apposite” so as to support a 

finding of good faith. Sparks, 711 F.3d at 65. As our 

foregoing discussion suggests: we disagree with this position. 

The difference between beepers and GPS trackers is one of 

kind, not degree. Any time technology shifts in this way, 
48

Davis, however, recognized that the good faith exception 

inquiry requires more. That is, in determining whether law 

enforcement personnel acted “with an objectively „reasonable 

good-faith belief‟ that their conduct [was] lawful,” we must 

consider whether the totality of circumstances is greater than 

the sum of its attendant parts. See Davis, 131 S. Ct. at 2427 

(quoting Leon, 468 U.S. at 909). We therefore undertake the 

balancing test outlined in Herring and Davis, and ask whether 

— in light of all the circumstances — the police activity in 

this case rises to the level of a “deliberate, reckless, or grossly 

negligent” violation of the Fourth Amendment. See Herring, 

555 U.S. at 144; Tracey, 597 F.3d at 151. We hold that it 

does.

Per the Government‟s argument, the legal landscape in 

this case predominantly consisted of the out-of-circuit GPS 

cases, the Supreme Court‟s beeper decisions, and the 

overarching privacy expectation framework for Fourth 

Amendment analysis adopted in Katz and deemed to be the 

sole rubric for analysis until Jones.

21

 (See, e.g., Appellant Br. 

 

courts should expect that law enforcement will tread lightly 

and will refrain from reasoning by (potentially ill-fitting) 

analogy. Cf. Kyllo v. United States, 533 U.S. 27, 35-36 

(2001) (discussing the Court‟s reticence to “leave the 

homeowner at the mercy of advancing technology”).

21 Our dissenting colleague points to a number of other 

decisions and Fourth Amendment doctrines which add further 

sauce to the Government‟s good faith goose. (See Dissent at 

20-29 (discussing, for example, privacy considerations in the 

exterior of an automobile).) While we do not disagree that 

these too were part of the relevant legal landscape at the time 

the police executed their search, we nevertheless hold that —
49

at 44, 50, 55 n.21; Oral Argument Tr. at 23.) Taken together, 

the Government contends, these sources of legal authority 

would lead a reasonable law enforcement officer to conclude 

that he was acting within the confines of the constitution 

when attaching a GPS tracker to the undercarriage of Harry 

Katzin‟s van. We find that, on balance, this collection of 

authority does not warrant applying the good faith exception. 

Try as we might to allay our concerns, we remain supremely 

discomfited by the lack of binding appellate guidance 

underlying the police action at issue in this case. Therefore, 

we hold that the police acted with sufficient constitutional 

culpability to require exclusion and, more importantly, that 

suppression in this case would help deter future Fourth 

Amendment violations.

Law enforcement personnel can rightly rely on a 

number of sources for Fourth Amendment guidance —

including on-point decisions by the Supreme Court and this 

Circuit, warrants, and statutes. We, both as a Court and as a 

society, expect that law enforcement officers will consult 

 

in light of our forthcoming discussion — such authority gets 

further and further afield of the relevant police conduct and 

could only supply marginal support to justify the police 

action.

The only possible exception is the advisory 

commentary on Federal Rule of Criminal Procedure 41. 

(Dissent at 32.) However, for the reasons articulated below, 

see infra note 24, we find that this commentary would not 

help the Government‟s position — even assuming the 

Government had seen fit to cite (let alone mention) the 

language in its briefs or at oral argument.
50

these sources — it is a part of how we expect reasonable 

officers to act. Davis, 131 S. Ct. at 2429. Deterring such 

activity, therefore, would not serve the purposes of the 

exclusionary rule. Id. This case, as we have just mentioned, 

is different. Nothing in a law enforcement officer‟s duties 

forces him to either rely on non-binding precedent or to 

conduct the Fourth Amendment calculus himself by 

extrapolating from, or analogizing to, existing case law. 

Where an officer decides to take the Fourth Amendment 

inquiry into his own hands, rather than to seek a warrant from 

a neutral magistrate — particularly where the law is as far 

from settled as it was in this case — he acts in a 

constitutionally reckless fashion.

Here, law enforcement personnel made a deliberate 

decision to forego securing a warrant before attaching a GPS 

device directly to a target vehicle in the absence of binding 

Fourth Amendment precedent authorizing such a practice. 

Indeed, the police embarked on a long-term surveillance 

project using technology that allowed them to monitor a 

target vehicle‟s movements using only a laptop, all before 

either this Circuit or the Supreme Court had spoken on the 

constitutional propriety of such an endeavor. (That the 

surveillance lasted only a few days is mere coincidence.22) 

 

22 We therefore reject the Government‟s attempts to 

distinguish Maynard. While it is true that the surveillance in 

Maynard lasted for nearly a month as compared to the several 

days in this case, it remains equally true that when the police 

attached their GPS device to Harry Katzin‟s van, they had no 

way of knowing when the next Rite Aid robbery would take 

place. We likewise disagree with our Dissenting colleague‟s 

assessment of Maynard. (Dissent at 29-31.) The good faith 
51

True, the police did not act in a total vacuum, but their chosen 

course of action when presented with such a novel 

constitutional situation is nonetheless troubling: In lieu of a 

binding proclamation from either this Circuit or the Supreme 

Court — and instead of seeking approval from a neutral 

magistrate — law enforcement personnel looked to other 

(non-binding or distinguishable) authorities like our sister 

circuits‟ decisions. Essentially, they extrapolated their own 

constitutional rule and applied it to this case. We fail to see 

how this absolves their behavior. The assumption by law 

enforcement personnel that their own self-derived rule 

sanctioned their conduct — to say nothing of their unstated 

belief that this Circuit would automatically side with a 

majority of the minority of our sister circuits — was 

constitutionally culpable.23

 

exception analysis cannot be post-hoc, and the police action 

at issue must be analyzed under the circumstances as they 

existed at the time the action was taken — in this case, before 

the police knew when their GPS surveillance would end.

23 The Government suggests that the good faith exception 

should apply because the police sought confirmation from 

“experienced government attorneys.” (Appellant Br. at 56.) 

The Government cites Messerschmidt v. Millender, 132 S. Ct. 

1235 (2012), for the proposition that it shows good faith on 

the part of an officer if he obtains “approval of the warrant 

application from a superior and a prosecutor before 

submitting it to a magistrate.” (Appellant Br. at 57.) 

However, Messerschmidt is inapposite. That case considered 

good faith in the context of an officer relying on a warrant 

that had been based on an allegedly paltry affidavit. Thus, the 

opinion of a third party tended to demonstrate that the officer 
52

The decisions in Knotts and Katz do not remedy the 

situation. The Government suggests that in this case law 

enforcement personnel properly reasoned that the GPS search 

did not require a warrant by analogizing to Knotts‟ discussion 

of electronic tracking devices. Doing so, the Government 

adds, was imminently reasonable given the prevailing Fourth 

Amendment framework at the time — the privacy theory 

from Katz. That is, the Government contends that because 

law enforcement personnel were aware that a search occurs 

when the police intrude upon a target‟s reasonable 

expectation of privacy, they acted in good faith by relying on 

our sister circuits‟ GPS decisions as well as Knotts‟ statement 

that, among other things, “[a] person travelling in an 

automobile on public thoroughfares has no reasonable 

expectation of privacy in his movements from one place to 

another.” Knotts, 460 U.S. at 281. We find such reasoning 

 

had not acted with knowledge of the affidavit‟s deficiency. In 

the instant case, the police lack even an affidavit. Moreover, 

a government attorney‟s approval, standing alone, cannot and 

should not suffice to demonstrate good faith. Cf. Leon, 468 

U.S. at 914 (“[T]he courts must also insist that the magistrate 

purport to perform his neutral and detached function and not 

serve merely as a rubber stamp for the police. . . . [A 

magistrate] who acts instead as an adjunct law enforcement 

officer cannot provide valid authorization for an otherwise 

unconstitutional search.” (internal quotation marks omitted)). 

Thus, while we agree that it is another “factor to consider,” 

(Oral Argument Tr. at 51-52; Dissent at 33), we nonetheless 

hold that, in this case, seeking the advice of a “government 

attorney[]” does not offer much support to the Government‟s 

position.
53

dangerous for the reasons already articulated above: Law 

enforcement can always derive some constitutional principle 

from existing decisions — which is particularly true when 

they also look directly to a generalized baseline case like 

Katz. It cannot be that the good faith exception applies in 

every instance when the police act in reliance on such a selfderived principle. If it did, then all Fourth Amendment 

protections would be rendered ineffective — the police could 

intrude upon anyone‟s Fourth Amendment rights without fear 

of suppression merely by relying on a particularly broadsweeping, self-derived constitutional principle. We fear that 

accepting the Government‟s position, in effect, would lead to 

the good faith exception swallowing the exclusionary rule.24

 

24 The Dissent argues that Federal Rule of Criminal Procedure 

41 — particularly the 2006 advisory committee notes to that 

rule — further supports a finding that the law enforcement 

officers in this case acted with an objectively good faith belief 

that their conduct was constitutional. (Dissent at 32.) In 

particular, the Dissent points to the following language from 

the 2006 advisory committee notes: “If . . . the officers intend 

to install and use [a tracking device] without implicating any 

Fourth Amendment rights, there is no need to obtain a 

warrant.” Fed. R. Crim. P. 41(b) advisory committee‟s note 

(2006) (citing Knotts, 460 U.S. 276). This language, 

however, stands for nothing more than the unremarkable 

proposition that the police need not obtain a warrant if their 

action does not violate the Fourth Amendment. Without our 

(or the Supreme Court‟s) having ruled on the matter, 

however, the police could not reasonably say that the use of a 

GPS tracker would not “implicat[e] . . . Fourth Amendment 

rights.” Indeed, even under the most generous rationale, this 
54

Moreover, since such constitutionally reckless action 

was the Government‟s default choice in this case, we hold 

that applying the exclusionary rule aptly serves its intended 

purpose: to “deter future Fourth Amendment violations.” 

Davis, 131 S. Ct. at 2426; see also id. at 2435 (Sotomayor, J., 

concurring) (“[W]hen police decide to conduct a search or 

seizure in the absence of case law (or other authority) 

specifically sanctioning such action, exclusion of the 

evidence obtained may deter Fourth Amendment 

violations . . . .”). The police practice at issue here effectively 

disregarded the possibility that we could find a GPS search to 

constitute a Fourth Amendment violation requiring a warrant. 

But a Fourth Amendment violation is a Fourth Amendment 

violation. While the police may feel free to act with 

impunity, confident in the illusory protection of non-binding 

precedent, each search could still be violating the 

Constitution. Thus, where we have not yet ruled on the 

constitutionality of a police tactic, law enforcement personnel

have two choices: (a) assume that their conduct violates the 

Fourth Amendment and that we will require them to obtain a 

warrant, or (b) gamble, at the risk of having evidence 

excluded, that we will find no Fourth Amendment violation in 

 

language could only have favored the Government‟s 

argument if the GPS search occurred prior to the Maynard

decision (i.e., before any circuit had suggested that GPS 

searches violated the Fourth Amendment). However, once 

the circuits split on the issue of whether using a GPS tracker 

constitutes a search, law enforcement officials were on notice 

that such devices could “implicat[e] . . . Fourth Amendment 

rights” and the commentary became borderline irrelevant for 

good faith purposes.
55

a particular situation.25 This is in line with the Supreme 

Court‟s suggestion that law enforcement officials should be 

incentivized to “err on the side of constitutional behavior.” 

United States v. Johnson, 457 U.S. 537, 561 (1982).26 

 

25 We do not hold, of course, that the police can never make 

assumptions about our future Fourth Amendment rulings. We 

merely hold that where law enforcement personnel choose to 

take the constitutional analysis into their own hands, they 

effectively do so without a safety net: If their analysis is 

correct and we ultimately affirm the constitutionality of a 

search, then the police are rewarded with full use of any 

evidence derived from the search. If their analysis is wrong, 

however, and the search is ultimately held to be 

unconstitutional, then the police cannot avoid the cost of 

suppression by relying on the good faith exception. Just as 

the police enjoy the benefits when they are correct, so, too, do 

they bear the costs when they are wrong. Of course, the 

police can avoid this entire issue by requesting a warrant in 

the first instance.

26 Johnson addressed retroactive application of Fourth 

Amendment decisions. In discussing the matter, the Court 

stated:

If, as the Government argues, all rulings resolving unsettled 

Fourth Amendment questions should be nonretroactive, then, 

in close cases, law enforcement officials would have little 

incentive to err on the side of constitutional behavior. 

Official awareness of the dubious constitutionality of a 

practice would be counterbalanced by official certainty that, 

so long as the Fourth Amendment law in the area remained 

unsettled, evidence obtained through the questionable practice 

would be excluded only in the one case definitively resolving 
56

Excluding the evidence in this case would incentivize just that 

and would therefore result in “appreciable deterrence” of 

future Fourth Amendment violations. Leon, 468 U.S. at 909 

(internal quotation marks omitted).

Thus, heeding the Supreme Court‟s views in Herring

and Davis, and after considering the Government‟s various 

arguments, we find that the “deterrent effect of suppression 

[in this case is] substantial and outweigh[s] any harm to the 

justice system.” Herring, 555 U.S. at 147. The police acted 

in the face of unsettled law at a time when courts were 

becoming more attuned to the argument that warrantless GPS 

surveillance violated the Fourth Amendment. Excluding the 

evidence here will incentivize the police to err on the side of 

constitutional behavior and help prevent future Fourth 

Amendment violations. We therefore conclude that the police 

actions taken here do not qualify under the good faith 

exception and hold that the exclusionary rule should apply in 

this case.27

 

the unsettled question. Failure to accord any retroactive 

effect to Fourth Amendment rulings would encourage police 

or other courts to disregard the plain purport of our decisions 

and to adopt a let‟s-wait-until-it‟s-decided approach.

Johnson, 457 U.S. at 561 (footnote and internal quotation 

marks omitted).

