Tag: Fourth Amendment

GPS Tracking and a ‘Mosaic Theory’ of Government Searches

The Electronic Frontier Foundation trumpets a surprising privacy win last week in the U.S. Court of Appeals for the D.C. Circuit. In U.S. v. Maynard (PDF), the court held that the use of a GPS tracking device to monitor the public movements of a vehicle—something the Supreme Court had held not to constitute a Fourth Amendment search in U.S. v Knotts—could nevertheless become a search when conducted over an extended period.  The Court in Knotts had considered only tracking that encompassed a single journey on a particular day, reasoning that the target of surveillance could have no “reasonable expectation of privacy” in the fact of a trip that any member of the public might easily observe. But the Knotts Court explicitly reserved judgment on potential uses of the technology with broader scope, recognizing that “dragnet” tracking that subjected large numbers of people to “continuous 24-hour surveillance.” Here, the DC court determined that continuous tracking for a period of over a month did violate a reasonable expectation of privacy—and therefore constituted a Fourth Amendment search requiring a judicial warrant—because such intensive secretive tracking by means of public observation is so costly and risky that no  reasonable person expects to be subject to such comprehensive surveillance.

Perhaps ironically, the court’s logic here rests on the so-called “mosaic theory” of privacy, which the government has relied on when resisting Freedom of Information Act requests.  The theory holds that pieces of information that are not in themselves sensitive or potentially injurious to national security can nevertheless be withheld, because in combination (with each other or with other public facts) permit the inference of facts that are sensitive or secret.  The “mosaic,” in other words, may be far more than the sum of the individual tiles that constitute it. Leaving aside for the moment the validity of the government’s invocation of this idea in FOIA cases, there’s an obvious intuitive appeal to the idea, and indeed, we see that it fits our real world expectations about privacy much better than the cruder theory that assumes the sum of “public” facts must always be itself a public fact.

Consider an illustrative hypothetical.  Alice and Bob are having a romantic affair that, for whatever reason, they prefer to keep secret. One evening before a planned date, Bob stops by the corner pharmacy and—in full view of a shop full of strangers—buys some condoms.  He then drives to a restaurant where, again in full view of the other patrons, they have dinner together.  They later drive in separate cars back to Alice’s house, where the neighbors (if they care to take note) can observe from the presence of the car in the driveway that Alice has an evening guest for several hours. It being a weeknight, Bob then returns home, again by public roads. Now, the point of this little story is not, of course, that a judicial warrant should be required before an investigator can physically trail Bob or Alice for an evening.  It’s simply that in ordinary life, we often reasonably suppose the privacy or secrecy of certain facts—that Bob and Alice are having an affair—that could in principle be inferred from the combination of other facts that are (severally) clearly public, because it would be highly unusual for all of them to be observed by the same public.   Even more so when, as in Maynard, we’re talking not about the “public” events of a single evening, but comprehensive observation over a period of weeks or months.  One must reasonably expect that “anyone” might witness any of such a series of events; it does not follow that one cannot reasonably expect that no particular person or group would be privy to all of them. Sometimes, of course, even our reasonable expectations are frustrated without anyone’s rights being violated: A neighbor of Alice’s might by chance have been at the pharmacy and then at the restaurant. But as the Supreme Court held in Kyllo v US, even when some information might in principle be possible to obtain public observation, the use of technological means not in general public use to learn the same facts may nevertheless qualify as a Fourth Amendment search, especially when the effect of technology is to render easy a degree of monitoring that would otherwise be so laborious and costly as to normally be infeasible.

Now, as Orin Kerr argues at the Volokh Conspiracy, significant as the particular result in this case might be, it’s the approach to Fourth Amendment privacy embedded here that’s the really big story. Orin, however, thinks it a hopelessly misguided one—and the objections he offers are all quite forceful.  Still, I think on net—especially as technology makes such aggregative monitoring more of a live concern—some kind of shift to a “mosaic” view of privacy is going to be necessary to preserve the practical guarantees of the Fourth Amendment, just as in the 20th century a shift from a wholly property-centric to a more expectations-based theory was needed to prevent remote sensing technologies from gutting its protections. But let’s look more closely at Orin’s objections.

