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Electronic copy available at: https://ssrn.com/abstract=3209587
INITIAL REACTIONS TO
CARPENTER V. UNITED STATES
Orin S. Kerr*
ABSTRACT
On June 22, 2018, the United States Supreme Court handed
down its much-anticipated Fourth Amendment ruling in Carpenter
v. United States. In the wake of Carpenter, Professor Kerr authored
three extensive blog posts on the decision that appeared at both
Lawfare and The Volokh Conspiracy. This paper presents the three
posts together in the order that they appeared. The first post
explores the basic reasoning of the opinion, the second post
discusses Carpenter’s impact on the law of subpoenas, and the third
post considers the timing of Carpenter searches.
TABLE OF CONTENTS
I. First Thoughts on Carpenter v. United States 1
(June 22, 2018)
II. Does Carpenter Revolutionize the Law of Subpoenas? 6
(June 26, 2018)
III. When Does a Carpenter Search Start 14
– and When Does It Stop?
(July 6, 2018)
* Frances R. and John J. Duggan Distinguished Professor of Law, University of Southern California Gould
School of Law.
Electronic copy available at: https://ssrn.com/abstract=3209587
1
I. FIRST THOUGHTS ON CARPENTER V. UNITED STATES June 22, 20181
The Supreme Court has handed down its long-awaited decision in Carpenter v. United States. The
opinion is only an hour old as I start to write this, but I wanted to offer some initial thoughts that I
will also cross-post at Lawfare.
I’ll do it in the form of a Question and Answer, asking questions you may have and offering
answers as best I can. Also, rather than wait to the end and post all of my thoughts at once, I’m
going to post over time. I’ll start with a few basic questions and add more over the course of the
afternoon.
(1) What Did the Court Rule?
The Court ruled that access to a person’s historical cell site records -- or at least 7 days or more of
cell site records -- is a Fourth Amendment search because it violates the person’s “legitimate
expectation of privacy in the record of his physical movements.” The Court also held that accessing
those records requires a warrant.
(2) Who Wrote the Opinion, and What Was the Vote Breakdown?
The Chief Justice wrote the opinion. It was a 5-4 decision, with the Chief joined by the four liberal-
leaning Justices (Ginsburg, Breyer, Kagan, and Sotomayor). The four remaining Justices dissented
(Kennedy, Thomas, Alito, and Gorsuch). Each of the four dissenters wrote their own dissents,
which may explain why the opinion took so much time.
(3) Is There a Clear Majority Opinion, or Were There a Bunch of Concurrences?
There’s a clear majority. The case was 5-4, but none of the Justices who joined the majority wrote
separately and all joined the opinion in full. The only separate opinions were dissents.
(4) Okay, So What Was the Reasoning of the Majority Opinion?
Relying on the concurring opinions in United States v. Jones, the Court holds that a person has
“reasonable expectation of privacy in the whole of their physical movements.” Access to historical
cell site records violates that reasonable expectation of privacy because it is a “sweeping mode[e]
of surveillance” that gives the government the power of “near perfect surveillance, as if it had
attached an ankle monitor to the phone’s user.” It is “tireless and absolute surveillance.” The
surveillance is “detailed, encyclopedic, and effortlessly compiled.” It “provides an all-
encompassing record of the holder’s whereabouts.” As a result, it violates the reasonable
expectation of privacy people have in their physical movements from the Jones concurrences.
1 This post appeared at the Volokh Conspiracy at https://reason.com/volokh/2018/06/22/first-thoughts-on-carpenter-
v-united-sta. It appeared at Lawfare under a different title at https://www.lawfareblog.com/understanding-supreme-
courts-carpenter-decision
Electronic copy available at: https://ssrn.com/abstract=3209587
2
(5) How Is Accessing Historical Cell-Site Records “Absolute Surveillance”? It’s Not Precise,
and It’s Only Generated When A Call is Made, Right?
This is one of the most interesting aspects of the opinion. Instead of focusing on the facts of this
case, the Court seems more interested in where the technology is thought to be going. The record
in this case indicates that the records only where precise to a range of 0.5 to 2 miles, and that
records where only generated when a call was actually placed. It just reveals the neighborhood the
phone was in when a call was made. But the Chief Justice’s opinion presents the technology as
vastly more invasive and detailed than the record indicates. It is absolute perfect surveillance, in
the Court’s vision, like a GPS device around a person’s ankle
In response to the dissent’s pointing out the record, the Chief Justice says we have to take into
account where the technology is going. “The accuracy of CSLI is rapidly approaching GPS-level
precision,” the Chief Justice predicts, and the Court has to adopt a rule in light of what the
technology will look like then. In effect, the technology isn’t actually perfect and absolute
surveillance now, but the Justices are confident that it is going to be that eventually.
(6) Does Any Accessing Historical Cell-Site Records Count as A Search? Or Is Short-Term
Warrantless Surveillance Permitted?
We don’t know. Regular readers will recall the debate over the mosaic theory, by which perhaps
short-term surveillance is not a search but long term surveillance is, on the thinking that long-term
surveillance lets the governent create a mosaic of a person’s life. That was key to
the Jones concurrences. The Court leaves open that there may be mosaic-based short-term vs.
long-term distinctions for cell-site collection: “[W]e need not decide whether there is a limited
period for which the Government may obtain an individual’s historical CSLI free from Fourth
Amendment scrutiny, and if so, how long that period might be. It is sufficient for our purposes
today to hold that accessing seven days of CSLI constitutes a Fourth Amendment search.”
(7) Might This Reasoning Be Based on Equilibrium-Adjustment?
Indeed! I have written about how the Supreme Court often engages in equilibrium-
adjustment when new technology threatens the balance of government power. If technology gives
the government too much new power that can be abused based on old rules, the Court expands
legal protection to restore old levels of power and limit abuses. On the flip side, if technology
threatens to narrow government power too much that can unduly limit the government’s ability to
solve crimes under old rules, the Court shrinks legal protection to restore old levels of power and
ensure the government can still solve enough cases.
In Carpenter, the Chief Justice is very clear that this what is going on. Throughout the opinion, he
roots his analysis in the idea that cell-site surveillance is a new tool that gives the government new
power that can be abused, and that the law must change course to ensure that the government
doesn’t get too much power from a mechanical application of the old rules.
