Fourth Circuit: Police need warrant to use tracking device that mimics cellphone tower

Police wanting to use a device mimicking a cellphone tower to locate people must first get a warrant, a Fourth Circuit panel ruled, reported Courthouse News Service.

Kerron Andrews was arrested by the Baltimore Police Department in May 2014, after the police secured a court order allowing them to use a cell-site simulator to obtain his real-time location information. Andrews’ cellphone provider had allowed the police to determine his location within a few blocks, before the police used a simulator to determine he was in a specific townhouse.

Andrews told the Fourth Circuit panel this past January that the court order did not satisfy the Fourth Circuit’s warrant requirement. The panel disagreed Thursday, while recognizing that cellphones pose a unique threat to individual privacy.

The precision of the technology used by the police is invasive, U.S. