[EDRM Editor’s Note: The opinions and positions are those of Michael Berman.]
In In Re Four Applications For Search Warrants Seeking Information Associated With Particular Cellular Towers A/K/A Tower-Dump Warrants, 2025 WL 603000 (S.D. Miss. Feb. 21, 2025), the court declined to issue “tower-dump” or “tower-extraction” search warrants, writing:
Before the Court are four search-warrant applications for location-and-time based cell-tower data, also known as tower-dump or tower-extraction warrants. The applications seek to obtain from four separate cellular service providers a list of phone numbers and identifiers for cellular devices that connected to cell towers covering nine locations during specific windows of time ranging from ten minutes to one hour for each location. The applications also request information about all communications made using those towers during the specified times. The time windows and locations correspond to crimes the Government suspects were committed by members of a violent street gang. Based on the Fifth Circuit’s recent decision in United States v. Smith, 110 F.4th 817, 820 (5th Cir. 2024), in which the court concluded that geofence warrants are per se “unconstitutional under the Fourth Amendment,” the Court concludes these tower-dump search warrants cannot be issued consistent with the Fourth Amendment. For the reasons explained below, the Court therefore declines to issue the warrants. [Emphasis added].
In Re Four Applications For Search Warrants Seeking Information Associated With Particular Cellular Towers A/K/A Tower-Dump Warrants, 2025 WL 603000 (S.D. Miss. Feb. 21, 2025).
Based on the Fifth Circuit’s recent decision in United States v. Smith, 110 F.4th 817, 820 (5th Cir. 2024), in which the court concluded that geofence warrants are per se “unconstitutional under the Fourth Amendment,” the Court concludes these tower-dump search warrants cannot be issued consistent with the Fourth Amendment.
In Re Four Applications For Search Warrants Seeking Information Associated With Particular Cellular Towers A/K/A Tower-Dump Warrants, 2025 WL 603000 (S.D. Miss. Feb. 21, 2025).
There is nothing new about tower dumps. In 2014, the ACLU reported that: “Cell tower dumps aren’t rare. A congressional inquiry found that companies received at least 9,000 tower dump requests in 2012, and in 2013 Verizon alone reported receiving 3,200 such requests.” K. Hass, Cell Tower Dumps: Another Surveillance Technique, Another Set of Unanswered Questions | ACLU (Mar. 27, 2014); see M. Kortz and C. Bavitz, Cell Tower Dumps – Boston Bar Association (Mar. 18, 2019); J. Remington, Police Use “Tower Dumps” To Collect Cell Phone Data Without A Warrant (Dec. 4, 2013).
Tower dumps have been both successful and controversial. N. Anderson, How “cell tower dumps” caught the High Country Bandits—and why it matters – Ars Technica (Aug. 29, 2013). Mr. Anderson reports how a tower dump helped the FBI solve a string of bank robberies. After other efforts to identify the robbers failed, the FBI used a tower dump:
The FBI actually received more than 150,000 registered cell phone numbers from this particular set of tower dumps, despite picking the most rural locations possible. What the case agents wanted to do was scan the logs from all four sites on the belief that no single person was likely to be at all four banks during the robbery—except for the robber.
So the FBI dumped all the numbers into a Microsoft Access database and ran a query. As expected, only a single number came back: Verizon Wireless phone number 928-205-xxxx had registered with the tower closest to three of the banks on the day of each robbery. (Verizon didn’t have a cell tower covering the fourth bank.) Further analysis found a second number, 928-358-xxxx, that had been in contact with 928-205-xxx and that had registered with two of the towers in question.
The FBI then went back to the judge and obtained more particular court orders covering these specific phone numbers. The phone numbers came back with subscriber names attached: Joel Glore and Ronald Capito. And the location data returned showed that these two phones had been present at most of the 16 bank robberies under investigation. Further, the data showed that both phones tended to travel from Show Low, Arizona, to the location of each bank just before each robbery. [Emphasis added].
N. Anderson, How “cell tower dumps” caught the High Country Bandits—and why it matters – Ars Technica (Aug. 29, 2013).
Thus, two suspects were identified. With additional investigation, they were apprehended.
Recently, there has been a split of authority between the Fourth and Fifth Circuits over geofence warrants. See Keeping an Eye on Geofence Warrants – E-Discovery LLC (Jan. 22, 2025). The Fourth Circuit is engaging in en banc review of its decision. A Maryland state court has permitted geofence warrants. Geofence Search Warrant Held Valid – E-Discovery LLC (Jun 28, 2024).
