Fourth Amendment

All posts tagged Fourth Amendment

In a post last spring, I discussed the growing use of “Stingrays” by law enforcement officers.  These devices (technically known as International Mobile Subscriber Identity (“IMSI”) catchers) simulate a cell phone tower and thus “trick” a cell phone into sending it data.  These devices are critical for law enforcement surveillance purposes, since criminals will frequently use a specific cell phone for a brief period of time before discarding it and obtaining a new one.  Thus, police officers who know that a suspect is involved in criminal activity and who have have sufficient evidence to obtain a Title III order to wiretap the suspect’s phone are faced with a  dilemma–they have the legal right to listen in on the suspect’s cell phone conversations, but they are unable to do so because there is no way to tell the phone company which phone needs to be tapped.  Armed with a Stingray, the law enforcement officers can fool the suspect’s phone into connecting to the simulated cell phone tower and sharing its identifying information.  The police are able to then take this information and give it to the cell service provider, who can then set up a wiretap for the suspect’s phone.


The problem is that a Stingray will usually gather not just the suspect’s identifying phone information, but also the identifying phone information of everyone else in the area.  Practically, police solve this problem by following the suspect from location to location with the Stingray and determining which cell phone is consistently among the group that is being detected–essentially using process of elimination to determine which piece of identifying data belongs to the suspect’s phone.  But legally, this method raises Fourth Amendment concerns, since the government is gathering information from many innocent people in the process.

I argued earlier that the government should not need a warrant to use Stingrays in this manner, because all they learn about these third parties is the IMSI of the third party’s cell phone–mere “address” information that is already shared with third parties and which does not contain any remotely private information about the user (indeed, the vast majority of cell phone users do not even know their cell phone’s IMSI, nor would they notice or care if other people knew it).  Thus, using a Stingray to obtain a suspect’s IMSI does not implicate the Fourth Amendment in any way.

However, the federal government is taking no chances, and the Department of Justice issued a memo in September of this year that requires its agents to obtain a search warrant prior to using a Stingray device, unless an emergency situation exists.  Consistent with this policy, the government has conceded this point in recent court cases.  This concession makes sense in most situations–if the government already has sufficient information to obtain a Title III wiretap order against an individual, then the government surely has sufficient information to obtain a search warrant,.  Unfortunately, this self-imposed requirement does limit the usefulness of Stingrays in some contexts.  In many cases, the government only has reasonable suspicion that the suspect is committing a crime, and may only want to obtain a pen/trap order to determine whom the suspect is calling and how often–information which is not constitutionally protected but which can be very useful in developing probable cause.  But by requiring probable cause at the outset, the government is denying itself the ability to use this basic investigative tool if the suspect is sophisticated enough to frequently switch cell phones.

More recently, a federal magistrate court imposed even more restrictions on the use of Stingray devices.  In a recent order, Magistrate Judge Iain D. Johnston of the Northern District of Illinois summarized the restrictions that he placed on law enforcement officers when he grants a warrant for using a Stingray.  Essentially Judge Johnston sets three requirements for law enforcement:

(1) Officers must make reasonable efforts to minimize the collection of third party cell phone identification information.

(2) Officers must destroy all third party identifying information that they do collect within 48 hours of its collection.

(3) Any data obtained from the Stingray device can only be used to identify the target’s identifying cell phone information and for no other purpose.

The first two limitations are sensible enough and do not seem to affect the effectiveness of the surveillance.  The use limitation of the third requirement, however, seems unnecessary–there may be a number of legitimate and useful other ways for law enforcement to use the information.  For example, once the police know the target’s IMSI, they can use the Stingray device at a later time to determine the suspect’s general location (This information is not protected under the Fourth Amendment unless it is continuously protected over a long period of time, as in the Jones case).  And some versions of the Stingray device may be able to operate as a pen register, telling the police the numbers the target is calling and the length of those calls.  This information is also unprotected under the Fourth Amendment (there are statutory restrictions on such information, but they are far lower than the probable cause that the police have already developed before they get a warrant).  But for now, the federal government seems content to live with these restrictions and as far as we know, has not challenged them in court.


locked cell phone

This week the New York Times published an op-ed which argued for allowing law enforcement officers with search warrants greater access to the cell phone data of criminal suspects.  The piece was co-written by an impressive set of authors: the District Attorney of Manhattan, the chief prosecutor of Paris, the commissioner of the City of London Police, and the chief prosecutor of the High Court of Spain.  They note that many modern cell phones are password protected, and that Apple and Google (whose operating systems together run about 96% of cell phones) no longer have a copy of that password and therefore police cannot access these cell phones even if they have legal authority to do so.  The piece argues that once law enforcement officers have obtained a warrant (having thus proved to a neutral magistrate that there is probable cause to believe there is incriminating information on the cell phone), there should be no technical barrier (such as password protection) to extracting that information from the digital device.  As they argue:

In the United States, Britain, France, Spain and other democratic societies, the legal system gives local law enforcement agencies access to places where criminals hide evidence, including their homes, car trunks, storage facilities, computers and digital networks.

Carved into the bedrock of each of these laws is a balance between the privacy rights of individuals and the public safety rights of their communities. For our investigators to conduct searches in any of our jurisdictions, a local judge or commissioner must decide whether good cause exists. None of our agencies engage in bulk data collection or other secretive practices. We engage in targeted requests for information, authorized after an impartial, judicial determination of good cause, in which both proportionality and necessity are tested.

