Author: Lior Strahilevitz & Matthew Tokson


The Path to Carpenter v. United States and Possible Paths Forward

Thanks to Matt Tokson for posting his thoughtful and smart reactions to the Carpenter case. I offered some less thoughtful and less smart thoughts about Carpenter earlier on Friday. After reflecting on the case over the weekend, I thought I’d offer a little bit more analysis of how the Court got here and where things are going from here.

1. The Forgotten but Major Role of Douglas Ginsburg and the DC Circuit. Casebooks generally focus on Supreme Court cases rather than lower court opinions in cases where the Supreme Court ultimately weighed in, and that’s understandable. But the intellectual heavy lifting in the case that would ultimately become known as Jones was done by the lower courts, and in particular by Judge Ginsburg’s masterful and at-the-time radical 2010 opinion in United States v. Maynard. (The case’s name changed by the time it made it to SCOTUS, but it’s the same dispute.) Here’s a post from Orin Kerr in the immediate aftermath of  the Maynard decision, which he described as “potentially revolutionary” but unpersuasive. To be sure, not everything that Judge Ginsburg wrote in Maynard eight years ago has come to pass, and the Carpenter Court is conspicuously less enthusiastic about the mosaic theory than the Jones concurrences were. But the idea that a comprehensive record of someone’s movements over time is deeply sensitive information got its most articulate defense by the DC Circuit, the DC Circuit opinion focused on the reasonable expectations of privacy analysis that was echoed in Carpenter rather than the narrower property theory that the Court ultimately adopted in Jones, and the fact that the opinion was the product of three of the country’s most widely respected appellate jurists (Ginsburg, Tatel, and Griffith) must have gotten the attention of Chief Justice Roberts, who served on the circuit court alongside all three (albeit briefly in the case of Judge Griffith.) With the benefit of hindsight I think we can now conclude that Maynard turned out to be “revolutionary” rather than “potentially revolutionary.” Maybe the Supreme Court would have eventually gotten to the same result in Carpenter anyway, but it’s entirely possible that the recent history would have played out very differently. And in remembering the role of the DC Circuit we should also note the contributions of Maynard’s court-appointed counsel (Sicilia Englert and Stephen Leckar) as well as the amici (the ACLU and EFF) in shaping the DC Circuit’s thinking. Maynard is worth a read or re-read for those seeking to understand how we got to Carpenter. 6/27 Update: Upon further reflection it’s worth noting that Judge Ginsburg’s opinion also anticipates the positive law model moves that Justice Gorsuch would later make in Carpenter, using several privacy tort law precedents (such as Nader and Galella) to develop the case for the idea that the Fourth Amendment protects geolocation privacy.

2. Where we go from here? I was curious about a hypothetical scenario after Carpenter and ran a very unscientific Twitter poll with the following scenario.

Here’s a hypothetical: Witness sees Uber black car speeding away from hit & run accident scene in NYC but doesn’t see plate or driver. Govt wants Uber to give it names of Uber drivers who were near scene at the time. After Carpenter does the government now need a search warrant?

The 41 people who responded split 20-21. I don’t want to make much of this kind of survey, but it’s a fun result. And I think there are very strong arguments in either direction. Uber drivers almost certainly have more situational awareness of their location being tracked by Uber than ordinary Americans do of their locations being tracked via cell towers. Matt’s research provides us with great data on the latter question. On the other hand, for an Uber driver sharing this information with Uber feels a little bit more free-choicey than the “choice” to use a cell phone, as nobody has to be an Uber driver, and for some of the drivers Uber presumably is only getting geolocation information while the drivers are using the app / on-the-clock, so the information collected isn’t quite as comprehensive. (I’m not an Uber driver so I don’t know for sure that drivers can turn off location services while they aren’t using the app. Consumers can do so.) And here the government just wants geolocation information at one moment in time, not over a long period of time.

If the government wants to figure out which Uber drivers were near the hit and run in question it is not at all clear that it can get a search warrant – there must be (at least) hundreds of black cars in New York and the car in question could be driven by any of their drivers. This hypothetical is essentially a slightly narrower version of the tower dump hypothetical about which the Court explicitly reserved judgment in Carpenter. It wouldn’t surprise me if the Court ultimately determines that cell tower dumps fall on the “search” side of the Fourth Amendment and these kind of “Uber dumps” fall on the non-search side under Miller and Smith.

Speaking of tower dumps, it will be interesting to see where Justice Gorsuch goes in those kinds of cases. From his opinion, it seems like he is still working these sorts of scenarios through and wants the benefit of briefing. From the positive law perspective, is using cell tower dumps to identify all the phones that were turned on within a half-mile radius of a tower a violation of one’s property rights? Probably, but the task of deciding is made harder by the lack of precedents. In the founding era, it would have been impossible for law enforcement to identify all the people within a half mile radius of a spot in Manhattan, especially when many of those people were indoors. So from the Gorsuch perspective, the government is turning peoples’ phones into an instrumentality for revealing their location, in some cases against their expectations and their wishes. Maybe that’s equivalent to a trespass to chattels? Justice Thomas, by contrast, would say that there’s no Fourth Amendment search of an individual here because cell phone carriers are collecting the information for business purposes and any property rights in the information belong to the companies rather than the cell phone users.

3. Hard issues for Gorsuch to work through. One of the things to admire about Justice Gorsuch’s dissent in Carpenter is that he is candid about what he has and hasn’t concluded. It is pretty clear that he is rejecting the third party doctrine, although not so much on originalist grounds as on the grounds that it does not comport with ordinary Americans’ actual intuitions. His discussion of Florida v. Riley (“Try that one out on your neighbors.”) and California v. Greenwood (“I doubt, too, that most people spotting a neighbor rummaging through their garbage would think they lacked reasonable grounds to confront the rummager.”) imply as much. Yet elsewhere in the opinion (page 7 of the slip op.) he also suggests that legislatures, not courts, are likely to have the best intuitions about peoples’ expectations. (He might be right about that if search-and-seizure law was written on a blank slate. But legislatures know that the courts have made themselves responsible for the bulk of criminal procedure law fine-tuning, and legislatures have devoted less attention to these issues than they otherwise would as a result. There are obviously some exceptions.)  That’s not hypocrisy. It’s just an indication of what Matt said earlier – criticizing Katz is easier that developing a better alternative.