First, there’s the question of novelty. Under the mosaic theory, he writes:

[W]hether 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.

I can’t think of one that explicitly adopts that argument.  But consider again the Kyllo case mentioned above.  Without a warrant, police used thermal imaging technology to detect the presence of marijuana-growing lamps within a private home from a vantage point on a public street. In a majority opinion penned by Justice Scalia, the court balked at this: The scan violated the sanctity and privacy of the home, though it involved no physical intrusion, by revealing the kind of information that might trigger Fourth Amendment scrutiny. But stop and think for a moment about how thermal imaging technology works, and try to pinpoint where exactly the Fourth Amendment “search” occurs.  The thermal radiation emanating from the home was, well… emanating from the home, and passing through or being absorbed by various nearby people and objects. It beggars belief to think that picking up the radiation could in itself be a search—you can’t help but do that!

When the radiation is actually measured, then? More promising, but then any use of an infrared thermometer within the vicinity of a home might seem to qualify, whether or not the purpose of the user was to gather information about the home, and indeed, whether or not the thermometer was precise enough to reveal any useful information about internal temperature variations within the home.  The real privacy violation here—the disclosure of private facts about the interior of the home—occurs only when a series of very many precise measurements of emitted radiation are processed into a thermographic image.  To be sure, it is counterintuitive to describe this as a “course of conduct” because the aggregation and analysis are done quite quickly within the processor of the thermal camera, which makes it natural to describe the search as a single act: Creating a thermal image.  But if we zoom in, we find that what the Court deemed an unconstitutional invasion of privacy was ultimately the upshot of a series of “public” facts about ambient radiation levels, combined and analyzed in a particular way.  The thermal image is, in a rather literal sense, a mosaic.

The same could be said about long-distance  spy microphones: Vibrating air is public; conversations are private. Or again, consider location tracking, which is unambiguously a “search” when it extends to private places: It might be that what is directly measured is only the “public” fact about the strength of a particular radio signal at a set of receiver sites; the “private” facts about location could be described as a mere inference, based on triangulation analysis (say), from the observable public facts.

There’s also a scope problem. When, precisely, do individual instances of permissible monitoring become a search requiring judicial approval? That’s certainly a thorny question, but it arises as urgently in the other type of hypothetical case alluded to in Knotts, involving “dragnet” surveillance of large numbers of individuals over time. Here, too, there’s an obvious component of duration: Nobody imagines that taking a single photograph revealing the public locations of perhaps hundreds of people at a given instant constitutes a Fourth Amendment search. And just as there’s no precise number of grains of sand that constitutes a “heap,” there’s no obvious way to say exactly what number of people, observed for how long, are required to distinguish individualized tracking from “dragnet” surveillance.  But if we anchor ourselves in the practical concerns motivating the adoption of the Fourth Amendment, it seems clear enough that an interpretation that detected no constitutional problem with continuous monitoring of every public movement of every citizen would mock its purpose. If we accept that much, a line has to be drawn somewhere. As I recall, come to think of it, Orin has himself proposed a procedural dichotomy between electronic searches that are “person-focused” and those that are “data-focused.”  This approach has much to recommend it, but is likely to present very similar boundary-drawing problems.