Here’s The Chief Justice in the conclusion:
Electronic copy available at: https://ssrn.com/abstract=3209587
3
As Justice Brandeis explained in his famous dissent, the Court is obligated—as
“[s]ubtler and more far-reaching means of invading privacy have become available
to the Government”—to ensure that the “progress of science” does not erode Fourth
Amendment protections. Olmstead v. United States, 277 U. S. 438, 473–474
(1928). Here the progress of science has afforded law enforcement a powerful new
tool to carry out its important responsibilities. At the same time, this tool risks
Government encroachment of the sort the Framers, “after consulting the lessons of
history,” drafted the Fourth Amendment to prevent. Di Re, 332 U. S., at 595
There’s another revealing passage when the Chief Justice is responding to Justice Alito on what
the standard should be for accessing the records, assuming that it is a search. After going through
some legal analysis, the Chief Justice sort of stops and says (without using the label), but this is
equilibrium-adjustment! Here’s the paragraph:
JUSTICE ALITO overlooks the critical issue. At some point, the dissent should
recognize that CSLI is an entirely different species of business record—something
that implicates basic Fourth Amendment concerns about arbitrary government
power much more directly than corporate tax or payroll ledgers. When confronting
new concerns wrought by digital technology, this Court has been careful not to
uncritically extend existing precedents. See Riley, 573 U. S., at ___ (slip op., at 10)
(“A search of the information on a cell phone bears little resemblance to the type
of brief physical search considered [in prior precedents].”)
The new technology is a “new phenomenon,” and an “entirely different species” of record. Old
rules don’t apply. Instead, the Court goes back to “the critical issue” of “basic Fourth Amendment
concerns about arbitrary government power” that are “wrought by digital techology.” In other
words, equilbrium-adjustment.
(8) Does This Reasoning Apply Just For Physical Location Tracking, Or Does It Apply More
Broadly?
That’s the big question. On one hand, the reasoning of the opinion is largely about tracking a
person’s physical location. The opinion takes as a given that you have a reasonable expectation of
privacy in the “whole” of your “physical movements.” The Court has never held that, so it’s sort
of an unusual thing to just assume! But the Court seems to be getting it mostly from Justice
Alito’s Jones concurrence, and the idea, as Alito wrote in Jones, that “society’s expectation has
been that law enforcement agents and others would not— and indeed, in the main, simply could
not—secretly monitor and catalogue every single movement of an individual’s car for a very long
period.”
The opinion is mostly rooted in that idea of tracking physical location, and in particular the idea
of near perfect and total surveillance that allows the government to monitor us as if we had GPS
trackers stapped to our ankles. Near the end, the Chief Justice adds a very interesting paragraph
saying that the opinion is narrow. It’s worth reading:
Electronic copy available at: https://ssrn.com/abstract=3209587
4
Our decision today is a narrow one. We do not express a view on matters not before
us: real-time CSLI or “tower dumps” (a download of information on all the devices
that connected to a particular cell site during a particular interval). We do not
disturb the application of Smith and Miller or call into question conventional
surveillance techniques and tools, such as security cameras. Nor do we address
other business records that might incidentally reveal location information. Further,
our opinion does not consider other collection techniques involving foreign affairs
or national security. As Justice Frankfurter noted when considering new
innovations in airplanes and radios, the Court must tread carefully in such cases, to
ensure that we do not “embarrass the future.” Northwest Airlines, Inc. v. Minnesota,
322 U. S. 292, 300 (1944).
(As an aside, isn’t it interesting that collection of cell-site records is a new-fangled surveillance
methid but security cameras are merely “conventional techniques and tools”? Why is that? Because
people can see cameras but not cell sites? But I digress.) In a footnote, he adds in response to a
dissent that “we “do not begin to claim all the answers today, and therefore decide no more than
the case before us.” Perhaps even more significantly, the Chief elsewhere says that it will be “the
rare case where the suspect has a legitimate privacy interest in records held by a third party,” and
that in “the overwhelming majority of investigations” there will be no Fourth Amendment
protection.
So you could look at that language and say that this is a narrow opinion only about perfect location
tracking by Big Brother.
On the other hand, there’s lots of language in the opinion that cuts the other way. Although the
Court “decides no more than the case before us,” it also recasts a lot of doctrine in ways that could
be used to argue for lots of other changes. Its use of equilibrium-adjustment will open the door to
lots of new arguments about other records that are also protected. For example, what is the scope
of this reasonable expectation of privacy in the “whole” of physical movements? Why is there?
The Jones concurrences were really light on that, and Carpenter doesn’t do much beyond citing
them for it: What is this doctrine and where did it come from? (And what other reasonable
expectations of privacy in things do people have that we didn’t know about, and what will violate
them?)
In addition, Carpenter’s view of Miller and Smith is narrower than the opinions
in Miller and Smith suggest. Carpenter suggests that the third-party doctrine is less of the bright-
line rule that the cases suggest and more of a fact-specific standard. At the very least that is going
to invite a boatload of litigation on how far this new reasoning goes.
(9) What’s the Status Of the Third-Party Doctrine?
It lives, but there is an equilibrium-adjustment cap on it. The old understanding was that the third-
party doctrine is a bright-line rule: When you voluntarily disclose information to someone, whether
to an undercover officer or a business you’re working with, you don’t have Fourth Amendment
rights in the recipient’s copy of that information. Chief Justice Roberts says that the third-party
doctrine is more limited than that.
Electronic copy available at: https://ssrn.com/abstract=3209587
5
As I read him, the Chief seems to be saying that there is an equilibrium-adjustment limit on the
third-party doctrine. Once the third-party doctrine starts to give the government massive new
powers, the third-party doctrine may no longer apply. Here’s the key passage:
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 Government thus is not asking for
a straightforward application of the third-party doctrine, but instead a significant
extension of it to a distinct category of information.
Part of the thinking here is an adoption of Carpenter’s rhetoric in his brief that the third-party
doctrine only “diminishes” an expectation of privacy. That’s not what the cases say; the cases say
that the doctrine entirely eliminates an expectation of privacy. But by adopting the idea that the
third-party doctrine only “diminishes” an expectation of privacy, the Court effectively sets up a
hierarchy: Because the information revealed by cell-site records collection is claimed to be vastly
more revealing and sensitive than the records in Smith and Miller, and the surveillance is more
pervasive, the third-party doctrine’s diminishing of privacy still leaves a lot of privacy behind that
is enough to satisfy the Fourth Amendment.
In effect, disclosure is enough to eliminate privacy when the records disclosed only involve a
normal amount of privacy. But when the records are super private and pervasive, disclosure isn’t
enough to eliminate Fourth Amendment rights.