An even bigger challenge for Justice Gorsuch will be to decide what kind of positive law matters. Baude and Stern are very clear that they would include not only property law but also tort law and general purpose statutes as legal content that informs the Fourth Amendment’s scope. Justice Thomas embraces the narrower conception (property law only) and it seems that Justice Gorsuch is inclined to go broader. But how much broader? As broad as Baude and Stern? He doesn’t resolve that question in his opinion. And what if a statute bars some actors but not the government from engaging in conduct? For Baude and Stern, such a statute still brings conduct within the scope of the Fourth Amendment. But does it for Gorsuch? With the Court’s present composition, there are presumably going to be some cases where the Chief Justice parts company with the more liberal justices, and Gorsuch’s determination of how much positive law to include could prove decisive in a number of cases. Scholars like Baude, Stern, Richard Re, and others have made significant progress on those questions, but Gorsuch is someone who pays attention to what’s happening in legal academia, so this is a spot where contemporary scholars with big ideas can have a major impact.

— Lior Strahilevitz



8 Takeaways From Carpenter

Thanks to Lior for his excellent overview and thoughts on Carpenter.  I gave some initial reactions on Twitter (@mtokson) and what follows are some still-preliminary thoughts.  It will take a few days to fully process Carpenter, one of the most important Fourth Amendment cases of the past several decades.  Here are some of my takeaways:

  1. Riley-esque. In general, the majority opinion reminded me of Riley v. California.  It recognized the unique privacy issues posed by cell phones and acknowledged the need to update Fourth Amendment law to address new surveillance technologies.  Ultimately, as Lior pointed out, the majority gave little in the way of concrete doctrine to guide future courts in determining when the third party doctrine should apply.  In some ways it also reminded me of the Katz majority – a largely normative opinion reaching what is generally acknowledged as the correct outcome but not really giving a rationale that can be traced to existing doctrine.  It is certainly a step in the direction of more overt normativity (in this case, a focus on how intimate cell phone data can be).  But it largely affirms existing doctrine, including Katz, Smith, and Miller, creating an exception to the third party doctrine rather than abandoning it.  Of course, that exception may ultimately swallow the doctrine.
  2. What is the Test? To the extent there is a test or legal standard to be discerned from Carpenter, I would state it something like: the third party doctrine does not extend to especially revealing or invasive forms of information, such as information that can reveal a citizen’s whereabouts for the past 5 years.  Perhaps the key doctrinal line is, “In light of the deeply revealing nature of CSLI, its depth, breadth, and comprehensive reach, and the inescapable and automatic nature of its collection, the fact that such information is gathered by a third party does not make it any less deserving of Fourth Amendment protection.”  This is a very fact-dependent and in some ways unique exception to the third party doctrine.  Most information disclosed to third parties is disclosed more voluntarily and less automatically than CSLI.  Nonetheless, this standard suggests that many forms of digital information will ultimately be protected by the Fourth Amendment, because they are especially revealing and/or especially comprehensive.  License plate or facial recognition monitoring seem to fit this description nicely, as Lior and others have suggested.  Web surfing data and speech recorded by a home speaker like Alexa are likely revealing and comprehensive enough to fit as well.  And every Justice with the possible exception of Thomas seems ready to protect email content via one theory or another.  This is why Carpenter is a huge victory for privacy despite its relatively vague and narrow holding.
  3. Roberts Gets It. Again as in Riley, Chief Justice Roberts seemed to grasp the threats to privacy that a new technology poses.  He understands that any suspect, indeed any person, “has effectively been tailed every moment of every day for five years, and the police may—in the Government’s view—call upon the results of that surveillance without regard to the constraints of the Fourth Amendment.”  This long-term, total surveillance is precisely why historical CSLI is so dangerous to privacy.  Roberts’s recognition of this also makes me less concerned about the Court’s failure to hold that historical CSLI tracking for less than 7 days is a search.  I expect they would so hold, if the appropriate case arises.
  4. Justice Thomas Is Not a Katz Person. Justice Thomas shocked me with his attack on both Katz’s test and its holding.  These days, very few people defend Olmstead or argue that the Fourth Amendment does not prohibit warrantless wiretapping.  Yet that appeared to be the thrust of Thomas’s argument.  I ultimately find it hard to disagree with Thomas that a strict originalist/textualist interpretation of the Fourth Amendment supports Olmstead and unfettered government wiretapping.  (I discuss this issue in detail in my recent paper on legal indeterminacy).  But I think the prevailing interpretation of “persons, houses, papers, and effects” as illustrative is a reasonable one.  And Thomas and I have very different views about precedent and constitutional interpretation in general.
  5. The Power of the Jones Concurrence. I counted at least 5 mentions of the Alito-plus-4 Jones concurrence in the Carpenter majority opinion, and even that understates the degree to which Carpenter leans on that concurrence.  Many thought that the Jones concurrence placed the cornerstone of a new Fourth Amendment approach, and I think that prediction is being borne out.  For one thing, holding that the government cannot track its citizens via GPS beeper but can track them via cell phone signal would be an arbitrary, bordering on absurd, result.  Although there is a colorable doctrinal argument for it, as Justice Alito’s dissent demonstrates.
  6. Echoes of Kyllo. I was struck by the echoes of the Kyllo case throughout the majority opinion.  The opinion glosses over the fact that the CSLI in Carpenter’s case wasn’t especially revealing or precise because, like Kyllo, it is concerned with future applications of the technology as well as past ones.  It assesses cell phone tracking in general, as a technique, rather than limiting its analysis to Carpenter alone.  The Court should be applauded for doing so, as it was largely applauded after Kyllo.  Too often, the Court focuses exclusively on the transaction at issue, even though the implications of its decisions reach virtually every application of a given surveillance technique.  If the government can search Greenwood’s trash, it can search everyone’s trash.
  7. Subpoenas. Justice Alito correctly points out the potentially massive importance of the majority’s conclusion that subpoenas are still searches if they implicate a suspect’s reasonable expectations of privacy.  The ‘subpoena exception’ has been a concern of Fourth Amendment scholars for many years.  As Alito points out, however, the Court still needs to reconcile its holding here with the general rule that subpoenas in civil and criminal cases alike require neither a warrant nor probable cause.  There is a potentially large mess here yet to be cleaned up.  Still, the majority (and Justice Gorsuch) are surely correct that subpoenas cannot be allowed to wholly circumvent Fourth Amendment protections for “papers.”
  8. 34 Questions. Justice Gorsuch’s well-written and sharp dissent raised more questions than it answered.  In fact, I counted 34 questions in the 21-page dissent.  Gorsuch gestured towards a positive law approach, a property-based approach, and an analogical approach, but in general the lack of concrete guidance in the dissent points to a universal truth of Fourth Amendment law – it’s far easier to critique the Katz test than to develop a workable alternative.  In the end, I can’t see any way to say that Carpenter has a genuine property right in his CSLI or in any records that Sprint made containing such information.  A meaningful concept of property simply doesn’t extend that far.  I also worry that a rigorous property-based approach ultimately leads to Thomas’s position, and from there to unfettered government surveillance in all sorts of areas.