It is this workable balance that proscribes the operations of local law enforcement in our cities, and guides our residents in developing their expectations of privacy. But in the absence of laws that keep pace with technology, we have enabled two Silicon Valley technology companies to upset that balance fundamentally.

Judging by the comments posted by the Times, the op-ed was not well-received by the readership: readers argued that encryption protects our data from thieves and hackers as well as from police; that political dissidents and activists rely upon it to communicate safely; and (echoing Riley v. California) that the sheer amount of information on a cell phone means that they need to be protected, even from police officers with search warrants.  The Electronic Frontier Foundation predictably warned that the piece was “nothing more than a blatant attempt to use fear mongering to further their anti-privacy, anti-security, and anti-constitutional agenda.”

It is hard to see what is “unconstitutional” about giving law enforcement access to information once they have obtained a warrant for that information.  Just because we now have the ability to easily password-protect  much of our personal data doesn’t mean that we somehow have greater constitutional rights in that information than we did twenty years ago.  Indeed, if the police had a search warrant for a fine cabinet, they should be able to look inside the file cabinet whether or not the owner has locked it.  The same argument should apply to cell phones–once a court has authorized the search, the police need to (and should be able to) conduct that search.

The real problem–and one that the authors of the op-ed do not really address–is how to go about ensuring that the police do have this ability once a warrant is issued.  The op-ed merely states that “regulators and lawmakers in our nations must now find an appropriate balance between the marginal benefits of full-disk encryption and the need for local law enforcement to solve and prosecute crimes.”  But it is one thing to ask for a “balance” and another to figure out what laws need to be passed to ensure that balance.  One option would be to require the manufacturers of digital devices to provide the government with a “master key” to every cell phone–but the danger of abuse in that context becomes quite obvious.  Another option would be to require the companies that design operating systems to keep a copy of every password (thus making it illegal for Apple or Google to use the operating systems they are currently using)–but this seems like a particularly severe government intrusion into the private sector.  Yet another option would be to allow police to compel the password from the owner of the device, but this raises serious Fifth Amendment questions.  Some courts have held that forcing a suspect to give up his own password is akin to self-incrimination, citing a United States Supreme Court decision which stated that the Fifth Amendment protects a defendant from producing documents which may be incriminating.

In short, the op-ed correctly identified a problem, but was silent on the solution.  Unless and until law enforcement officers develop the tools to break through password-protected phones, this problem will grow more and more severe until one of the more draconian solutions listed above becomes necessary.


In a 5-4 decision yesterday, the Supreme Court held in United States v. Patel that hotel owners cannot be required to turn over their registries to law enforcement without some kind of judicial review.  The case centered on a Los Angeles municipal code provision that required all hotels to keep a registry with information about there guests and to turn the information over to law enforcement upon request.  Law enforcement officers did not need to make any kind of showing of need before making the request, nor did the officers need to get judicial approval.  A hotel owner sued the United States government, mounting a facial challenge to the ordinance on the grounds that it allowed for a suspicionless search that violated its rights.  Five Justices agreed.

There are three interesting aspects to this opinion:

First, eight of the Justices held that plaintiffs can bring facial challenges under the Fourth Amendment.  In my preview of this case, I predicted that the Supreme Court would not allow facial challenges because it would open the door to too many hypothetical cases.  This prediction proved to be completely incorrect.  The Court noted that it allowed facial challenges in many other contexts, and that there was no reason to prohibit them in the Fourth Amendment context.  The Court also noted that a facial challenge to a statute can succeed even if there were some situations in which the search would be authorized by some authority other than the challenged statute:

Similarly, when addressing a facial challenge to a statute authorizing warrantless searches, the proper focus of the constitutional inquiry is searches that the law actually authorizes, not those for which it is irrelevant. If exigency or a warrant justifies an officer’s search, the subject of the search must permit it to proceed irrespective of whether it is authorized by statute. Statutes authorizing warrantless searches also do no work where the subject of a search has consented. Accordingly, the constitutional “applications” that petitioner claims prevent facial relief here are irrelevant to our analysis because they do not involve actual applications of the statute.

Second, this holding will have an important effect on the development of the third party doctrine in Fourth Amendment jurisprudence.  Under the third party doctrine, an individual gives up all of his or her Fourth Amendment rights in an item or a piece of information if he or she hands it over to a third party.  That third party is free to give it to law enforcement, and the original owner of the item or document has no right to object.  Patel does not change any of that.  However, what if the third party–the hotel, the bank, or the internet service provider–does not want to turn the information over to law enforcement upon request?  Before Patel, the third party’s rights to object were relatively fuzzy, but Patel set out clear standards: the government must get some kind of “precompliance review” of its request before the third party can be forced to turn over the information.  This means either an administrative warrant (which is issued by a judge) or–if the government obtained a subpoena and the third party challenged the subpoena–a review of the subpoena by a judge or magistrate.  Granted, the standard for obtaining an administrative warrant or defending a subpoena is relatively low, but the requirement of precompliance review by a neutral judicial official is still a significant one.

Of course, none of this matters if the third party decides to cooperate with law enforcement–as has happened very frequently in the past.  But in the wake of the Snowden revelations and the public outcry that followed, more and more companies are beginning to assert their rights to keep this information from the government–both because the information has intrinsic value to them and because their customers are demanding more privacy.  Some companies, like Google, are challenging subpoenas more and more often.  Thus, for scholars and judges who complain about the third party doctrine, this may perhaps provide some solace–we still may not have the right to protect our information, but the companies we give it to are developing both the incentives and the legal ability to protect it for us.

