D.C. Circuit Introduces “Mosaic Theory” Of Fourth Amendment, Holds GPS Monitoring a Fourth Amendment Search

Today the D.C. Circuit held that government use of a GPS device to monitor the location of a car on public roads is a Fourth Amendment “search” when conducted over a long-term period (in his case, a month). The case is United States v. Maynard, and it was written by Judge Douglas Ginsburg and joined by Judges Tatel and Griffith. If it stays on the books, it is a potentially revolutionary Fourth Amendment decision: It introduces a new “mosaic” theory of the Fourth Amendment that allows individual law enforcement steps that are not searches to become a search when collected together. A lot of readers are going to love it for that reason, and I expect it’s going to be a huge hit in privacy law and libertarian circles. But I don’t find the opinion persuasive as a matter of Fourth Amendment law: I don’t think a mosaic theory can work. So I wanted to blog about it, and then why I don’t think it’s persuasive.

I. Some Background

I’ve blogged before about whether installation of a GPS device to monitor the location of a car on public roads is a Fourth Amendment “search.” In my view, Supreme Court precedent is pretty clear here: It is not a Fourth Amendment search under United States v. Knotts, 460 U.S. 276 (1983), which held that the use of a “beeper” device to monitor the location of a car on public roads — a beepter being “a radio transmitter, usually battery operated, which emits periodic signals that can be picked up by a radio receiver” — is not a search. Knotts held:

A person traveling in an automobile on public thoroughfares has no reasonable expectation of privacy in his movements from one place to another. When [the defendant] 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.

In my view, the reasoning of Knotts applies to the use of a single GPS device to determine a person’s public location. That wouldn’t apply for use of a location device in a home or private place, as the Court held the year after Knotts in United States v. Karo. And I agree that as matter of policy, we might want a privacy statute to limit what the Fourth Amendment does not. But the Supreme Court’s statement, “A person traveling in an automobile on public thoroughfares has no reasonable expectation of privacy in his movements from one place to another” — seems to apply in the same way regardless of whether the device used to determine those movements is a beeper or a GPS device. You can read my extended analysis on that here: Does the Fourth Amendment Prohibit Warrantless GPS Surveillance?

Until today, all three federal circuits that have addressed the issue have agreed with that and held that use of a GPS device is not a search: United States v. Pineda-Moreno, 591 F.3d 1212 (9th Cir. 2010); United States v. Garcia, 474 F.3d 994 (7th Cir. 2007) (Posner, J.); and United States v. Marquez, 605 F.3d 604 (2010). In contrast, several state supreme courts have held that such surveillance is a violation of state equivalents of the Fourth Amendment. State courts are permitted to interpret their state versions of the Fourth Amendment more broadly than the federal Fourth Amendment, and many do: The practical effect of such rulings is to govern the state police in their state but not the federal government. So the precedents have been unanimous that use of a GPS device is not a search under the Fourth Amendment.

II. United States v. Maynard

That brings us to this morning’s decision by the D.C. Circuit in United States v. Maynard. Maynard is a complicated drug conspiracy straight out of The Wire. The defendant here, Jones, ran a nightclub in DC and was part of a conspiracy to sell crack and cocaine. As part of the complex investigation, which included wiretaps and all other sorts of investigative tools, the government slapped a GPS device on the Jeep that Jones drove around town. Perhaps I am just missing something, but I believe the only time the court tells us how the GPS surveillance was actually used is in a footnote on page 29-30. According to that footnote, the prosecution used the pattern of where Jones drove, and at what times, to show that he was in cahoots with the other members of the drug conspiracy. (Season 4 of the Wire? Or was it 5? I can’t remember.) The GPS was on the Jeep for four weeks. There’s some evidence that the government had obtained a warrant but it had expired by the time it was used here — see the footnote on page 38 — but it is agreed now that the government did not have a warrant to install the GPS device when it did. Jones now has challenged the use of the evidence in his case drawn from the

Maynard starts its analysis with a passage from Knotts that had left open the possibility of a different result in very different circumstances:

[The defendant] expresses the generalized view that the result of the holding sought by the Government [that use of a beeper is not search] would be that “twenty-four hour surveillance of any citizen of this country will be possible, without judicial knowledge or supervision.” But the fact is that the reality hardly suggests abuse; if such dragnet-type law enforcement practices as respondent envisions should eventually occur, there will be time enough then to determine whether different constitutional principles may be applicable.