In his dissent, Justice Gorsuch suggests that this means that Smith and Miller are “on life support,”
but I don’t see that in the majority. After all, the Chief says in his opinion that [w]e do not disturb
the application of Smith and Miller.” Rather, the idea seems to be that there’s an equilibrium-
adjustment limit on how far the Justices will take the third-party doctrine. At some point the
surveillance is just too much to allow, and at that point the third-party doctrine doesn’t apply. The
facts of Smith and Miller were on one side of the line, and seven days of this technology crossed
over to the other side.
What other technology and its uses might also cross it? We don’t yet know.
Electronic copy available at: https://ssrn.com/abstract=3209587
6
II. DOES CARPENTER REVOLUTIONIZE THE LAW OF SUBPOENAS? June 26, 20182
The Supreme Court’s decision in Carpenter v. United States has lots of new directions in it. One
direction that some commentators have focused on is its impact on the law of subpoenas. For
example, Marty Lederman writes today that the subpoena analysis in Carpenter is “extraordinary”
and “groundbreaking” and may trigger “a fundamental transformation of national subpoena
practices.” In their dissents, Justice Alito and Justice Kennedy also suggest that the subpoena
analysis in the case is a major break from the past.
I have a different view. There is a lot that is extraordinary and groundbreaking in Carpenter. But
I think Carpenter makes only a small and likely necessary resolution of an unsettled question in
the law of subpoenas. In this post, I will explain the problem and say why I think Carpenter doesn’t
have a major impact on subpoena law. I will also argue that if you think the majority is right on
the law of searches, it is also likely right, at least as to the result, in its subpoena holding.
This is a really long post, so here’s a roadmap of where I’m going.
Part I introduces the two basic kinds of legal process in the law of criminal procedure: warrants
and subpoenas. Part II explains how the dynamic of third-party storage alters the balance of
criminal procedure law on which the two kinds of legal process are based. Part III shows that
when a target has constitutional rights in remotely-stored information, there was a legal uncertainty
before Carpenter on whether the subpoena rules continue to apply – but a good reason, rooted in
a need to maintain the balance of the Fourth Amendment, to think they don’t.
Part IV turns to Carpenter and shows how the majority’s decision responds to the problems
explained in Parts I-III. Finally, Part V argues that the majority’s approach to the law of subpoenas
is only a small and likely necessary resolution of how the subpoena doctrine applies that should
have relatively limited impact on the law of criminal procedure.
I. The Two Paths of Legal Process
Imagine the government believes that a person possesses evidence of crime in his home.
Investigators want to get that evidence. But how? The law traditionally provides two forms of
legal process to do it.
The first path, and the most familiar, is to get a warrant. A warrant authorizes the investigators to
physically break into the place where the evidence is thought to be, rifle through the place, and
take away the evidence they find.
A warrant is the best known form of government legal process in criminal investigations. But it’s
not the only one. The government can also obtain evidence using a grand jury subpoena. A grand
2 This post appeared at the Volokh Conspiracy at https://reason.com/volokh/2018/06/26/does-carpenter-
revolutionize-the-law-of. It appeared at Lawfare at https://www.lawfareblog.com/does-carpenter-revolutionize-law-
subpoenas.
Electronic copy available at: https://ssrn.com/abstract=3209587
7
jury subpoena directs its recipient to bring the described evidence to the grand jury at some future
place and time. Unlike a warrant, the police don’t barge in and take stuff. Rather, the subpoena
recipient is tasked with gathering the evidence himself, from the stuff in his possession, and later
bringing the evidence to the grand jury (or the police/prosecutors working with the grand jury).
Recognizing these two path matters because they are regulated by two very different legal regimes.
When the government gets a search warrant, the Fourth Amendment is the big limit on the police.
The police need to show probable cause to believe that the evidence will be located in the place to
be searched. They need to specifically describe the place to be searched, and they need to describe
specifically the evidence that they are seeking.
The law of grand jury subpoenas for evidence is very different. The Fourth Amendment applies,
but its role is modest. No probable cause is required to issue a subpoena. The government can
issue a subpoena – in the name of the grand jury, but really by the prosecutors who run the grand
jury – just to see if a crime might have been committed. A recipient does have Fourth Amendment
rights at stake, but he can challenge the subpoena only on the ground that it is overbroad or
compliance is overly burdensome.
The flip side is that the recipient of a subpoena can challenge it under the Fifth Amendment right
against self-incrimination. The recipient can claim that complying with the subpoena implies
certain statements – that the records exist, that the recipient has them, and that the recipient thinks
that they are authentic – and that he can’t be forced to testify against himself.
Note the key difference. When investigators want to break in and get the evidence themselves,
they proceed by way of a warrant and the Fourth Amendment is the big legal barrier. When
investigators want to have the evidence produced for them, they proceed by way of a subpoena
and the Fifth Amendment is the big legal barrier. Two different paths with two different legal
regimes limiting government access.
II. What Changes When A Target’s Evidence Is Stored With A Third Party?
Now let’s complicate matters. Let’s imagine that a target of an investigation has stored his
evidence with someone else. Maybe Alice leaves a box of her personal files with Bob to store in
Bob’s basement. Maybe Carl becomes a customer at a mailbox service that receives and stores
his mail for him. Maybe David keeps his files stored in “the Cloud” with an online cloud service
like Dropbox. In each of these cases, the person’s evidence is located far from them in the
possession of another person or company.
Now imagine you’re the government, and you want to collect the suspect’s evidence. That
evidence is now stored with a third party, whether it’s Bob, the mailbox service, or Dropbox. The
question is, how does the fact of third-party possession change the legal framework? What law
applies to collecting the evidence now?
The option to get a warrant and conduct the search directly remains. You could break in and take
the evidence. That would be legal, but it’s probably a bit unseemly. For example, you probably
don’t want local police breaking into Dropbox’s company headquarters and looking through its
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8
servers on their own to find a user’s files. And that wouldn’t be necessary, either, because the
companies are just neutral parties. The police can work with them to retrieve the evidence. So
even if a warrant is obtained, the police would want the third-party providers to gather the
information. In effect, it would be a warrant that is executed like a subpoena.
But that brings us to the key question. Can the government still use a subpoena to get the
information stored with third parties? Can they serve a subpoena on Bob for Alice’s box of files?
Can they serve a subpoena on the mailbox service for Carl’s mail? Can they serve a subpoena on
Dropbox for David’s files?
If you assume that none of the targets have Fourth Amendment rights in the records that they have
stored with third parties, then the answer is easy. Not only can the government use a subpoena,
but there is very little in the way of limits on that power. By hypothesis, the targets have no Fourth
Amendment rights. And unlike with the subpoena stored by the target, there is no Fifth
Amendment privilege to assert. This is a big difference. The Supreme Court held in Fisher v.