The final aspect of the holding is one that flew a little bit under the radar, but that nevertheless is important.  The Patel Court assumed, without deciding, that a government search of the hotel’s registry qualified as a special needs search rather than a traditional law enforcement search.  The Court essentially said that there was no need to get into this question into more depth, because even under the lower “special needs” standard, the ordinance was unconstitutional, so it would clearly be unconstitutional under the more stringent law enforcement standard (which requires probable cause and–usually–a warrant).  But the very fact that the Court was willing to even make this assumption for argument’s sake is a bit troubling, and may presage yet another broadening of the already overbroad special needs definition.

Of course, the “special needs” justification has already been broadened way beyond the health and safety inspections of Camera and has been applied to searches which do little more than deter crime.  For example, as I discussed in an earlier article, almost every circuit court has held that the searches at airports are legitimate under the “special needs” doctrine, under the theory that they prevent terrorist action and thus protect public safety.  (The Supreme Court has yet to consider airport searches, but the Court has approved of them in dicta).   So already we have prevention of violent crime as a special need in order to keep society safe.  Likewise, the Supreme Court has approved of drunk driving checkpoints as a special need which keeps other motorists safe by preventing drivers from committing the crime of driving while intoxicated–which in a sense is per se reckless activity.

So we already apply the special needs search doctrine in order to prevent violent or reckless crimes–but at least those applications have some connection to protecting public safety.  Applying the special needs search doctrine to prevent drug use or prostitution in hotel rooms seems to be yet another step–a significant one–towards blurring the line between special needs searches and plain old fashioned law enforcement searches.  This was a line, for example, that the Court was unwilling to cross in Indianapolis v. Edmond.

To be fair, footnote 2 of Patel makes it clear that the Court is not making a decision one way or another on this particular issue.  So perhaps the Court simply wanted to make a broader point about the requirements for special needs searches and so decided to use Patel–even though in the end the search in question might not be an administrative search.  But this nuance may get lost as the months and the years go by, and many lawyers and judges will begin to think of Patel as the “administrative search case” and thus will think of the police accessing hotel records as a special needs administrative search.  Hopefully the Court can clarify this issue before that point.




A few months ago I wrote about (and strongly criticized) the Eleventh Circuit’s decision in United States v. Davis, in which the court held that the government needed to obtain a search warrant before it could access cell tower location information that located the defendant’s cell phone.  Now the Eleventh Circuit, in an en banc decision, has overturned the three-judge panel and held that the third-party doctrine applies to these records; thus, a warrant is not required.


The court began by citing the Fifth Circuit decision which also applied the third party doctrine in deciding this issue.  Then the court applied Smith v. Maryland and found that the Davis case was legally no different from Smith:

For starters, like the bank customer in Miller and the phone customer in Smith, Davis can assert neither ownership nor possession of the third-party’s business records he sought to suppress. Instead, those cell tower records were created by MetroPCS, stored on its own premises, and subject to its control. Cell tower location records do not contain private communications of the subscriber. This type of non-content evidence, lawfully created by a third-party telephone company for legitimate business purposes, does not belong to Davis, even if it concerns him. Like the security camera surveillance images introduced into evidence at his trial, MetroPCS’s cell tower records were not Davis’s to withhold. Those surveillance camera images show Davis’s location at the precise location of the robbery, which is far more than MetroPCS’s cell tower location records show.

The Court not only applies the third party doctrine, it presents a robust defense of the doctrine in this context, harkening back to the Katz test:

As to the subjective expectation of privacy, we agree with the Fifth Circuit that cell users know that they must transmit signals to cell towers within range, that the cell tower functions as the equipment that connects the calls, that users when making or receiving calls are necessarily conveying or exposing to their service provider their general location within that cell tower’s range, and that cell phone companies make records of cell-tower usage. See In re Application (Fifth Circuit), 724 F.3d at 613-14. Users are aware that cell phones do not work when they are outside the range of the provider company’s cell tower network. Id. at 613. Indeed, the fact that Davis registered his cell phone under a fictitious alias tends to demonstrate his understanding that such cell tower location information is collected by MetroPCS and may be used to incriminate him.

Even if Davis had a subjective expectation of privacy, his expectation of privacy, viewed objectively, is not justifiable or reasonable under the particular circumstances of this case. The unreasonableness in society’s eyes dooms Davis’s position under Katz. In Smith, the Supreme Court presumed that phone users knew of uncontroverted and publicly available facts about technologies and practices that the phone company used to connect calls, document charges, and assist in legitimate law-enforcement investigations. See 442 U.S. at 742-43, 99 S. Ct. at 2581. Cell towers and related records are used for all three of those purposes. We find no reason to conclude that cell phone users lack facts about the functions of cell towers or about telephone providers’ recording cell tower usage.

Although the third party doctrine has been routinely criticized, applying it makes sense in this context.  As the court notes, surely every reasonable person knows that the telephone company can track their general location using the person’s cell phone–how else could cell phones function?  And, notwithstanding the famous concurrence in United States v. Jones, a person generally does not have a reasonable expectation of privacy in a public place.

