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Criminal Nuggets

Jul 4, 2018

Carpenter v. United  States, SCOTUS June 2018. Episode 508 (Duration 17:52)

Police need a warrant to capture your CSLI.

SCOTUS on cell site location information

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The Charges

Defendant was charged with six counts of robbery and an additional six counts of carrying a firearm during a federal crime of violence.

He was convicted and sentenced to more than 100 years in prison.


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.

Defendant argued the Government’s seizure of the records violated the Fourth Amendment because they had been obtained without a warrant supported by probable cause.

Cell Site Location Information
(The Technology)

Cell phones continuously scan their environment looking for the best signal, which generally comes from the closest cell site.

Most modern devices, such as smartphones, tap into the wireless network several times a minute whenever their signal is on, even if the owner is not using one of the phone’s features. Each time the phone connects to a cell site, it generates a time-stamped record known as cell-site location information (CSLI).

The precision of this information depends on the size of the geographic area covered by the cell site. The greater the concentration of cell sites, the smaller the coverage area. As data usage from cell phones has increased, wireless carriers have installed more cell sites to handle the traffic. That has led to increasingly compact coverage areas, especially in urban areas.

Wireless carriers collect and store CSLI for their own business purposes.

The Investigation

The FBI was investigating a series of robberies of Radio Shack and TMobile stores in Detroit.

They obtained the suspects CSLI under the Stored Communications Act. That statute, as amended in 1994, permits the Government to compel the disclosure of certain telecommunications records when it “offers specific and articulable facts showing that there are reasonable grounds to believe” that the records sought “are relevant and material to an ongoing criminal investigation.” 18 U. S. C. §2703(d).

That showing falls well short of the probable cause required for a warrant.

Altogether the Government obtained 12,898 location points cataloging Carpenter’s movements—an average of 101 data points per day.

His Location Convicted Him

The prosecution produced maps that placed the defendant’s phone near four of the charged robberies. In the Government’s view, the location records clinched the case: They confirmed that he was “right where the . . . robbery was at the exact time of the robbery.” 

The Fourth Amendment

 The Fourth Amendment protects

“[t]he right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures.”

The “basic purpose of this Amendment,” our cases have recognized, “is to safeguard the privacy and security of individuals against arbitrary invasions by governmental officials.” For much of our history, Fourth Amendment search doctrine was “tied to common-law trespass” and focused on whether the Government “obtains information by physically intruding on a constitutionally protected area.” United States v. Jones, 565 U. S. 400, 405, 406, n. 3 (2012).

More recently, the Court has recognized that “property rights are not the sole measure of Fourth Amendment violations.” Soldal v. Cook County, 506 U. S. 56, 64 (1992). In Katz v. United States, 389 U. S. 347, 351 (1967), we established that “the Fourth Amendment protects people, not places,” and expanded our conception of the Amendment to protect certain expectations of privacy as well.

Expectation of Privacy

When an individual “seeks to preserve something as private,” and his expectation of privacy is “one that society is prepared to recognize as reasonable,” we have held that official intrusion into that private sphere generally qualifies as a search and requires a warrant supported by probable cause.

Point Is To Restrict Government

Our cases have recognized some basic guideposts.

First, that the Amendment seeks to secure “the privacies of life” against “arbitrary power.” Boyd v. United States, 116 U. S. 616, 630 (1886).

Second, and relatedly, that a central aim of the Framers was “to place obstacles in the way of a too permeating police surveillance.” United States v. Di Re, 332 U. S. 581, 595 (1948).

Two Lines Of Cases

This sort of digital data—personal location information maintained by a third party—does not fit neatly under existing precedents. Instead, requests for cell-site records lie at the intersection of two lines of cases, both of which inform our understanding of the privacy interests at stake.

Expectation of Privacy In
Physical Location & Movement

The first set of cases addresses a person’s expectation of privacy in his physical location and movements.

In United States v. Jones, FBI agents installed a GPS tracking device on Jones’s vehicle and remotely monitored the vehicle’s movements for 28 days. The Court decided the case based on the Government’s physical trespass of the vehicle. 565 U. S., at 404–405.

Since GPS monitoring of a vehicle tracks “every movement” a person makes in that vehicle, the concurring Justices concluded that “longer term GPS monitoring in investigations of most offenses impinges on expectations of privacy”—regardless whether those movements were disclosed to the public at large.

Third Party Doctrine
(Shared Information Is Not Private)

In a second set of decisions, the Court has drawn a line between what a person keeps to himself and what he shares with others.

We have previously held that “a person has no legitimate expectation of privacy in information he voluntarily turns over to third parties.” Smith, 442 U. S., at 743–744. This third-party doctrine largely traces its roots to Miller.

Bank Records

While investigating Miller for tax evasion, the Government subpoenaed his banks, seeking several months of canceled checks, deposit slips, and monthly statements. See United States v. Miller, 425 U. S. 435, 443 (1976).

Pen Register

Three years later, Smith applied the same principles in the context of information conveyed to a telephone company. The Court ruled that the Government’s use of a pen register—a device that recorded the outgoing phone numbers dialed on a landline telephone—was not a search. See Smith v. Maryland, 442 U. S. 735.

The Court explained, such an expectation “is not one that society is prepared to recognize as reasonable.”

Intersection Of The Cases

The question we confront today is how to apply the Fourth Amendment to a new phenomenon:

the ability to chronicle a person’s past movements through the record of his cell phone signals.

  1. Such tracking partakes of many of the qualities of the GPS monitoring we considered in Jones. Much like GPS tracking of a vehicle, cell phone location information is detailed, encyclopedic, and effortlessly compiled.