27 It bears noting that we do not deal here with a situation 

where some on-point binding precedent exists. That is, we 

are not presented with a case wherein law enforcement 

personnel were asked to apply on-point binding appellate law 

to a new factual scenario. Indeed, we recognize that applying 
57

V. STANDING AND THE KATZIN BROTHERS

Fourth Amendment rights are personal rights, and a 

defendant seeking to suppress evidence must therefore 

demonstrate a violation of his own Fourth Amendment rights 

before he can be granted any form of relief. See Minnesota v. 

Carter, 525 U.S. 83, 88 (1998); United States v. Mosley, 454 

F.3d 249, 253 (3d Cir. 2006). Thus, having held that the 

District Court rightly suppressed the evidence found in Harry 

Katzin‟s van, we must now consider whether all three of the 

brothers had standing to challenge the admissibility of this 

evidence. The Government would have us divide the stop 

into two distinct incidents: (1) the stop of Harry Katzin and 

(2) the stop of Mark and Michael Katzin, with each stop 

presenting a different constitutional situation. For the reasons 

discussed below, we hold that the stop of Harry Katzin‟s van 

must be treated as a single incident implicating the Fourth 

Amendment rights of all three brothers and, consequently, we 

find that all three had standing.

 

existing precedential frameworks to subtle factual 

permutations is something that police officers — and other 

law enforcement personnel — do all the time. We have no 

occasion (or desire) to curtail such practices in this opinion. 

Thus, for example, we do not purport to limit the ability of an 

officer to decide whether a particular situation gives rise to 

exigent circumstances while standing outside an apartment 

door with suspicious sounds emanating from within. Such a 

case could lead to a different outcome under the Herring and 

Davis balancing test given that, unlike here, the officer would 

not be leaping recklessly into an unexplored constitutional 

situation.
58

We begin by stating the obvious: There is not, nor can 

there be, any dispute as to whether Harry Katzin — as the 

owner of the van — has standing to challenge the 

constitutionality of the GPS search as well as the stop and 

subsequent search of his van, and to seek suppression of any 

evidence discovered within the vehicle. Indeed, the 

Government concedes as much. (Appellant Br. at 69.) 

Certainly, then, the District Court rightly suppressed the 

evidence as against Harry Katzin.

The Government does challenge the standing of Mark 

and Michael Katzin. (Id. at 67-74.) Since “a search of a car 

does not implicate the rights of non-owner passengers,” the 

Government contends that such passengers are “generally 

held to lack „standing‟ to object to evidence discovered in a 

search of a vehicle.” Mosley, 454 F.3d at 253 (citing Rakas v. 

Illinois, 439 U.S. 128, 147 (1978)). This much is true. 

However, we have also held that “when a vehicle is illegally 

stopped by the police, no evidence found during the stop may 

be used by the government against any occupant of the 

vehicle unless the government can show that the taint of the 

illegal stop was purged.” Id. at 251.28

 

28 We explicitly noted in Mosley that courts “should not be 

distracted by the fact that this case involves evidence found in 

a car.” Mosley, 454 F.3d at 253. As Mosley explained, the 

constitutional violation stems not from the “search of the car . 

. . [but] the seizure of [the passenger].” Id. at 253 & n.6 (“[A] 

Fourth Amendment seizure of every occupant occurs the 

moment that vehicle is pulled over by the police.”) The same 

is true of the case at bar: while the police did search Harry 

Katzin‟s van, this was done only after pulling the van to the 

side of the road, thereby “seizing” all three brothers.
59

This Court in United States v. Mosley considered the 

illegal stop and subsequent search of a vehicle carrying three 

individuals, during the course of which the police discovered 

several firearms from the car. We held that the stop and 

subsequent search of the car was to be treated as a single 

event, thereby rejecting an approach that would split the 

inquiry between several “individual constitutional violations, 

each with [its own] victim, each of whom may seek to 

suppress only the fruits of the violation of his individual 

rights.” Id. at 257-58. In part, this conclusion was 

occasioned by our holding that “[t]he relationship between 

the seizure of a passenger in a moving vehicle, which 

necessarily occurs when that vehicle is stopped by the police, 

and the subsequent discovery of evidence during that stop, is 

one of ineluctable and undeniable correlation.” Id. at 266. 

Additionally, while we acknowledged that “Fourth 

Amendment rights are personal rights,” we also expressly 

rejected “blind adherence to a phrase which at most has 

superficial clarity and which conceals underneath that thin 

veneer all of the problems of line drawing which must be 

faced in any conscientious effort to apply the Fourth 

Amendment.” Id. at 267 (quoting Rakas, 439 U.S. at 147). 

In light of our decision in Mosley, Mark and Michael Katzin 

argue that they have standing to challenge the admissibility of 

evidence seized from Harry Katzin‟s van by virtue of being 

subjected to an illegal stop that thereby rendered any evidence 

discovered in Harry Katzin‟s van fruit of the poisonous tree. 

Id. at 256 (“Where the traffic stop itself is illegal, it is simply 

impossible for the police to obtain the challenged evidence 

without violating the passenger‟s Fourth Amendment rights.”) 

We agree.29

 

29 It bears noting that Mark and Michael Katzin challenge the 
60

True, precedent exists to support the proposition that 

an individual cannot challenge the legality of a search which 

was executed based on information obtained as a 

consequence of some illegal search or seizure of a third party. 

See, e.g., United States v. Chase, 692 F.2d 69, 70-71 (9th Cir. 

1982). Such holdings are premised on the principle 

underlying the Government‟s position: Fourth Amendment 

rights “are personal and may be enforced by exclusion of 

evidence only by one whose own legal rights and interests 

were infringed by the search and seizure.” Id. (discussing 

Rakas v. Illinois, 439 U.S. 128). The presence of Mosley, 

however, alters this analysis.

The Government effectively contends that we must 

treat the stop of Harry Katzin‟s van as constituting two stops: 

The first, a stop (i.e., seizure) of Harry Katzin himself as a 

result of the GPS search. The second, a stop of Mark and 

Michael Katzin based on the probable cause developed 

through use of information derived from the GPS search. The 

Government would have us evaluate the legality and 

attendant Fourth Amendment consequences (if any) of each 

stop individually. We rejected this individualized approach in 

Mosley, holding instead that “an illegal traffic stop of a car 

occupied by a driver and a passenger [constitutes] a single 

constitutional violation, with [multiple] victims, each of 

whom can seek to suppress all fruits of that violation.” 

Mosley, 454 F.3d at 257-58; id. at 267 (“It defies common 

 

stop of Harry Katzin‟s van, not the GPS search itself. That in 

the course of challenging the stop this Court must necessarily 

consider the constitutionality of the GPS search is merely 

incidental: Mark and Michael seek to vindicate their own 

rights, not those of their brother.
61

sense and common experience to transmute one action into 

three, and we will not endorse a Fourth Amendment approach 

that relies on such a transmutation.”) In effect, then, the 

illegality of the stop as it related to Harry Katzin is extended 

to his brothers (passengers). Consequently, we hold that 

Mark and Michael had standing to contest the stop and that 

the District Court rightly suppressed the evidence as to all 

three brothers.

VI. CONCLUSION

For the reasons discussed above, we will affirm the 

District Court‟s suppression of evidence discovered inside of 

Harry Katzin‟s van.
1

VAN ANTWERPEN, Circuit Judge, concurring in part and

dissenting in part.

To briefly recap: In December 2010, law enforcement 

officers, after consulting an Assistant United States Attorney, 

and in accord with the general policy of the United States 

Department of Justice, magnetically attached an 

independently battery operated ―slap on‖ Global Positioning 

System device (―GPS device‖ or ―GPS‖) upon the 

undercarriage of Harry Katzin‘s vehicle, while that vehicle 

was parked on a public street. It was conceded at argument 

that the officers had probable cause to do so, although they 

did not obtain a warrant. For two days, law enforcement used 

that GPS to track the vehicle‘s whereabouts on public roads. 

The vehicle never entered a private garage, never entered the 

curtilage of a home, nor did it enter a similarly private area. 

The information from that GPS then led to the seizure of 

evidence and the arrest of Harry Katzin and his two brothers, 

due to their involvement in a major ongoing scheme to steal 

drugs from Rite Aid pharmacies.

At that time, the Supreme Court, in cases involving 

electronic beepers in vehicles, had held that ―[a] person 

traveling in an automobile on public thoroughfares has no 

reasonable expectation of privacy in his movements from one 

place to another.‖ United States v. Knotts, 460 U.S. 276, 281 

(1983); see also United States v. Karo, 468 U.S. 705, 713–16

(1984). All but one of the United States Court of Appeals to 

have addressed the issue, in light of Knotts, Karo, and other 

general Fourth Amendment principles, held that GPS or 

similar electronic surveillance (―GPS-like device‖ or ―GPSlike‖) could be conducted in the same way that occurred here: 

without an authorizing warrant. This view was reflected in 
2

then-current Rule 41(b) of the Federal Rules of Criminal 

Procedure, the commentary to which stated that a warrant was 

not required to conduct electronic vehicle surveillance ―[i]f . . 

. the officers intend to install and use [an electronic 

surveillance] device without implicating any Fourth 

Amendment rights.‖ FED. R. CRIM. P. 41(b) advisory comm. 

note (2006). No decision from our Circuit was on point. 

Then came United States v. Jones, 565 U.S. __, 132 S. Ct. 

945 (2012).

In light of the Supreme Court‘s decision in Jones, and 

for the reasons discussed in the majority opinion, I agree that 

the Fourth Amendment now requires law enforcement 

officers to obtain a warrant, issued upon probable cause, 

before they install a GPS or a GPS-like device on a person‘s 

automobile, or other mobile property, and thereafter use that 

device to conduct continuing surveillance. See Majority 

Opinion (―Maj. Op.‖) at 18.

1

I disagree, however, with the majority‘s conclusion 

that the District Court was correct to suppress the evidence 

obtained as a result of the warrantless GPS installation and 

subsequent surveillance. See Maj. Op. at 34–56. Given preJones Supreme Court precedent, the consensus regarding 

GPS and GPS-like use across the federal courts, and other 

relevant considerations, I would hold that the law 

enforcement officers here acted ―with an objectively 

 ̳reasonable good-faith belief‘ that their conduct [was] 

 

1

I also agree with the majority that, under our decision 

in United States v. Mosely, 454 F.3d 249 (3d Cir. 2006), each 

of the Katzin brothers has standing to seek suppression of the 

evidence obtained from Harry Katzin‘s vehicle.
3

lawful.‖ Davis v. United States, 564 U.S. __, 131 S. Ct. 2419, 

2427 (2011) (quoting United States v. Leon, 468 U.S. 897, 

909 (1984)). For that reason, suppression in this case is 

unwarranted, and I would reverse the District Court. 

I. 

It is indisputable that the installation and use of the 

GPS device in this case was a ―search‖ under the Fourth 

Amendment. See Jones, 132 S. Ct. at 949. Furthermore, I 

agree with the majority that this particular search now

requires a warrant, and that because the law enforcement 

officers here acted without a warrant a violation of the Fourth 

Amendment occurred. But ―[t]he fact that a Fourth 

Amendment violation occurred . . . does not necessarily mean 

that the exclusionary rule applies.‖ Herring v. United States, 

555 U.S. 135, 140 (2009); United States v. Tracey, 597 F.3d 

140, 151 (3d Cir. 2010). See also Illinois v. Gates, 462 U.S. 

213, 223 (1983) (―[W]hether the exclusionary rule‘s remedy 

is appropriate in a particular context has long been regarded 

as an issue separate from the question whether the Fourth 

Amendment rights of the party seeking to invoke the rule 

were violated by police conduct.‖).

The exclusionary rule ―is a  ̳prudential‘ doctrine,‖ 

Davis, 131 S. Ct. at 2426 (quoting Pa. Bd. of Probation and 

Parole v. Scott, 524 U.S. 357, 363 (1998)), utilized to 

―compel respect for the constitutional guaranty‖ embodied in 

the Fourth Amendment, id. (quoting Elkins v. United States, 

364 U.S. 206, 217 (1960)). See also United States v. Brown, 

631 F.3d 638, 646 (3d Cir. 2011) (―[T]he exclusionary rule is 

merely a  ̳judicially created remedy designed to safeguard 

Fourth Amendment rights generally through its deterrent 
4

effect.‘‖ (quoting United States v. Calandra, 414 U.S. 338, 

348 (1974))). Suppression of evidence obtained through a 

violation of the Constitution is ― ̳not a personal constitutional 

right,‘ nor is it designed to  ̳redress the injury‘ occasioned by 

an unconstitutional search.‖ Davis, 131 S. Ct. at 2426 

(quoting Stone v. Powell, 428 U.S. 465, 486 (1976)). And 

introduction of illegally obtained evidence at trial ―work[s] no 

new Fourth Amendment wrong.‖ Calandra, 414 U.S. at 354. 

Instead, the exclusionary rule‘s ―sole purpose . . . is to deter 

future Fourth Amendment violations.‖ Davis, 131 S. Ct. at 

2426. 

But application of the exclusionary rule is not 

warranted ―in every circumstance in which it might provide 

marginal deterrence.‖ Herring, 555 U.S. at 141 (quoting 

Scott, 524 U.S. at 368). Suppression is prudent only where it 

would ―result in appreciable deterrence.‖ Leon, 468 U.S. at 

909 (emphasis added) (quoting United States v. Janis, 428 

U.S. 433, 454 (1976)); see also Davis, 131 S. Ct. at 2426–27 

(explaining that ―[w]here suppression fails to yield 

 ̳appreciable deterrence,‘ exclusion is  ̳clearly unwarranted‘‖ 

(omission omitted) (quoting Janis, 428 U.S. at 454)); 

Herring, 555 U.S. at 141 (same); Arizona v. Evans, 514 U.S. 

1, 11 (1995) (same); Virgin Islands v. John, 654 F.3d 412, 

417 (3d Cir. 2011) (same). In other words, suppression is 

warranted only where its deterrence benefits outweigh the 

substantial social costs inherent in ―preclud[ing]

consideration of reliable, probative evidence.‖ Scott, 524 

U.S. at 364; see also Davis, 131 S. Ct. at 2427 (―For 

exclusion to be appropriate, the deterrence benefits of 

suppression must outweigh its heavy costs.‖); Tracey, 597 

F.3d at 151 (―To determine whether to apply the rule in a 
5

particular case, we weigh the benefits of the rule‘s deterrent 

effects against the costs of exclusion . . . .‖). 