Exactly what this passage in Knotts was supposed to mean is a bit of a mystery. Some folks think it means surveillance of many people at once. My own sense is that it was dealt with the next year in United States v. Karo, when the Supreme Court distinguished Knotts and held that a warrant is required for use of a beeper to monitor whereabouts inside rather than outside. But the DC Circuit takes the view in today’s decision that GPS surveillance, even just in public and for one suspect, is such a dragnet-type practice. Thus the DC Circuit concludes that Knotts is inapplicable and the court can reach its own conclusion as to whether use of a GPS device to monitor public location is a search.

Maynard then concludes that long-term GPS monitoring is a search. To understand the Maynard court’s reasoning, you need to recall the basic distinction in Fourth Amendment law between inside surveillance and outside surveillance. In Fourth Amendment law, stuff inside — inside homes, inside cars, inside packages, and hidden from public view — is generally protected. In contrast, stuff outside — stuff exposed to the public — is not protected. That creates an obvious problem for holding that GPS monitoring in public places is a search: The monitoring is occurring entirely when the GPS device is outside, obtaining information that an outside observer could obtain. That was the basic reasoning of Knotts: A cop physically following the car in Knotts could get the same basic information as the beeper provided.

Maynard rules that this reasoning does not apply when the monitoring is conducted by way of a GPS device over a long period of time. The court makes two arguments. The first argument relies on what I have called the probabilistic model of Fourth Amendment protection: that whether an expectation of privacy is reasonable hinges on the likelihood that monitoring will occur. As I have explained, the Supreme Court uses this in some instances and rejects it in others. In Maynard, the court adopts the probabilistic model (citing all the probabilistic-model cases) to the entirety of the monitoring that occurred (considered as a single entity) and says that it’s very unlikely that a stranger would conduct that extent of monitoring:

[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. 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.

(p 26). The court then addresses a potential counterargument to its view:

The Government does not separately raise, but we would be remiss if we did not address, the possibility that although the whole of Jones‘s movements during the month for which the police monitored him was not actually exposed to the public, it was constructively exposed because each of his individual movements during that time was itself in public view. When it comes to privacy, however, precedent suggests that the whole may be more revealing than the parts. Applying that precedent to the circumstances of this case, we hold the information the police discovered using the GPS device was not constructively exposed.

The main precedent on which the Court relies is a FOIA case, United States Department of Justice v. National Reporters Committee, 489 U.S. 749 (1989), which held that in interpreting the privacy exemption to FOIA, the privacy interests should be measured by the sum of the parts of all the documents involved, not each document by document. The Maynard court concludes:

The whole of one‘s movements over the course of a month is not constructively exposed to the public because, like a rap sheet, that whole reveals far more than the individual movements it comprises. The difference is not one of degree but of kind, for no single journey reveals the habits and patterns that mark the distinction between a day in the life and a way of life, nor the departure from a routine that, like the dog that did not bark in the Sherlock Holmes story, may reveal even more.

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.” 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.

Finally, the court notes with approval that several states require a warrant for GPS surveillance, and that state courts have interpreted their state constitutions to reach the same result. The court also distinguishes the federal circuits that have gone the other way because they did not look at the aggregate impact of the monitoring, but only looked at the individual acts of monitoring: “The federal circuits that have held use of a GPS device is not a search were not alert to the distinction drawn in Knotts between short-term and prolonged surveillance.”

III. Why I Find Maynard Unpersuasive

Maynard is going to be celebrated by the New York Times, by privacy advocates, and by a lot of libertarian-minded readers. But strictly as a matter of Fourth Amendment law, I don’t think it’s persuasive. Maynard introduces a novel theory of the Fourth Amendment: That whether government conduct is a search is measured not by whether a particular individual act is a search, but rather whether an entire course of conduct, viewed collectively, amounts to a search. That is, individual acts that on their own are not searches, when committed in some particular combinations, become searches. Thus in Maynard, the court does not look at individual recordings of data from the GPS device and ask whether they are searches. Instead, the court looks at the entirety of surveillance over a one-month period and views it as one single “thing.”

