The Right to Keep Personal Data Private: Carpenter v. U.S.

The Supreme Court could in this case make major strides in ensuring that Fourth Amendment protections keep pace with advancing technology.

In 2011, FBI agents in Detroit obtained several months’ worth of location records from cellphone companies for suspects in a robbery investigation — all without a warrant. They were able to do so because of an outdated legal theory called the “third-party doctrine” that has been used by law enforcement to access personal data without ever having to demonstrate probable cause to a judge.

Infographic: A Surveillance Time Machine

Timothy Carpenter, represented by the ACLU, argues that the government violated his Fourth Amendment rights when it obtained his location records without a warrant. The court’s decision in the case will also have implications for the extent of the Constitution’s protections against warrantless search and seizure of much of the private data collected and stored by current  technologies.

What is this case about?

Every time a cellphone makes or receives a call or  text message or accesses a wireless data connection — as when it automatically checks for emails or social media messages — the phone company logs and retains a record of the phone’s location based on the cell tower and cellular antenna the phone was connected to. The volume and precision of that location data has increased over time, and today, cellphone location data can paint a detailed picture of where we go over the course of days, weeks, and months. The question in this case is whether the Fourth Amendment protects that data by requiring police to get a search warrant from a judge before requesting it from the phone company.

What is the third-party doctrine and why does it matter?

The third-party doctrine says that by sharing information or records with a “third party,” meaning a business or another person, a person gives up any reasonable expectation that the information will remain private.  The doctrine was established in Supreme Court cases from the 1970s, which reasoned that without an expectation of privacy, there is no Fourth Amendment protection for certain records voluntarily shared with businesses, such as canceled checks sent to a bank or phone numbers dialed on a phone and transmitted over a phone company's equipment. The government, along with some lower courts, have extended that principle to cover all kinds of sensitive digital records. But as Justice Sonia Sotomayor wrote several years ago, “[t]his approach is ill suited to the digital age, in which people reveal a great deal of information about themselves to third parties in the course of carrying out mundane tasks."

How would this case affect data collection beyond cellphones?

If the justices were to apply the government’s 1970s-era view of the third-party doctrine to cellphone location data,  it could throw open a huge array of highly sensitive digital records to warrantless access by police. Today, our most sensitive records aren’t necessarily held in homes and cabinets. They’re held by third parties. The contents of emails, text messages, and social media messages are stored by companies like Google, Verizon, and Facebook; family photos reside with Apple, Flickr, and the like; and information about health conditions, relationships, finances, political opinions, sexual orientation, and daily habits is stored on servers of the many companies that provide internet service and smartphone apps. And as the “internet of things” begins to take off, we will see information about the interior of our homes and the state of our bodies being constantly collected and stored in the cloud. It is critical that the Supreme Court explain that the Fourth Amendment protections these kinds of data.

What are the options before the Supreme Court?

The broad question before the court is whether law enforcement’s warrantless acquisition of historical cellphone location data violates the Fourth Amendment. If the court decides that this constitutes a Fourth Amendment search, it could further rule that a warrant is required -- as it should — or it could send the case back to the lower court for further consideration. This is the latest in a series of recent cases in which the Supreme Court has made clear that interpretations of the Fourth Amendment must keep up with evolving technology.  The court’s decision will set a precedent for years to come, making it crucial that it ensures that the police are subject to limits on search and seizure in the digital age.  

More on our upcoming Supreme Court cases

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The cat was already let out of the hat with "Stingray". This technology was put into the hands of state police departments who have given to loca good ole boy departments to target blacks and Mexicans. I know because I saw it.

For those who don't know, Stingray is a piece of mobile equipment that mimics a cell phone tower and forces all communication of cellular devices to be forced through the device.

In normalized terms, when cops are using a Stingray device it captures the communications of all phones within a mile or so radius. So when your iPhone is on it connects to the police operated device and they record all texts, phone calls, emails, or other data sent from the phone. Doesn't matter to whom or where the data is being sent, it is captured as it leaves the device.


What about widespread invasion of privacy by regular citizens on other citizens who can then "stalk" and group stalk their victims of they don't agree with them at work, in the neighborhood or just plain don't like them! They can then harrass, follow or even harm them at will or ruin their finances, reputation and lives. This is readily being done by people buying hacker apps like m spy, etc. and the SSL 7 cell network flaw that the FBI, and other government agencies knows about. It was featured on 60 minutes and it's not fixed yet!. It's so dangerous and makes people vulnerable to malicious, noses and evil people or groups. We really need to do something about that!!