United States that the recipients of a subpoena can’t assert the Fifth Amendment privilege of
someone else. In addition, companies have no Fifth Amendment privilege to assert.
This means that if you assume no Fourth Amendment rights for the targets, the fact of third-party
storage greatly shifts the legal terrain: It empowers the government by eliminating Fifth
Amendment protection when the government wants to proceed by subpoena. The only
constitutional limit now is that the possessors of the evidence can try to assert their modest Fourth
Amendment objections based on the burdensomeness of complying with the subpoena. But in most
cases that’s a very limited objection. And because the Internet and communications networks
work using third parties, the shift to third-party storage is a really big deal.
Statutes can certainly come in and try to even the playing field. That’s exactly what the Stored
Communications Act was designed to do. It imposes a court order requirement using the
“reasonable suspicion” standard on access to unprotected records even though the Fourth
Amendment doesn’t apply. But that’s a statute, not the Constitution.
III. The Puzzle of Fourth Amendment Rights in Records Stored With a Third Party
Now we get to the big question: How does the subpoena power apply if we assume that the target
retains Fourth Amendment rights in the records stored with the third party? Imagine Alice has
Fourth Amendment rights in the contents of the box she left with Bob. Imagine Carl has Fourth
Amendment rights in the mail left with the mailbox service. And imagine David has Fourth
Amendment rights in the files stored with Dropbox. Can the government subpoena those records
from the possessor (Bob/mailbox/Dropbox) just like it could if the target had no Fourth
Amendment protection in the records?
Appreciate the importance of the question. If the traditional subpoena rules continue to apply, then
the fact of the target having Fourth Amendment rights in the information doesn’t matter all that
much. The government can still just subpoena all the protected records, and they can do so without
probable cause or even reasonable suspicion. The only apparent impact of finding the target has
Fourth Amendment rights would be that the target has standing to challenge the subpoena. But
Electronic copy available at: https://ssrn.com/abstract=3209587
9
because the only Fourth Amendment limit on the subpoena is the burdensomeness on the recipient
of the subpoena, it’s not clear that the this would matter.
If the traditional subpoena rules continue to apply, then, we end up with a equilirbrium-adjustment
problem: Applying the old law to the new facts of third-party storage may suddenly give the
government a major power advantage by eliminating Fifth Amendment privilege from the
subpoena equation. Technological change could put the government in a position where they could
subpoena everything, with few limits, even if the target of the investigation has Fourth Amendment
rights in the information.
Until Friday’s Carpenter decision, there was surprisingly little caselaw on what legal standard
governed use of a subpoena on a third-party to collect information in which a target has Fourth
Amendment rights. And believe me I have looked, as I’ve been interested in this issue for a long
time. (I wrote an amicus brief partially on this question in 2002, and I had a section about it in the
2006 First Edition of my Computer Crime Law casebook.) The main reason for the absence of
cases is the third-party doctrine. Under the third-party doctrine, targets usually don’t have any
Fourth Amendment rights in the records the government might want to subpoena from the third
party.
The sparse caselaw that does exist has tended to involve subpoenas to compel the possessor to
hand over sealed documents when the government then obtained a warrant to open them. See,
e.g., United States v. Barr, 605 F. Supp. 114, 119 (S.D.N.Y. 1985) (mail box service). But that
doesn’t answer the question of whether a subpoena could be used to open the documents.
In other cases, courts simply said without any analysis that target Fourth Amendment rights meant
that a warrant was required. See, e.g., United States v. Warshak, 631 F.3d 266, 288 (6th Cir. 2010)
(holding that a user has Fourth Amendment rights in the contents of their remotely stored e-mail
and therefore a warrant is required); United States v. Bach, 310 F.3d 1063, 1066 n.1 (8th Cir. 2002)
(noting, in a case involving access to remotely stored e-mail, that the court “analyze[s] this case
under the search warrant standard, not under the subpoena standard”)
Given all of this, the issue of whether a subpoena could be used to access target-protected data
held by a third party was uncertain. For what it’s worth, my own view has been that if you
recognize a target’s full Fourth Amendment rights in the records, then the subpoena standard is
insufficient. As I wrote in a 2010 article (at page 1044), the reason is that a subpoena can compel
a provider to hand over records but it can’t be used to open the constitutionally-protected set of
records obtained. The government could in theory subpoena the records under my view, but it
would still need a warrant to open them. A warrant is still required.
But that was just my view, and until Carpenter there was no Supreme Court discussion of the
question.
IV. The Subpoena Analysis in Carpenter
That brings us – finally! – to Carpenter. Up through page 18 of the Court’s opinion, the majority
concludes that a cell phone user has Fourth Amendment rights in the cell phone provider’s cell site
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10
location records. The next question is what standard the government must satisfy to compel access
to those records. The Chief Justice rather breezily concludes that a warrant is required, finding
that the statutory Terry standard of the Stored Communications Act is insufficient.
The Chief Justice then turns to contrary arguments in Justice Alito’s dissent. In his dissent, Justice
Alito notes that the traditional standard for compelling disclosure is the mere reasonableness
subpoena standard. Because the statutory Terry standard is pretty much a subpoena with a required
finding of reasonable suspicion, Justice Alito argues that the same constitutional analysis should
apply to that court order as traditionally applies to subpoenas.
The Chief Justice disagrees with the following passage. This is the language that some think is a
radical change, so it’s worth reprinting in full:
JUSTICE ALITO contends that the warrant requirement simply does not apply
when the Government acquires records using compulsory process. Unlike an actual
search, he says, subpoenas for documents do not involve the direct taking of
evidence; they are at most a “constructive search” conducted by the target of the
subpoena. Post, at 12. Given this lesser intrusion on personal privacy, JUSTICE
ALITO argues that the compulsory production of records is not held to the same
probable cause standard. In his view, this Court’s precedents set forth a categorical
rule—separate and distinct from the third-party doctrine—subjecting subpoenas to
lenient scrutiny without regard to the suspect’s expectation of privacy in the
records. Post, at 8–19.
But this Court has never held that the Government may subpoena third parties for
records in which the suspect has a reasonable expectation of privacy. Almost all of
the examples JUSTICE ALITO cites, see post, at 14–15, contemplated requests for
evidence implicating diminished privacy interests or for a corporation’s own books.
The lone exception, of course, is Miller, where the Court’s analysis of the third-
party subpoena merged with the application of the third-party doctrine. 425 U. S.,
at 444 (concluding that Miller lacked the necessary privacy interest to contest the
issuance of a subpoena to his bank).