With that background, we turn to In Re Four Applications For Search Warrants Seeking Information Associated With Particular Cellular Towers A/K/A Tower-Dump Warrants. FBI affidavits stated that “law enforcement suspects the involvement of various members of a violent street gang—including seven named in the applications—in numerous homicides, shootings, and vehicle thefts occurring over a 14-month period in urban and suburban areas.”
The government sought information, described in more detail in the court order, “from every user of a cellular device that connected to any of the cell towers providing service to the locations of those nine incidents ‘to help identify or eliminate suspects’ by pinpointing individuals whose devices ‘were in the general vicinity of’ the crime scenes.”
The court wrote:
Thus, while the Government’s aim is to identify or rule out suspects in the crimes that took place at each location, it is asking the Court to give it access to information about every communication in the covered time and area made by every person, including more detailed location data (beyond the address serviced by a given tower) that the “sector” information will provide. In terms of the temporal scope of the Government’s request, each warrant application seeks data for devices connecting to the towers serving the nine locations for a combined total of 220 minutes. So the Government wants the Court to require the four cellular providers to provide data for a total of 880 minutes—or more than 14 hours—for every device connecting to any of the towers serving those locations.
In Re Four Applications For Search Warrants Seeking Information Associated With Particular Cellular Towers A/K/A Tower-Dump Warrants, 2025 WL 603000 (S.D. Miss. Feb. 21, 2025).
The government confirmed that the collected information “will include the cellular telephone identifiers of otherwise innocent and uninvolved individuals.” It made two additional points. First, it did not seek the content of communications. Second, the extraneous data would not be used to investigate innocent parties (without a court order) and would be disposed of after the prosecutions ended.
The Four Applications court held that the tower dump was a search within the meaning of the Fourth Amendment. In addition to Supreme Court cell phone precedent, it looked at the Fifth Circuit’s geofence opinion. Quoting another decision, it wrote:
Even a brief snapshot can expose highly sensitive information—think a visit to “the psychiatrist, the plastic surgeon, the abortion clinic, the AIDS treatment center, the strip club, the criminal defense attorney, the by-the-hour-motel, the union meeting, the mosque, synagogue or church, or the gay bar,” or a location other than home during a COVID-19 shelter-in-place order. [Cleaned up]
Id.
And, the Four Applications court wrote that: “Here, based on a review of publicly accessible maps, the areas within one mile of each of the Government’s specified locations include residential neighborhoods, a mall, medical clinics, schools, shopping centers, a supermarket, churches, a courthouse, hotels, interstate highways, a train station, and an airport. It is unclear how many people are implicated by the Government’s requested tower dumps, but it is plausible the total will easily exceed the three people in Smith by hundreds if not thousands given the population density of the covered areas.”
The Four Applications court concluded that the tower-dump warrants failed to satisfy the Fourth Amendment, looking at the geofence warrant precedent. Quoting Prof. Stephen E. Henderson, it wrote that the government will always seek a larger database because “by definition there will be evidence of crime in that larger set.” However:
Doing so leads to an “absurd” understanding of probable cause: “[A] prosecutor confident that a bank customer is committing tax fraud could access the combined records of all customers of that bank because, somewhere in there, she is very sure is evidence of crime.”
Id.
The Four Applications court held that the tower-dump warrant requests were not supported by probable cause and particularity, writing: “If the Court were to issue the warrants, it would be authorizing the Government to search the data for every cellular device (including cell phones) of every single individual near the crime scenes without a showing of probable cause as to each individual.” It added:
Stated another way, the Government is essentially asking the Court to allow it access to an entire haystack because it may contain a needle. But the Government lacks probable cause both as to the needle’s identifying characteristics and as to the many other flakes of hay in the stack. And unlike in Smith, where only three devices turned up in the geofence in rural DeSoto County, Mississippi, the haystack here could involve the location data of thousands of cell phone users in various urban and suburban areas.
Id.
Stated another way, the Government is essentially asking the Court to allow it access to an entire haystack because it may contain a needle. But the Government lacks probable cause both as to the needle’s identifying characteristics and as to the many other flakes of hay in the stack.
In Re Four Applications For Search Warrants Seeking Information Associated With Particular Cellular Towers A/K/A Tower-Dump Warrants, 2025 WL 603000 (S.D. Miss. Feb. 21, 2025).
Quoting precedent, the Four Applications court wrote: “Hamstringing the government is the whole point of our Constitution…. Our decision today is not costless. But our rights are priceless.” [cleaned up].
The Four Applications court concluded: “As explained above, the tower-dump search warrants sought by the Government are materially indistinguishable from the geofence search warrant foreclosed by Smith. Accordingly, the Court declines to issue the search warrants.”
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