Elizabeth Harp

It is obvious that electronic information is easily corrupted. No court should make a decision based on electronic data period.


You're absolutely right, Anonymous, message at 9/15/17! Neighborhood Watch groups are now widespread, using social media apps designed for their use to track citizens who are targeted by some connected neighbor who dislikes the target, or a corporate employee who's being sacked by the employer, or a disgruntled landlord, etc... this is very malicious and corrupt, obviously. My understanding is the Neighborhood Watch (gangstalkers) are rewarded by payments, either funded by high wealth individuals/corporations, or through Fusion Centers that have sprouted up since the Patriot Act (so in fact, our taxes pay select groups of citizens to stalk innocent citizens). This is deplorable, without any ethical oversight and without any end in sight. ACLU is the only watchdog group that seems to even shine a light of understanding on this. Detection of these groups behaviors is designed to blend into normal everyday, so the 'program' is extremely difficult to prove. We can hold out faith and hope that eventually someone who participates as a 'watcher' or 'follower' grows the f* up and whistle blows on the program. Until then, I think we must find patience and continue to get the word out, sponsor and donate to worthy causes like the ACLU and DemocracyNow and work diligently and thoughtfully to document and communicate this huge social ill.


I agree 100%! I was gangstalked years ago and still get triggered by it as a result.

Beverly Cuellar

This is happening to me. I'm being gang stalked, cyberrapped, sexually exploited, harassed, I've had my bank accounts hacked, have my life threatened on a regular basis online. They harass my kids and the cops know about it but aren't doing anything about it. I was threatened to drop the issue or I'd go to jail. There is no control or oversight, and police and government personnel are targeting people based on personal vendettas. Something has to be done. It is way out of control.


I agree that people stalking one another is hideous and insidious. Still, the Fourth Amendment limits government, not citizen, infringement of privacy.


Read this:

And this:

Real Spying

Y'all are missing the point. The Supreme Court should ban spying altogether.

The defense department has a network of ultra low sound wave sensors that can pick up faint sounds outdoors then discriminate them from "noise".

What does this mean? It means the US government and others are working on ultra technical sound collection devices that can hear a conversation being made in the middle of a 1,000 acres between two people at 20 decibels.

The equipment captures all sound emitted into the atmosphere from planet earth, then using frequency selection, they listen to one sound at a time like a tree falling in Mexico, or a conversation between Fidel Castro and Raul on the balcony of the residence.

It's here. They are capable. Soon your own thoughts will not be yours alone.


The Framers of the Constitution explicitly outlawed "preemption policies" of any kind. The U.S. Constitution has never been amended to legalize these practices.

Back then those practicing preemption policies and guilt-by-association were the Red Coats - our enemy at the time. In the 18th Century this practice was called a "General Warrant".

The tyranny and evil of "General Warrants" was the driving force in creating the Fourth Amendment. It is essentially the unAmerican mindset of "if you have nothing to hide and done nothing wrong, you shouldn't mind officials searching your home, papers and personal effects". Today many, if not most, police officials and national security officials embrace the tactics of America's 18th Century enemy instead of their own oath of office.

In the 1960's and 1970's, during the so-called "War on Drugs", the U.S. Supreme Court essentially amended the Fourth Amendment - without obtaining a constitutional amendment. This illegal amendment process, in cases like "Terry v. Ohio", created the slippery slope for today's "War on a Tactic" after 9/11 using the tactics of the 18th Century Red Coats.

Alexander Hamilton, the Founding Father that helped design and define America's court system in the Federalist Papers essays, essentially declared that "constitutionality ALWAYS supersedes legal precedence or tradition". Since the vast majority of court cases use legal precedence of past cases - this is a huge deal for ACLU attorneys. It means that today's U.S. Supreme Court has a constitutional duty to correct cases like "Terry v. Ohio" which illegally amended the Fourth Amendment.

If Americans aren't appalled by using the tactics of the 18th Century Red Coats, what about using the tactics of the communists during the Cold War? Is anyone disturbed or appalled by adopting the tactics of the East German Stasi instead of the Founding Fathers?

At minimum, write your member of Congress demanding "Civics Education" in American government for high school students, bureaucrats and police officers!


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