The "mosaic theory" and Fourth Amendment law.

Author:Ostrander, Benjamin M.


In 2004, an FBI-Metropolitan Police Department Safe Streets Task Force began investigating Antoine Jones, owner of the D.C. nightclub "Levels" and suspected drug kingpin, for narcotics violations. (1) Mr. Jones allegedly ran a drug ring that consisted of at least nine other defendants and spanned from 2003 to 2005, involving hundreds of kilograms of cocaine shipped from Mexico. (2) During the investigation, law enforcement agents used a number of investigative techniques, one being Global Positioning System (GPS) surveillance. (3) The agents secretly planted a GPS device on the undercarriage of a Jeep exclusively driven by Mr. Jones, and for nearly one month the device continuously tracked his movements. (4) At the conclusion of the investigation, the Task Force obtained warrants and seized a large quantity of contraband from the homes of several of the defendants. (5) They also searched an alleged "stash house," and seized ninety-seven kilograms of cocaine, three kilograms of crack cocaine, and more than $800,000 (6)--making it the largest cocaine seizure in D.C. history. (7) The digital location pattern that resulted from the month-long tracking of Jones--including his visits to the "stash house"--was used as evidence implicating his involvement in the cocaine trafficking. (8) Mr. Jones was eventually convicted of conspiracy to distribute and to possess with intent to distribute five or more kilograms of cocaine and fifty grams or more of cocaine base. (9) On appeal, however, the District of Columbia Circuit Court of Appeals overturned Jones's conviction. (10) Relying on a novel and potentially revolutionizing theory (11) in Fourth Amendment law--the "mosaic theory"--the D.C. Circuit held that prolonged GPS tracking constituted a "search" within the meaning of the Fourth Amendment. (12) The "mosaic theory," often used in the national security context, (13) holds that individual law enforcement actions that are not searches become a search when aggregated, as the whole reveals more than the individual acts it comprises. (14) Thus, in the context of electronic tracking, this theory contends that although the tracking of each individual movement is not a search, when aggregated, the resulting location pattern becomes a search as it reveals more than the individual movements it comprises. (15)

This Note suggests that despite the intuitive appeal of a "mosaic theory" in Fourth Amendment law, (16) it is not only wrong in principle but also impractical in application. Rather than resorting to an aggregation theory of the Fourth Amendment, this Note contends that the use of potentially invasive pattern-detecting technologies that are not deemed "searches" in the first instance should be statutorily regulated.

Part I examines the historical origins of the Fourth Amendment and tracks its treatment of electronic tracking devices. Part II discusses Maynard and the "mosaic theory," and ultimately suggests that the "mosaic theory" is inconsistent with existing Fourth Amendment precedent. Part III explores the far-reaching implications of the "mosaic theory" in Fourth Amendment law. Finally, Part IV contends that rather than regulating pattern-detecting technologies constitutionally at the aggregate level, privacy interests should be statutorily protected.


    The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized. (17) At its core, the Fourth Amendment protects individuals from arbitrary and intrusive official conduct. (18) The Fourth Amendment's mandates apply only to governmental conduct, which amounts to a "search" or "seizure" within the meaning of the Amendment. (19) Thus, defining what constitutes a search or a seizure within the meaning of the Fourth Amendment is of critical importance. Despite the Fourth Amendment's historical lineage, the term "search" has resisted a canonical formulation. (20) For years, the determination of what constituted a search was property-based. (21) That is, for the Fourth Amendment to be implicated, the government must have made a physical intrusion into a "constitutionally protected area." (22) Having difficulty applying this property-based approach to developing technologies, (23) the Supreme Court reformulated the Fourth Amendment search analysis in the seminal (24) case of Katz v. United States. (25)