The costs of suppression are substantial. ―Exclusion 

exacts a heavy toll on both the judicial system and society at 

large.‖ Davis, 131 S. Ct. at 2427. ―The principal cost of 

applying the rule is, of course, letting guilty and possibly 

dangerous defendants go free—something that  ̳offends basic 

concepts of the criminal justice system.‘‖ Herring, 555 U.S. 

at 141 (quoting Leon, 468 U.S. at 908). But in addition to its 

―costly toll upon truth-seeking and law enforcement 

objectives,‖ Scott, 524 U.S. at 364–65 (internal quotation 

mark omitted), ―[i]ndiscriminate application of the 

exclusionary rule,‖ in some circumstances, ―may well 

 ̳generate disrespect for the law and administration of 

justice,‘‖ Leon, 468 U.S. at 908 (alteration omitted) (quoting 

Stone, 428 U.S. at 491). Consequently, ―[o]ur cases hold that 

society must swallow this bitter pill when necessary, but only 

as a  ̳last resort.‘‖ Davis, 131 S. Ct. at 2427 (quoting Hudson 

v. Michigan, 547 U.S. 586, 591 (2006)). 

Against these costs, ―we weigh the benefits of the 

rule‘s deterrent effects.‖ Tracey, 597 F.3d at 151. But we 

must fight any instinct to ― ̳reflexive[ly]‘ appl[y]‖ the rule. 

Davis, 131 S. Ct. at 2427 (quoting Evans, 514 U.S. at 13). 

The necessary analysis calls for a ―rigorous weighing of [the] 

costs and deterrence benefits,‖ focusing primarily ―on the 

 ̳flagrancy of the police misconduct‘ at issue.‖ Id. (quoting 

Leon, 468 U.S. at 911). See also John, 654 F.3d at 417 

(explaining that the exclusionary rule is ―trigger[ed]‖ only 

where police conduct is ―sufficiently deliberate that exclusion 

can meaningfully deter it, and sufficiently culpable that such 
6

deterrence is worth the price paid by the justice system‖

(quoting Herring, 555 U.S. at 144)). 

Of course, ―the deterrence benefits of exclusion  ̳vary 

with the culpability of the law enforcement conduct‘ at 

issue.‖ Davis, 131 S. Ct. at 2427 (alteration omitted) (quoting 

Herring, 555 U.S. at 143). On the one hand, ―[w]hen the 

police exhibit  ̳deliberate,‘  ̳reckless,‘ or  ̳grossly negligent‘ 

disregard for Fourth Amendment rights, the deterrent value of 

exclusion is strong and tends to outweigh the resulting costs.‖ 

Id. (quoting Herring, 555 U.S. at 144); see also John, 654 

F.3d at 418 (condoning suppression where police conduct was 

― ̳deliberate, reckless, or grossly negligent‘‖ (quoting Tracey, 

597 F.3d at 151)). But on the other hand, ―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, 

131 S. Ct. at 2427–28 (citations and internal quotation marks 

omitted) (quoting Herring, 555 U.S. at 137; Leon, 468 U.S. at 

909, 908 n.6, 919).

Under this so-called ―good-faith‖ exception to the 

exclusionary rule, beginning with United States v. Leon, the 

Supreme Court has consistently ruled that the costs of 

suppression are not outweighed by the little, if any, deterrent 

benefit of suppressing evidence obtained ―in [a] reasonable 

good-faith belief that a search or seizure was in accord with 

the Fourth Amendment.‖ Leon, 468 U.S. at 909 (quoting 

Gates, 412 U.S. at 255 (White, J., concurring)); see also

Evans, 514 U.S. at 11–12 (―[W]here the officer‘s conduct is 

objectively reasonable, excluding the evidence will not 

further the ends of the exclusionary rule in any appreciable 
7

way . . . .‖ (alteration in original) (internal quotation mark 

omitted) (quoting Leon, 468 U.S. at 919–20)); Illinois v. 

Krull, 480 U.S. 340, 348–49 (1987) (―[E]vidence should be 

suppressed  ̳only if it can be said that the law enforcement 

officer had knowledge, or may properly be charged with 

knowledge, that the search was unconstitutional under the 

Fourth Amendment.‘‖ (quoting United States v. Peltier, 422 

U.S. 531, 542 (1975))); Leon, 468 U.S. at 922 n.23 (―[O]ur 

good faith inquiry is confined to the objectively ascertainable 

question whether a reasonably well trained officer would 

have known that the search was illegal . . . .‖). Under such 

circumstances, ―a reasonable officer cannot have been 

expected to know that what he was doing was 

unconstitutional,‖ and, as a result, ―he is unlikely to be 

discouraged in his actions by the knowledge that the fruits of 

his unconstitutional searches will be suppressed.‖ John, 654 

F.3d at 417. Thus, at bottom, ―the harsh sanction of exclusion 

 ̳should not be applied to deter objectively reasonable law 

enforcement activity.‘‖ Davis, 131 S. Ct. at 2429 (quoting 

Leon, 468 U.S. at 919).

II. 

Admittedly, the majority posits several pages focused 

on the balancing test outlined in Herring and Davis; the test 

which I describe at length above. See supra Part I. But while 

purporting to consider whether, ―in light of all the 

circumstances in this case,‖ the law enforcement officers‘ 

conduct ―rises to the level of a  ̳deliberate, reckless, or grossly 

negligent‘ violation of the Fourth Amendment,‖ Maj. Op. at 

48, the majority fragments its analysis by discussing whether 

Knotts and Karo and the cases from our sister circuits 
8

addressing GPS and GPS-like devices are ―binding appellate 

precedent‖ under Davis.

Of course, the question of whether Davis‘s specific 

holding—that is, that law enforcement reliance on ―binding 

appellate precedent‖ qualifies as objective good-faith 

conduct—lingers in the background of this case. In the event 

the Government were arguing that the law enforcement 

officers here relied on ―binding appellate precedent,‖ I would 

have no qualms with the majority addressing whether Knotts

and Karo and the relevant cases from our sister courts 

properly qualified under that moniker. But, as the majority 

makes clear, that is not the Government‘s argument.

Furthermore, although a seemingly reasonable 

analytical choice, the majority‘s decision to first address 

whether those cases qualify as ―binding appellate precedent‖ 

later infects the more general good-faith analysis. That is, the 

majority allows its conclusion that the ―Beeper Cases‖ and

the ―Out-of-Circuit GPS Cases‖ are not ―binding appellate 

precedent‖ to emaciate the weight given to law enforcement 

reliance thereon in the more general good-faith analysis. 

In effect, the majority‘s search for Davis-like ―binding 

appellate precedent‖ in this case places a heavy thumb on the 

scale in favor of suppression. Such an analysis does not 

comply with the Leon line of cases, which, since their 

inception, have time and again stated that the touchstone for 

the good-faith exception is ― ̳the objectively ascertainable 

question whether a reasonably well trained officer would 

have known that the search was illegal‘ in light of  ̳all of the 

circumstances,‘‖ Herring, 555 U.S. at 145 (quoting Leon, 468 

U.S. at 922 n.23); not whether the officers relied upon 
9

―binding appellate precedent,‖ or ―some seemingly 

immutable authority or information,‖ as the majority implies. 

See Maj. Op. at 36; see also id. at 49 (―Try as we might to 

allay our concerns, we remain supremely discomfited by the 

lack of binding appellate guidance underlying the police 

action in this case.‖). 

At bottom, the majority claims that this case is 

―different.‖ The officers here acted ―different[ly],‖ (and, 

thus, sufficiently culpable so as to justify application of the 

exclusionary rule), the majority concludes, because the 

officers relied on ―non-binding precedent‖ from our sister 

circuits and ―extrapolate[ed] from, or analogiz[ed] to, existing 

case law‖ rather than seeking a warrant. Maj. Op. at 50. But 

the conclusion that this case is ―different‖ results primarily 

from the majority‘s prior determinations that analogous and 

non-binding precedent are materially ―different‖ from the 

―binding appellate precedent‖ dealt with in Davis; and, thus, 

without ―binding appellate precedent,‖ the rationale of Davis

and the other good-faith cases do not apply. 

I do not think this case is ―different‖ from other cases 

involving the good-faith exception, where courts are 

presented with specific facts and particularities and then 

asked whether ―a reasonably well trained officer would have 

known that the search [conducted] was illegal in light of all 

the circumstances.‖ Herring, 555 U.S. at 145 (internal 

quotation marks omitted) (quoting Leon, 468 U.S. at 922 

n.23). Davis is obviously important because the facts in that 

case—officer reliance on ―binding appellate precedent‖—are 

the most analogous of the Supreme Court‘s several good-faith 

cases with which the Government, and we, have to work. 

Regardless, the predominant importance of Davis is its 
10

affirmation of deterrence and police culpability as the 

lynchpins of the exclusionary rule analysis. The majority 

thus erroneously elevates the ―binding appellate precedent‖ 

language to its own good-faith test instead of treating it as a 

single consideration in the exclusionary rule analysis. 

Nevertheless, ―of great significance to the instant 

case,‖ the majority insists, ―is the fact that in Davis the police 

relied on binding appellate precedent that  ̳specifically 

authorize[d the] particular police practice.‘‖ Maj. Op. at 39

(quoting Davis, 131 S. Ct. at 2429). Thus, the majority 

stresses, that Davis must be read as ―extend[ing] good faith 

protection only to acts that are explicitly sanctioned by clear 

and well-settled precedent.‖ Maj. Op. at 40. First, I take 

great issue with the majority‘s suggestion that the good-faith 

exception was ―extend[ed]‖ by Davis, or any other case, 

―only‖ to the specific factual circumstances therein. Courts 

apply a single good-faith exception to either condone or 

condemn varying factual circumstances. See Davis, 131 S. 

Ct. at 2428 (―The Court has over time applied [the]  ̳goodfaith‘ exception across a range of cases.‖).

More importantly, the Davis dissent, other courts, and 

commentators do not read the Davis majority‘s articulation of 

the good-faith exception as limited to only ―binding appellate 

precedent.‖ See Davis, 131 S. Ct. at 2439 (Breyer, J., 

dissenting) (―[A]n officer who conducts a search that he 

believes complies with the Constitution but which, it 

ultimately turns out, falls just outside the Fourth 

Amendment‘s bounds is no more culpable than an officer 

who follows erroneous  ̳binding precedent.‘ Nor is an officer 

more culpable where circuit precedent is simply suggestive 

rather than  ̳binding,‘ where it only describes how to treat 
11

roughly analogous instances, or where it just does not exist.‖); 

United States v. Sparks, 711 F.3d 58, 63 (1st Cir. 2013) (―The 

[Davis] Court‘s emphasis on the absence of police culpability 

could be read to imply that good-faith reliance on out-ofcircuit appellate precedent is also acceptable.‖); United States 

v. Baez, 878 F. Supp. 2d 288, 294–95 (D. Mass. 2012) (―Baez 

argues that Davis should be limited to its precise holding. . . . 

[But] th[at] interpretation is entirely too static . . . . It is 

apparent that both the majority opinion and the concurring 

and dissenting opinions anticipated the principles of Davis

would be worked out in subsequent cases raising themes and 

variations.‖); Orin S. Kerr, Fourth Amendment Remedies and 

Development of the Law: A Comment on Camreta v. Greene 

and Davis v. United States, 2011 CATO SUP. CT. REV. 237, 

255 (2011) (―If the exclusionary rule solely concerns 

culpability . . . its [sic] hard to see why binding precedent is 

required. Reliance on binding precedent seems inherently 

reasonable, but reliance is often reasonable without binding 

precedent. A local police officer who conducts a search 

widely upheld among the circuits but not yet addressed by the 

[U.S. Court of Appeals] in his jurisdiction is no more 

culpable than an officer who conducts a search upheld only 

by his regional circuit. If the former has acted reasonably, 

then surely so has the latter.‖).2

 

2

The majority supports its limiting reading of Davis

by pointing to the opinion below from the Eleventh Circuit,

and several similar cases from our sister circuits, wherein 

courts ―stress. . . that [the] precedent on a given point must be 

unequivocal before [those courts would] suspend the 

exclusionary rule‘s operation.‖ United States v. Davis, 598 

F.3d 1259, 1266 (11th Cir. 2010); see also United States v. 

McCane, 573 F.3d 1037, 1045 (10th Cir. 2009) (―Relying 
12

Finally, the majority argues that Davis itself forecloses 

the conclusion that law enforcement reliance on analogous or 

non-binding out-of-circuit precedent could ever constitute 

good faith. Quoting language from Davis,

3

the majority 

 

upon the settled case law of a United States Court of Appeals 

certainly qualifies as an objectively reasonable law 

enforcement behavior.‖); United States v. Jackson, 825 F.2d 

853, 866 (5th Cir. 1987) (―The exclusionary rule should not 

be applied to searches which relied on Fifth Circuit law prior 

to the change of that law . . . .‖); id. at 878 (Hill, J., 

concurring) (―Outside of situations where we have authorized 

the specific conduct undertaken and then later declared it 

unconstitutional, I believe the analogy to Leon and Krull

weakens and the exception should probably not be applied.‖). 

But the Supreme Court refrained from creating a similar 

restraint. See Davis, 131 S. Ct. at 2435–36 (Sotomayor, J., 

concurring) (noting that Davis left ―the markedly different 

question [of] whether the exclusionary rule applies when the 

law governing the constitutionality of a particular search is 

unsettled . . . unanswered‖). I therefore hesitate before 

reading into Davis a limitation apparently at odds with its 

rationale. See Kerr, supra at 255.

3

The language quoted by the majority reads as 

follows:

This Court reviews criminal convictions from 

12 Federal Courts of Appeals, 50 state courts of 

last resort, and the District of Columbia Court 

of Appeals. If one or even many of these courts 

uphold a particular type of search or seizure, 

defendants in jurisdictions in which the 

question remains open will still have an 
13

claims that the case explained that ―its holding was limited to 

jurisdiction[s] where the law was clearly settled.‖ Maj. Op. at 

42 n.17. But the language to which the majority refers, 

quoted in full at footnote 3, supra, is pure dicta, responding 

not to an argument about what the good-faith exception 

should or should not apply to but to the policy concern that 

―applying the good-faith exception to searches conducted in 

reliance on binding precedent will stunt the development of 

Fourth Amendment law.‖ Davis, 131 S. Ct. at 2432; see also 

id. at 2433 (―[A]pplying the good-faith exception in this 

context will not prevent judicial reconsideration of prior 

Fourth Amendment precedents.‖).4 Furthermore, directly 

 

undiminished incentive to litigate the issue. 