The en banc decision also provides an “alternative” justification for its ruling, which is that even if the third party doctrine did not apply, the search was “reasonable” because the intrusion into privacy was minimal, cell tower location information is routinely used by government investigators, Congress has explicitly endorsed this type of investigation in the Stored Communications Act, and the government’s interest in tracking down criminals is “compelling.”  Professor Orin Kerr had a number of withering critique of this alternative justification in his blog post; one of which was that the “reasonableness” test (as opposed to the warrant requirement) should only be applied in non-criminal cases:

A basic summary of the Supreme Court’s cases might run something like this: When the search involves some kind of non-criminal investigation or purpose, the warrant requirement is often suspended. In that non-criminal context, reasonableness instead becomes a general balancing of interests. The Court has been expanding the general balancing cases, most recently in Maryland v. King. But the Katz rule of a warrant by default is still the Supreme Court’s blackletter law for a traditional criminal investigation search.

In this case, the Eleventh Circuit appears to take a different approach. It begins with the Supreme Court’s non-criminal cases and then applies them to the context of a classic criminal investigation. Instead of the Katz rule of a warrant, the court begins with general balancing. It’s important to catch criminals, the court reasons, and the statute has some good protections given that this wasn’t such an invasive practice. So on the whole the government’s conduct based on reasonable suspicion seems reasonable and therefore constitutional.

This alternative holding is a major development, I think. It’s at odds with the usual rule that a criminal search requires a warrant, and instead replaces it with a totality of the circumstances inquiry into whether the criminal search was the kind of thing that we would generally say is good or would generally say is bad. There’s not only no warrant requirement, there’s no probable cause requirement: It’s just a free-floating reasonableness inquiry.

Professor Kerr has a good point here, but he might be fighting a losing battle.  In reality,  the distinction between “criminal searches” and “non-criminal searches” is becoming blurred almost beyond recognition.  Special needs searches have always been evaluated on a “reasonableness” standard, and many of them are nothing but criminal searches thinly masquerading as non-criminal searches (for example, testing for drugs in schools, stopping cars to check for drunk drivers, and searching passengers before they board an airplane).  Most recently, in Maryland v. King, the Supreme Court applied the reasonableness test to DNA swab of arrestees which was used to determine if the arrestee had committed any other crimes was not a “criminal search.”  Applying the reasonableness test to the obtaining of cell phone location data in a bank robbery investigation definitely pushes the envelope even further, but it continues a trend which has been building for a while.

Of course, this aspect of the Davis en banc decision is merely dicta, so perhaps nothing at all will come of it.  But as far as the holding of the case is concerned, the court has at least brought consistency back to this area of law.


Ohio’s Supreme Court is beginning to get a reputation for aggressively protecting Fourth Amendment rights in the digital age.  Six years ago in State v. Smith it held that police officers may not search a cell phone incident to an arrest, foreshadowing the United States Supreme Court’s Riley decision by five years.  Today the Court released a decision which set out strict requirements for law enforcement officials who are seeking search warrants for computers.  The Court held that the search warrant in question lacked particularity because it essentially authorized a limitless search of the defendant’s computer.

egged cartext








In the case, State v. Castagnola, the defendant was initially being prosecuted for selling alcohol to a minor.  He then took the ill-advised step of egging the prosecutor’s car to show his displeasure with the case.  He then took an even less-advised step and bragged about the egging to a friend, first by text and then in person.  The “friend” ended up being a police informer, who was wearing a wire at the time of the defendant’s verbal confession.  The police then obtained a search warrant and searched the defendant’s home (including his computer) for evidence of the egging incident.  Instead, they found evidence of child pornography.  The defendant was ultimately convicted of the child pornography charge.

The issue at the Ohio Supreme Court was two-fold:

First, the defendant told the police informant that he found the prosecutor’s address by tracing him through a parking ticket the prosecutor had received a few years earlier.  In the detective’s affidavit seeking a warrant, the detective erroneously said that the defendant had mentioned that he found the prosecutor’s address after conducting an “online” search–thus supporting the detective’s request to search the defendant’s computer in order to find evidence of the search.  But the defendant in fact never mentioned how he searched for the prosecutor.  The detective had inferred that the search occurred online, but the Court held that such an inference was not strong enough to rise to the level of probable cause that the defendant had used a computer, noting that “[a]lthough we are in the computer age, records of court activity still exist in paper form and are available to the public in clerk of courts’ offices around the state.”  In other words, even though the defendant had admitted that he had searched through court records for the prosecutor’s address, the likelihood that he did so using a computer does not suffice to establish probable cause.

Second, the warrant’s language, which copied the language from the detective’s affidavit, authorized the police to search:

Records and documents either stored on computers, ledgers, or any other electronic recording device to include hard drives and external portable hard drives, cell phones, printers, storage devices of any kind, printed out copies of text messages or emails, cameras, video recorders or any photo imaging devices and their storage media to include tapes, compact discs, or flash drives.

The Ohio Supreme Court noted that this language violated the Fourth Amendment’s particularity requirement because it did not include any “limitation on what records or documents” were allowed to be searched.  Event though the warrant later specified that any evidence that was recovered was to be used as evidence in a retaliation and criminal damaging case, the warrant was still overly broad.  Thus, the evidence should have been excluded–which almost certainly means that the child pornography case will now be dismissed.

The Court’s first conclusion seems a bit strained–is it really feasible to think that the defendant actually went to the county clerk’s office in person to look up the prosecutor’s old parking ticket?  An inference that the defendant conducted an online rather than a physical search seems not only reasonable (and thus sufficient to support probable cause) but almost certain.