-Matt Tokson


Ten Thoughts on Today’s Blockbuster Fourth Amendment Decision – Carpenter v. United States

Today the Supreme Court decided that the government generally needs a search warrant to obtain historic cell-site geolocation information. You can see Orin Kerr’s post — no doubt the first of many — for a helpful breakdown of the votes and holding, plus thoughtful analysis. In this post I am going to flag ten quick and initial reactions to the Court’s landmark ruling. Matt Tokson will follow-up with thoughts of his own, so you should stay tuned for those.

  1. From a pedagogy perspective, this case is loads of fun, and an editing challenge. If I were in charge of a casebook I’d want to assign most of the Kennedy, Thomas, and Gorsuch dissents, along with the majority opinion, and excerpts from the Alito dissent. Every Criminal Procedure or Privacy professor can look forward to “I can’t believe how much reading you assigned for the Carpenter class” on teaching evaluations.
  2. It’s good to be the Chief. At many points the majority opinions echoes Justice Sotomayor’s concurrence in Jones (and the Chief Justice’s opinion in Riley). I think had Justice Sotomayor written the majority opinion she would have written something that was a lot more intellectually satisfying by tackling some of the hard questions that the dissents raised and by pointing to the scholarship and theory that built the intellectual case for the majority’s bottom line. The dissents, especially the Thomas and Gorsuch opinions, use Fourth Amendment scholarship to explain exactly where they are coming from, whereas the majority opinion very conspicuously avoids that kind of engagement. The result is a majority opinion that’s cryptic, by design. The majority text and approach are consistent with the Chief’s dim views about legal scholarship generally and with his stated preference for minimalist decisions. My suspicion is that none of the other four justices in the majority would have written the opinion like the Chief Justice did, but they were happy to get a hugely consequential win and avoided writing separately for that reason.
  3. Nate Wessler’s time machine metaphor worked beautifully. Wessler, arguing the case for Carpenter, in I think his first ever SCOTUS oral argument, put on a virtuoso performance. His strongest moment was his invocation of the “time machine” idea – it’s one thing for the government to know where you are now, but quite another for it to go back in time and determine all the places you’ve been during the past few weeks or months. What’s interesting is that this argument is in tension with the structure of electronic surveillance law. Under the federal Stored Communications Act, email communications that have been stored for more than 180 days may be obtained by the government with only a subpoena or court order (with notice), whereas a warrant is required for the government to access stored communications that have been in storage for 180 or fewer days. The idea embedded in the statute is that it’s more intrusive for the government to know what’s happening now or recently than what happened long ago. Wessler’s time machine metaphor flipped this idea around and Chief Justice Roberts and the majority bought it. See, e.g., page 13 of the slip opinion (“With access to CSLI, the Government can now travel back in time to retrace a person’s whereabouts.”). Lawyers everywhere should start echoing the same theme, and the Wessler / Carpenter time-machine metaphor could influence Congress going forward as it legislates with respect to electronic surveillance. UpdateAs Kiel helpfully points out in the comment below, and as I failed to realize, the time-machine argument originated with my law school classmate, Professor Stephen Henderson, in this paper: Kudos to Stephen! Let’s call it the Henderson / Wessler / Carpenter metaphor going forward.
  4. Two Models of Fourth Amendment Protection. There are basically two theories of what constitutes a search operating in the majority opinion, with the key language on page 15. Collecting cell site location information is a search because it’s unexpected and it’s a search because it’s sensitive. The key language for the former, what Orin Kerr calls the “probabilistic model” is this: “Unlike the nosy neighbor who keeps an eye on comings and goings, they are ever alert, and their memory is nearly infallible.” The sentence that follows immediately articulates Kerr’s “private facts model” — “There is a world of difference between the limited types of personal information addressed in Smith and Miller and the exhaustive chronicle of location information casually collected by wireless carriers today.” The application of the probabilistic model would have been strongly supported by extensive survey research on what people actually expect, and given that the scholarship was brought up twice at oral argument (including a Matt Tokson shout-out) it’s plausible that the scholarship influenced the Chief Justice and the majority, but no one should be surprised that the Chief Justice didn’t want to rely on actual data and preferred to rely on a folksy intuition instead. The intuition is consistent with all the survey research, and not citing the data lets the Chief be noncommital on the methodological question of how to apply the Katz test. (Contrast Justice Gorsuch’s approach, in bullet point 8 below.) The majority’s application of the private facts model is the weakest part of the majority opinion. Justice Kennedy skewers the majority for failing to explain why cell site location information is more sensitive and revealing than pen registry information. As does Justice Gorsuch (pg. 3 – “Why is someone’s location when using a phone so much more sensitive than who he was talking to (Smith) or what financial transactions he engage in (Miller)? I do not know and the Court does not say.”) All the majority says (on page 16) is that “telephone logs reveal little in the way of ‘identifying information.’ … In mechanically applying the third-party doctrine to this case, the Government fails to appreciate that there are no comparable limitations on the revealing nature of CSLI.” This distinction is wafer thin. As Justice Kennedy suggests on pages 17-18 of his dissent, a comprehensive record of everyone you’ve called and how long you’ve spoken with them reveals a great deal about who your intimates are, often allows inferences about what was said, can identify associations that people are taking steps to keep secret, and reveals information sensitive information about other people (the recipients of those calls). The line the Court is drawing becomes an indelible part of the Constitution’s meaning, but we shouldn’t kid ourselves in thinking that it’s grounded in any hard evidence or strong theory. And that should make us think it’s a line that could get erased before too long.
