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Chief's Counsel

The Mosaic Theory and Electronic Public Safety Technology

By Mark H. Newbold, Deputy City Attorney–Police, Charlotte-Mecklenburg Police Department, Charlotte, North Carolina

Everyone has heard of the saying that “the whole is greater than its parts.” The mosaic theory attempts to apply this basic proposition to the Fourth Amendment. Generally speaking, what a person puts into the plain view of the public is not considered to be protected under the Fourth Amendment.1 If an officer could have manually conducted surveillance of an individual while that person moves about on a public thoroughfare, then the Fourth Amendment arguably is not implicated and the officer would not have to obtain a warrant. However, under the mosaic theory, the continuous and persistent electronic surveillance by police of a person even in a public area does in fact implicate the Fourth Amendment because the cumulative data obtained by heightened surveillance creates a much more detailed and comprehensive picture of the subject—a picture that actual physical surveillance could never construct, which includes or excludes highly personal and confidential habits that the individual and some sections of society consider as an invasion of a person’s privacy and autonomy.

Following is a review of the mosaic theory and its current viability as constitutional theory that may be raised in the future.

The History and Development of the Mosaic Theory

The mosaic theory was adopted by the Eleventh Circuit Federal Court of Appeals in United States v. Maynard, 615 F.3d 544, 560 (D.C. Cir. 2010). Interestingly, Frederick Maynard was a codefendant of Antoine Jones, the defendant in the landmark U.S. Supreme Court case of United States v. Jones, 132 S. Ct. 945 (2012), wherein Justice Antonin Scalia revived the ancient precedent that the Fourth Amendment attaches any time the government physically trespasses upon a person, a house, a place, or an effect.2

Unlike the Supreme Court in Jones, the court in Maynard took a position on the effect of pervasive and continuous surveillance via a global positioning system (GPS) tracking device on a person’s right to privacy. Ironically, the mosaic theory was not raised by criminal defendants who had come under intense electronic scrutiny. Instead, the government first broached the theory as justification for not responding to Freedom of Information Act requests.

The Supreme Court addressed the distinction between a whole and the sum of its parts in United States Department of Justice v. National Reporters Committee, 489 U.S. 749 (1989), which arose not under the Fourth Amendment but under the Freedom of Information Act, 5 U.S.C. § 552. There the respondents had requested, pursuant to the FOIA, that the FBI disclose rap sheets compiling the criminal records of certain named persons. Although the “individual events in those summaries [were] matters of public record,” the Court upheld the FBI’s invocation of the privacy exception to the FOIA, holding the subjects had a privacy interest in the aggregated “whole” distinct from their interest in the “bits of information” of which it was composed. Id. at 764. Most relevant to the Fourth Amendment, the Court said disclosure of a person’s rap sheet “could reasonably be expected to constitute an unwarranted invasion of personal privacy.”3

In addition, the court in Maynard adopted the government’s reasoning in refusing to release snippets of national security information, which, if analyzed piecemeal, appear to be innocuous: “As with the ‘mosaic theory’ often invoked by the government in cases involving national security information, ‘What may seem trivial to the uninformed, may appear of great moment to one who has a broad view of the scene.’”4

The court in Maynard then applied the mosaic theory to persistent and continuous electronic monitoring by police of a subject’s movements by means of a GPS tracking device. Unlike the court in Jones, the Maynard court did not resurrect the doctrine of physical trespass but instead inserted the mosaic theory as the source of establishing a protected privacy interest.

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. Repeated visits to a church, a gym, a bar, or a bookie tell a story not told by any single visit, as does one’s not visiting any of these places over the course of a month. The sequence of a person’s movements can reveal still more; a single trip to a gynecologist’s office tells little about a woman, but that trip followed a few weeks later by a visit to a baby supply store tells a different story. A person who knows all of another’s travels can deduce whether he is a weekly church goer, a heavy drinker, a regular at the gym, an unfaithful husband, an outpatient receiving medical treatment, an associate of particular individuals or political groups—and not just one such fact about a person, but all such facts.5

The Maynard court distinguished itself from the holding in Katz and reasoned that persistent and continuous surveillance is not the same as putting oneself into the plain view of the public. In

[a]pplying the foregoing analysis to the present facts, we 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. It is 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 another thing entirely 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.6

Although not adopted by the court in Maynard, a similar theory was discussed by the U.S. Supreme Court in City of Ontario, California v. Quon, 130 S. Ct. 2619, 2630 (2010). In Quon, a government employer reviewed numerous personal text messages sent by an employee to determine whether the employee was improperly using the device. Although not essential to its decision, the Court noted and recognized that the review of cumulative electronic data stored on a third-party server may require constitutional protection because a wholesale review might impinge on a combination of privacy interests and the use of the device as a means of self expression: “[C]ell phone and text message communications are so pervasive that some persons may consider them to be essential means or necessary instruments for self-expression, even self-identification. That might strengthen the case for an expectation of privacy.”7

The Mosaic Theory after Jones

Did the U.S. Supreme Court all but kill the mosaic theory in its ruling in Jones v. United States? In this writer’s view, the answer is no. Justice Scalia clearly recognized that the police practice of continuous and pervasive electronic surveillance may implicate the Fourth Amendment: “It may be that achieving the same result through electronic means, without an accompanying trespass, is an unconstitutional invasion of privacy, but the present case does not require us to answer that question.”8 Justice Scalia notes further in his response to Justice Samuel Alito and Justice Sonia Sotomayor’s position:

The concurrence posits that “relatively short-term monitoring of a person’s movements on public streets” is okay, but that “the use of longer term GPS monitoring in investigations of most offenses” is no good. That introduces yet another novelty into our jurisprudence. . . . We may have to grapple with these “vexing problems” in some future case where a classic trespassory search is not involved and resort must be had to Katz analysis; but there is no reason for rushing forward to resolve them here.9


A decade ago, no one could have predicted the exact course high-tech surveillance would take in the realm of law enforcement. Advancements in technology—particularly in electronic surveillance—are nothing new to law enforcement. After all, the eavesdropping device used in Katz to monitor a conversation in a public phone booth was no doubt considered high tech at that time.