This Court can then grant certiorari, and the 

development of Fourth Amendment law will in 

no way be stunted.

Davis, 131 S. Ct. at 2433.

4 As an aside, I fail to see how allowing law 

enforcement reliance on analogous or non-binding out-ofcircuit precedent to influence substantially the good-faith 

analysis would foreclose development of Fourth Amendment 

law. Leon made clear that ―[t]here is no need for courts to 

adopt the inflexible practice of always deciding whether the 

officers‘ conduct manifested objective good faith before 

turning to the question [of] whether the Fourth Amendment 

has been violated.‖ 468 U.S. at 924. ―Defendants seeking 

suppression of the fruits of allegedly unconstitutional 

searches or seizures undoubtedly raise live controversies‖ 

which federal courts are ―empower[ed] . . . to adjudicate‖; 

and ―courts have considerable discretion in conforming their 
14

preceding this brief discussion, the Court reiterated that the 

sole focus of the exclusionary rule is ―deterrence of culpable 

law-enforcement conduct.‖ Id. at 2432–33.

In short, I disagree with the way the majority‘s opinion 

reads to suggest that Davis alone answers the questions 

presented in this appeal. In Davis, the Court was presented 

with a unique set of facts to which its holding was expressly 

directed: officer reliance on ―binding appellate precedent‖ 

later overruled. See Davis, 131 S. Ct. at 2429. Identified by 

both the concurrence and the dissent, Davis did not touch the 

questions of ―whether the exclusionary rule applies when the 

law governing the constitutionality of a particular search is 

unsettled,‖ id. at 2435 (Sotomayor, J., concurring), or ―where 

circuit precedent is simply suggestive rather than  ̳binding,‘ 

where it only describes how to treat roughly analogous 

instances, or where it just does not exist,‖ id. at 2439 (Breyer, 

J., dissenting). 

Of paramount importance to this case is that the 

reasoning underlying Davis does address those questions. 

Davis and the Court‘s good-faith jurisprudence teach us that 

we must look at the totality of the circumstances and ask 

whether, in light of those circumstances, the officers were 

acting with ―deliberate, reckless, or grossly negligent 

disregard for Fourth Amendment rights,‖ which would justify 

suppression, or, instead, whether they were acting ―with an 

objectively reasonable good-faith belief that their conduct 

[was] lawful‖ or ―involve[d] only simple, isolated 

negligence.‖ Davis, 131 S. Ct. at 2427–28 (citations and 

 

decisionmaking processes to the exigencies of particular 

cases.‖ Id. at 924–25.
15

internal quotation marks omitted). For that reason, I disagree 

with the majority‘s conclusion that authority falling outside 

the specific semblance of Davis is ―different‖ and thus always 

insufficient to support a finding of good-faith in every

circumstance.

In Davis, the Court explained that Leon ―imported‖ the 

reasoning of United States v. Peltier, 422 U.S. 531 (1975) 

―into the good-faith inquiry.‖ Davis, 131 S. Ct. at 2432. In 

Peltier, border patrol agents conducted a stop-and-search of 

an automobile ―within a reasonable distance from‖ the 

Mexican border pursuant to a federal statute, federal 

regulations promulgated in accordance with that statute, and a 

―continuous judicial approval‖ of ―the statute and the . . . 

policy‖ across the federal courts. Peltier, 422 U.S. at 540–42. 

Although that statute and policy were overturned by the 

Court‘s decision in Almeida-Sanchez v. United States, 413 

U.S. 266 (1973), the Peltier Court refrained from applying 

the exclusionary rule. See id. at 542. 

Essential to the Peltier Court‘s decision was the nowfamiliar reasoning that ―evidence obtained from a search 

should be suppressed only if it can be said that the law 

enforcement officer had knowledge, or may properly be 

charged with knowledge, that the search was unconstitutional 

under the Fourth Amendment.‖ Id. Especially relevant here, 

the Court stated that ―unless we are to hold that parties may 

not reasonably rely upon any legal pronouncement emanating 

from sources other than this Court, we cannot regard as 

blameworthy those parties who conform their conduct to the 

prevailing statutory or constitutional norm.‖ Id. 
16

Thus, if the logic of Peltier was ―imported . . . into the 

good-faith inquiry‖ as Davis states, 131 S. Ct. at 2432, then a 

―uniform treatment‖ of a particular law enforcement act by 

the federal judiciary or a ―prevailing . . . norm‖ can, in the 

proper circumstances, support a finding of good faith. See 

Herring, 555 U.S. at 145 (― ̳[O]ur good-faith inquiry is 

confined to the objectively ascertainable question whether a 

reasonably well trained officer would have known that the 

search was illegal‘ in light of  ̳all the circumstances.‘‖ 

(quoting Leon, 468 U.S. at 922 n.23)); cf. United States v. 

Duka, 671 F.3d 329, 347 n.12 (3d Cir. 2011) (noting that 

―[t]he objective reasonableness of the officers‘ reliance on the 

statute . . . is further bolstered by the fact that the particular 

provision at issue had been reviewed and declared 

constitutional by several [out-of-circuit] courts‖ (citing Davis,

131 S. Ct. at 2434)).

All in all, my problem with the method of the 

majority‘s good-faith analysis is that it myopically focuses 

too much on the facts and narrow holdings of Davis and other 

good-faith cases, and considers too little, if at all, the 

reasoning and principles of law underlying those decisions. 

The majority‘s analysis is a search for some sort of 

―immutable authority or information that justifies [the law 

enforcement officers‘] course of action.‖ See Maj. Op. at 36. 

But the good-faith exception to the exclusionary rule is not 

limited to those circumstances. The good-faith inquiry, like 

other Fourth Amendment analyses, requires us to ―slosh our 

way through the factbound morass of  ̳reasonableness.‘‖ 

Scott v. Harris, 550 U.S. 372, 383 (2007).

5

 The question is, 

 

5

The majority insinuates that my analysis would 

―burden district courts with [an unwarranted] type of case-by-
17

and always has been, whether the officers acted with a 

―reasonable good-faith belief that a search or seizure was in 

accord with the Fourth Amendment.‖ Leon, 468 U.S. at 909

(quoting Gates, 462 U.S. at 255 (White, J., concurring)); see 

also Davis, 131 S. Ct. at 2427–28; Herring, 555 U.S. at 145; 

Evans, 514 U.S. at 11–12; Krull, 480 U.S. at 348–49. Davis

answers ―yes‖ to police actions taken in reliance on ―binding 

appellate precedent.‖ Davis, 131 S. Ct. at 2429. See also 

Herring, 555 U.S. at 147–48 (answering ―yes‖ where officers 

relied on an error in a police-maintained outstanding warrant 

database); Evans, 514 U.S. at 14–16 (answering ―yes‖ where 

officers relied on an error in court-maintained database); 

Krull, 480 U.S. at 349–50 (answering ―yes‖ where officers 

relied on a subsequently invalidated statute); Leon, 468 U.S. 

at 922 (answering ―yes‖ where officers relied on a 

subsequently invalidated warrant). What we are asked to 

answer is whether the result is the same when officers act in 

 

case assessment,‖ and create ―a sprawling, amorphous, and 

self-contradicting doctrine.‖ Maj. Op. at 45. But all of the 

questions that the majority fears—i.e., ―how many circuits 

had addressed the police practice in question, what each one 

said, whether the statements were mere dicta‖; and ―what if 

our sister courts had all ruled in near-unanimity on a point, 

with one stalwart (perhaps, highly persuasive) holdout?‖—

are exactly the sorts of questions we should be asking; 

particularly where the Supreme Court instructs us to answer 

the good-faith question by focusing on whether ―a reasonably 

well trained officer would have known that the search 

[conducted] was illegal in light of all the circumstances.‖ 

Herring, 555 U.S. at 145 (internal quotation marks omitted) 

(quoting Leon, 468 U.S. at 922 n.23).
18

the circumstances in which they did here. As the following 

analysis shows, I answer that question in the affirmative.

III.

A.

Before determining if the officers in this case acted 

with an objectively reasonable belief that their conduct 

complied with the Fourth Amendment, we must first 

determine what, precisely, their conduct was. Jones lumps 

the police conduct that occurred here into a singular act, see 

Jones, 132 S. Ct. at 949 (installation of a GPS and its use to 

monitor a vehicle are a search), as does the majority. But

before Jones, GPS or GPS-like surveillance was often treated 

as two distinct acts: (1) the installation of the GPS or GPSlike device, and (2) the subsequent surveillance of the 

automobile.6 Thus, for the purpose of my exclusionary rule 

analysis, I find it appropriate to similarly separate the 

officers‘ conduct here into those two distinct Fourth 

Amendment acts. See Sparks, 711 F.3d at 66–67 (bifurcating 

 

6

See, e.g., Karo, 468 U.S. at 711–13 (analyzing Fourth 

Amendment implications of beeper installation); id. at 713–

18 (analyzing Fourth Amendment implications of beeper 

surveillance); Knotts, 460 U.S. at 280 n.** (certiorari granted 

on Fourth Amendment implications of beeper use and 

―pass[ing]‖ on the issue of beeper installation); United States 

v. Pineda-Moreno, 591 F.3d 1212, 1215–16 (9th Cir. 2010) 

(analyzing GPS installation separately from GPS use); United 

States v. Moore, 562 F.2d 106, 111–12 (1st Cir. 1977) (same, 

but with beepers).
19

its exclusionary rule / good-faith exception analysis with 

regard to, first, the GPS‘s installation and, second, its 

subsequent monitoring).7

B.

Application of the exclusionary rule depends on 

whether the officers, at the time they were acting, would have 

or should have known their installation of the GPS and their 

 

7

I pause to note that separating GPS use into these two 

distinct Fourth Amendment acts is not appropriate for 

determining whether a Fourth Amendment search has 

occurred. The Jones majority clearly rejected the 

concurrence‘s suggestion that it do so. Compare Jones, 132 

S. Ct. at 951 n.5 (finding the distinction between GPS 

―installation‖ and ―use‖ irrelevant for determining whether a 

Fourth Amendment ―search‖ had occurred, reasoning ―[a] 

trespass on  ̳houses‘ or  ̳effects,‘ or a Katz invasion of 

privacy, is not alone a search unless it is done to obtain 

information; and the obtaining of information is not alone a 

search unless it is achieved by such a trespass or invasion of 

privacy‖), with id. at 958 (Alito, J., concurring) (finding it a 

―questionable proposition that [the] two procedures cannot be 

separated for purposes of the Fourth Amendment analysis,‖ 

and reasoning that it is clear that both the ―installation‖ and 

―use‖ of the GPS, on their own, do not constitute a search). 

But it is conceded that a search did occur in this case. My 

analysis focuses on an entirely different question; to wit: 

whether the officers would have known, at the time of their 

actions, that their conduct was a ―search.‖ Because, as 

discussed in supra note 6, this question was often bifurcated 

at the time, my analysis proceeds accordingly.
20

subsequent use of the GPS to track Harry Katzin‘s vehicle 

were unconstitutional. See Krull, 480 U.S. at 348–49. 

Relevant to this determination are the Supreme Court‘s case 

law dealing with electronic surveillance and general searches 

of automobiles, subsequent treatment of GPS and GPS-like 

surveillance across the federal courts, and other 

considerations.

1.

United States v. Knotts, 460 U.S. 276 (1983) and 

United States v. Karo, 468 U.S. 705 (1984) are the authorities 

most relevant to our analysis. In Knotts, Minnesota law 

enforcement officers utilized an electronic beeper to conduct 

surveillance on a vehicle driven by a man suspected to be part 

of an illegal narcotics operation. 468 U.S. at 277–80. In 

determining the Fourth Amendment implications of that 

activity, the Court determined that the alleged search 

―amounted principally to the following of an automobile on 

public streets and highways.‖ Id. at 281. The Court rejected 

the argument that this constituted a search under the Fourth 

Amendment, and held that ―[a] person traveling in an 

automobile on public thoroughfares has no reasonable 

expectation of privacy in his movements from one place to 

another.‖8 Id. Because when one drives an automobile on 

 

8 At the time, this holding was in accord many of the 

courts of appeals to have addressed the issue. A compelling 

number of courts found beeper surveillance did not implicate 

the Fourth Amendment. See, e.g., United States v. Michael, 

645 F.2d 252, 257–58 (5th Cir. 1981) (en banc) (holding 

―subsequent monitoring,‖ after installation of beeper upon 

reasonable suspicion, ―did not violate . . . reasonable 
21

 

expectation[s] of privacy‖); United States v. Hufford, 539 

F.2d 32, 33–34 (9th Cir. 1976) (holding one‘s movements in 

his vehicle on a public road ―were knowingly exposed to the 

public, and therefore are not a subject of Fourth Amendment 

protection‖), partially overruled by Jones, 132 S. Ct. 945, as 

recognized by United States v. Pineda-Moreno, 688 F.3d 

1087, 1091 (9th Cir. 2012); cf. United States v. Bruneau, 594 

F.2d 1190, 1196–97 (8th Cir. 1979) (holding that ―monitoring 

the airborne location of an aircraft with a [beeper] is not a 

search within the fourth amendment‖); United States v. 

Clayborne, 584 F.2d 346, 350–51 (10th Cir. 1978) (holding 

use of beeper ―as a substitute for persistent extensive visual‖ 

surveillance, when it enters a ―clandestine laboratory‖ 

exposed to ―outside viewing‖ and ―ingress and egress of the 

public‖ did not per se violate the Fourth Amendment). 