JUSTICE ALITO overlooks the critical issue. At some point, the dissent should
recognize that CSLI is an entirely different species of business record—something
that implicates basic Fourth Amendment concerns about arbitrary government
power much more directly than corporate tax or payroll ledgers. When confronting
new concerns wrought by digital technology, this Court has been careful not to
uncritically extend existing precedents. See Riley, 573 U. S., at ___ (slip op., at 10)
(“A search of the information on a cell phone bears little resemblance to the type
of brief physical search considered [in prior precedents].”).
If the choice to proceed by subpoena provided a categorical limitation on Fourth
Amendment protection, no type of record would ever be protected by the warrant
requirement. Under JUSTICE ALITO’s view, private letters, digital contents of a
cell phone—any personal information reduced to document form, in fact—may be
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11
collected by subpoena for no reason other than “official curiosity.” United States v.
Morton Salt Co., 338 U. S. 632, 652 (1950). JUSTICE KENNEDY declines to
adopt the radical implications of this theory, leaving open the question whether the
warrant requirement applies “when the Government obtains the modern-day
equivalents of an individual’s own ‘papers’ or ‘effects,’ even when those papers or
effects are held by a third party.” Post, at 13 (citing United States v. Warshak, 631
F. 3d 266, 283–288 (CA6 2010)). That would be a sensible exception, because it
would prevent the subpoena doctrine from overcoming any reasonable expectation
of privacy. If the third-party doctrine does not apply to the “modern-day equivalents
of an individual’s own ‘papers’ or ‘effects,’” then the clear implication is that the
documents should receive full Fourth Amendment protection. We simply think that
such protection should extend as well to a detailed log of a person’s movements
over several years.
This is certainly not to say that all orders compelling the production of documents
will require a showing of probable cause. The Government will be able to use
subpoenas to acquire records in the overwhelming majority of investigations. We
hold only that a warrant is required in the rare case where the suspect has a
legitimate privacy interest in records held by a third party.
In his dissent, Justice Alito responds:
[The majority] decides that a “search” of Carpenter occurred within the meaning of
the Fourth Amendment, but then it leaps straight to imposing requirements that—
until this point— have governed only actual searches and seizures. See ante, at 18–
19. Lost in its race to the finish is any real recognition of the century’s worth of
precedent it jeopardizes. For the majority, this case is apparently no different from
one in which Government agents raided Carpenter’s home and removed records
associated with his cell phone.
Against centuries of precedent and practice, all that the Court can muster is the
observation that “this Court has never held that the Government may subpoena third
parties for records in which the suspect has a reasonable expectation of privacy.”
Ante, at 19. Frankly, I cannot imagine a concession more damning to the Court’s
argument than that. As the Court well knows, the reason that we have never seen
such a case is because—until today— defendants categorically had no “reasonable
expectation of privacy” and no property interest in records belonging to third
parties. See Part II, infra. By implying otherwise, the Court tries the nice trick of
seeking shelter under the cover of precedents that it simultaneously perforates.
Not only that, but even if the Fourth Amendment permitted someone to object to
the subpoena of a third party’s records, the Court cannot explain why that individual
should be entitled to greater Fourth Amendment protection than the party actually
being subpoenaed. When parties are subpoenaed to turn over their records, after all,
they will at most receive the protection afforded by [the subpoena cases] even
though they will own and have a reasonable expectation of privacy in the records
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at issue. Under the Court’s decision, however, the Fourth Amendment will extend
greater protections to someone else who is not being subpoenaed and does not own
the records. That outcome makes no sense, and the Court does not even attempt to
defend it.
V. What’s Happening Here, and a (Partial) Defense of the Majority’s Approach
What’s going on here? Although the majority could articulate the point a lot better than it did, I
take it what the Court is doing is engaging in equilibrium-adjustment – one operating over the
combination of the Fourth and Fifth Amendment together.
In a world of local storage, where suspects keep their evidence in their possession, the government
has the two paths explained in Part I. They are limited by Fourth Amendment probable cause if
they want to break in themselves, and they are limited by the Fifth Amendment right against self-
incrimination if they want to compel records. But computers and the Internet are new worlds of
remote storage. A typical Internet user has his protected records stored hundreds or thousands of
miles away in the possession of big companies that have no Fifth Amendment rights and can’t
assert them for their users. Applying the usual subpoena standard when the target has Fourth
Amendment rights would result in a dramatic expansion of government power that would let the
government get everything with few limits.
By insisting on a warrant requirement, the Court is restoring the prior equilibrium. Changing the
legal rule when a third-party has Fourth Amendment rights in the information corrects for the
otherwise distorting effect of third-party storage on the degree of legal protection. The same
warrant rule applies that would apply if this were a traditional case of local storage. In effect, the
Court’s approach collapses the two paths into one when there is third-party storage, which can
account that the factual assumptions on which the legal framework for subpoenas has been
generated– an environment in which targets are protected from subpoenas by the Fifth Amendment
– no longer apply.
To be clear, I don’t think the Justices were thinking about the shift from the Fifth Amendment
protection to the Fourth Amendment protection. I suspect they were just thinking about this as a
Fourth Amendment. But the Chief Justice’s opinion recognizes that you need to have a full warrant
protection for the third-party stored information or else the target’s newfound rights don’t mean
much. As the Chief Justice states, “If the choice to proceed by subpoena provided a categorical
limitation on Fourth Amendment protection, no type of record would ever be protected by the
warrant requirement.”
All of this suggests that the operative legal rule here is that the existence of third-party rights
triggers a higher protection for the third party to restore the equilibrium. As the Court holds, “a
warrant is required in the rare case where the suspect has a legitimate privacy interest in records
held by a third party.” If the government wants to get records that a suspect has stored, without
the help of the suspect, the same warrant protection applies regardless of whether the suspect has
stored the information at home or remotely.
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This understanding illuminates important limits on the Court’s subpoena rule and shows why it
will only apply “in the rare case.” For example, I gather that rule wouldn’t stop the government
from issuing a subpoena to the target for the target’s records that he has stored in the Cloud, for
example. The fact that the records are “held by a third party” doesn’t matter because the
government isn’t getting the records from the third party but rather is going directly to the suspect.
The Fifth Amendment issues would then control, leaving the two paths as they were without third-
party storage.
Similarly, this approach shows why I disagree with this interpretation of Carpenter by Marty
Lederman in his post today:
At a minimum, however, it is fair to assume that questions of the reasonable
expectations of privacy of the “first party” subject of the records sought by
production orders will now play a much larger role in subpoena litigation and other
challenges to compulsory process.