Off the top of my head, I don’t think I have ever seen that approach adopted in any Fourth Amendment case. And if that approach is valid, then Fourth Amendment law is about to look very different than how it has traditionally looked. The Fourth Amendment regulates searches and seizures — that is individual acts of searching and seizing — and it tells the police what it can and can’t do based on what is a search. But if the Fourth Amendment recognizes a mosaic theory, then the Fourth Amendment will regulate entire investigations as a whole: The question will be whether the investigation measured in the aggregate amounts to a Fourth Amendment violation. Some law professors have tried to argue for such an approach — see, for example, Dan Solove’s articles. But it’s never been used in an actual case, as far as I know.

Much of the problem is knowing when the line is crossed when a bunch of non-searches become a search. The Supreme Court has stressed the need for clear rules that tell the police what they can and cannot do. But how do the police know when a mosaic has been created such that the sum of law enforcement techniques, when aggregated, amount to a search? Are they supposed to carry around a D.H. Ginsburg Aggregatormeter that tells them when it’s time to get a warrant? Take the case of Maynard. One-month of surveillance is too long, the court says. But how about 2 weeks? 1 week? 1 day? 1 hour? I have no idea.

Even stranger, the mosaic theory has the bizarre consequence of creating retroactive unconstitutionality. The Maynard opinion indicates that it would have been okay to monitor Jones for a short time. Let’s say that would allow monitoring for a few trips over the course of one day. At the end of that one day, the first day of monitoring would be constitutional. If the prosecution wanted to admit that evidence, it would be fine. But by continuing to monitor the GPS device for more time, that first day of monitoring eventually and retroactively becomes unconstitutional. It becomes part of the mosaic, and the key point of Maynard is that the entire mosaic is considered one entity.

This will place tremendous emphasis on defining the exact scope of the mosaic. If you’re a defense attorney, you now need to argue that the monitoring of your client was part of a broader mosaic to get that part tossed out. In the Maynard case, the scope of the one mosaic was clear: It was the GPS evidence from the month of monitoring. But I don’t know why it would have to be grouped that way. If you can group different pieces of evidence into mosaics, then you need a theory of grouping: You need a new theory to explain what parts of what surveillance are in the mosaic and what parts of what surveillance are outside the mosaic. This is a whole new type of Fourth Amendment challenge, and I don’t see what principles there are that could keep it from becoming an extraordinary mess.

Finally, and more mundanely, I find Maynard unpersuasive for the ways it ignores and misrepresents a wide range of Fourth Amendment cases and principles. To list a few:

a) The probabilistic model doesn’t really work in the technological surveillance setting. (Here I’ll be using the four models framework I developed in this article; give the 1st section a quick read if you want to follow it easily.) The Supreme Court has picked the private facts model in the technological surveillance setting, not the probabilistic model, for reasons that make sense as I explained here. The court ignores that by invoking the probabilistic cases, but not persuasively: The clear weight of authority in this setting is the private facts model, not the probabilistic model.

b) The court’s reliance on state laws for its view that the expectation of privacy is reasonable seems plainly foreclosed by Virginia v. Moore and California v. Greenwood.

c) Even if the court wants to say that this is the “dragnet” case referred to in Knotts, I don’t think it works to invoke that section and then essentially ignore Knotts. The opinion seems to use that “dragnet” section from Knotts as an escape hatch: And once it’s free, nothing from Knotts is relevant anymore. But Knotts is plainly the most relevant Supreme Court precedent here, and even if it’s distibguishable, the court needs to work within that framework.

d) The Maynard court’s reliance on a FOIA case is particularly weird. What’s the connection between FOIA and the Fourth Amendment? Privacy is a protean concept: You can’t just scan the precedents that use the word and then try to import the concept.

e) Judge Ginsburg should have cited Thurgood Marshall’s dissent in Smith v. Maryland as suport for his mosaic theory: The two are very similar. But then I suppose citing a dissent for authority is a bit dicey for a circuit judge.

IV. Looking Forward

I suspect DOJ will be filing a petition for rehearing in this case. Stay tuned.

Incidentally, this DC Circuit panel is 2/3 of the panel that created the constitutional right to drugs that the en banc court later overturned in Abigail Alliance. The two opinions are somewhat similar in their very libertarian outlook; I wonder if they will meet the same fate of being overturned en banc.