Tag: reasonable expectation of privacy

Will GPS Tracking Render the Fourth Amendment Quaint?

If the government put a GPS monitor on your car and used it to track every vehicular movement of yours for four weeks, do you think that would violate your Fourth Amendment rights? The government would like to be able to do that kind of thing without getting a warrant, and the Supreme Court will soon decide whether it can.

On November 8th, the Court will hear oral argument in U.S. v. Jones. Yours truly was the lead author of Cato’s amicus brief in the case, which may have a significant effect on how Fourth Amendment law intersects with new information technologies for decades to come.

In 2004, suspecting that Antoine Jones was dealing drugs, the FBI secretly attached a GPS tracking device to his car without a valid warrant. The FBI used this device to monitor and record the car’s movements, noting its location every ten seconds when it was in motion, for nearly a month before finally arresting Jones. The U.S. Court of Appeals for the D.C. Circuit found that the FBI’s action was unconstitutional because it violated Jones’s “reasonable expectation of privacy”—the two-part Fourth Amendment standard developed in the landmark case of Katz v. United States. Though he traveled on public roads, the totality of his movements was available to nobody and thus was private.

Our brief argues that the government’s conversion of Jones’s vehicle into a surveillance device was an unreasonable seizure under the Fourth Amendment. Even though he didn’t lose a “possessory” interest in his car, the government invaded Jones’s various property rights, including the right to exclude, the right to manage, the right to use, and the right to the profits. Similarly, using his car to collect detailed data on his movements over this extended period without getting a warrant was an unreasonable search. The data reflecting his movements would never have come into existence without the government attaching its GPS device to his car. These are tough, interesting issues arising in the new circumstances created by information technology.

We spent as much time in the brief on the “reasonable expectations of privacy” test. The product of one Justice’s lone concurrence in the Katz case, it holds that if a person has an actual (subjective) expectation of privacy and that expectation is one society is prepared to accept, then the Fourth Amendment protects the object of that expectation.

Courts have never faithfully applied this test, and for good reason: it’s a doctrinal mess that reverses the Fourth Amendment’s focus. Courts have second-guessed what the citizenry thinks in terms of privacy rather than examining government action to see if it is reasonable. Under “reasonable expectations” doctrine, things that are left in plain view are always available to the government while things that are hidden—well, the Court will look to see whether keeping it private comports with “reasonable expectations.”

The majority ruling in Katz rested on physical and legal protection that Katz had given to the sound of his voice when he entered a telephone booth. Because Katz had secured the privacy of his conversation, the government wasn’t allowed to access it using a wiretap—not without a warrant. That’s the rule the Court should apply here. The government can’t use uncommon surveillance technology to access private information, including private information about things that happened “in public,” without a valid warrant.

With information technology still rapidly increasing in power, it is critically important that the Supreme Court update Fourth Amendment law while maintaining its consistency with ancient property principles. Doing so will ensure that technology doesn’t render the Fourth Amendment’s protections for our “persons, papers, houses, and effects” quaint.

You can read more, and our brief, on the Cato.org page about U.S. v. Jones.

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.

Revise the Maryland Wiretap Law?

As I said in this piece in the Baltimore Sun, Maryland police officers are misusing that state’s wiretap law to deter anyone who would film them performing their duties. Maryland officers have asserted that any audio recording of a conversation, even in a public place, is a violation of the state’s wiretapping law and a felony punishable by five years in prison and a $10,000 fine. Officers made this claim to deter filming of an arrest at the Preakness, and when motorcyclist Anthony Graber videotaped his traffic stop.

As Radley Balko points out, the officers’ reading of the law is out of step with the language of the statute itself and Maryland rulings interpreting the scope of the law. Is it time for a revision of this law, or is it just the officers’ interpretation that is the problem? I discussed this on the Kojo Nnamdi Show with the prosecutor pressing charges against Anthony Graber, State’s Attorney Joseph Cassilly, and Graber’s lawyer, David Rocah of the Maryland ACLU.