Alternatively, some courts alluded that it implicated a 

person‘s privacy interests, but did not hold such surveillance 

required a warrant. See, e.g., United States v. Moore, 562 

F.2d 106, 111–12 (1st Cir. 1977) (holding beeper surveillance 

requires probable cause, but no warrant), abrogated by United 

States v. Knotts, 460 U.S. 276, 286 (1983), as recognized by 

United States v. Sparks, 711 F.3d 58, 65 (1st Cir. 2013) 

(―Knotts . . . abrogated Moore‘s probable cause requirement 

for beeper surveillance . . . .‖); cf. United States v. Shovea, 

580 F.2d 1382, 1387–88 (10th Cir. 1978) (―The utilization of 

an electronic tracking device, without prior court approval, 

may be justified by probable cause and exigent 

circumstances.‖). Conversely, a few cases did require a 

formal warrant; but many of those cases involved installations 

and surveillance occurring in private areas. See, e.g., United 
22

public roads, he ―voluntarily convey[s] to anyone who 

want[s] to look‖9his location, progress, and route, he has no 

 

States v. Bailey, 628 F.2d 938, 944, 945–46 (6th Cir. 1980). 

That was not the case in Knotts, nor is it the case here. 

The Fifth Circuit at one time held that beeper 

surveillance plainly implicated the Fourth Amendment. See 

United States v. Holmes, 521 F.2d 859, 865–67 (5th Cir. 

1975) (―A person has a right to expect that when he drives his 

car into the street, the police will not attach an electronic 

surveillance device to his car in order to track him. Although 

he can anticipate visual surveillance, he can reasonably 

expect to be  ̳alone‘ in his car when he enters it and drives 

away. . . . The[] failure to obtain a warrant is fatal.‖). But that 

view seems to have been abrogated, if not overruled, by later 

pre-Knotts cases. See Michael, supra.

9

The proposition that one has no reasonable 

expectation of privacy in information willingly conveyed to 

third parties remains unquestioned. Smith v. Maryland, 442 

U.S. 735, 743–44 (1979) (―This Court consistently has held 

that a person has no legitimate expectation of privacy in 

information he voluntarily turns over to third parties.‖); see 

also, e.g., California v. Greenwood, 486 U.S. 35, 40–41 

(1988) (no reasonable expectation of privacy in garbage bags 

willingly left on street curb for pick up by third party). But 

see Jones, 132 S. Ct. at 957 (Sotomayor, J., concurring) (―[I]t 

may be necessary to reconsider the premise that an individual 

has no reasonable expectation of privacy in information 

voluntarily disclosed to third parties.‖).
23

reasonable privacy interest in ―whatever stops he ma[kes]‖ 

nor his ―final destination‖ or otherwise. Id. at 281–82.10

 

10 The Knotts Court also based its holding on the 

similarly well-established ―open fields‖ doctrine, see Air 

Pollution Variance Bd. of Colo. v. W. Alfalfa Corp., 416 U.S. 

861, 864–65 (1974); United States v. Lee, 274 U.S. 559, 563 

(1927); Hester v. United States, 265 U.S. 57, 59 (1924), 

stating the beeper‘s ability to enhance visual surveillance was 

of no consequence. Knotts, 460 U.S. at 282 (―Nothing in the 

Fourth Amendment prohibited the police from augmenting 

the sensory faculties bestowed upon them at birth with such 

enhancement as science and technology afforded them in this 

case.‖); see also Boyd v. United States, 116 U.S. 616, 628 

(1886) (― ̳The eye cannot . . . be guilty of a trespass . . . .‘‖ 

(quoting Entick v. Carrington, 95 Eng. Rep. 807 (K.B. 

1765))). Technological enhancements of purely visual 

surveillance have, since Knotts, received similar treatment. 

See Florida v. Riley, 488 U.S. 445, 488–52 (1989) (aerial 

surveillance of interior of partially covered greenhouse from a 

helicopter 400 feet overhead is not a search); Dow Chem. Co. 

v. United States, 476 U.S. 227, 238–39 (1986) (aerial 

photographs taken from an airplane over an industrial 

complex are not searches); California v. Ciraolo, 476 U.S. 

207, 211–14 (1986) (aerial surveillance of an open 

greenhouse from an airplane 1,000 feet overhead is not a 

search); Texas v. Brown, 460 U.S. 730, 739–40 (1983) 

(plurality opinion) (using flashlight to look into car interior 

and open glove compartment at night is not a search). But see 

Kyllo v. United States, 533 U.S. 27, 33–34 (2001) (use of 

infrared light technology to detect heat waves radiating off a 

home is a search because that information ―could not 

otherwise have been obtained without physical intrusion into 
24

A little over a year later, the Court reaffirmed this 

conclusion in Karo. But Karo clarified that the use of 

beepers to monitor cars and other objects was not without 

limits. Only in situations in which officers employ electronic 

devices to obtain information that could otherwise be 

obtained by visual surveillance in public places are officers 

able to rely upon Knotts‘s holding. See Karo, 468 U.S. at 

713–16. Thus, the use of a beeper to monitor objects within 

private residences implicates the Fourth Amendment and 

requires a warrant. See id. at 714, 717–18.

What Knotts initially left undecided, however, was 

whether the installation of the beeper was a search under the 

Fourth Amendment. See Knotts, 460 U.S. at 290 n.**; id. at 

286 (Brennan, J., concurring). In both Knotts and Karo, the 

officers themselves neither installed nor placed the beepers 

onto or into the vehicles. In Knotts, the officers, with the 

consent of a chemical manufacturing company, installed a 

beeper inside a container for chemicals. The company agreed 

that the next time a suspected narcotics manufacturer came to 

purchase chemicals, they would put the chemicals he 

purchased in that particular container. After purchasing the 

chemicals, the suspect willingly placed the bugged container 

into his car, allowing the police to easily monitor his 

movements. 460 U.S. at 278. In Karo, the officers 

cooperated with a government informant so as to ensure that 

Karo, who was suspected of manufacturing narcotics, was 

similarly duped into purchasing a container of chemicals 

 

a constitutionally protected area‖ and ―the technology in 

question [was] not in general public use‖ (internal quotation 

marks omitted) (quoting Silverman v. United States, 365 U.S. 

505, 512 (1960))).
25

containing a beeper. Once the purchase had occurred, and 

Karo placed the container in his car, the officers utilized the 

beeper to monitor his movements. 468 U.S. at 708.

Karo held that where officers arrange for a suspect to 

obtain an item containing a beeper, even if the suspect has no 

knowledge of the item‘s foreign tenant, that transfer did not 

intrude upon that suspect‘s reasonable expectations of 

privacy. Id. at 712. In short, the transfer ―created a potential

for an invasion of privacy,‖ but the mere fact that officers 

arranged for a beeper to come into the possession of an 

individual or into an individual‘s property ―infringed no 

privacy interest.‖ Id. Moreover, Karo reasoned that ―[a]t 

most, there was a technical trespass on the space occupied by 

the beeper.‖ Id. But the Court concluded that ―[t]he 

existence of a physical trespass is only marginally relevant to 

the question of whether the Fourth Amendment has been 

violated . . . , for an actual trespass is neither necessary nor 

sufficient to establish a constitutional violation.‖ Id. at 712–

13.11 As a result, the Court held that ―any impairment of . . . 

 

11 Karo‘s conclusion that ―an actual trespass is neither 

necessary nor sufficient to establish a constitutional violation‖ 

was, until Jones, sacrosanct in Fourth Amendment law. In

Katz v. United States, 389 U.S. 347 (1967), the Supreme 

Court turned Fourth Amendment questions away from their 

common-law trespass foundation. See 389 U.S. at 353 

(―[T]he trespass doctrine . . . can no longer be regarded as 

controlling.‖). Thereafter, the Fourth Amendment touchstone 

was whether the government had intruded upon a person‘s 

reasonable expectations of privacy. See id. at 360 (Harlan, J., 

concurring); see also Jones, 132 S. Ct. at 950; United States 

v. Mosley, 454 F.3d 249, 253 (3d Cir. 2006) (―[T]he Fourth 
26

 

Amendment‘s protection against unreasonable searches is 

predicated on the invasion by the government of a person‘s 

reasonable expectation of privacy . . . .‖). For instance, in 

Oliver v. United States, 466 U.S. 170 (1984), the police 

officers undoubtedly trespassed upon the petitioner‘s 

property. But, because it was found that the officers were 

trespassing upon only the ―open fields‖ of petitioner‘s 

property, he could not ―demand privacy‖ for activities 

conducted or incriminating evidence found upon that 

property. 466 U.S. at 177–78. The vast consensus was, then, 

that a physical ―trespass‖—regardless of whether it would 

have been considered an actual ―trespass‖ under the common 

law—became a ―search‖ only when that trespass infringed 

upon a person‘s reasonable expectation of privacy. See, e.g., 

Rakas v. Illinois, 439 U.S. 128, 143 (1978) (―[C]apacity to 

claim the protection of the Fourth Amendment depends not 

upon a property right in the invaded place but upon whether 

the person who claims the protection of the Amendment has a 

legitimate expectation of privacy in the invaded place.‖); 

United States v. Acosta, 965 F.2d 1248, 1256–57 (3d Cir. 

1992). Indeed, the courts of appeals addressing the Fourth 

Amendment implications of GPS and GPS-like installation 

after Knotts and Karo made little of the physical trespass that 

occurred when police installed devices directly upon 

automobiles, primarily because the invasion of privacy that 

occurred was minimal or non-existent. See United States v. 

Marquez, 605 F.3d 604, 609–10 (8th Cir. 2010); United 

States v. Pineda-Moreno, 591 F.3d 1212, 1215 (9th Cir. 

2010); United States v. Garcia, 474 F.3d 994, 997 (7th Cir. 

2007); United States v. McIver, 186 F.3d 1119, 1126–27 (9th 

Cir. 1999); see also United States v. Michael, 645 F.2d 252, 

257–58 (5th Cir. 1981).
27

privacy interests that may have occurred was occasioned by 

the monitoring of the beeper,‖ not its installation. Id. at 

713.12 

Thus, at bottom, before Jones, Knotts and Karo

established that no Fourth Amendment search occurred where 

officers use beeper-based electronics to monitor an 

automobile‘s movements on public roads because a person 

has no reasonable expectation of privacy with regard to that 

information. But, because the facts of Karo correspondingly 

limited its holding, those cases did not address whether 

installation of a beeper onto or into a vehicle, in all 

circumstances, was a search. Nonetheless, Karo‘s reasoning 

regarding the Fourth Amendment implications of a beeper 

installation on an automobile is telling, and was certainly 

informative in the subsequent treatment of the issue 

throughout the federal courts.

Additionally, several other well settled Fourth 

Amendment principles are relevant. Before Jones, the 

 

12 The Karo Court also rejected the argument that the 

transfer of the bugged container constituted a seizure, holding 

that no ―possessory interest was interfered with in a 

meaningful way.‖ Karo, 468 U.S. at 712; see also id. (―A 

 ̳seizure‘ of property occurs when  ̳there is some meaningful 

interference with an individual‘s possessory interests in that 

property.‘‖ (quoting United States v. Jacobsen, 466 U.S. 109, 

113 (1984)). Later cases did not disturb this holding, see, 

e.g., United States v. Garcia, 474 F.3d 994, 996 (7th Cir. 

2007), and Appellees here do not allege the GPS installation 

or subsequent surveillance was a seizure.
28

Supreme Court had made perfectly clear that persons did not 

enjoy a reasonable expectation of privacy in the exterior of 

their automobiles. New York v. Class, 475 U.S. 106, 114 

(1986); see also Cardwell v. Lewis, 417 U.S. 583, 591 (1974). 

Similarly axiomatic were the principles that a simple 

―trespass‖ or ―physical intrusion‖ alone, absent an 

infringement upon a reasonable expectation of privacy, was 

not a ―search,‖ see supra Note 11; that information willingly 

conveyed to third parties, such as when a car ―travels public 

thoroughfares where its occupants and its contents are in plain 

view,‖ Cardwell, 417 U.S. at 590, retains no reasonable 

expectation of privacy, see supra Note 9; and that objects 

willingly placed or left in the ―open fields,‖ regardless of 

whether those fields are trespassed upon, see Oliver, 466 U.S. 

at 177–80, do not enjoy a reasonable expectation of privacy, 

see supra Note 10.

2.

After Knotts and Karo, what resulted was a uniform 

consensus across the federal courts of appeals to address the 

issue that the installation and subsequent use of GPS or GPSlike device was not a search or, at most, was a search but did 

not require a warrant. See, e.g., United States v. Marquez, 

605 F.3d 604, 609–10 (8th Cir. 2010) (reasoning that 

installation and use of GPS requires only reasonable 

suspicion, since monitoring on public roads is not a search); 

United States v. Pineda-Moreno, 591 F.3d 1212, 1215–16

(9th Cir. 2010) (holding that GPS installation and use was not 

a search); United States v. Garcia, 474 F.3d 994, 997–98 (7th 

Cir. 2007) (same); United States v. McIver, 186 F.3d 1119, 

1126–27 (9th Cir. 1999) (same); see also United States v. 

Michael, 645 F.2d 252, 256–58 (5th Cir. 1981) (en banc) 
29

(holding that installation and use of beeper requires only 

reasonable suspicion, since monitoring on public roads is not 

a search).13 

Most federal district courts, including the Middle 

District of Pennsylvania, had reached the same result. United 

States v. Jesus-Nunez, No. 1:10-cr-00017-01, 2010 WL 

2991229, **3–5 (M.D. Pa. July 27, 2010) (―Since there was 

no Fourth Amendment search or seizure by the Government‘s 

use of the GPS device, the court finds that the agents did not 

need probable cause or even reasonable suspicion to attach 

and monitor the [GPS] device to Defendant‘s cars.‖); e.g.,

United States v. Burton, 698 F. Supp. 2d 1303, 1307–08 

(N.D. Fla. 2010); United States v. Moran, 349 F. Supp. 2d 

425, 467–68 (N.D.N.Y. 2005).