I don’t think that’s right. Or at least I don’t think it shouldn’t be right. As I see it, the first party
subject to the subpoena has all the protections it has always had: Mostly Fifth Amendment
protections against complying with any subpoena under the act of production doctrine. That’s the
traditional two paths described in part one, and I don’t think it changes in a case of local possession.
Carpenter’s subpoena holding reflected a need for equilibrium-adjustment; it shouldn’t change
anything in traditional cases where no equilibrium-adjustment is needed
To be sure, there are some difficult questions of application of the majority’s rule. I explored these
issues a year ago in a long blog post, Third Party Rights and the Carpenter Cell-Site Case. For
example, who gets notice of the government’s access? Who can object? As I wrote then:
Is the idea that a company served with a subpoena for business records has to figure
out if the subpoena implicates only its own Fourth Amendment rights (in which
case the subpoena complies with the Fourth Amendment so long as it is not
overbroad) or if it also implicates a user’s Fourth Amendment rights (in which case
the subpoena is insufficient and a warrant is required?). If the government issues a
subpoena for business records and it turns out that a customer also had rights in the
data, would we say that compelled compliance with the subpoena violated the rights
of the user but not the company?
These are issues to work through, I recognize, but I gather they should apply only in “the rare case”
when a third-party has stored records with a target’s protected information.
All of this is not to suggest that I think the majority’s subpoena holding has it quite right. I would
have probably preferred the Court take the view I suggested in my 2010 article noted above, by
which the government can still technically subpoena the records but can’t open the records without
a warrant. This avoids the conceptual puzzles that Justice Alito notes by having the same rule
apply in all situations: A subpoena can be used to compel records without probable cause, but the
government needs a warrant to open Fourth Amendment protected records. That approach isn’t
perfect, for reasons I explore in my article (see footnote 170). But I think it would be better.
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Finally, I am certainly sympathetic with the concerns of Justice Alito and Justice Kennedy in their
dissents. I think Carpenter’s search holding is wrong. In my view, users don’t have Fourth
Amendment rights in their historical cell-site records. But if you accept that erroneous holding as
correct, and you then need to figure out what the reasonableness standard is for compelling access,
I think something like the majority’s rule, in which the target is still ultimately protected by the
same protections that would apply if the information were locally stored, is probably right.
Carpenter creates a strange new world in a lot of ways. But I see its subpoena holding as more a
necessary corollary to its search holding and not a groundbreaking departure in its own right.
III. WHEN DOES A CARPENTER SEARCH START
– AND WHEN DOES IT STOP? July 6, 20183
The Supreme Court’s recent decision in Carpenter v. United States raises lots of fascinating and
novel Fourth Amendment questions. In this post I want to focus on one important set of questions:
When does a Carpenter search start, and when does it stop? I don’t have a lot of answers to these
question. But the questions are important to consider. This post will explore the questions and will
end with a set of hypotheticals to bring out the tough issues.
This is a long post, so here is a roadmap. I’ll begin by explaining why the timing of Fourth
Amendment searches was pretty easy before Carpenter, and I’ll turn next to why Carpenter
complicates the issue. I’ll then discuss the stages of surveillance and explain why the timing of
Carpenter searches is pretty important. After briefly covering the timing of searches suggested by
the Jones concurrences, the next section goes through the language of Carpenter and argues that
the opinion leaves the timing questions pretty open. I’ll end with four hypotheticals designed to
bring out different ways of thinking about when Carpenter searches start and stop.
I. Before Carpenter, the “When” of Search Law Was Simple
In traditional Fourth Amendment law, identifying when a search starts and stops is easy. That’s
true because Fourth Amendment law has always before been connected to a place or thing. There
was always some specific place, thing, or person that was searched, and the search occurred when
the information about that place or person was revealed. The place searched could be a house (as
in Kyllo), a structure (the phone booth in Katz), a car (as in the Jones majority), or a person (like
a Terry frisk). But it was always a specific and identifiable place, thing, or person – what the text
of the Fourth Amendment refers to as the “persons, houses, papers, and effects” that the
Amendment protects.
3 This post appeared at the Volokh Conspiracy at https://reason.com/volokh/2018/07/06/when-does-a-carpenter-
search-start-and-w. It appeared at Lawfare at https://www.lawfareblog.com/when-does-carpenter-search-start-and-
when-does-it-stop.
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Identifying when a search occurs under this traditional approach is very simple. You just look at
the moment when information from the place, thing, or person is revealed to the government.
Figuring out the timing of that search is traditionally straightforward. For example, imagine the
police break open a door to an apartment and rifle through its contents for an hour before leaving.
Identifying when the search occurred is obvious. The search begins when the door is opened, lasts
for an hour, and ends when the police leave. It’s pretty intuitive.
II. How Carpenter Makes the “When” Question Difficult
The timing of a Carpenter search does not seem intuitive, however. Carpenter is unique among
majority opinions of the Supreme Court in that it recognizes a right against the government
collecting a set of facts in the abstract. And that unique kind of right has big implications for the
timing of Carpenter searches.
Let me explain what I mean. The starting premise of the Carpenter opinion is that, at some point
in the past, you wouldn’t have expected the government to be able to collect lots of location
information about a suspect. “Prior to the digital age,” Carpenter states, “law enforcement might
have pursued a suspect for a brief stretch, but doing so for any extended period of time was difficult
and costly and therefore rarely undertaken.” Quoting Justice Alito’s Jones concurrence, Carpenter
concludes that this means that there was in the past a reasonable expectation “that law enforcement
agents and others would not—and indeed, in the main, simply could not—secretly monitor and
catalogue every single movement” of a person over time.”
Accessing CSLI is a search, Carpenter reasons, because that has changed. Because technology
has now made that kind of surveillance easy and potentially very common, the law needs to step
in and make that surveillance difficult and rare again. As I have written before, this is the theory
of equilibrium-adjustment. When technology dramatically expands the government’s power under
an old legal rule, the thinking goes, the Court changes the legal rule to restore the prior level of
government power. To ensure that the government doesn’t have unlimited power to catalog your
movements over time, Carpenter holds that a search occurred and a warrant was needed. New
technology means that you no longer have a reasonable expectation of privacy in your movements
over time; the law gives back to you the reasonable expectation of privacy that you once had. The
law giveth what technology taketh away.
But when exactly does the search occur? The Court’s phrasing on this point is fascinating. The
majority writes, in a key section, that “[t]he location information obtained from Carpenter’s
wireless carriers was the product of a search.” The product of a search. A search occurred at some
point, such that at the end we can say that a search caused the information to be obtained. But
exactly when?