If you ask some officers in Maryland, any recording of a conversation violates the wiretap statute. If you ask a judge, you will get an entirely different reading of the law. Even though Maryland’s wiretapping statute is considered a “unanimous consent” or “two-party consent” law, its language is different from other states put in the same category such as Massachusetts and Illinois. Where Massachusetts and Illinois have no protection for recordings of conversations outside of electronic means of communication, the first section of the Maryland wiretapping law restricts unlawful interceptions of “oral communications” to words spoken in a “private conversation.”

While the analysis for wire communications is made without regard to privacy, Maryland courts held in Fearnow v. C & P Telephone Co. that a “private conversation” is one where there is a “reasonable expectation of privacy.” Fourth Amendment jurisprudence provides plenty of guidance on where a “reasonable expectation of privacy” exists. Simply put, a traffic stop on an interstate is not a place where Anthony Graber or the officers who cited him have a reasonable expectation of privacy.

This conclusion is bolstered by the guidance given to the Montgomery County Police by the Maryland Attorney General in this 2000 advisory opinion on recording traffic stops. Since 1991, the wiretapping statute had an exemption for police dash cameras where officers could record interactions with motorists when they warned the citizen that the traffic stop would be recorded. The 2000 letter addresses the possibility that other people could show up after the receipt of consent from a motorist and potential “inadvertent interceptions.” The opinion concludes that there is little for officers to worry about, but the state legislature expanded the law enforcement exception in 2002 to address this concern anyway. In a footnote, the advisory opinion makes the point that, in any case, the motorists being pulled over have no reasonable expectation of privacy:

It is also notable that many encounters between uniformed police officers and citizens could hardly be characterized as “private conversations.” For example, any driver pulled over by a uniformed officer in a traffic stop is acutely aware that his or her statements are being made to a police officer and, indeed, that they may be repeated as evidence in a courtroom. It is difficult to characterize such a conversation as “private.”

The Attorney General’s office provided further guidance on the issue in this letter to a state legislator in 2009, advising that surreptitious recording of a meeting of the Democratic Club would probably not be a violation of the Maryland wiretapping law because statements made in this setting lack a “reasonable expectation of privacy.”

So, under the interpretation of the law supporting Anthony Graber’s prosecution, dash camera footage of Anthony Graber’s traffic stop is not a violation of the law, but Graber’s helmet-mounted footage is. The law enforcement officer, a public official performing public duties, retains a “reasonable expectation of privacy” on the side of I-95, but Anthony Graber has none. This is an assertion made contrary to the interpretation of the courts of Maryland, the Maryland Attorney General, and common sense.

This injustice could be resolved in several ways. First, as Radley suggests, the Maryland Attorney General could issue an opinion clarifying the wiretapping law with regards to recording police activity. Advisory opinions are not generally given sua sponte, so a state legislator or other official would have to request the AG’s interpretation. Second, Anthony Graber’s case may provide a rebuttal to an expansive reading of the statute by Maryland law enforcement officers. Third, the legislature could step in to deter future abuse of the statute by expressly stating that public discussions are not “private conversations.”

I discussed this on the Kojo Nnamdi Show with David Rocah and Joseph Cassilly. Rocah wants to preserve the “two-party consent” statute. The legislature, in fact, can clarify the  definition of “private conversations” without changing the consent requirement of the law with regard to electronic communications.

On the other hand, State’s Attorney Joseph Cassilly recalled occasions when citizens have come to his office with recordings of threats or extortion demands and he was required to tell them that under Maryland law (1) their recording was not admissible as evidence because it did not have the consent of the threatening or extorting party (though I see no reason that a letter with the same communication would be inadmissible); and (2) the victim of the threat or extortion committed a felony violation of the wiretapping law by making the recording in the first place. That may be the law, but it’s not justice.

In any case, the prosecution of Anthony Graber is an abuse of police power. If Maryland law enforcement officers continue to use the state’s wiretapping law to shield their activities from public view, the backlash may result in a revision of the law in its entirety.

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?