The only case to break from this consensus was United 

States v. Maynard, 615 F.3d 544 (D.C. Cir. 2010). In 

Maynard, the D.C. Circuit held that prolonged use of a GPS 

device to monitor the movements of defendant Jones‘s 

vehicle ―24 hours a day for four weeks,‖ was a ―search‖ 

under the Fourth Amendment. 615 F.3d at 555. According to 

the D.C. Circuit, Knotts was not controlling of the question, 

as the court reasoned that Knotts‘s holding endorsed only that 

 

13 Michael was also the law in the Eleventh Circuit. 

See Bonner v. City of Prichard, 661 F.2d 1206, 1209 (11th 

Cir. 1981) (en banc) (decisions of the Fifth Circuit prior to 

October 1, 1981 are binding on the Eleventh Circuit); United 

States v. Smith, 387 F. App‘x 918, 920–21 (11th Cir. 2010) 

(unpublished) (citing United States v. Michael, 645 F.2d 252 

(5th Cir. 1981) to support the proposition that GPS 

installation was not a search). 
30

― ̳[a] person traveling in an automobile on public 

thoroughfares has no reasonable expectation of privacy in his 

movements from one place to another,‘ not that such a person 

has no reasonable expectation of privacy in his movements 

whatsoever, world without end.‖ Id. at 557 (alteration in 

original) (citation omitted) (quoting Knotts, 460 U.S. at 281). 

The court reasoned that the Supreme Court in Knotts, and the 

later cases across the courts of appeals, all ―reserved‖ the 

issue of ―whether  ̳wholesale‘ or  ̳mass‘ electronic 

surveillance of many individuals requires a warrant.‖ Id. at 

558.14 

As a result, the court concluded that although it may be 

―one thing for a passerby to observe or even to follow 

someone during a single journey as he goes to the market or 

returns home from work,‖ it is a whole other thing ―for that 

stranger to pick up the scent again the next day and the day 

after that, week in and week out, dogging his prey until he has 

identified all the places, people, amusements, and chores that 

make up that person‘s hitherto private routine.‖ Id. at 560. 

The court‘s analysis in Maynard, therefore, was focused not 

on the installation of the device but rather the prolonged use 

 

14 The Supreme Court in Knotts, in response to the 

argument that its holding would allow ―twenty-four hour 

surveillance of any citizen of this country . . . without judicial 

knowledge or supervision,‖ opined that ―the  ̳reality hardly 

suggests abuse,‘‖ and suggested that ―if such dragnet-type 

law enforcement practices . . . should eventually occur, there 

will be time enough then to determine whether different 

constitutional principles may be applicable.‖ Knotts, 460 

U.S. at 283–84 (quoting Zurcher v. Stanford Daily, 436 U.S. 

547, 566 (1978)).
31

of the GPS and the quality and quantity of information 

obtained over an extended period of time. Id. at 562 

(―Prolonged surveillance reveals types of information not 

revealed by short-term surveillance, such as what a person 

does repeatedly, what he does not do, and what he does 

ensemble. These types of information can each reveal more 

about a person than does any individual trip viewed in 

isolation.‖).15

Other than Maynard, only a handful of dissenting 

opinions questioned Knotts‘s and Karo‘s holdings or their 

applicability to GPS installation and subsequent surveillance. 

See Karo, 468 U.S. at 736 (Stevens, J., dissenting) (―The 

impact of beeper surveillance upon interests protected by the 

Fourth Amendment leads me to what I regard as the perfectly 

sensible conclusion that absent exigent circumstances 

Government agents have a constitutional duty to obtain a 

warrant before they install an electronic device on a private 

citizen‘s property.‖); United States v. Pineda-Moreno, 617 

F.3d 1120, 1124–26 (9th Cir. 2010) (Kozinski, C.J., 

dissenting from denial of rehearing en banc) (arguing that 

 

15 I pause here to note that the majority characterizes

Maynard as having held that the mere act of attaching a GPS 

device onto a person‘s vehicle for the purpose of conducting 

continual surveillance, alone, constituted a search. See Maj. 

Op. at 16; see also id. at 27 n.9 (describing that Maynard

―explained that warrantless installation of a GPS device by 

the police was per se unreasonable under the Fourth 

Amendment‖). Such a characterization is unfaithful to the 

panel‘s opinion, which explicitly tailored its holdings to the 

fact that the surveillance conducted in that case lasted for a 

month. See Maynard, 615 F.3d at 558, 560.
32

GPS surveillance is a search because GPS devices ―have little 

in common with the primitive devices in Knotts,‖ and provide 

officers ―the power to track the movements of every one of 

us, every day of our lives‖); Michael, 645 F.2d at 260–70 

(Tate, J., dissenting) (disagreeing with majority that ―an 

individual living under our Constitution has no reasonable 

expectation of privacy such as would protect him from a 

trespass upon his property by governmental agents, a trespass 

that enables them to maintain continuous electronic 

surveillance over his movements twenty-four hours per day 

continuously and indefinitely‖).

3.

I also find several other considerations relevant. First, 

and most important, is Rule 41(b) of the Federal Rules of 

Criminal Procedure, which governs the issuance of warrants 

in all federal criminal proceedings. The 2006 Advisory 

Committee‘s Note explains that Rule 41(b) was amended, in 

part, to ―address the use of tracking devices.‖ Fed. R. Crim. 

P. 41(b) advisory comm. note (2006). In describing the ideal 

procedure, the Note states that ―[w]arrants may be required to 

monitor tracking devices when they are used to monitor 

persons or property in areas where there is a reasonable 

expectation of privacy.‖ Id. (citing Karo, 468 U.S. 705). 

Elaborating, the note instructs that ―if the officers intend to 

install or use the device in a constitutionally protected area, 

they must obtain judicial approval to do so.‖ Id. But, ―[i]f, 

on the other hand, the officers intend to install and use the 

device without implicating any Fourth Amendment rights, 

there is no need to obtain the warrant.‖ Id. (citing Knotts, 

460 U.S. 276).
33

Moreover, the law enforcement officers consulted with 

an Assistant United States Attorney before conducting the 

installation of the GPS unit and the subsequent surveillance. 

(See Appellant Br. at 56.) I agree with the majority that ―a 

government attorney‘s approval, standing alone, cannot and 

should not suffice to demonstrate good faith.‖ Maj. Op. at 52

n.23. But, as Appellees‘ attorney conceded at oral argument, 

it is certainly another consideration to take into account in the 

good-faith analysis. (See Oral Arg. Trans. at 52: 4–6 

(conceding that the officers‘ reliance on the opinion of an 

Assistant United States Attorney was ―a factor to look at‖ in 

determining whether the officers acted in good faith).) See 

also Tracey, 597 F.3d at 153 (concluding that approval from a 

government attorney, inter alia, was one consideration 

evidencing that ―[a] reasonable officer would . . . have 

confidence in the validity of the [search]‖); United States v. 

Otero, 563 F.3d 1127, 1134 (10th Cir. 2009) (same); United

States v. Fama, 758 F.2d 834, 837 (2d Cir. 1985) (same).

IV.

In my view, in light of the legal landscape discussed 

above, when the officers installed the GPS device16 upon the 

undercarriage of Harry Katzin‘s vehicle, and then used that 

 

16 By ―installed the GPS device,‖ of course, I mean 

that the officers magnetically attached the ―slap on‖ GPS 

device upon the undercarriage of Harry Katzin‘s vehicle. 

That device was totally independent of the car, operating 

under its own power. Also, it was not physically installed 

onto the car using screws, adhesives, or otherwise. Its 

attachment was occasioned only magnetically. Thus, for the 

purpose of my analysis, I focus on those facts.
34

device to monitor the vehicle‘s movements for two days 

while it traversed public thoroughfares, those officers were 

acting with ―an objectively  ̳reasonable good-faith belief‘ that 

their conduct [was] lawful.‖ Davis, 131 S. Ct. at 2427 

(quoting Leon, 468 U.S. at 909). I find that the officers‘ 

actions in this case do not ―exhibit  ̳deliberate,‘  ̳reckless,‘ or 

 ̳grossly negligent‘ disregard for Fourth Amendment rights,‖ 

id. (quoting Herring, 555 U.S. at 144), and, thus, ―the 

deterrent value‖ of excluding the evidence found pursuant to 

the officers‘ conduct would not ―outweigh the resulting 

costs.‖ Id. Simply put, in this case, ―exclusion cannot not 

 ̳pay its way.‘‖ Id. at 2428 (quoting Leon, 468 U.S. at 908 

n.6). 

A. 

The officers here were acting with an objectively 

reasonable good-faith belief that their warrantless installation 

of the GPS device upon the undercarriage of Harry Katzin‘s 

automobile did not run afoul of the Fourth Amendment. 

Based on fundamental Fourth Amendment principles 

which would have been familiar to any reasonably well 

trained law enforcement officer, there was no possibility that 

the officers, at the time they installed the GPS upon Harry 

Katzin‘s vehicle, would have ―had knowledge‖—nor could 

we now ―charge[] [them] with knowledge‖—―that the search 

was unconstitutional under the Fourth Amendment.‖ Krull, 

480 U.S. at 348–49 (quoting Peltier, 422 U.S. at 542).

Before Jones, the touchstone of any Fourth 

Amendment analysis was whether the Government had 

invaded upon a person‘s reasonable expectation of privacy. 
35

See Katz, 389 U.S. at 360 (Harlan, J., concurring); see also 

Bond v. United States, 529 U.S. 334, 338 (2000); California 

v. Ciraolo, 476 U.S. 207, 211 (1986). ―[A]n actual trespass 

[was] neither necessary nor sufficient to establish a 

constitutional violation.‖ Karo, 468 U.S. at 713 (emphasis 

added); see also supra note 11. As a result, a reasonably well 

trained law enforcement officer would have known that the 

installation of the GPS unit upon the undercarriage of Harry 

Katzin‘s vehicle was a Fourth Amendment ―search‖ only in 

the event that it was apparent that Harry Katzin had a 

reasonable expectation of privacy in that area.

Of course, Harry Katzin had a reasonable expectation 

of privacy with respect to the interior of his vehicle; even if 

that privacy interest was diminished. See Cardwell, 417 U.S. 

at 589–90. But it would have been objectively reasonable for 

a law enforcement officer to conclude that he lacked a 

reasonable expectation of privacy in the exterior—

specifically, the undercarriage—of the vehicle. 

In Cardwell v. Lewis, 417 U.S. 583 (1974) and again 

in New York v. Class, 475 U.S. 106 (1986), the Supreme 

Court made it quite clear that persons lack a reasonable 

expectation of privacy in the exterior of their automobiles. 

See Cardwell, 417 U.S. at 591 –92 (―With the search limited 

to the examination of the tire on the wheel and the taking of 

paint scrapings from the exterior of the vehicle left in the 

public parking lot, we fail to comprehend what expectation of 

privacy was infringed.‖); Class, 475 U.S. at 114 (plurality 

opinion) (―The exterior of a car, of course, is thrust into the 

public eye, and thus to examine it does not constitute a 

 ̳search.‘‖ (citing Cardwell, 417 U.S. at 588–89)). In light of 

this long-standing Supreme Court precedent, the officers 
36

would have had an ―objectively reasonable good-faith belief‖ 

that Harry Katzin lacked a reasonable expectation in the 

exterior of his vehicle, and thus that ―their conduct was 

lawful‖ when they installed the GPS on the car‘s 

undercarriage. Davis, 131 S. Ct. at 2427 (internal quotation 

mark omitted).17

Again, I make no claim that Class or Cardwell qualify 

as ―binding appellate precedent‖ under Davis. That does not 

end the inquiry, however. Instead, what resolves the inquiry 

is that, in light of the pre-Jones legal landscape, the law 

enforcement officers here could have reasonably concluded 

that Supreme Court precedent authorized, or at the very least

affirmed the constitutionality of, their conduct. Regardless of 

 

17 The majority is correct to point out, in its brief 

discussion of Class‘s applicability to our warrant analysis, 

that Jones dismissed Class‘s relevancy with regard to whether 

a search occurs where officers install and subsequently track a 

GPS device upon an automobile. See Maj. Op. at 34 n.14. 

That does not mean, however, that Class and Cardwell are 

similarly irrelevant to our good-faith analysis. At the time the 

officers were acting, those two cases were generally

understood to stand for the proposition that one lacks a 

reasonable expectation of privacy in the exterior of his 

automobile. See, e.g., Pineda-Moreno, 591 F.3d at 1215 

(―[T]he undercarriage of a vehicle, as part of its exterior, is 

not entitled to a reasonable expectation of privacy.‖); United 

States v. George, 971 F.2d 1113, 1119–20 (4th Cir. 1992) 

(―There is thus little question in the aftermath of Cardwell 

and Class that one does not have a reasonable expectation of 

privacy in the visible exterior parts of an automobile that 

travels the public roads and highways.‖).
37

the alternate facts in Class and Cardwell, those cases‘ 

holdings and principles of law, which would have been 

known by a reasonably well trained law enforcement officer,

made it clear that before Jones a person lacked a reasonable 

expectation of privacy in the exterior of his automobile, and, 

thus, a simple trespass thereupon by law enforcement officers 

would not have constituted a ―search.‖ As a result, I cannot 

conclude that the law enforcement officers‘ conduct in 

installing the GPS device to the undercarriage of Harry 

Kaztin‘s vehicle was a ― ̳deliberate,‘  ̳reckless,‘ or  ̳grossly 

negligent‘ disregard of Fourth Amendment rights.‖ Davis, 

131 S. Ct. at 2427 (quoting Herring, 555 U.S. at 144).

B.

Similarly, the officers here were acting with an 

objectively reasonable good-faith belief that their warrantless 

use of the GPS to monitor Harry Katzin‘s vehicle while it 

traversed public roads over the course of two days was 

constitutionally permissible.

First, the majority distinguishes, and thus dismisses, 

Knotts and Karo on their facts. Paramount, the majority says, 

are that facts that ―[n]either case involved a physical trespass 

onto the target vehicle; in both cases the police placed the 

beeper inside of a container which was then loaded into the 

target vehicle by the driver . . . . [and] both Karo and Knotts

addressed the use of beepers, which . . . are markedly 

different from GPS trackers.‖ Maj. Op. at 40. True, these 

factual distinctions would matter much if the Government 

were arguing that Knotts and Karo qualified as ―binding 

appellate precedent‖ under Davis. But, as discussed above, 

that is not the Government‘s argument. A reasonably well 
38

trained police officer, acting in December 2010, would have 

thought Knotts and Karo to have meant exactly what they 

said with regard to GPS and GPS-like surveillance. Those 

cases made absolutely clear that ―[a] person traveling in an 

automobile on public thoroughfares has no reasonable 

expectation of privacy in his movements from one place to 

another,‖ Knotts, 460 U.S. at 281, because the ―movements 

of the automobile‖ while on public roads ―could have been 

observed by the naked eye.‖ See Karo, 468 U.S. at 713–14. 

