Argued March 19, 2013.
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
Robert A. Zauzmer, Esq. [ARGUED] Emily McKillip, Esq. Zane D. Memeger, Esq. Thomas M. Zaleski, Esq. Office of United States Attorney, Counsel for Appellant The United States of America.
Thomas A. Dreyer, Esq. [ARGUED], Counsel for Appellee Harry Katzin.
William A. DeStefano, Esq. Stevens & Lee Counsel for Appellee Michael Katzin
Rocco C. Cipparone, Jr., Esq. [ARGUED], Counsel for Appellee Mark Louis Katzin, Sr.
Benjamin E. Wizner, Esq. American Civil Liberties Union National Security Project, Catherine N. Crump, Esq. [ARGUED] Nathan Wessler, Esq. American Civil Liberties Union Counsel for Amicus Appellees the American Civil Liberties Union Foundation.
Witold J. Walczak, Esq. Sara J. Rose, Esq. American Civil Liberties Union, Catherine N. Crump, Esq. [ARGUED] American Civil Liberties Union, Counsel for Amicus Appellees the American Civil Liberties Union Foundation of Pennsylvania.
Catherine N. Crump, Esq. [ARGUED] American Civil Liberties Union, Hanni M. Fakhoury, Esq. Marcia Hoffman, Esq. Electronic Frontier Foundation, Counsel for Amicus Appellees the Electronic Frontier Foundation
Peter Goldberger, Esq., Catherine N. Crump, Esq. [ARGUED] American Civil Liberties Union, Counsel for Amicus Appellee the National Association of Criminal Defense Lawyers.
Before: SMITH, GREENAWAY, JR., and VAN ANTWERPEN, Circuit Judges.
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 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.
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 range-limited: 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 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 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 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
[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). A 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 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 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 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.
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).
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. 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.
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. 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).
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.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.
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 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").
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.See, e.g., United States v. 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 ...