2. At the same time, the fact that the individual continuously reveals his location to his wireless carrier implicates the third-party principle of Smith and Miller. But while the third-party doctrine applies to telephone numbers and bank records, it is not clear whether its logic extends to the qualitatively different category of cell-site records.

After all, when Smith was decided in 1979, few could have imagined a society in which a phone goes wherever its owner goes, conveying to the wireless carrier not just dialed digits, but a detailed and comprehensive record of the person’s movements.

Analysis-Even Greater
Privacy Concerns

The location information obtained from Carpenter’s wireless carriers was the product of a search.

A person does not surrender all Fourth Amendment protection by venturing into the public sphere. To the contrary, “what [one] seeks to preserve as private, even in an area accessible to the public, may be constitutionally protected.” Katz, 389 U. S., at 351–352.

Although such records are generated for commercial purposes, that distinction does not negate Carpenter’s anticipation of privacy in his physical location. Mapping a cell phone’s location over the course of 127 days provides an all-encompassing record of the holder’s whereabouts. As with GPS information, the timestamped data provides an intimate window into a person’s life, revealing not only his particular movements, but through them his “familial, political, professional, religious, and sexual associations.” These location records “hold for many Americans the ‘privacies of life.’” Riley, 573 U. S., at ___ (slip op., at 28) (quoting Boyd, 116 U. S., at 630).

In fact, historical cell-site records present even greater privacy concerns than the GPS monitoring of a vehicle we considered in Jones.

Feature of Human Anatomy

Unlike the bugged container in Knotts or the car in Jones, a cell phone—almost a “feature of human anatomy,” Riley, 573 U. S., at ___ (slip op., at 9)—tracks nearly exactly the movements of its owner. While individuals regularly leave their vehicles, they compulsively carry cell phones with them all the time.

A cell phone faithfully follows its owner beyond public thoroughfares and into private residences, doctor’s offices, political headquarters, and other potentially revealing locales.

Like An Ankle Monitor
That Travels Backwards In Time

Accordingly, when the Government tracks the location of a cell phone it achieves near perfect surveillance, as if it had attached an ankle monitor to the phone’s user.

Moreover, the retrospective quality of the data here gives police access to a category of information otherwise unknowable. With access to CSLI, the Government can now travel back in time to retrace a person’s whereabouts, subject only to the retention polices of the wireless carriers, which currently maintain records for up to five years.

Everyone Is Tracked

Critically, because location information is continually logged for all of the 400 million devices in the United States—not just those belonging to persons who might happen to come under investigation— this newfound tracking capacity runs against everyone.

Unlike with the GPS device in Jones, police need not even know in advance whether they want to follow a particular individual, or when. Whoever the suspect turns out to be, he 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.

Only the few without cell phones could escape this tireless and absolute surveillance.

Seismic Shift In Technology

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.

The Government’s position fails to contend with the seismic shifts in digital technology that made possible the tracking of not only this defendant's location but also everyone else’s, not for a short period but for years and years.

Sprint Corporation and its competitors are not your typical witnesses. Unlike the nosy neighbor who keeps an eye on comings and goings, they are ever alert, and their memory is nearly infallible. 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.


Given the unique nature of cell phone location records, the fact that the information is held by a third party does not by itself overcome the user’s claim to Fourth Amendment protection. Whether the Government employs its own surveillance technology as in Jones or leverages the technology of a wireless carrier, we hold that an individual maintains a legitimate expectation of privacy in the record of his physical movements as captured through CSLI.

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.

Yet this case is not about “using a phone” or a person’s movement at a particular time. It is about a detailed chronicle of a person’s physical presence compiled every day, every moment, over several years. Such a chronicle implicates privacy concerns far beyond those considered in Smith and Miller.

We therefore decline to extend Smith and Miller to the collection of CSLI. Given the unique nature of cell phone location information, the fact that the Government obtained the information from a third party does not overcome Carpenter’s claim to Fourth Amendment protection.

The Government’s acquisition of the cell-site records was a search within the meaning of the Fourth Amendment.

Get A Warrant

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.

The standard in the Stored Communications Act is not a permissible mechanism for accessing historical cell-site records. Before compelling a wireless carrier to turn over a subscriber’s CSLI, the Government’s obligation is a familiar one—get a warrant.

Subpoena Not Going To Do It

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 collected by subpoena for no reason other than “official curiosity.” 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.

Exigent Circumstances Still Apply

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.

Further, even though the Government will generally need a warrant to access CSLI, case-specific exceptions may support a warrantless search of an individual’s cell-site records under certain circumstances. 

One well recognized exception applies when ‘“the exigencies of the situation” make the needs of law enforcement so compelling that [a] warrantless search is objectively reasonable under the Fourth Amendment."

Fleeing Suspect, Imminent Harm, Destruction of Evidence

Such exigencies include the need to pursue a fleeing suspect, protect individuals who are threatened with imminent harm, or prevent the imminent destruction of evidence.

As a result, if law enforcement is confronted with an urgent situation, such fact-specific threats will likely justify the warrantless collection of CSLI. Lower courts, for instance, have approved warrantless searches related to

  • bomb threats
  • active shootings and
  • child abductions.

Our decision today does not call into doubt warrantless access to CSLI in such circumstances.

This Is A Narrow Decision

Further, the 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.


We decline to grant the state unrestricted access to a wireless carrier’s database of physical location information. 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. The Government’s acquisition of the cell-site records here was a search under that Amendment. The judgment of the Court of Appeals is reversed, and the case is remanded for further proceedings consistent with this opinion.

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