  5. The Missing Two Models of Fourth Amendment Protection. What of the Positive Law Model of Fourth Amendment Protection and the Policy Model? The Positive Law Model (the idea that property rights and other aspects of state law determine what is protected against Fourth Amendment searches) is treated as largely irrelevant here, with a quick brush-off in footnote 1 on page 5 of the majority opinion. Justices Thomas and Gorsuch are much more enthusiastic about the positive law model and would make it the only test or the primary test for determining the scope of the Fourth Amendment, respectively. The Policy Model, involving a tradeoff between costs and benefits of government surveillance, is nowhere to be seen in the majority opinion. The result of Carpenter is that law enforcement investigations will get much more difficult, and the police will have to curtail their use of particular surveillance techniques after this decision. This consequence is something the dissenters bemoan, but the majority basically shrugs and says what the Court said in Riley – “get a warrant.”
  6. Is Katz a Dog? Justice Thomas says we should get rid of the Katz test. His is a very lively opinion. Neither Gorsuch nor Alito join him, though Gorsuch expresses some sympathy. Justice Thomas was very generous to cite an article that Matthew Kugler and I wrote on page 17. Then on page 19 he embraces a view of Fourth Amendment circularity that is called into doubt by the same article he cited and mostly refuted by its subsequent companion piece. Maybe this is why the Chief Justice is reluctant to cite legal scholarship. Look, any reliance on scholarship is going to be selective – that’s the difference between opinions and scholarship, and even strategic selectivity is less concerning in a dissent than in a majority opinion. So my quibbles notwithstanding, Justices Thomas and Gorsuch deserve credit for engaging with some of the key pertinent scholarship and taking important ideas seriously.
  7. Which Alito? With Justice Alito, the big question heading into this case was always which part of his Jones concurrence would control – the part viewing the installation of a GPS tracking device as a clear search, or the part calling out for legislative rather than judicial resolution of these kinds of questions. The answer seemed very clear after oral argument and it’s manifest in his opinion. Legislatures, not judges, should be making these judgments. Congress did that here through the statute and the justices should stay out of the way.
  8.  Gorsuch is asking the big questions. I think the majority reached the right result in Carpenter for many of the right reasons. That said, I’m a fan of the Gorsuch dissent, and it’s certainly my favorite of the five opinions. A lot of law students are going to really love it and find the candid analysis clarifying and tantalizing. Justice Gorsuch is doing what a lot of Fourth Amendment scholars have wanted the Court as a whole to do for a long time — examine in a clear-headed way the meta question of how the Court decides whether something is a search. Here too, though, we can quibble with Justice Gorsuch in some respects — he spends some time talking about the foundational piece of empirical Fourth Amendment search scholarship – Slobogin and Schumacher’s fabulous Duke Law Journal paper and uses its data to note that “judicial judgments often fail to reflect public views.” It is true that Slobogin and Schumacher point to some divergences, but to me the main take-away of their piece is that the public largely agrees with much of the search hierarchy that the Court has built, with a few exceptions like the government’s use of undercover agents. If you think that judge – citizen divergences are the rule rather than the exception it is a lot more tempting to toss overboard the probabilistic approach to the Fourth Amendment’s scope. But the data from Slobogin and Schumacher and subsequent work by others strongly suggests that those divergences are more the exception than the rule. In any event, the influence of Baude and Stern’s Positive Law Model on Justice Gorsuch is obvious, and he gets bonus points for even staying current with the SSRN draft of a forthcoming Stephen Sachs piece.   
  9. Wither the third party doctrine? The most important sentence in Justice Gorsuch’s opinion appears at page 20: “Nor can I fault the Court today for its implicit but unmistakable conclusion that the rationale of Smith and Miller is wrong; indeed, I agree with that.” Justice Gorsuch is going to be on the Court for a very long time and he is signaling that in a properly presented case he will reject the third-party doctrine. That’s huge. What is less certain is whether his characterization of the majority opinion is apt. I suspect his description applies to some but not all of the justices in the Carpenter majority.
  10. A New Fourth Amendment. At the end of the day, it’s that last point about the third-party doctrine that is the real show-stopper. Carpenter upsets the apple cart of Fourth Amendment jurisprudence in a fundamental way. In some previous cases the lower courts had pushed back against the third party doctrine (think of Warshak – the 6th Circuit’s email case, to which the DOJ acquiesced) or individual justices had done so in concurrences (Justice Sotomayor in Jones, most famously), but presumably many scholars are going to regard Carpenter as the beginning of the end for the third-party doctrine. Verizon and AT&T and Apple and Google and Amazon are collecting an enormous quantity of sensitive information about all of us, and the Supreme Court is now saying explicitly that our sharing of that information with these companies is not tantamount to consent that it be shared with the government. We are moving towards a world of the Internet of Things, automated license plate readers, proliferating facial recognition software, drone delivery, connected self-driving cars, and rapid further technological change. The lengthy Carpenter opinions are a treat to read. But they will be the gift that keeps on giving — Today the Court just made Fourth Amendment law a lot more interesting for the next decade or three.