I think this is hard to figure out because Carpenter holds, for the first time, that a search occurred
without it being a taking of information from any particular place, thing, or person. A search
occurred because it needed to have occurred to regulate a practice that needed to be regulated to
keep the government from having too much power. But the gathering of information was not
taken from a particular place or thing or person at a particular moment. Rather, the government
simply ended up with too much information about someone. How it ended up with too much
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information isn’t particularly relevant in the Court’s view. The point is the result, not the process.
Somewhere in the steps that ended up with the government getting all that information, a search
occurred.
III. The Stages of Surveillance
Why does this matter? It matters because modern systems of records collection and access often
have several different stages. It’s often important to figure out which stage or stages is the one
that counts as a Fourth Amendment search.
Let’s break down how it might work when the government ends up with cell site location records.
I will break down the process into eight stages, some of which will blend together in practice but
that may be conceptually helpful to keep distinct. To be clear, the eight stages are highly stylized
and somewhat arbitrary; this or different methods of surveillance can be described differently. But
at least as an exercise, consider the following eight steps.
(1) Creation of the Record. The relevant record first must be created, either because it is
necessarily created to deliver the product or services or because a computer was programmed to
create the record for other reasons. For example, if a cell phone call is made from an account at
2:34pm, and cell site 2342837413 is used to connect the call, the network will have generated that
information.
(2) Preservation of the Record. Next the record must be stored. Here the cellular provider
decides that this particular record will be saved and preserved, either for its own business purposes
or pursuant to a legal obligation.
(3) Creation of a Database. The cellular provider takes all of the similar records and puts them
into a database with similar records. For example, if a person made five phone calls on a particular
day, the provider might have a database file for that day that looks like this:
March 2 at 2:34pm connection to site 2342837413.
March 2 at 3:09pm connection to site 2342837413.
March 2 at 4:12pm connection to site 2342837413
March 2 at 4:18pm connection to site 1893472393.
March 2 at 4:51pm connection to site 2342837413.
(4) The Database File Is Sent to The Analyzing Agency. Acting pursuant to a court order, he
cellular provider takes the database file and sends it to the government. The file is received by the
government but not yet opened.
(5) The Database File Is Opened by The Analyzing Agency. The government agency opens
the file and a person there examines the data.
(6) Another Database Is Obtained to Make The First Database File Useful. In this case, the
initial file was a list of times and raw numbers of cell sites. The raw numbers don’t tell you much
yet, though, as you don’t yet know where the cell sites are. (All you know is that the phone was
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using one cell site, then used a second, then went back to the first.) To get locations from the
database you need a second file, one that associates cell site numbers with their physical locations.
In our case, the cellular provider might then send on a second file that looks like this:
Site 2342837413 is located at 6th Street and Elm Road.
Site 2362383929 is located at 23rd Street and Elm Road.
Site 1283839292 is located at 96th Street and Johnson Place.
Site 1893472393 is located at 47th Street and Baker Avenue.
(7) The Databases Are Combined. At this stage the two databases are put together to make the
information useful in a way that can be easily queried. In this case, putting the entries together
might look like this:
March 2 at 2:34pm connection to the site at 6th Street and Elm Road..
March 2 at 3:09pm connection to the site at 6th Street and Elm Road.
March 2 at 4:12pm connection to the site at 6th Street and Elm Road.
March 2 at 4:18pm connection to the site at 47th Street and Baker Avenue.
March 2 at 4:51pm connection to the site at 6th Street and Elm Road.
(8) The Combined Database Is Queried. With the database assembled, it can now be queried.
For example, a government analyst may query the database for the times that the phone was in the
area of Baker Avenue, with the response being March 2 at 4:18pm. Or the query might be for the
location of the phone after 4pm on March 2, which would return the three points at 4:12pm,
4:18pm, and 4:51 pm. Or the query might be for any times when the phone was in the area of 96th
Street and Johnson Place, which would return a null response.
Those are the eight stages. The big question: When does the search start, and when does it end?
IV. How the Jones Concurrences Answered the “When” Question
This problem first arose with the concurring opinions in United States v. Jones. In Jones, the
government placed a GPS device on a car the suspect was driving and monitored the car’s location
for 28 days. The Jones concurrences introduced the basic premise of Carpenter that a search
occurs because the monitoring simply gathered too much information. But the concurrences had
different ways to describe when the search occurred.
As I noted in The Mosaic Theory of the Fourth Amendment, the two concurring opinions in Jones
both looked beyond the initial data acquisition stage, albeit in somewhat different ways, for when
a search occurred:
Justice Alito’s opinion in Jones looked to whether a person reasonably expects others to
“secretly monitor and catalog” a person’s movements. Justice Sotomayor asked “whether
people reasonably expect that their movements will be recorded and aggregated” in a
manner that creates the mosaic. Cataloging and aggregating are verbs that describe
subsequent analysis instead of initial collection. These phrases suggest that the mosaic
theory requires some step beyond the acquisition stage.
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If so, courts will need to determine what kinds of post-acquisition conduct are required to
create a mosaic. Imagine the government collects a great deal of information but never
combines it into a single database. Has a mosaic been created? Or imagine the evidence is
collected into a database but never analyzed. Does that cross the line? If some analysis of
the evidence is required to trigger the mosaic, what kind of analysis counts? Does any
analysis suffice, or is there some threshold of sophistication or computational complexity
before the mosaic line has been crossed?
Carpenter seems to have adopted the basic mosaic approach of the Jones concurrences. Given
that the Jones concurrences suggest that some later-stage analysis is at least part of the search –
some cataloging or aggregation is required -- it raises the possibility that Carpenter searches
require a similar range of steps.
V. What Carpenter Says About Timing – And What It Doesn’t Say
That brings us, finally, to Carpenter itself. The Carpenter majority opinion gives us a few clues
on the timing of when a search at least starts. But the clues don’t seem particularly precise or
consistent. And while they talk about when the search may start, they don’t seem to tell us when
the search ends.
That’s not necessarily criticism of the majority, to be clear. The timing question wasn’t presented
to the Justices because it didn’t matter in that case. But if we’re looking ahead to how to apply
Carpenter, the timing clues left in the opinion start to matter.
So let’s take a look. Some language in the majority opinion say that a search occurs when the
government “accesses” a database that contains the relevant records. To me, accessing seems to
mean looking through the database to get useful information. Here are a few examples:
(1) “This case presents the question whether the Government conducts a search under the
Fourth Amendment when it accesses historical cell phone records that provide a
comprehensive chronicle of the user’s past movements.”
(2) “Allowing government access to cell-site records contravenes that expectation.”