But the Court’s second conclusion is surely correct–courts are already struggling with how to draft warrants in order to properly limit searches of computers, and a broad warrant that permits the police to search through every digital file on every digital device does seem overbroad.  Indeed, the law enforcement technician gave a somewhat weak explanation of why she was looking at picture files when she was allegedly looking for evidence of a search for the prosecutor’s court files.  (She explained that she “went to the images [folder] to find images associated with court websites.”)  On this point, at least, the Ohio Supreme Court’s message is clear: narrow your computer search (and your language in the search warrant) to items that are related to the crime you are investigating.






This week the Court decided Rodriguez v. United States, and held in a 6-3 decision that the police cannot prolong a traffic stop even for a few minutes in order to conduct a drug dog sniff.  More broadly, the Court held that the duration of a traffic stop, like the duration of a Terry stop, must be “reasonable,” and thus may not be lengthened by police conduct which was beyond the “mission” of the traffic stop.

Drug Dog Car Sniff

In my preview of this case, I predicted that the Court would be forced to define what is “reasonable” by essentially legislating from the bench and listing precisely the actions that officers can and cannot do during a routine traffic stop.   I wrote that the Court would define “reasonableness” as “what we are used to seeing the police doing, rather than what is actually reasonable for the police to do.  Thus, in this case, well-established practice will create the constitutional rule, rather than (as it should be) the other way around.”

My prediction was mostly correct, but I give the Rodriguez Court credit for at least trying to create a principled distinction between what is “reasonable” during a traffic stop and what is not.   Specifically, the Court said that the police officer may take a reasonable amount of time to “address the traffic violation that warranted the stop;” to “attend to related safety concerns;” and to conduct “ordinary inquiries incident to [the traffic] stop.”  This last category is included to allow police to “ensure that vehicles on the road are operated safely and responsibly.”  In contrast, the police officer is not allowed to take any extra time to “detect evidence of ordinary criminal wrongdoing.”  The Court used these guidelines to conclude that it is impermissible to take extra time during a traffic stop to use a drug dog.

Unfortunately, the Court’s attempt at making a principled distinction falls short.  The Court helpfully provides a list of what falls under the “ordinary inquiries” category: checking the driver’s license, inspecting the automobile’s registration and proof of insurance, and determining whether there are outstanding warrants against the driver.  But as Justice Thomas points out in his dissent, this last action–checking for warrants–does not really ensure that the vehicle is operated safely and responsibly–it is, plain and simple, an investigation into whether the suspect has been involved in criminal activity.  As such, it seems indistinguishable from the drug dog sniff, at least under the paradigm provided by the Court.

Interestingly, Rodriguez appears to limit another common activity during a traffic stop–questioning the suspect in order to learn if the suspect is engaged in criminal activity and/or requesting to search the car.  The Court does note that the police may “conduct certain unrelated checks during an otherwise lawful traffic stop,” but it states that “[s]he may not do so in a way that prolongs the stop, absent . . . reasonable suspicion.”  Thus, Rodriguez seems to prohibit any investigatory questioning unrelated to the reason behind the stop which prolongs the length of the stop.  It will be interesting to see how lower courts interpret this aspect of the case–does this mean that if the police officer has completed the warrant check and the citation, she is not allowed to ask any further investigatory questions of the driver unless they are somehow related to the offense?  Or maybe lower courts will interpret Rodriguez even more strictly.  As Professor Rory Little notes at SCOTUSblog: “the Court says only that an officer ‘may conduct certain unrelated checks’ during a stop, without discussing what limitations ‘certain’ may imply.  The majority also says that ‘on-scene investigation into other crimes … detours from that mission’ of traffic safety.”  Lower courts will have to interpret this language to determine which questions are or are not permitted to lengthen a traffic stop.

Professor Little also discusses another “loose end” in the Rodriguez decision: he sees the case, when considered alongside the rejection of the front-door dog-sniff in Jardines, as evidence that the Court is backing away from its 1983 decision United States v. Place which stated that drug dog sniffs are not a Fourth Amendment search.  (This would also mean, presumably, that the Court is backing away from its affirmation of Place in the 2005 decision of  Illinois v. Caballes).  He calls Place “one of the more extreme extensions of the ‘reasonable expectation of privacy’ test,” and argues that its rationale is now suspect in light of Jardines, Riley v. California (which prohibited searching cell phones incident to a lawful arrest), and Kyllo v. United States (which prohibited warrantless thermal imaging of a home).   These cases, Little notes, are evidence that the Court has “recognized that privacy has some scope beyond ‘expectations’ that the real world may compel us to abandon,” and that the Court is coming to the realization that drug dogs are like any other investigative tool and should be treated as such.

I am not so sure about this conclusion.  The Court’s rationale that drug dog sniffs do not constitute a Fourth Amendment search is based on a very specific doctrine–the binary search doctrine–and nothing in Kyllo, Jardines, or Riley affects that doctrine in any way.  The binary search doctrine states that government surveillance is not a Fourth Amendment search if it is only able to reveal the absence or presence of illegal activity.  The doctrine is based on the theory (first discussed in Rakas v. Illinois) that the Fourth Amendment only protects legitimate expectations of privacy.  In contrast, the Court’s recent limitations on the use of drug dogs have been based on other doctrines.  In Jardines, the limitation was based on the new  “trespass” Fourth Amendment test found in Jones; and in Rodriguez, the limitation was based on the doctrine that although a drug dog sniff is not a Fourth Amendment search, it is a Fourth Amendment seizure.  All that Rodriguez stands for is that the seizure aspect of the drug dog sniff needs to be justified by reasonable suspicion, and that any unreasonable delay that prolongs a seizure in order to conduct a drug dog sniff is unconstitutional–which is exactly what the Court held in Place thirty-two years ago.