— Lior Strahilevitz


Quick Reactions to Today’s Carpenter Oral Argument – Post 2

[Lior Strahilevitz (Chicago) and Matt Tokson (Utah) have been blogging about Carpenter v. United States all week.  Below are Matt’s thoughts about the Carpenter oral argument and his reply to Lior’s previous post on the Carpenter oral argument. 11/30 update: Lior’s replies to some of Matt’s questions and arguments are italicized and in brackets.]

Hi Lior – I was thrilled about the shout outs for our Empirical Fourth Amendment Scholars’ brief and my Northwestern University Law Review article during today’s oral arguments, at pages 17 and 48 of the transcript.  In fact, I blame my delay in posting on all the excitement this has generated.  I look forward to your piece on the effects of this decision on public expectations of privacy.

I too was struck by Justice Kennedy’s quip on page 26 that if he knows that cell phone companies collect location data, everyone else must too.  (It followed a more serious assertion that “almost everybody” knows that their cell phone companies store their location data.)  It’s not just that we have survey evidence that shows most people don’t know this.  But Justice Kennedy is in the economic and educational elite, a group that likely knows far more than the average Joe about technology and surveillance.  More to the point, he’s a judge hearing a case about the specific technology.  So of course he’s heard of it.  As I describe on page 172 of my paper about knowledge and the Fourth Amendment,  judges do a poor job of assessing societal knowledge, in part because they are humans and humans tend to automatically (and irrationally) impute their own knowledge to other people.  Assuming that it was meant to be taken seriously, this is a very clear example of that phenomenon.

Like you, I was intrigued by the question of property rights in third party cell phone records.  As sympathetic as I am to the idea that people have a strong interest in their cell phone records, one that is protected to some degree by statute, I confess I don’t see how to characterize this as a property right without distorting the concept of property.  Lior, did you have any thoughts on Carpenter’s attorney’s brief mention of trade secrets in his back-and-forth with Gorsuch? That struck me as a potentially interesting analogy. [Lior chiming in: I don’t see how the trade secrets analogy gets Carpenter any traction in this case. Trade secrets are private information that have commercial value to a firm, so when we’ve seen trade secrets analogies arise in Fourth Amendment cases it’s involved things like aerial surveillance of a chemical plant, as in Dow Chemical. Carpenter’s cell phone carrier has a trade secret interest in the data, but the interest is limited by the Stored Communications Act and the carrier isn’t asserting such a proprietary interest in this litigation. That does not mean that Carpenter loses under the positive law model. Will Baude argues here and Richard Re argues here that Carpenter should win under the positive law model. I just think if they win it’s going to be on something besides a trade secrets rationale. That said, Justice Gorsuch’s line of questioning suggests he might have something up his sleeve. Maybe him and his law clerks have combed through Michigan property law and come up with a really helpful precedent for the property rights perspective.]

Let me highlight a few other themes from the oral argument.  First was that none of the Justices seemed to care for the mosaic theory pushed by Carpenter’s counsel.  Even the Justices that appeared to favor Carpenter noted that it was tough to draw a conceptual line between 1 day of historical cell phone tracking and 100 days.  Maybe they shared the intuitions of the people surveyed in Lior and Matthew Kugler’s study on the mosaic theory. [Lior again: I don’t think that’s the explanation. In Jones five justices seemed to have intuitions that were very much in line with the mosaic theory, and with Judge Ginsburg’s eloquent articulation of it in the DC Circuit. But in the intervening years they might have come around to the view that making the mosaic theory into workable doctrine is very hard, as Orin Kerr and other scholars have suggested.] In this case at least, I think the Justices are correct to eschew the mosaic theory.  With historical location surveillance, the potential scope of surveillance, and the resulting chilling effects, extend for years.  So even if the police only track me for 1 day, I would be subject to tracking for my entire life, or at least as far back as records are kept.  Justice Roberts seemed sympathetic to this view in his remarks on page 12.

Second, the most successful argument made by the government and the Justices sympathetic to its position was that Smith and Miller are expansive precedents and the surveillance they allow is no worse than that of limitless location tracking.  I think the amicus brief filed by the Scholars of Criminal Procedure and Privacy did a great job of explaining the distinctions between those cases and Carpenter.  For instance, information technology and infrastructure has changed radically since the 1970s; those cases involved voluntary and knowing transmissions of information and Carpenter very likely does not; cell phones, unlike land lines, can be tracked even if the user takes no action, etc.  But even setting those distinctions aside, it would be perfectly appropriate for the Court to declare that the principles of Smith and Miller are obsolete and that their questionable holdings will be upheld simply as a matter of stare decisis.  Indeed, one aspect of Miller might be eliminated as simply untenable.  Justice Alito notes on page 5 that things like credit card receipts can reveal a great deal about a person’s movements and habits.  And he’s right.  The Court might consider limiting the scope of Miller to less revealing and less intimate bank records and account information – perhaps by signaling a willingness to do so in this case and then waiting for a defendant to challenge the warrantless collection of credit card records in a later case. [Lior: This is a very good point. One of the things I keep thinking about is the discussion in Riley of how the process of getting a warrant has changed. As the Chief Justice mentioned in Riley and McNeely, magistrate judges can authorize searches that arrive via email very quickly on an iPad. That wasn’t true in 1979. So maybe the Court sees the transaction costs of getting a warrant falling and the probable cause standard as appropriately protective of privacy interests. There probably was probable cause in Smith v. Maryland, and in Carpenter, for that matter. So maybe this will be another “get a warrant” kind of opinion that signals trouble for the 1970s era third party doctrine precedents in future cases.]

