S.D.Miss.: Cell tower dump violated 4A as a de facto geofence warrant

U.S. District Judge affirms U.S.M.J.’s decision that cell tower dumps violated the Fourth Amendment. The request was essentially a geofence warrant without a showing of need. In re Four Applications for Search Warrants Seeking Info. Associated with Particular Cellular Towers, 2026 U.S. Dist. LEXIS 176165 (S.D. Miss. Aug. 5, 2026):

Digital surveillance has been a huge boon to the government. By leveraging time-and-location data from cellular devices, agents can ascertain the identities of previously unknown suspects. This technique has enhanced law enforcement’s ability to investigate and prosecute crime. But digital surveillance can also provide the government with unfettered access into individuals’ lives. Such intrusions would have been unthinkable to those 55 men gathered in Philadelphia in 1787. Therein lies the problem—the technological resources at the government’s disposal unlock efficient and effective ways to solve crime in the twenty-first century, but they also expose individuals’ whereabouts at all times, including in sensitive places. The government now has the capacity to identify any individual with a cell phone, at any public or private location. As technology continues to evolve, open questions remain about what surveillance actions meet constitutional muster. The Fourth Amendment’s protection against expansive government surveillance, nevertheless, must stay true to the Founders’ core principles.

Law enforcement, in this matter, is investigating a series of violent crimes that were committed in Jackson, Mississippi. Some suspects’ identities are known. Others are not. To identify all those potentially involved, the Government applied for search warrants. These warrants would permit law enforcement to use “tower dumps” to access the time-and-location-data of all devices that connected to cell towers around the area where these crimes allegedly occurred. With this information, the Government asserts that it will be able to identify all potential suspects. Even so, law enforcement would also have access to the cellular records of countless individuals, the vast majority of whom were merely passing by a location at the “wrong” time. That is an unreasonable search under the Fourth Amendment. To uphold core constitutional principles, this Court finds that tower dumps are per se unconstitutional. The Government’s request to reverse the Magistrate Judge’s decision denying its applications for search warrants is denied.

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More broadly, however, Carpenter recognizes that while there is not a “single rubric definitively resolv[ing] which expectations of privacy are entitled to protection, the analysis is informed by historical understandings of what was deemed an unreasonable search and seizure when the Fourth Amendment was adopted.” Id. at 304-05 (cleaned up). The “basic guideposts” are “that the Amendment seeks to secure ‘the privacies of life’ against ‘arbitrary power”‘ and “a central aim of the Framers was ‘to place obstacles in the way of a too permeating police surveillance.'” Id. at 305 (citations omitted). These two principles are useful for the Court “when applying the Fourth Amendment to innovations in surveillance tools.” Id. With these new technologies, the Court “has sought to assure preservation of that degree of privacy against government that existed when the Fourth Amendment was adopted.” Id. (quotation marks and citation omitted). To uphold these protections, the Court found that “[a]llowing government access to cell-site records contravenes that expectation.” Id. at 311. The Court, thus, clarified that under the reasonable expectation of privacy test, “[a] person does not surrender all Fourth Amendment protection by venturing into the public sphere.” Id. at 310. Carpenter, in short, counsels against technologies that give the government unfettered, arbitrary, and intrusive access to individuals’ movements.

In the Supreme Court’s latest Fourth Amendment case, Chatrie v. United States, the Court builds upon its holding in Carpenter by applying its previous reasoning to geofencing and Location History. See Chatrie, 146 S. Ct. at 2206. The Court, once again, held that an individual has a reasonable expectation of privacy in their cellular data. But the Court went a step further and clarified that “police invade that expectation [of privacy in cellular information], and thus conduct a search, when they acquire that information, even though for only a limited period of time and even though via a third-party tech company.” Id. The Chatrie Court, thus, filled an important gap in Carpenter by expressly determining that the temporal aspect of a search has no bearing on whether or not a search occurred. Id. at 2209-12; see specifically id. at 2210 (“[T]he durational bounds on the data actually acquired do little to address the Fourth Amendment’s concern about ‘a too permeating police surveillance.'”) Put simply, a search is search, regardless of its duration.

The Court now turns to United States v. Smith, the leading Fifth Circuit case on digital surveillance technologies. Drawing on Carpenter’s logic the Fifth Circuit determined that geofence warrants are “unconstitutional under the Fourth Amendment.” 110 F.4th at 820.