NOTE:  Other commentators have also reacted to this case:  Orin Kerr has stated that he believes the case is correctly decided and that the Court was wise to adopt the “safety-based rationale” for traffic stops, while Steven Schwinn discussed the case on the Constitutional Law Prof Blog.

The Supreme Court took on a number of cases this year which have attracted a lot of media and legal attention.  The case involving same-sex marriage has already garnered many headlines and at last count over one hundred ten amicus curaie briefs, while the case discussing tax subsidies in the Affordable Health Care Act has widespread political and economic implications.   In contrast, this term’s criminal procedure cases deal with narrow, technical issues that have mostly flown under the media radar.  But even in a relatively obscure group, the case of Grady v. North Carolina, which was quietly decided in a brief five-page per curia decision last week, surely ranks as the most obscure.  Grady dealt with an interesting Fourth Amendment question: whether attaching an GPS-tracking ankle bracelet to a convicted sex offender constitutes a “search” under the Fourth Amendment.  But the ultimate decision in the case turned on a relatively obvious and well-established point of law: that the Fourth Amendment applies to civil as well as criminal cases (see Ontario v. Quon and Camara v. Municipal Court), and so the North Carolina court was in error when it dismissed the case merely because it was civil in nature.  Thus, the per curiam decision and the dearth of outside interest in the case.

Ankle monitor

Nevertheless, the Grady decision has a couple of interesting aspects to it.  First, it is now the third case to apply the “property rights” test for a search (after Jones, which held that attaching a GPS device to a car was a search; and Jardines, which held that bringing a drug dog to the front porch to sniff for contraband was a search).   (The property rights test defines a search as “physical occupation of private property by the government with the intent to gather information,” which surely applies in Grady).   And unlike Jones and Jardines, the  majority decision does not even mention the Katz test with regard to Grady’s challenge, even to say (as it did in the plurality in Jones and the majority in Jardines) that it need not reach the question of whether the government action invaded the defendant’s reasonable expectation of privacy.  And unlike Jones and Jardines, there was no concurrence specifically describing how the government action would fare under the Katz test.  As the Court stated in Jardines, “[o]ne virtue of the Fourth Amendment’s property-rights baseline is that it keeps easy cases easy.”  In this case, the property-rights test made the case so easy that there was no need to even refer to the more traditional Katz test when deciding the case.

The Justices’ decision to not mention the traditional Katz test does not mean the Katz test has any less support than before, of course–in both Jones and Jardines, the Court mentioned that the property rights test was meant to supplement, not replace, the reasonable expectation of privacy test.   And there are plenty of recent cases (such as Riley v. California or Maryland v. King) which relied on the Katz test.  But anyone who thought (or hoped) the property rights test would fall into disuse will now be sorely disappointed–it has now been used to decide three Fourth Amendment cases in the last four years.

Grady re-affirms the property rights test, it also unintentionally highlights the absurdity of using the test when the Katz test could just as easily–and more intuitively–resolve the case.  This absurdity was present in Jones, which held that the Fourth Amendment violation occurred when the government “physically intruded” by attaching of a small device to the underside of the defendant’s car, rather than when the government monitored every location the car travelled to for the next twenty-eight days.   It was present in Jardines, when the Court held that the police officer  violated the defendant’s rights when he stood on the porch with a dog, rather than (as in Kyllo) when he used an unusual tool to gather private information about the inside of the defendant’s home.  But the absurdity is most obvious in Grady.  Here is an individual whose location–in public and in private–will be tracked by the government for the rest of his lifeAnd yet the Supreme Court has held that his Fourth Amendment rights would be violated because the government spent a few seconds attaching a bracelet to his ankle.  Almost anyone who reads this case–lawyer or lay person–will be surprised that this is now the focus of Fourth Amendment jurisprudence.  This case is just as “easy” to decide when using the Katz test; there is no question that monitoring a person’s movements in private violates that person’s reasonable expectation of privacy.  But the Court seems determined to always use the Jones property rights analysis first, even if it seems counter-intuitive to do so.

None of this helps Mr. Grady, of course.  Although the Court held that attaching the ankle monitor was a search, it remanded the case to determine whether attaching such a a monitor to a convicted sex offender is reasonable.  Given the Court’s recent decisions on reasonableness and on sex offenders, Grady should not be too hopeful.


Next week the Eleventh Circuit will hear the en banc appeal of United States v. Davis.  This case involves the use of cell tower location information to track the movements of a suspect.  Last year a three judge panel ruled that the government needed to obtain a warrant before it could acquire this information from the phone company.  Next week, the Eleventh Circuit will re-hear the case en banc and decide whether they will pull back from the broad holding and expansive reasoning of the original decision.

cell tower location display

In the Davis case, the government suspected the defendant of numerous armed robberies.  During its investigation, the government obtained a court order to acquire the cell tower location data from the defendant’s phone pursuant to the Stored Communications Act (“SCA”).  At the outset, it should be noted that this information is the least intrusive and least precise type of location information that is available from an individual’s cell phone.  Cell tower location information merely tells the phone company (and in this case, the government) the one or two towers which were used to contact the suspect’s phone when he made or received a phone call, as well as the direction the suspect was in relation to the tower(s).  These are usually, but not always, the closest cell phone towers to the suspect at the time he or she used the cell phone.  The data is only created when the suspect actually uses the cell phone–usually when he or she is making or receiving a call.  In contrast, when law enforcement officers have the phone company “ping” a cell phone, or when it uses the GPS device built into the cell phone,the officers obtain a real-time, continuous, precise location of the suspect, regardless of whether the suspect is using the cell phone at the time.