More broadly, Breyer seems to endorse the idea that more sensitive and personal data will be protected, while less sensitive data may not be, on pages 66-67.  In the end, I would guess that the Court distinguishes Miller and Smith along these lines.

Finally, I am reasonably confident that the Court will wind up favoring Carpenter.  Based on the transcript, I have a hard time seeing Sotomayor, Ginsburg, Breyer, or Kagan siding with the government here, and I think Gorsuch feels strongly that the government cannot obtain these records without violating citizens’ rights.  Chief Justice Roberts has shown himself in cases like Riley v. California to be attuned to the problems that new technologies pose to privacy.  More generally, I think the most important theme of the argument and the case is simply that the Court, and society in general, is uncomfortable with the enormous scope of the power that the government is claiming here.  Justice Kagan on page 69, Justice Gorsuch on page 73, and other Justices as well signal that they cannot endorse the concept that there is no constitutional limit on the government’s collection of even very sensitive information just because it rests in the databases of a third party. [Lior: Maybe. The fun part about this is that we don’t know what cards Justice Gorsuch is holding in his hand. The justices asked lots of hard questions to both advocates. And a majority opinion reversing the Sixth Circuit is going to be a challenging opinion to write, with a lot of heavy lifting, so conference votes could conceivably shift.]

That said, oral argument is no guarantee of how Justices will eventually vote.  I’ll be waiting excitedly to see how the case eventually comes out.




Quick Reactions to Today’s Carpenter Oral Argument – Post 1

Dear Readers,

As you may know, the Court heard oral argument in Carpenter v. United States this morning, and the transcript was posted this afternoon. Matt Tokson (Utah) and Lior Strahilevitz (Chicago) have been blogging about Carpenter all week, so what follows are there thoughts on the argument. Lior will post his thoughts here first, and then Matt will share his thoughts in a subsequent post. The transcript is available here, and the dialogue will provide page references to the transcript.


First off – kudos to Matt, whose ears must have been burning today! The Empirical Fourth Amendment Scholars’ amicus brief that he wrote with Matthew Kugler, Sarah Schrup, Christine Scott-Hayward, and me got a couple of mentions during the oral argument, at pages 17 and 48 of the transcript. Both Carpenter’s attorney, Nathan Wessler, and Justice Sotomayor brought up the brief and the scholarship summarized therein, particularly Matt’s terrific Northwestern Law Review article.  I’m glad the empirical article and brief seemed to be helpful to counsel and at least one justice. Regardless of what the Court decides in Carpenter, it will be fun to see how public expectations of privacy adjust to the decision in real time. That is something that I’ve written about with Matthew Kugler (Northwestern), in an article that the University of Chicago Law Review published this morning. And we’ll have more work like that in the future.

I’ll also take a moment to brag about my Chicago colleague Will Baude, whose Harvard Law Review article with James Stern (William & Mary) pretty clearly shaped Justice Gorsuch’s approach to the case.  If you want to make the point that empirical and theoretical legal scholarship can be helpful to the Supreme Court when it considers hard cases, this was a good day.

Second, I thought I’d highlight a few moments in the oral argument transcript that jumped out at me. I thought the best move a lawyer made in the case was Wessler’s response to questioning from Justices Alito and Ginsburg. Wessler was faced with what I regard as one of the government’s two best arguments – the idea that Congress should determine when reasonable expectations of privacy exist, and they’ve done that in the Stored Communications Act. (The government’s other strong argument is that the Court should just follow Smith and Miller, and view the third party doctrine as dispositive.) That’s an argument that Justice Alito seems partial to, based on his Jones concurrence. Wessler argued (at pg. 19) that we can view Congress as having given law enforcement options – get a warrant when it’s trying to collect particularly sensitive information and a 2703(d) order when it’s getting less sensitive information. Indeed, you can push Wessler’s argument further and say that the government’s reading of the Stored Communications Act arguably renders the section 2703(c)(1)(A) warrant requirement superfluous. Because, after all, why would the government ever seek a warrant when it can just get a 2703(d) order much more easily? Wessler’s argument didn’t occur to me previously, but it really blunts the government’s point, though I’m not at all sure it convinced Justice Alito. That’s excellent lawyering on Wessler’s part, though, a real high point in a fine argument.

Third, I am not sure how to read the laughter after Justice Kennedy’s statement on page 26 that if he knows his cell phone is being tracked via cell tower geolocation and those records are being stored, then most people must know it too. I mean, if he was being sarcastic, then great. Of course an experienced Supreme Court justice who has been an appellate jurist for decades, is extremely well-educated, relatively affluent, etc. is going to know more than the average person, even when it comes to cell phone technology. Only a third of Americans can name even a single branch of government! So I guess I really want to know whether Justice Kennedy was being self-effacing or whether he was being serious. If the latter, then I really wish he would sit down to digest the data Matt collected, which shows how little most people understand about what data their phones collect and the phone companies store. Lawyers have to always keep in mind how unrepresentative our own social networks are of the nation as a whole. Combating that problem is why we collect this data.

Fourth, the Court was struggling a little bit with the question of property rights in stored cell site records. Pg. 55. I’m not sure the ball was advanced very far. As a scholar of both property law and privacy law, I found the discussion intriguing though. I do think there are examples of situations in which a third party might have property rights in information, but the information concerns me so I have some residual property interest in it as well. This was a point that Wessler made in rebuttal. The first example that springs to mind is a photograph of me that a journalist takes without my consent. It is surely the case that if someone breaks into the journalist’s office and steals the photo, then uses the image of me for commercial purposes without my permission, they’ve violated my right of publicity. And that’s true even though I didn’t create the image or even know of its existence. So there are definitely instances where property law (or IP law) explicitly does something like what Justice Gorsuch was suggesting. But I am not sure there is a conversion case that gets us all the way there, so probably the positive law approach requires reasoning from first principles rather than relying on clear common law precedents. (Hobby horse Property professor moment: I was gratified when Justice Alito described the right to destroy property (pg. 56) as a hallmark test for whether someone owns something.)