Thus, the Fourth Amendment simply was not implicated. See 

id.; see also Sparks, 711 F.3d at 65 (―After Knotts . . . [it was] 

settled . . . [that] using a beeper to monitor a person‘s 

movements in a car on public roads did not implicate the 

Fourth Amendment, because there was no privacy interest to 

be infringed.‖). At the time the officers were acting, Knotts‘s 

holding was familiar and sacrosanct. See, e.g., Marquez, 605 

F.3d at 609; Garcia, 474 F.3d at 996; McIver, 186 F.3d at 

1126. 

This may well be enough to justify the officers‘ good 

faith in performing warrantless GPS surveillance of Harry 

Katzin‘s automobile. See Sparks, 711 F.3d at 66–67 

(concluding good-faith exception applied to GPS surveillance 

because Knotts ―clearly authorized the agents to use a GPSbased tracking device‖). But I need not answer that question, 

because ―good faith‖ is determined in light of ―all of the 

circumstances.‖ Leon, 468 U.S. at 922 n.23; see also 

Herring, 555 U.S. at 145. In this case, in addition to Knotts

and Karo, the officers were also guided, and reasonably 

relied, upon a ―uniform treatment‖ of ―continuous judicial 

approval‖ across the federal courts with regard to the 

constitutionality of warrantless GPS use. See Peltier, 422 

U.S. at 541–42; see also Caleb Mason, New Police 
39

Surveillance Technologies and the Good-Faith Exception: 

Warrantless GPS Tracker Evidence After United States v. 

Jones, 13 NEV. L. J. 60, 65 (2012) (before Jones, ―everyone 

thought‖ that the ―key fact‖ from Knotts and Karo ―was that 

the cars were being monitored while they were on public 

roads, where anyone could see them‖). Specifically, nearly 

every federal court to consider the issue had concluded that a

warrant was unnecessary to conduct GPS surveillance, the 

sole exception being Maynard.

18

Consequently, in light of Knotts and Karo, and their 

subsequent treatment, it was ―objectively reasonable‖ for the 

law enforcement officers to have believed that the use of the 

GPS device to conduct surveillance upon Harry Katzin‘s 

vehicle while it moved along public roadways was not a 

Fourth Amendment ―search.‖ See Knotts, 460 U.S. at 282–83 

(explaining that where one ―travel[s] over the public streets 

he voluntarily convey[s] to anyone who want[s] to look the 

fact that he [is] traveling over particular roads in a particular 

direction, the fact of whatever stops he ma[kes], and the fact 

of his final destination‖); Ciraolo, 476 U.S. at 224 (Powell, J., 

dissenting) (―Comings and goings on public streets are public 

matters, and the Constitution does not disable police from 

observing what every member of the public can see.‖); id. at 

215 (majority opinion) (―The Fourth Amendment simply does 

 

18 The majority claims that, under the logic of my 

analysis, Maynard should have put the law enforcement 

officers ―on notice that [GPS] devices could implicate Fourth 

Amendment rights.‖ Maj. Op. at 54 n.24 (alteration, 

omission, and internal quotation marks omitted). For the 

reasons set forth at infra Part V, I disagree.
40

not require the police traveling in the public . . . to obtain a 

warrant in order to observe what is visible to the naked eye.‖). 

C.

Moreover, two additional considerations bolster my 

conclusion that the law enforcement officers here acted with 

―an objectively  ̳reasonable good-faith belief‘ that their 

conduct was lawful.‖ Davis, 131 S. Ct. at 2427 (quoting Leon, 

468 U.S. at 909).

First is the fact that the warrantless installation of the 

GPS device and its subsequent surveillance complied with the 

commentary to Rule 41(b) of the Federal Rules of Criminal 

Procedure, which states that ―[i]f . . . the officers intend to 

install and use [a GPS] device without implicating any Fourth 

Amendment rights, there is no need to obtain [a] warrant.‖ 

FED. R. CRIM. P. 41(b) advisory comm. note (2006). As 

discussed, it was objectively reasonable for the officers to 

have concluded that Harry Katzin lacked a reasonable 

expectation of privacy in the undercarriage of his automobile, 

and the GPS device was never used to conduct surveillance in 

any area but the public roadways upon which the car was 

traveling. Thus, a reasonable reading of this commentary 

would have led to the equally reasonable conclusion that the 

officers here did not require a warrant to act.19

 

19 Although the Government neglected to argue this 

fact, similar arguments have been made in similar cases, 

including cases heard by District Courts in this Circuit. See, 

e.g., United States v. Lopez, __ F. Supp. 2d __, C.A. No. 10-

cr-67(GMS), 2013 WL 3212347, at *3 (D. Del. June 26, 

2013); United States v. Willford, __ F. Supp. 2d __, Crim. No. 
41

Second, the law enforcement officers consulted with 

an Assistant United States Attorney before conducting the 

installation of the GPS unit and the subsequent surveillance. 

(See Appellant Br. at 56.) More than likely, that attorney‘s 

discussion with the officers about the constitutionality of their 

conduct proceeded along similar lines as my analysis above. 

But, important for our purposes, the fact that the officers 

consulted with a government attorney before acting, who then 

approved their desired course of action, although certainly not 

dispositive on its own, is a consideration weighing in favor of 

the conclusion that ―[a] reasonable officer would . . . have 

confidence in the validity of the [search].‖ Tracey, 597 F.3d 

at 153; see also Otero, 563 F.3d at 1134; Fama, 758 F.2d at 

837.

Thus, taking into consideration the Supreme Court 

jurisprudence, the near unanimous treatment by the federal 

 

ELH-11-0258, 2013 WL 2552446, at *20 (D. Md. June 7, 

2013). Furthermore, the majority claims this commentary is a 

codification of ―nothing more than the unremarkable 

proposition that the police need not obtain a warrant if their 

action does not violate the Fourth Amendment.‖ Since 

Maynard put law enforcement ―on notice‖ that GPS use could 

affect Fourth Amendment rights, the majority reasons, the 

Rule has no substantive effect on the good-faith analysis. 

Maj. Op. at 54 n.24. Again, as I discuss at infra Part V, I do 

not read Maynard to have such an effect, and, thus, I am at a 

loss to see how a reasonably well trained law enforcement 

officer, acting at the time the officers did in this case, could 

have known that their actions ―implicat[ed] . . . the Fourth 

Amendment.‖
42

courts to have addressed the issue, the commentary to Rule 

41(b) of the Federal Rules of Criminal Procedure, and the fact 

the officers here consulted with an Assistant United States 

Attorney, it is clear that the officers were not acting with 

― ̳deliberate,‘  ̳reckless,‘ or  ̳grossly negligent‘ disregard of 

Fourth Amendment rights,‖ Davis, 131 S. Ct. at 2427 

(quoting Herring, 555 U.S. at 144), when they conducted the 

warrantless installation and subsequent surveillance of the 

GPS device upon Harry Katzin‘s automobile, but were 

instead acting with ―an objectively  ̳reasonable good-faith 

belief‘ that their conduct [was] lawful.‖ Id. (quoting Leon, 

468 U.S. at 909). 

V.

The majority holds otherwise, because, in its view, the 

difference between the beepers used in Knotts and Karo and 

the GPS device used in this case is ―one of kind, not degree,‖ 

Maj. Op. at 47 n.20, which makes all the ―differen[ce].‖ 

Furthermore, the majority chides reliance on Knotts, Karo, 

and the relevant cases from our sister circuits because United 

States v. Maynard, which held that prolonged GPS 

surveillance was a search and did require a warrant, put the 

officers on notice ―that such devices could  ̳implicat[e] . . . 

Fourth Amendment rights.‘‖ Maj. Op. at 54 n.24. I disagree 

that these two considerations render the officers‘ conduct here 

objectively unreasonable and sufficiently culpable so as to 

incur the wrath of the exclusionary rule. 

Certainly, the technological difference between the 

beepers of the 1980s and modern GPS devices is a 

consideration to take into account in determining whether the 

law enforcement officers were acting with an objectively 
43

reasonable belief their actions were lawful. Modern ―GPS 

units do not require police to follow the suspect visually, do 

not allow the driver to detect tailing, and do not require an 

expensive deployment of equipment and manpower.‖ United 

States v. Hernandez, 647 F.3d 216, 221 (5th Cir. 2011); see 

also Maynard, 615 F.3d at 565 (opining that ―practical 

considerations prevent visual surveillance from lasing [as] 

long‖ as ―the use of the GPS in [that] case‖); Pineda-Moreno, 

617 F.3d at 1126 (Kozinski, C.J., dissenting from denial of 

rehearing en banc) (―[T]here‘s no hiding from the all-seeing 

network of GPS satellites that hover overhead, which never 

sleep, never blink, never get confused and never lose 

attention.‖). 

Admittedly, this makes GPS devices different from the 

beepers used in Knotts and Karo. Beepers do not 

independently determine their geographic location, but, 

instead, ―emit[] periodic signals that can be picked up by a 

radio receiver‖ within range of the beeper‘s radio transmitter. 

See Knotts, 460 U.S. at 277. Beepers thus aid law 

enforcement by assisting officers in visual surveillance of a 

suspect, rather than doing the work of the officer altogether. 

See Pineda-Moreno, 617 F.3d at 1124 (Kozinski, C.J., 

dissenting from the denial of rehearing en banc) (―[M]odern 

[GPS] devices . . . can record the car‘s movements without 

human intervention—quietly, invisibly, with uncanny 

precision.‖).

Notwithstanding these technological differences, ―[i]t 

is the exploitation of technological advances that implicates 

the Fourth Amendment, not their mere existence.‖ Karo, 468 

U.S. at 712. ―Certainly, a GPS tracker is more capable than a 

beeper,  ̳but nothing inheres in the technology to take it out of 
44

Knotts‘s holding.‘‖ Sparks, 711 F.3d at 66 (footnote omitted) 

(quoting United States v. Cuevas-Perez, 640 F.3d 272, 278 

(7th Cir. 2011) (Flaum J., concurring)); see also United States 

v. Andres, 703 F.3d 828, 835 (5th Cir. 2013) (finding that 

―any possible technological differences between a 1981 

 ̳beeper‘ and the GPS device‖ insufficient because the two 

devices‘ ―functionality [were] sufficiently similar‖); United 

States v. Jones, 625 F.3d 766, 768 (D.C. Cir. 2010) (Sentelle, 

C.J., dissenting from the denial of rehearing en banc) (―There 

is no material difference between tracking the movements of 

the Knotts defendant with a beeper and tracking the Jones

appellant with a GPS.‖).

Regardless of the technological differences, the GPS 

reported to law enforcement no more information than that 

which the officers could have obtained through pure visual 

surveillance. Jesus-Nunez, No. 1:10-cr-00017-01, 2010 WL 

2991229, at *3; see also Cuevas-Perez, 640 F.3d at 275 

(dismissing as immaterial the increased accuracy of GPS 

devices since ―real-time information is exactly the kind of 

information that drivers make available by traversing public 

roads‖). Every piece of data the GPS unit provided law 

enforcement officers could have been otherwise obtained by a 

police officer tracking Harry Katzin‘s vehicle on foot or in his 

squad car on a public street;20 by an officer keeping an eye on 

 

20 See California v. Greenwood, 486 U.S. 35, 41 

(1988) (―[T]he police cannot reasonably be expected to avert 

their eyes from evidence of criminal activity that could have 

been observed by any member of the public.‖); Texas v. 

Brown, 460 U.S. 730, 740 (1983) (plurality opinion) (―The 

general public could peer into the interior of Brown‘s 

automobile from any number of angles; there is no reason 
45

the vehicle through use of a telescope or binoculars, or 

utilizing a flashlight or spotlight so as to not lose the car 

under the shadow of the night;

21 or by an officer utilizing an 

airplane or a helicopter to follow the vehicle along the public 

roadways.22 

 

[the officer] should be precluded from observing as an officer 

what would be entirely visible to him as a private citizen.‖);

Katz v. United States, 389 U.S. 347, 351 (1967) (―What a 

person knowingly exposes to the public . . . is not a subject of 

Fourth Amendment protection.‖).

21 See Brown, 460 U.S. at 739–40 (plurality opinion) 

(―It is . . . beyond dispute that [the officer‘s] action in shining 

his flashlight to illuminate the interior of Brown‘s car 

trenched upon no right secured to the latter by the Fourth 

Amendment.‖); United States v. Lee, 274 U.S. 559, 563 

(1927) (―For aught that appears, the cases of liquor were on 

deck and, like the defendants, were discovered before the 

motorboat was boarded. Such use of a searchlight is 

comparable to the use of a marine glass or a field glass. It is 

not prohibited by the Constitution.‖).

22 See Florida v. Riley, 488 U.S. 445, 448–449, 451–52 

(1989) (an officer ―circl[ing] twice over respondent's property 

in a helicopter at the height of 400 feet‖ was not a search 

because ―the police may see what may be seen from a public 

vantage point where they have a right to be‖ (alteration and 

internal quotation marks omitted)); California v. Ciraolo, 476 

U.S. 207, 213–14 (1986) (―Any member of the public flying 

in this airspace who glanced down could have seen 

everything that these officers observed.‖). 
46

The efficiency or efficacy of an officer‘s natural senses 

often benefit from advances in technology. See Dow Chem. 

