This post documents a surveillance practice and the civil-liberties questions it raises. Most of the documented cases come from investigations by the Electronic Frontier Foundation and the Associated Press, linked throughout so you can verify every claim. Details are accurate as of publication on June 26, 2026. Surveillance practices, contracts and pending legislation change quickly, so check the linked sources for the current picture.
The Supreme Court ruled in 2018 that police need a warrant to get your phone’s location history from your cell carrier. Law enforcement found a way around that ruling. They buy the same kind of data on the open market, from brokers, with no warrant at all.
This is not a loophole anyone bothers to hide. It is a working business model, and it has been used in real cases against real people across the country.
How the Data Gets to Police
It starts with apps on your phone. A weather app, a game or a coupon app asks for your location. You tap allow. That location does not just go to the app. It gets packaged and sold into a chain of data brokers, most of which you have never heard of and never agreed to.
One of those brokers built a search tool for police. Fog Data Science sells a product called Fog Reveal, which EFF walked through in detail. It lets an officer browse location data like Google Maps results. They can draw a box on a map and pull every device that was in that area, then track those devices to everywhere else they have been. Police use it to find what they call “bed-down” locations, meaning where a device sleeps at night, and to build a “pattern of life” for the person carrying it. EFF found these terms in a Chino, California police department presentation.
The Associated Press, working from EFF’s records, reported that Fog sold its tool in around 40 contracts to nearly two dozen agencies, and that it had been used since at least 2018 in cases ranging from a nurse’s murder in Arkansas to tracing a potential January 6 participant. The tool is rarely mentioned in court records, which makes it hard for defense attorneys to even know it was used.
Fog’s data partner, Venntel, is a much larger broker that has supplied location data to ICE, CBP, the FBI, the IRS and the DEA. Venntel marketing materials sent to the Department of Homeland Security, obtained by the ACLU, claimed the company collects more than 15 billion location points from over 250 million devices every day. Another broker, Babel Street, sells a tool called Locate X built on similar data.
Why “It’s Anonymized” Is Not a Defense
Brokers insist the data is anonymized and free of personal information. That claim does not survive contact with how the tool is used. The entire purpose of Fog Reveal is to follow a single device to its home and its workplace. Once you know where a phone sleeps every night and where it goes every weekday, you know who owns it. Anonymized location data that follows you everywhere is not anonymous.
The Rights in Question
Fourth Amendment. In Carpenter v. United States (2018), the Supreme Court held that the government generally needs a warrant to get a person’s historical cell-site location records, because of the “privacies of life” those records reveal. That case was about one suspect over a few months. The broker data covers hundreds of millions of devices, all the time. Buying it instead of subpoenaing the carrier does not change what the data reveals. EFF argues that the Fourth Amendment analysis should not depend on where the data came from. If a warrant is required to get it from the carrier, a warrant should be required to get it from a broker.
Due process. When the surveillance tool never appears in the court record, a defendant cannot challenge how evidence against them was gathered. That undercuts the basic right to confront the case against you.
The purchase loophole. DHS’s own internal emails, in the ACLU records, show staff acknowledging that “legal, policy, and privacy reviews have not always kept pace.” A senior privacy official flagged that access had been purchased without a required privacy assessment. The people running this knew the ground was shaky.
What Could Close It
There is a bipartisan bill for exactly this. The Fourth Amendment Is Not For Sale Act would require the government to get a court order before buying Americans’ data, such as phone location records, from brokers. The principle behind it is plain: the government should not be able to purchase its way around the Constitution.
Until something like that passes, the rule in practice is simple and grim. The protection you have against warrantless tracking by your phone company does not apply when the government just buys the same information from someone else.
What You Can Do
You can shrink your own exposure and push to close the loophole at the same time.
On your phone, open your location settings and revoke access for apps that do not need it, because those apps are where this data starts. Then reset or delete your mobile advertising ID, the identifier brokers use to stitch your movements together. On iPhone, turn off “Allow Apps to Request to Track.” On Android, delete your advertising ID under Settings, Privacy.
On the policy side, the bipartisan Fourth Amendment Is Not For Sale Act would require the government to get a court order before buying this kind of data from brokers. Tell your members of Congress you support it. At the state level, strong consumer-privacy laws that limit data sales do the same work closer to home.
Sources
- EFF: Fog Revealed, a guided tour of how cops browse your location data
- EFF: How law enforcement buys cell phone location data wholesale
- EFF: How the federal government buys our cell phone location data
- AP: Tech tool offers police mass surveillance on a budget
- ACLU: New records detail DHS purchase of cell phone location data
- Carpenter v. United States, 585 U.S. ___ (2018)