Under the SCA, the government need only show “specific and articulable facts” that the information could be linked to a crime in order to obtain a court order.  Davis argued (and the three judge panel agreed) that acquiring this location information was a Fourth Amendment search, and so the government needed to obtain a warrant based on probable cause before gaining access to this data.  The three-judge panel acknowledged that this was a case of first impression, and so it relied heavily on Justice Alito’s four justice concurrence in the Jones case in its reasoning.  In Jones, four justices found that a twenty-eight day continuous surveillance using a GPS was a Fourth Amendment search because of the “mosaic doctrine”–i.e., the government learned so much public information about the defendant that it created a mosaic which revealed private, protected information.  The three-judge panel in Davis acknowledged the difference between the two fact patterns, but argued that the case was “sufficiently similar” to make it “clearly relevant” to their analysis.

In fact, the distinctions between Davis and Jones are significant, and they all point to the conclusion that the search in Davis does not deserve Fourth Amendment protection.  The only reason the Alito concurrence found that the government surveillance in Jones constituted a search was because of the large number of trips that were tracked; in the Davis case, the government only examined a small number of incidents (specifically, the times when a robbery was occurring).  But the Davis three judge panel ignored this distinction, arguing that tracking a person’s public location even once could constitute a search: “…[E]ven on a person’s first visit to a gynecologist, a psychiatrist, a bookie, or a priest, one may assume the visit is private if it was not conducted in a public way.”  The Jones case also involved tracking an individual at all times, while the police in Davis only gained location information from the defendant when he voluntarily provided that information to the phone company by using his cell phone.  And finally, the Jones location information was much more precise, showing the police exactly where the defendant’s car was located; the Davis location information only showed the general area where the defendant was located.  (The three judge panel brushed this difference aside, arguing that because the prosecutor claimed the cell phone location placed the defendant “near each of six crime scenes,” it could place him “near any other scene” as well, including the “home of a lover, or a dispensary of medication, or a place of worship, or a house of ill repute.”)

Essentially the Davis panel appeared to be arguing that since an individual may want to keep his general location at any given time private from the government, the Fourth Amendment protects the government from learning that information unless it first obtained a warrant.  This is certainly not supported by Jones and directly contradicts Knotts, which allows the government to use electronic means to track an individual over the course of one trip.

The only significant difference the Davis panel found between its case and the Jones case was that the Jones case involved tracking a car, whereas the Davis case involved tracking a cell phone.  The Davis court concluded that a person has less reasonable expectation of privacy in the movements of a car, because it is easily visible when in public, than it does in the movements of an individual (as tracked through a cell phone), which may not be so easily visible.  Unfortunately for the Davis court, no other court has made any such distinction.  The only distinction that matters is whether the location being tracked is in public (as in Knotts) or in private (as in Karo)–and, after Jones, whether there is so much information that it creates a mosaic.  Neither of those distinctions existed in Davis.

Finally, the Davis court had to overcome one more obstacle in order to come to its extraordinary conclusion: it had to deal with the third party doctrine.  As a general rule, a person loses all Fourth Amendment protection for any information that he or she turns over to a third party (such as a phone company).  The Davis court argued that the third party doctrine only applies when a person “voluntarily and knowingly” conveys information to a third party, and then claimed that a cell phone user has no idea that he or she is conveying her location to the phone company when he or she makes a cell phone call.  The first step of this argument seems questionable as a matter of law (there is no strong support for the proposition that the third party doctrine only applies to “voluntary and knowing” transfer of information) and the second step of this argument seems flat out wrong as a matter of fact (regardless of what the defendant in Davis might have thought, most people must know that the cell phone company needs to determine the location of their phone in order to send calls to it).

The Davis court ultimately ruled for the government and refused to suppress the evidence based on the good faith exception to the exclusionary rule, but its reasoning and dicta regarding cell phone location information still stands.  If the en banc court does not overturn that aspect of the case, it will represent a radical expansion of the Jones case–an expansion that is not consistent with the rest of Fourth Amendment doctrine in this area.


Last year, the United States Marshal’s Service tracked down a fugitive named Steven Denson to a house in Witchita, Kansas.  Before they stormed the house, however, they took a sensible precaution and placed a radar device on the outside of the wall to determine the location of the individual in the house.  They then entered the house, arrested the fugitive, and found a number of illegal guns as well.

ranger-radarradar through wall

The marshals had a warrant for Denson’s arrest, but they did not have a search warrant for the home.  Thus, they were only permitted to enter the home if they had “reason to believe” that Denson was inside the home at the time.  Denson challenged the entry into the home, arguing that the police officers only developed a reason to believe he was inside after using the radar device, which violated his Fourth Amendment rights.