Co. v. United States, 476 U.S. 227, 231 (1986) (changes in 

technology not only ―enhance[] industrial process, and indeed 

all areas of life,‖ but ―they have also enhanced law 

enforcement techniques‖). But ―[t]he mere fact that human 

vision is enhanced‖ by some form of technological advance, 

by itself, ―does not give rise to constitutional problems.‖ Id.

at 238; see also Silverman v. United States, 365 U.S. 505, 513 

(1961) (Douglas, J., concurring) (―[N]either should the 

command of the Fourth Amendment be limited by nice 

distinctions turning on the kind of electronic equipment 

employed.‖). Again, ―[i]t is the exploitation of technological 

advances that implicates the Fourth Amendment, not their 

mere existence.‖ Karo, 468 U.S. at 712. ―Nothing in the 

Fourth Amendment prohibit[s] the police from augmenting 

the sensory facilities bestowed upon them at birth with such 

enhancement as science and technology afforded them in this 

case.‖ Knotts, 460 U.S. at 282. The information obtained 

through use of the GPS was information otherwise observable 

by the naked eye. See id. at 281–82. The GPS unit simply 

made it easier for the law enforcement officers to obtain. See 

id. at 284 (―Insofar as respondent‘s complaint appears to be 

simply that scientific devices such as beepers enabled police 

to be more effective in detecting crime, it simply has no 

constitutional foundation.‖). And at the time the officers here 

acted, it was indubitable that Harry Katzin lacked any 

reasonable expectation of privacy in the information the GPS 

unit was procuring. See id at 281.23 Thus, even taking into 

 

23 Today, the question remains open as to whether 

Jones effectually abrogated Knotts‘s conclusion that persons 

lack any reasonable expectation of privacy in the information 
47

consideration the technological difference between the 

beepers used in Knotts and Karo and the GPS units used in 

this case, the officers were clearly not ―exploit[ing]‖ GPS 

technology in a way so as to put them on notice that their 

 

the GPS unit was procuring. The only question answered in 

Jones was whether a search had occurred through the 

installation and subsequent use of the GPS device. Thus, the 

Fourth Amendment implications of the information obtained 

by the GPS surveillance, alone, were not discussed. Jones did 

state that ―Knotts noted the  ̳limited use which the 

government made of the signals from [that] particular beeper; 

and reserved the question whether  ̳different constitutional 

principles may be applicable‘ to  ̳dragnet-type law 

enforcement practices‘ of the type that GPS tracking made 

possible [in that case].‖ Jones, 132 S. Ct. at 952 n.6 (citations 

omitted). But Justice Scalia‘s opinion for the majority 

refrained from altering Knotts‘s conclusion that ―the 

information obtained—the location of the automobile 

carrying the [beeper] on public roads . . .—had been 

voluntarily conveyed to the public,‖ and was therefore not a 

search. Id. at 951–52. Nonetheless, five justices wrote or 

joined the concurring opinions in Jones, all of which seemed 

to endorse the so-called ―mosaic‖ theory expressed in 

Maynard—which would unequivocally limit the holding in 

Knotts to apply in only short-term surveillance. See Orin 

Kerr, The Mosaic Theory of the Fourth Amendment, 111 

MICH. L. REV. 311, 326 (2012). This question does not need 

to be answered today; but emphasizes the major shift caused 

by Jones in Fourth Amendment law, and the vastly different 

legal regime under which the law enforcement officers here 

were acting.
48

actions were unconstitutional.24 See Cuevas-Perez, 640 F.3d 

at 279–80 (Flaum, J., concurring) (opining before Jones that 

―[t]he holding of Knotts is that a person has no expectation of 

privacy in movements from one place to another on public 

 

24 The majority concludes otherwise, alluding that my 

preferred disposition would ―leave [persons] at the mercy of 

advancing technology.‖ Maj. Op. at 48 n.20 (citing Kyllo v. 

United States, 533 U.S. 27, 35–36 (2001)). This case is 

categorically distinct from Kyllo. In Kyllo, the officers 

utilized technology to observe infrared radiation, which is 

otherwise invisible to the naked eye. 533 U.S. at 29. 

Furthermore, the officers utilized that technology in order to 

determine the relative temperature of the interior of a home, 

an area entitled to almost absolute protection under the Fourth 

Amendment. Id. at 29–30; see also Florida v. Jardines, 569 

U.S. __, 133 S. Ct. 1409, 1414 (2013) (―[W]hen it comes to 

the Fourth Amendment, the home is first among equals.‖). In 

contrast, the use of the GPS device in this case provided 

information otherwise observable by the naked eye on a 

public street. What is more, although the Court found it 

―foolish to contend that the degree of privacy secured to 

citizens by the Fourth Amendment has been entirely 

unaffected by the advance of technology,‖ Kyllo made much 

of the fact that the technology used in that case was ―not in 

general public use.‖ 533 U.S. at 33–34. Alternatively, GPS 

technology is widespread, and one need look only on the 

dashboard of his vehicle or the screen of his cellular 

telephone to spot one. Kyllo‘s concerns, of course, arise in all 

Fourth Amendment cases dealing with advanced technology. 

But it is safe to say that those concerns are not implicated by 

out facts.
49

roads; by its terms, the holding is indifferent to the 

technology used to observe those movements‖).

Nor does the existence of United States v. Maynard, 

615 F.3d 544 (D.C. Cir. 2010) affect the officers‘ reasonable 

belief that their conduct was lawful. First, the Maynard 

holding was based on the fact that the GPS surveillance 

conducted in that case lasted for four weeks, which allowed 

law enforcement to obtain ―information not revealed by shortterm surveillance.‖ See Maynard, 615 F.3d at 562; CuevasPerez, 640 F.3d at 274 (―[T]he Maynard court repeatedly 

distinguished the surveillance at issue there from surveillance 

during a single journey.‖). Conversely, the GPS tracking in 

this case lasted for only two days, (see Appendix at 112–15, 

143–50.), and Appellees make no argument that the 

information obtained by the GPS device ―reveal[ed] more‖ 

about their personal lives ―than does any individual trip 

viewed in isolation.‖ Maynard, 615 F.3d at 562.25 Besides, 

 

25 The majority claims this is a distinction without a 

point, because ―when the police attached their GPS device to 

Harry Katzin‘s van, they had no way of knowing when the 

next Rite Aid robbery would take place‖; thus characterizing 

the GPS tracking here as ―a long-term surveillance project.‖ 

See Maj. Op. at 50 & n.22. But for purposes of whether a 

Fourth Amendment violation occurred it matters not what law

enforcement officers could have done but what they did do. 

See Dow Chem. Co., 476 U.S. at 238 n.5 (―Fourth 

Amendment cases must be decided on the facts of each case, 

not by extravagant generalizations.  ̳[W]e have never held 

that potential, as opposed to actual, invasions of privacy 

constitute searches for purposes of the Fourth Amendment.‘‖ 

(alteration in original) (quoting Karo, 468 U.S. at 712)); cf. 
50

―Knotts gave scant reason to think that the duration of the 

tracking in that case was material to the Court‘s reasoning.‖ 

Sparks, 711 F.3d at 67.26

 

United States v. Jacobsen, 466 U.S. 109, 122 (1984) (―The 

concept of an interest in privacy that society is prepared to 

recognize as reasonable is, by its very nature, critically 

different from the mere expectation, however well justified, 

that certain facts will not come to the attention of the 

authorities.‖).

26 The Knotts Court did say, however, that ―if dragnettype law enforcement practices‖ such as ―twenty-four hour 

surveillance of any citizen of this country . . . without judicial 

knowledge or supervision,‖ ―should eventually occur, there 

will be time enough then to determine whether different 

constitutional principles may be applicable.‖ Knotts, 460 

U.S. at 283–84. But merely acknowledging that ―different 

constitutional principles may be applicable‖ does not imply 

what those principles may be and how they impact the 

relevant analysis. See Shelby Cnty. v. Holder, 570 U.S. __, 

133 S. Ct. 2612, 2637 n.3 (2013) (Ginsburg, J., dissenting) 

(―Acknowledging the existence of  ̳serious constitutional 

questions‘ does not suggest how those questions should be 

answered.‖ (citation omitted)). Nonetheless, I seriously doubt 

that the ―dragnet-type law enforcement practices‖ referred to 

by the Knotts Court, whatever they may be, are akin to what 

occurred in this case, where law enforcement officers had 

evidence to suggest that Harry Katzin was a serious criminal; 

evidence his attorney admitted at argument gave rise to 

probable cause. (See Oral Arg. Trans. at 43:7–16.) 
51

Furthermore, consider this hypothetical: Imagine, under facts 

identical to our case, the D.C. Circuit‘s Maynard decision 

was, instead, the only case holding that GPS use was not a 

search and did not require a warrant. If, under those 

circumstances, the officers claimed to rely only upon

Maynard for a reasonable belief that their conduct complied 

with the Constitution, that consideration would weigh more 

toward a finding of law enforcement culpability. But, here, 

we are presented with the alternative, and Maynard was the 

only holding (i.e., not a dissent or concurring opinion) from 

any court at the time the officers executed the warrantless 

GPS surveillance that considered their conduct illegal. As a 

result, the fact that Appellees are pointing to Maynard as the 

only case that said the law enforcement officers could not do 

what they did is a consideration that weighs in the officers‘ 

favor.

****

Under the majority‘s rule, where law enforcement

officers engage in ―extrapolat[ion] [of] their own 

constitutional rule,‖ or where officers ―assum[e] that their 

own self-derived rule sanction[s] their conduct,‖ those 

officers act with sufficient culpablity so as to justify 

application of the exclusionary rule. Maj. Op. at 51. I agree 

that ―[t]he justifications for the good-faith exception [may] 

not extend to situations in which police officers have 

interpreted ambiguous precedent.‖ Sparks, 711 F.3d at 67

(quoting Davis, 598 F.3d at 1267). But that is not the case 

here, ―where new developments in the law have upended the 

settled rules on which police relied.‖ Id. at 68.
52

Before Jones, all but one federal court of appeals to 

address the issue unequivocally concluded that Knotts, Karo, 

and other relevant Supreme Court precedent sanctioned the 

law enforcement conduct that occurred here. These Fourth 

Amendment principles, upon which the law enforcement 

officers relied in this case, were settled maxims of 

constitutional jurisprudence, some of them governing law 

enforcement conduct for decades. The majority, viewing this 

case through Jones-colored lenses, rules with the benefit of a 

hindsight that was unavailable to the officers here. 

United States v. Jones changed things; and changed 

them in a way very few—if any at all—predicted. The 

exclusionary rule does not require us to punish the law 

enforcement officers here for failing to predict that sea 

change.27 The District Court below put it quite aptly:

 

27 I have serious reservations about the implications of 

the majority‘s ruling in this case. Nevertheless, I admit my 

position might encourage some law enforcement officers to 

bend and twist existing precedent and legal principles to their

breaking points. In some cases, law enforcement ―reliance‖ 

could be marginal at best.

But I have confidence that courts are aptly suited to 

discern the true ―good-faith actors‖ from the bad; and that, in 

circumstances such as those presented in this case, we will be 

able to definitively answer the question of whether law 

enforcement officers were acting with objectively reasonable 

good faith. Rulings that officers come up short will help 

deter undesirable law enforcement conduct.
53

[T]he Court hastens to emphasize that it has no 

concern that the prosecutorial and law 

enforcement personnel here were undertaking 

their work in this investigation and prosecution 

in a calculated or otherwise deliberately cavalier 

 

The majority recognizes that ―applying existing 

precedential framework to subtle factual permutations is 

something that police officers—and other law enforcement 

personnel—do all the time.‖ Maj. Op. at 57 n.27. But while 

insisting that its opinion does not ―curtail such practices,‖ the 

majority punishes the law enforcement officers in this case

for performing that exact practice. There may not have been 

a case from our Circuit or the Supreme Court specifically 

detailing what the officers should have done in the particular 

circumstances presented here. But there were cases from the 

Supreme Court that came very close; close enough, in fact, 

that some of our sister courts found them to be controlling as 

precedents in situations similar to the case at bar. 

Obviously there is not enough time, history, or reporter 

space to answer every single Fourth Amendment question. 

As a result, the exclusionary rule has developed to provide a 

remedy on the backend. Often the hurried judgments of an 

officer, however well intentioned, simply do not comply with 

constitutional rights. But as a matter of Fourth Amendment 

policy, I would rather allow the officer more freedom in 

performing his job—particularly where the answer to the 

―appl[ication of] existing precedential framework to subtle 

factual permutations‖ is so readily apparent as it was in this 

case—than protect courts from overly burdensome 

suppression motions. Ruling on suppression motions is part 

of our job. 
54

or casual manner in the hopes of just meeting 

the outer limits of the constitutional contours of 

the Katzins‘ rights. Indeed, these actors could 

well profess surprise at the specific outcome of 

Jones.

United States v. Katzin, Crim. No. 11-226, 2012 WL 

1646894, at *10 n.15 (E.D. Pa. May 9, 2012). Regardless of 

this seemingly dispositive conclusion, the District Court 

found, and the majority now affirms, that the exclusionary 

rule requires suppression of the evidence obtained by such 

non-culpable law enforcement conduct.

Doing so renders the exclusionary rule a ―strictliability‖ regime, something which it emphatically is not. See 

Davis, 131 S. Ct. at 2429. The exclusionary rule is ―a 

 ̳prudential‘ doctrine,‖ id. at 2426 (quoting Scott, 524 U.S. at 

363), which requires a ―rigorous weighing of [the] costs and 

deterrence benefits,‖ id. at 2427, lest a ―guilty and possibly 

dangerous defendant[] go[es] free,‖ Herring, 555 U.S. at 141. 

As a society, we willingly swallow that ―bitter pill‖ when we 

must. Davis, 131 S. Ct. at 2427. But under the circumstances 

present in this case, I do not find the law enforcement conduct 

to be ―sufficiently culpable‖ so that the benefit from deterring 

that conduct ―is worth the price paid by the justice system,‖ 

John, 654 F.3d at 417, even if it might create a marginal 

incentive for officers to ―err on the side of constitutional 

behavior.‖ United States v. Johnson, 457 U.S. 537, 561 

(1982). Marginal deterrence is not the trigger of the 

exclusionary rule, Herring, 555 U.S. at 141; law enforcement 

culpability, and, thus, the opportunity for appreciable 

deterrence is. Leon, 468 U.S. at 909; John, 654 F.3d at 417. 

In consequence, because I find that the law enforcement 
55

officers here lacked the requisite culpability in their actions so 

as to justify application of the exclusionary rule, I respectfully 

dissent from the majority‘s conclusion to the alternative. I 

would reverse the District Court below.