(3) “With just the click of a button, the Government can access each carrier’s deep
repository of historical location information at practically no expense.”
(4) “Accordingly, when the Government accessed CSLI from the wireless carriers, it
invaded Carpenter’s reasonable expectation of privacy in the whole of his physical
movements.”
(5) “We decline to grant the state unrestricted access to a wireless carrier’s database of
physical location information.”
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Other parts of the opinion refer to the relevant stage as “acquiring” the records instead of
“accessing” them. The word “acquiring” can have different meanings. On the whole, though, that
word seems to suggest a relatively early stage of merely coming into possession of the records
even if they are not actually examined or queried.
Here are some of the passages that refer to acquiring or similar language instead of accessing:
(1) “The case before us involves the Government’s acquisition of wireless carrier cell-
site records revealing the location of Carpenter’s cell phone whenever it made or
received calls.”
(2) “The Government’s acquisition of the cell-site records was a search within the meaning
of the Fourth Amendment.”
(3) “Having found that the acquisition of Carpenter’s CSLI was a search, we also conclude
that the Government must generally obtain a warrant supported by probable cause before
acquiring such records.”
(4) “The Government’s acquisition of the cell-site records here was a search under that
Amendment.”
(5) “Before compelling a wireless carrier to turn over a subscriber’s CSLI, the
Government’s obligation is a familiar one—get a warrant.”
So which is the search, acquiring the records or accessing them? Possessing them or making use
of them? I’m not entirely sure.
Beyond the possible acquisition/access distinction, there are two important additional uncertainties
on how Carpenter deals with the timing.
First, Carpenter assumes that all of the records have been combined into a database that can be
queried to get all the relevant information. It doesn’t say how the law should apply when the
relevant information has to be obtained from combining databases. Recall stages 6 and 7 above in
Part III. The first database didn’t actually have the locations of the cell towers. It had only raw
numbers. The second database was needed to link site numbers to actual places.
I wonder, in this hypothetical, would just the first database count as “location information” for
Carpenter purposes? Is either acquiring or accessing that database alone a search? There is no
actual “location” information in that database. It is just meaningless numbers. But it’s a good step
towards having location information. Is that enough? Does it matter how easy or hard it is to
combine those meaningless numbers with the location information? For example, does it matter
if the second database file, with the links between site numbers and location, is a closely-guarded
secret versus if it is something that can be looked up on the public web or is given out relatively
freely by the provider? You can see why it matters. Going back to the eight stages of surveillance
in Part III, the answers tell you when a search starts: Does it begin at stage 4, 5, 6, 7, or 8? It’s
hard to say, I think.
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The next uncertainty is when the search ends. Let’s say you identify a stage when a search starts.
Does the search end there, too? Or is the search ongoing for some set of the stages of surveillance?
This isn’t a hard problem in traditional Fourth Amendment law because you would traditionally
say that once data has been searched, further examination is not a search again. As the Supreme
Court stated in Illinois v. Andreas, 463 U.S. 765, 771–72 (1983), “once the police are lawfully in
a position to observe an item firsthand, its owner’s privacy interest in that item is lost.”
Observation can be a search, but searching once eliminates the expectation of privacy. Or at least
that’s the traditional view of the Supreme Court’s caselaw.
But does Carpenter change that? If Carpenter searches are about accessing information, you
might get new searches at different stages of the surveillance as more information is obtained. You
might have one search at one stage and a second or third search later. If the government has a
warrant at the outset, of course, the warrant should suffice for all the steps. A warrant authorizes
as many distinct searches as are needed to search the described place for the described evidence.
But what happens if an exception to the warrant requirement applies at one step but not another?
Say you can get to a particular stage of surveillance where a search has occurred but a warrant was
not necessary because an exception to the warrant requirement applied such as exigent
circumstances. Next say that the exception no longer applies going forward. Are subsequent stages
of surveillance new searches that now require a warrant to execute? Or is the search over from the
earlier stage of surveillance so the subsequent stage can occur without Fourth Amendment
oversight?
VI. Four Closing Hypotheticals
Here are a four hypotheticals to bring out these uncertainties and make the issues concrete. To be
clear, these aren’t exam questions where I know the best answers and I’m wondering who among
you readers can find them. Rather, these are uncertain issues under Carpenter that I’m not sure
how courts will answer. I’m curious to know what you think of them.
(1) “Has David Ever Been To California?” Say David has been charged with killing a man in
New York. The exact time of the death is unclear, but the crime is thought to have happened in
recent weeks. David’s alibi is that he was in California all of the last month and that he could not
have committed the crime in New York. Investigators want a representative from David’s cell
provider to testify at trial to answer just one question: Whether, based on a review of the last month
of David’s CSLI records, David’s phone connected to any cell sites in California at any time in the
last month. Is obtaining that testimony a Fourth Amendment search that first requires a warrant,
and if so what kind of probable cause showing is required for it?
(2) “Just Tell Me If When There Was a Match.” Imagine the government is investigating a robbery
conspiracy. Investigators want the provider to disclose the times and dates in the last year when
the cell phones used by the four suspects were connected to the same cell tower within 15 minutes
of each other. Investigators don’t want to know where the cell sites were located. They only want
a list of times, if any, when all four cell phones were using the same cell site (without knowing
where that was). An employee at the provider takes its databases and combine them to look for
matches. He responds to the government with a list of times, and those times happen to match to
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the dates of known robberies. Was it a Fourth Amendment search to obtain that list of times? If
so, do all of them have standing to challenge the search?
(3) “The Emergency Passed.” The police are investigating an ongoing kidnapping. In an effort
to find out where the kidnapper is, the police ask the suspect’s cellular provider to disclose the
whereabouts of the suspect’s phone for the last month. The provider does so without a warrant in
light of the exigent circumstances of needing to find the kidnapper right away. The government
gets the location information covering one month under the exigent circumstances exception to the
warrant requirement. The kidnapper is not found, however. A year later, investigators in a different
case come to think that the same suspect may have also committed a string of burglaries around
the same time. They want to examine the location information that was originally obtained to find
the kidnapper, but this time they want to analyze the records to see if the locations matched the
burglaries. Is this later examination another search, and if so does it require a warrant?
(4) “We’ll Query the Database in An Emergency” Congress enacts a terrorist surveillance
program that requires every cellular provider to hand over all CSLI to the government once a week.
The government is required to save all the CSLI files for all time without looking at any of the
data. When an emergency amounting to exigent circumstances occurs, however, the government
can query the CSLI database to obtain location records relating to particular suspects. Has a search
occurred if no emergency has occurred yet and the records have been obtained but not opened or
analyzed?