Orin also suggests that the court improperly relies upon a “probabilistic” model of the Fourth Amendment here (looking to what expectations about monitoring are empirically reasonable) whereas the Court has traditionally relied on a “private facts” model to deal with cases involving new technologies (looking to which types of information it is reasonable to consider private by their nature). Without recapitulating the very insightful paper linked above, the boundaries between models in Orin’s highly useful schema do not strike me as quite so bright. The ruling in Kyllo, after all, turned in part on the fact that infrared imaging devices are not in “general public use,” suggesting that the identification of “private facts” itself has an empirical and probabilistic component.  The analyses aren’t really separate. What’s crucial to bear in mind is that there are always multiple layers of facts involved with even a relatively simple search: Facts about the strength of a particular radio signal, facts about a location in a public or private place at a particular instant, facts about Alice and Bob’s affair. In cases involving new technologies, the problem—though seldom stated explicitly—is often precisely which domain of facts to treat as the “target” of the search. The point of the expectations analysis in Maynard is precisely to establish that there is a domain of facts about macro-level behavioral patterns distinct from the unambiguously public facts about specific public movements at particular times, and that we have different attitudes about these domains.

Sorting all this out going forward is likely to be every bit as big a headache as Orin suggests. But if the Fourth Amendment has a point—if it enjoins us to preserve a particular balance between state power and individual autonomy—then as technology changes, its rules of application may need to get more complicated to track that purpose, as they did when the Court ruled that an admirably simple property rule was no longer an adequate criterion for identifying a “search.”  Otherwise we make Fourth Amendment law into a cargo cult, a set of rituals whose elegance of form is cold consolation for their abandonment of function.

Compare and Contrast

Fourth Amendment:

“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.”

Supreme Court (Katz v. U.S.):

“[S]earches 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.”

Washington Post:

“The Obama administration is seeking to make it easier for the FBI to compel companies to turn over records of an individual’s Internet activity without a court order if agents deem the information relevant to a terrorism or intelligence investigation.”

Internet Privacy Law Needs an Upgrade

Imagine for a moment that all your computing devices had to run on code that had been written in 1986. Your smartphone is, alas, entirely out of luck, but your laptop or desktop computer might be able to get online using a dial-up modem. But you’d better be happy with a command-line interface to services like e-mail, Usenet, and Telnet, because the only “Web browsers” anyone’s heard of in 1986 are entomologists. Cloud computing? Location based services? Social networking? No can do, though you can still get into a raging debate about the relative merits of Macs and PCs.

When it comes to federal privacy law, alas, we are running on code written in 1986: The Elecronic Communications Privacy Act, a statute that’s not only ludicrously out of date, but so notoriously convoluted and unclear that even legal experts routinely lament the “mess” of electronic privacy law. Scholar Orin Kerr has called it “famously complex, if not entirely impenetrable.” Part of the problem, to be sure, lies with the courts.  It is scandalous that in 2010, we don’t even have a definitive ruling on whether or when the Fourth Amendment requires the government to get a search warrant to read e-mails stored on a server. But the ECPA statute, meant to fill the gap left by the courts, reads like the rules of James T. Kirk’s fictional card game Fizzbin.

Suppose the police want to read your e-mail. To come into your home and look through your computer, of course, they’d need a full Fourth Amendment search warrant based on probable cause. If they want to intercept the e-mail in transit, they have to go still further and meet the “super-warrant” standards of the Wiretap Act. Once it lands on your Internet Service Provider’s server, a regular search warrant is once again the standard—assuming your ISP is providing access “to the public.” If it’s a more closed network like your work account, your employer is permitted to voluntarily hand it over. But if you read the e-mail, or leave it on the server for more than 180 days, then suddenly your ISP has become a “remote computing service” provider rather than an “electronic communications service provider” vis a vis that e-mail. So instead of a probable cause warrant, police can get a 2703(d) order based on “specific and articulable facts” showing the information is “relevant and material” to an investigation—a much lower standard—provided they notify you. Except they can ask a judge to delay notification if they think that would impede the investigation. Oh, unless your ISP is in the Ninth Circuit, where opened e-mails still get the higher level of protection until they’ve “expired in the normal course,” whatever that means.