The Tenth Circuit rejected Denson’s argument  and held that the officers did not violate the Fourth Amendment.  According to the court, the officers already had reason to believe that Denson was inside even before they used the radar device.  Thus, the court applied the independent source doctrine from the Supreme Court’s holding in Murray v. United States and allowed the search to stand without resolving the question of whether the radar device violated Denson’s Fourth Amendment rights.  Here is the Tenth Circuit’s description of the device:

the government brought with it a Doppler radar device capable of detecting from outside the home the presence of  “human breathing and movement within.”  All this packed into a hand-held unit “about 10 inches by 4 inches wide, 10 inches long.”  The government admits that it used the radar before entering — and that the device registered someone’s presence inside.  It’s obvious to us and everyone else in this case that the government’s warrantless use of such a powerful tool to search inside homes poses grave Fourth Amendment questions.  New  technologies bring with them not only new opportunities for law enforcement to catch criminals but also new risks for abuse and new ways to invade constitutional rights.  See, e.g., Kyllo v. United States, 533 U.S. 27, 33-35 (2001) (holding that using warrantless thermal imaging to show activity inside a home violated the Fourth Amendment).  Unlawful searches can give rise not only to civil claims but may require the suppression of evidence in criminal proceedings.  We have little doubt that the radar device deployed here will soon generate many questions for this court and others along both of these axes.  At the same time, in a criminal proceeding like ours the government is free to rely on facts gleaned independently from any Fourth Amendment violation.

This analysis seems cautious to a fault.  There is no conceivable way that the use of the radar device is consistent with the Kyllo case.  If law enforcement officers are conducting a Fourth Amendment search when they use a thermal imager to detect the emanations of heat inside of a home, then they are certainly conducting a Fourth Amendment search when they use a radar to detect the presence, movement, and location of individuals inside a house.  And although these devices are apparently becoming more and more popular among law enforcement, they have certainly not risen to the level of being “in general public use,” as required by Kyllo.

The use of the radar device to establish probable cause is even more clearly unconstitutional given the Supreme Court’s recent case of Florida v. Jardines, which held that a drug-dog sniff at the front door of a house constituted a Fourth Amendment search.  In Jardines, the court held that the use of a surveillance tactic which ordinarily does not implicate the Fourth Amendment becomes an unconstitutional search when it is used at the front door of a home.  In the Tenth Circuit’s case, the court was reviewing a surveillance tactic that is more intrusive than the thermal imager in Kyllo and which involved a United States Marshall placing the device directly on the outer wall of a home–a location where an individual arguably has a greater expectation of privacy than the front door.

Regardless, the Tenth Circuit’s holding in this case was almost certainly correct.  Even without the information from the radar device, the United States Marshals had sufficient evidence to establish probable cause (or at least “reason to believe,” which may be an even lower standard) that Denson was in the home.  Denson was the primary account holder on the utility for the home; and he was unemployed and running from the police, and the electric meter was  “going faster than normal”–all of which would lead the officers to believe that someone was home at the time.  Furthermore, the use of the radar device by the marshals seems perfectly legitimate in this case–once the marshals had established probable cause to believe that Denson was inside, they used the device to ensure their safety for when they entered the house.  This is a perfectly reasonable, non-investigatory use of the technology.

But even though the marshals acted properly and the Tenth Circuit reached the proper result, one could still hope that the court had been a little bolder with its dicta regarding the radar device.  Surely the question of whether the use of the radar gun was consistent with Kyllo had been fully briefed and argued by both sides, and thus there was no reason not to firmly state that the use of this device to establish probable cause violates the Fourth Amendment.  Instead, the court decided to avoid the issue and save it for another day.  This inevitably means that in some future case, a law enforcement officer will use a radar device to establish probable cause in the fruitless hope that this kind of surveillance is constitutional–with the result that the defendant’s conviction will be overturned and a criminal will walk free.  Stronger guidance on this point might have avoided that unfortunate result.

In  Griffin v. Wisconsin and United States v. Knights, the Supreme Court upheld warrantless searches of the homes of probationers as justified by the Fourth Amendment’s “special needs” doctrine.   According to the Court, probation conditions served two purposes: rehabilitation and protecting society from future criminal violations by the probationer.  Under the creative logic of the special needs doctrine, these are purposes unrelated to crime control and thus the usual requirements of warrants and probable cause to not apply to law enforcement searches of probationers.  Also, probationers (like school children) have a lesser Fourth Amendment privacy interest than ordinary citizens.  The Supreme Court also noted that in both Griffin and Knights, the sentencing court had explicitly set out a probation condition that allowed the police to conduct a warrantless search the probationer’s home.   But the Court left open the question as to whether or not the constitutionality of the warrantless search depended on such an explicit condition, or whether the non-law enforcement purpose and reduced privacy interests of probationers alone was sufficient to permit such searches.

The Fifth and Eleventh Circuits ruled that probationers could not object to warrantless searches of their home even if this was not an explicit condition of their probation, but recently the Fourth Circuit came down on the other side of this issue.   In United States v. Hill, 13-4806 (4th Cir. 2015), the court held that the probationers’ knowledge of the warrantless search condition in Griffin and Knights were “critical” to the Supreme Court’s determination that the probationers had a diminished expectation of privacy in their home.   (A pre-Griffin case in the Fourth Circuit had already come to this conclusion, and the Fourth Circuit determined that none of the Supreme Court case law since then had explicitly overruled this principle).   Thus, the police officers violated his rights when (acting with what was likely only reasonable suspicion) they entered his home with a drug dog and found narcotics behind a ceiling tile in the bathroom.

This creates a circuit split on this issue, though the issue is narrow enough that it seems doubtful that the Supreme Court will take notice.  Meanwhile, the Fourth Circuit decision is unlikely to result in a significant setback for the government; the most probable effect of the ruling will be that prosecutors in the Fourth Circuit will now simply seek to add a warrantless search condition to every probationary sentence.