Fifth, Justice Sotomayor made an interesting argument in distinguishing Miller from Carpenter on the basis that human beings handle deposited checks and other banking information but all the data collected to create historic cell site information was fully automated, so a human being never saw it. I can think of at least one smart scholar who agrees with her.

A final thought. People in the room who have great instincts, like Orin Kerr and Paul Ohm, both seemed to think that Carpenter will prevail based on their tweets. From the transcript I’m less sure about that. But this is an instance where I think that there’s probably a lot of information to be gleaned from body language and tone of voice that doesn’t come through in the transcript.

Matt, what jumped out to you? And what did our readers think?

[See this post for Matt Tokson’s responses.]





The Fourth Amendment Does Not Require “Demonstrative Action” to Protect Privacy

In a previous post, we discussed the test that the Supreme Court will likely use to resolve United States v. Carpenter, the major Fourth Amendment case that will be argued in the Supreme Court tomorrow. We responded to Orin Kerr’s argument that the Supreme Court should not consider people’s actual expectations of privacy in resolving Carpenter. In this post, we will examine Orin’s proposed alternative test and discuss the state of public knowledge about cell phone location tracking.

In Orin’s recent blog post, he discusses the connection between people’s knowledge of cell phone technology and their expectations of privacy in their cell phone’s location. Each of the appeals courts to examine the constitutionality of historical cell phone location tracking has based its decision in part on the extent of societal knowledge about cell phone technology. Controversially, most of these courts, including the Sixth Circuit in Carpenter, have concluded that cell phone users are generally aware that their cell phone companies are tracking their locations and storing records of their movements. This is a somewhat remarkable claim regarding public knowledge of an obscure and complex location tracking technology—and empirical surveys of cell phone users suggest that it is mistaken.

One of us has recently conducted a large-scale survey indicating that Americans are overwhelmingly not aware that their cell phone providers collect location information on them via their cell phones. Indeed, most people do not seem to be aware that their movements can be tracked using their cell phone signals. Accordingly, they do not knowingly disclose information about their movements to third parties.  Nor do they consent to such disclosure, because one cannot consent to something unconsciously or unknowingly.

To his credit, Orin acknowledges the possibility that cell phone users are unaware of cell phone location tracking. He instead argues that users may eventually acquire this knowledge, in which case a decision in Carpenter’s favor on the basis of societal knowledge would eventually become “wrong.”

We have several responses to this.  One is that a decision premised on an accurate assessment of societal knowledge at the time when Carpenter was tracked would not become “wrong” just because people eventually gain advanced knowledge of cell phone technology. Regardless of some hypothetical future defendant’s knowledge, it is fairly clear that Carpenter did not knowingly disclose his movements to a third party, and therefore did not forfeit his Fourth Amendment protections. Carpenter’s contemporaries (i.e., present-day Americans) generally shared his expectations.

Moreover, a large increase in knowledge of cell phone technology is unlikely in the foreseeable future. Public ignorance of even basic science is widespread and persistent. And, as we discussed in our previous post, social science studies indicate that Supreme Court cases have little impact on the perceptions or knowledge of the general public.

In any event, we consider Orin’s proposed alternative test for the Fourth Amendment’s scope to be untenable. Orin argues in Part IV of his amicus brief that the Court should ignore actual expectations of privacy and instead look to whether a citizen has “exhibited” an expectation of privacy by taking affirmative steps to prevent observation. Thus Orin contends that an expectation of privacy must be “demonstrated by an act” in order to receive constitutional protection.

Although Katz himself acted to protect his privacy by closing the telephone booth door before placing a call, a “demonstrative action” test would be a major departure from existing Fourth Amendment law, and an unwelcome one.

Fourth Amendment law is full of examples of courts finding Fourth Amendment protection for information accessible to others, even when the target has taken no demonstrative action to protect it.  Kyllo engaged in no demonstrative action to prevent heat from escaping his house.  Bond engaged in no demonstrative action to prevent the touching of his luggage. Five Justices agreed that tracking Jones’s location via GPS violated the Katz test, although Jones took no affirmative step to prevent the observation of his movements. Most people take no demonstrative action to prevent observation of their emails or the web sites they visit.  Like Carpenter, the people in these examples reasonably expect privacy in their information and belongings. In fact, people who reasonably expect privacy in a given situation may be less likely to take action to protect their privacy, because such action is likely unnecessary. Requiring citizens to take affirmative steps to prevent observation of their information in order to claim Fourth Amendment protection would drastically depart from existing law and substantially shrink the scope of the Fourth Amendment.


Should Fourth Amendment Law Pay Attention to What People Expect? If So, How?

In our previous post we responded to Orin Kerr’s argument that an originalist should vote to affirm the Sixth Circuit in Carpenter v. United States, the blockbuster case that will be argued in the Supreme Court on Wednesday. In this post we will say why we think his attack on the probabilistic model is misguided. Because all the published social science research suggests that average Americans regard warrantless access to historic cell site records as unexpected, the probabilistic model strongly suggests that Carpenter should win his case. As a matter of full disclosure, we were two of the principal drafters of the Empirical Fourth Amendment Scholars’ amicus brief that was filed in Carpenter.  Orin’s brief takes issue with that brief’s approach beginning at page 25 of his amicus brief and in this blog post. In the paragraphs that follow we will explain why we think his criticisms are not persuasive.