    Katz was convicted in federal court on a charge of interstate transmission of wagering information by telephone. (26) At trial, the court allowed the government to introduce incriminating evidence of the defendant's telephone conversations, which were overheard by FBI agents who had attached to the outside of a public phone booth an electronic listening and recording device. (27) On appeal, the Court held that the government's attachment and use of the electronic listening device was a "search and seizure" within the meaning of the Fourth Amendment. (28) In so holding, the Court moved away from the view that the scope of the Fourth Amendment "turn[ed] upon the presence or absence of a physical intrusion into any given enclosure," (29) for "the correct solution of Fourth Amendment problems is not necessarily promoted by incantation of the phrase 'constitutionally protected area.'" (30) Rather,

    the Fourth Amendment protects people, not places. What a person knowingly exposes to the public, even in his own home or office, is not a subject of Fourth Amendment protection. But what he seeks to preserve as private, even in an area accessible to the public, may be constitutionally protected. (31) In a concurring opinion, Justice Harlan provided the framework under which the Court would thereafter analyze Fourth Amendment searches--the "reasonable expectation of privacy" test. (32) Pursuant to this test, "there is a twofold requirement, first that a person have exhibited an actual (subjective) expectation of privacy and, second, that the expectation be one that society is prepared to recognize as 'reasonable.'" (33) Although Katz was hailed as a dramatic shift in Fourth Amendment law, it is not clear there was a profound divergence from the property-based

    approach. (34)

    In United States v. Knotts, (35) the Supreme Court confronted the issue of whether the warrantless use of an electronic tracking device fell within the ambit of the Fourth Amendment. (36) In Knotts, Minnesota narcotics officers received information that codefendants Armstrong and Petschen were obtaining large amounts of chloroform--often used to manufacture illicit drugs from a chemical company. (37) With the consent of the chemical company, the officers attached a beeper (38) inside a five-gallon container of chloroform, which the company was to give to the codefendants upon purchase. (39) After the purchase by Armstrong, officers followed the car by maintaining visual surveillance and by monitoring the signal emitted from the beeper. (40) During the codefendant's journey to respondent Knotts's secluded cabin in rural Wisconsin, Petschen's evasive maneuvers precluded the officers from maintaining visual surveillance. (41) With the assistance of a helicopter, the signal from the beeper was tracked to the cabin, where--after obtaining a search warrant--officers discovered a drug laboratory. (42) In reversing the Eighth Circuit, the Court held that the warrantless monitoring of the beeper was not a "search" within the meaning of the Fourth Amendment. (43) In so holding, the Court rejected the argument that the defendants had an expectation of privacy in their movements:

    A person traveling in an automobile on public thoroughfares has no reasonable expectation of privacy in his movements from one place to another. When Petschen traveled over the public streets he voluntarily conveyed to anyone who wanted to look the fact that he was traveling over particular roads in a particular direction, the fact of whatever stops he made, and the fact of his final destination when he exited from public roads onto private property. (44) Noting that the officers could have obtained the information through visual surveillance, the Court held that "[n]othing 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." (45)

    A year later in United States v. Karo, (46) the Court confronted the issue of whether the monitoring of a beeper in a private residence not open to visual surveillance is a search under the Fourth Amendment. (47) In Karo, the Drug Enforcement Administration (DEA) installed and subsequently monitored a beeper placed within a can of ether as it was transferred among several residences, a serf-storage facility, and ultimately to a residence where the ether was being used to extract cocaine. (48) In holding the monitoring a search, the Court distinguished the case from Knotts (49) on the ground that the monitoring revealed information about the interior of the private residence--confirmation that the ether was actually within the residence and remained there until a warrant was obtained--that could not have otherwise been obtained absent a warrant, and such information was not voluntarily exposed. (50) Hence, "[i]ndiscriminate monitoring of property that has been withdrawn from public view would present far too serious a threat to privacy interests in the home to escape entirely some sort of Fourth Amendment oversight." (51) Thus, after Knotts and Karo, the government is free to conduct sustained and prolonged surveillance of citizens as long as the monitoring is limited to movements in public areas. (52)

    To date, the Supreme Court has yet to confront the...

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