Law enforcement should and must take advantage of any and all technology that assists in crime prevention and suppression. At the same time, there is no doubt that the use of high-tech surveillance is a subjective privacy concern to some. As security cameras, license plate readers, and shot spotters are installed and linked to each other—not to mention other private and governmental databases—there will be increased discussion in the public sector as to what if any restrictions should be implemented to protect personal integrity. This increased concern certainly will meet the first requirement in establishing a reasonable expectation of privacy as set forth under Katz.

In addition, the increased recognition by society of an evolving privacy interest when there is persistent and continuous governmental surveillance is closely approaching Katz’s second prong in establishing an expectation of privacy recognized by society. Further, there is language within Katz that the court could draw from in support that continuous and pervasive surveillance may deprive someone of a reasonable expectation of privacy: “reasonable expectations of privacy may be defeated by electronic as well as physical invasion.”10

In the absence of guidance from the court, law enforcement can expect restrictions—some of them overly restrictive—to be imposed by local and state initiatives. For example, at least two state bills have been recently introduced restricting the use of drones for surveillance purposes.11 Also, at least one major city recently received scrutiny from its city council as to the use and placement of its security cameras.12

The law enforcement community—including associated lawyers—must continue to lead the public conversation on the use of public safety electronic technology. Otherwise, its fate will be left in the hands of others. Simply pushing out a directive that requires the officer to comply with constitutional principles and state statutes is inadequate. Instead, a transparent and public discussion needs to occur in addition to specific guidance to officers. People tend to fear what they do not understand, and that fear provides a platform for small vocal groups that wish to implement unrealistic restrictions on law enforcement. Internal regulations that specifically restrict the length of data retention and the regular purging of data unrelated to legitimate public safety concerns are excellent starting points.

In addition, heightened restrictions need to be implemented when monitoring First Amendment activities. The First Amendment adds both associational and expressive rights to the mosaic theory. The public discussion should also address issues related to the use of electronic surveillance in predictive analysis. Consideration should be given to establishing an acceptable balance of the benefits of predictive analysis against wholesale collection of data that may impinge on privacy rights, personal autonomy concerns, and associational and expressive interests. ♦

1See the oft quoted concurring opinion offered by Justice Harlan in Katz v. United States, 389 U.S. 347, 361 (U.S. 1967), wherein he puts forth the two-part test that later emerges into the concept of reasonable expectation of privacy: “The question, however, is what protection it affords to those people. Generally, as here, the answer to that question requires reference to a ‘place.’ My understanding of the rule that has emerged from prior decisions is that 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.’ Thus a man’s home is, for most purposes, a place where he expects privacy, but objects, activities, or statements that he exposes to the ‘plain view’ of outsiders are not ‘protected’ because no intention to keep them to himself has been exhibited. On the other hand, conversations in the open would not be protected against being overheard, for the expectation of privacy under the circumstances would be unreasonable.” See also Smith v. Maryland, 442 U.S. 735, 744 (U.S. 1979), wherein it is noted “[t]his Court has held repeatedly that the Fourth Amendment does not prohibit the obtaining of information revealed to a third party and conveyed by him to Government authorities, even if the information is revealed on the assumption that it will be used only for a limited purpose and the confidence placed in the third party will not be betrayed.”
2See United States v. Jones, 132 S. Ct. 945, 950 (U.S. 2012), wherein the court reasoned that “[a]t bottom, the Court must ‘assur[e] preservation of that degree of privacy against government that existed when the Fourth Amendment was adopted.’ [quoting Kyllo v. United States, 533 U. S. 27], at 34. As explained, for most of our history the Fourth Amendment was understood to embody a particular concern for government trespass upon the areas (‘persons, houses, papers, and effects’) it enumerates.”
3United States v. Maynard, 615 F.3d 544, 561 (D.C. Cir. 2010).
4Id. at 562, quoting CIA v. Sims, 471 U.S. 159, 178 (1985).
5Maynard, 615 F.3d at 562.
7City of Ontario, California v. Quon, 130 S. Ct. 2619, 2630 (2010).
8United States v. Jones, 132 S. Ct. 945, 954 (U.S. 2012).
10Katz, at 389 U.S. at 362.
11See Florida’s Senate Bill 92 at See also Virginia Senate Bill 954 at (both accessed January 24, 2013).
12See Ray Reyes, “Tampa Council Put Off Fate of RNC Surveillance Cameras,” Tampa Tribune, September 21, 2012, (accessed January 23, 2013), for a discussion of interactions between police, city administrators, and elected officers as to the fate of cameras used for the 2012 Republican National Convention.

Please cite as:

Mark H. Newbold, "The Mosaic Theory and Electronic Public Safety Technology," Chief’s Counsel, The Police Chief 80 (March 2013): 12–13.



From The Police Chief, vol. LXXX, no. 3, March 2013. Copyright held by the International Association of Chiefs of Police, 515 North Washington Street, Alexandria, VA 22314 USA.

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