It is important to begin with a tip of the cap to Orin for his terrific and influential article, Four Models of Fourth Amendment Protection, which articulated a very persuasive descriptive claim, which is that in its approach to cases involving the question of whether police conduct is a search, the Supreme Court has not applied a consistent methodology. Sometimes, Orin notes, the Court applies a probabilistic model, which asks, if the police hadn’t conducted the surveillance at issue, how likely it is that a bystander would have learned the private information that the defendant is trying to exclude. Sometimes, he notes, the Court asks whether what the government did to gather the information at issue would have violated the target’s legal rights, arising out of property law or perhaps privacy tort law. This is the positive law model. Sometimes, the Court focuses on how sensitive the information sought and obtained was. This is the private facts model. And sometimes, the Court engages in a cost-benefit analysis of the government’s surveillance. Orin calls this the policy model. In many instances, Orin notes, the Court engages in more than one methodology at once. And the Court has at various times approached “search” cases in inconsistent ways, embracing methodologies that were attacked in earlier cases and attacking methods that were embraced in subsequent cases. To many readers of Orin’s seminal article, Fourth Amendment law sounds like a mess.

This messiness has prompted some scholars to argue that the Supreme Court could make Fourth Amendment law more coherent and much more predictable by just sticking with one model. For example, Will Baude and James Stern have argued on both originalist and pragmatic grounds that the Court should just stick with the positive law model in Fourth Amendment search cases. See also Will’s recent blog post. Chris Slobogin has argued that something like the probabilistic model should predominate, though aspects of the policy model also work their way into Slobogin’s balancing framework.  And various other scholars, including one of us, have also embraced a Fourth Amendment jurisprudence where the probabilistic model looms large.

Orin draws very different implications from his paper. Whereas other scholars see maddeningly inconsistent and unpredictable Fourth Amendment law, Orin thinks four models are better than one, arguing that it is optimal for the Supreme Court to mix-and-match different models to different circumstances. Orin argues that there are patterns that help explain why the Court usually favors one model or another, but the Court seems unaware of these patterns and does not inevitably adhere to them. This was true when Orin published his article a decade ago, and it remains true today, even though Orin’s article has already been cited nine times by state and federal courts. We think it’s fair to say that while Orin’s descriptive claim (there are four models) has convinced many Fourth Amendment scholars, his normative claim (there ought to be four models) has won fewer converts.

We think one reason why is straightforward. If everyone agrees that there is one model to determine whether surveillance constitutes a Fourth Amendment search then the fight is limited to what results are dictated by that model. By contrast, if there is a fight over both which model applies and what outcome results from the application of the model, then Fourth Amendment results will be quite unpredictable. This makes it harder for police officers to figure out ex ante what they can do without a warrant and increases the temptation for judges to reach results that are consistent with their ideological priors.

Another reason why we aren’t persuaded by Orin’s normative argument is that hard Fourth Amendment cases often involve areas of overlap between two different models. For example, Orin argues that “the private facts model appears particularly often in cases involving new technologies” (pg. 543) and that “the positive law model tends to govern physical access to houses, packages, letters, and automobiles” (pg. 544). So what is the Court to do in a case like Jones, which involved new technology used to track an automobile? Orin’s framework doesn’t provide a correct answer, and the opinions in that case articulated a mix of private facts arguments, probabilistic arguments, and positive law arguments, which were decisive to the majority.  Or consider various cases involving shared access to a home or car. Are those cases where the positive law model should apply, or the probabilistic model, which Kerr says “mostly surface in investigations that occur in group settings.” (pg. 544)? The Court gets to choose, and its choice will determine the outcome. A choice of four models and no clear rule about which applies makes Fourth Amendment precedent a less meaningful constraint on judges.

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Carpenter v. United States and the Role of Originalism

Orin Kerr is undeniably one of the country’s leading authorities on the Fourth Amendment, particularly its applications to computers and other electronic devices. We have learned a great deal from his scholarship and blogging on these issues, and we admire both the clarity of his writing and the deep reservoir of legal knowledge he brings to these subjects. But we humbly submit that in his blogging and briefing of Carpenter v. United States, a blockbuster Fourth Amendment case that will be argued on Wednesday, he’s missed the mark. In a series of blog posts, we’ll give our own account of the issues presented in Carpenter.

Carpenter concerns the ability of the government to obtain a cell phone subscriber’s historic cell site information without a warrant. As people carry cell phones around with them and use them to make calls, signals from those phones are pinging off the nearest cell phone towers, and their proximity to various towers at differing times of day permits the police to reconstruct the cell phone user’s whereabouts in physical space. Cell phone carriers retain this historic cell site location, evidently for periods ranging between a year and seven years, depending on the carrier. The Sixth Circuit held that no warrant is required for the government to obtain this information from a cell phone provider, and the Supreme Court granted cert.

In a blog post about Carpenter, Orin argues that originalists should probably support the respondents in Carpenter. We have a few points to add to the excellent amicus brief by several legal scholars evaluating the Fourth Amendment’s original meaning.

First, if the question is whether the Founding Fathers would have countenanced law enforcement’s warrantless tracking of an individual’s location for weeks at a time, we suspect the answer is probably not. Or they might have thought that if the government wanted to do that, it would have needed to expend very substantial resources each time, by arranging for round-the-clock tails whenever a surveillance left home. What troubles many about the use of historic cell site records is that it has become very cheap and easy for the government to gather information about many peoples’ whereabouts over a long period of time without them even knowing about it. That gives the government an awful lot of power in a way that exposes a lot of sensitive personal information without a strong government justification for collecting it. One function of the Fourth Amendment is to raise the costs of certain kinds of government searches, precisely so that the government will only elect to expend those resources when they really need the sensitive information at issue. This is a point that Justice Alito’s concurring opinion in Jones makes forcefully, at the beginning of Part V.  (See also this terrific paper by Minzner and Anderson.)  The precise issue of geolocation surveillance didn’t come up during Founding era debates in part because the kind of massive surveillance the government is now engaged in would have been unimaginable, especially in a country without professional police forces and a much smaller government than we have today.

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