That’s for e-mail contents.  But maybe they don’t actually need to read your e-mail; maybe they just want some “metadata”—the equivalent of scanning the envelopes of physical letters—to see if your online activity is suspicious enough to warrant a closer look.  Well, then they can get what’s called a pen/trap order based on a mere certification to a judge of “relevance” to capture that information in realtime, but without having to provide any of those “specific and articulable facts.” Unless it’s information that would reveal your location—maybe because you’re e-mailing from your smartphone—in which case, well, the law doesn’t really say, but the Justice Department thinks a pen/trap order plus one of those 2703(d) orders will do, unless it’s really specific location information, at which point they get a warrant. If they want to get those records after the fact, it’s one of those 2703(d) orders—again, unless a non-public provider like your school or employer wants to volunteer them. Oh, unless it’s a counterterror investigation, and the FBI thinks your records might be “relevant” somehow, in which case they can get them with a National Security letter, without getting a judge involved at all.

Dizzy yet? Well, a movement launched today with the aim of dragging our electronic privacy law, kicking and screaming, into the 21st century: The Digital Due Process Coalition.  They’re pushing for a streamlined law that provides clear and consistent protection for sensitive information—the kind of common sense rules you’d have thought would already be in place.  If the government wants to read the contents of your letters, they should need a search warrant—regardless of the phase of the moon when an e-mail is acquired. If they want to track your location, they should need a warrant. And all that “metadata” can be pretty revealing in the digital age—maybe some stricter oversight is in order before they start vacuuming up all our IP logs.

Reforms like these are way overdue. You wouldn’t trust your most sensitive data to software code that hadn’t gone a few years without a security patch. Why would you trust it to legal code that hasn’t had a major patch in over two decades?

On Fourth Amendment Privacy: Everybody’s Wrong

Everybody’s wrong. That’s sort of the message I was putting out when I wrote my 2008 American University Law Review article entitled “Reforming Fourth Amendment Privacy Doctrine.”

A lot of people have poured a lot of effort into the “reasonable expectation of privacy” formulation Justice Harlan wrote about in his concurrence to the 1967 decision in U.S. v. Katz. But the Fourth Amendment isn’t about people’s expectations or the reasonableness of their expectations. It’s about whether, as a factual matter, they have concealed information from others—and whether the government is being reasonable in trying to discover that information.

The upshot of the “reasonable expectation of privacy” formulation is that the government can argue—straight-faced—that Americans don’t have a Fourth Amendment interest in their locations throughout the day and night because data revealing it is produced by their mobile phones’ interactions with telecommunications providers, and the telecom companies have that data.

I sat down with podcaster extraordinaire Caleb Brown the other day to talk about all this. He titled our conversation provocatively: “Should the Government Own Your GPS Location?

School Webcams and Strange Gaps in Surveillance Law

Last week, I noted the strange story of a lawsuit filed by parents who allege that their son was spied on by school officials who used security software capable of remotely activating the webcams in laptops distributed to students. A bit more information on that case has since come out. The school district has issued a statement which doesn’t get into the details of the case, but avers that the remote camera capability has only ever been used in an effort to locate laptops believed to have been lost or stolen. (That apparently includes a temporary “loaner computer that, against regulations, might be taken off campus.”)  They do, however, acknowledge that they erred in failing to notify parents about this capability.  The lawyer for the student plaintiff is now telling reporters that school officials called his client in to the vice principal’s office when they mistook his Mike and Ike candies for illegal drugs.

Perhaps most intriguingly, a security blogger has done some probing into the technical capabilities of the surveillance software used by the school district. The blogger also rounds up comments from self-identified students of the high school, many of whom claim that they noticed the webcam light on their school-issued laptops flickering on and off—behavior they were told was a “glitch”—which may provide some reason to question the school’s assertion that this capability was only activated in a handful of cases to locate lost laptops. The FBI, meanwhile, has reportedly opened an investigation to see whether any federal wiretap laws may have been violated.

It’s this last item I want to call attention to. The complaint against the school district states a number of causes of action.  The most obvious one—which sounds to me like a slam dunk—is a Fourth Amendment claim. But there are also a handful of claims under federal wiretapping statutes, specifically the Electronic Communications Privacy Act and the Stored Communications Act. These are more dubious, and rest on the premise that the webcam image was an “electronic communication” that school officials “intercepted” (as those terms are used in the statute), or alternatively that  the activation of the security software involved “unauthorized” access by the school to its own laptop. The trouble is that courts considering similar claims in the past have held that federal electronic surveillance law does not cover silent video surveillance—or rather, the criminal wiretap statutes don’t.

That leads to a strange asymmetry in a couple of different ways. First, intelligence surveillance covered by the Foreign Intelligence Surveillance Act does include silent video monitoring. Second, it seems to provide less protection for a type of monitoring that is arguably still more intrusive. If officials had turned on the laptop’s microphone, that would fall under ECPA’s prohibition on intercepts of “oral communications.” And if the student had been engaged in a video chat using software like Skype, that would clearly constitute an “electronic communication,” even if the audio were not intercepted. But at least in the cases I’m familiar with, the courts have declined to apply that label to surreptitiously recorded silent video—which one might think would be the most invasive of all, given that the target is completely unaware of being observed by anybody.

One final note: The coverage I’m seeing is talking about this as though it involves one school doing something highly unusual. It’s not remotely clear to me that this is the case. We know that at least one other school district employs similar monitoring software, and a growing number of districts are experimenting with issuing laptops to students. I’d like to see reporters start calling around and find out just how many schools are supplying kids with potential telescreens.

Government-Mandated Spying on Bank Customers Undermines both Privacy and Law Enforcement

I recently publicized an interesting map showing that so-called tax havens are not hotbeds of dirty money. A more fundamental question is whether anti-money laundering laws are an effective way of fighting crime – particularly since they substantially undermine privacy.

In this new six-minute video, I ask whether it’s time to radically rethink a system that costs billions of dollars each year, forces banks to snoop on their customers, and misallocates law enforcement resources.

The Government Can Monitor Your Location All Day Every Day Without Implicating Your Fourth Amendment Rights

If you have a mobile phone, that’s the upshot of an argument being put forward by the government in a case being argued before the Third Circuit Court of Appeals tomorrow. The case is called In the Matter of the Application of the United States of America For An Order Directing A Provider of Electronic Communication Service To Disclose Records to the Government.

Declan McCullagh reports:

In that case, the Obama administration has argued that Americans enjoy no “reasonable expectation of privacy” in their—or at least their cell phones’—whereabouts. U.S. Department of Justice lawyers say that “a customer’s Fourth Amendment rights are not violated when the phone company reveals to the government its own records” that show where a mobile device placed and received calls.

The government can maintain this position because of the retrograde “third party doctrine.” That doctrine arose from a pair of cases in the early 1970s in which the Supreme Court found no Fourth Amendment problems when the government required service providers to maintain records about their customers, and later required those service providers to hand the records over to the government.

I wrote about these cases, and the courts’ misunderstanding of privacy since 1967’s Katz decision, in an American University Law Review article titled “Reforming Fourth Amendment Privacy Doctrine”:

These holdings were never right, but they grow more wrong with each step forward in modern, connected living. Incredibly deep reservoirs of information are constantly collected by third-party service providers today. Cellular telephone networks pinpoint customers’ locations throughout the day through the movement of their phones. Internet service providers maintain copies of huge swaths of the information that crosses their networks, tied to customer identifiers. Search engines maintain logs of searches that can be correlated to specific computers and usually the individuals that use them. Payment systems record each instance of commerce, and the time and place it occurred. The totality of these records are very, very revealing of people’s lives. They are a window onto each individual’s spiritual nature, feelings, and intellect. They reflect each American’s beliefs, thoughts, emotions, and sensations. They ought to be protected, as they are the modern iteration of our “papers and effects.”

This is a case to watch, as it will help determine whether or not your digital life is an open book to government investigators.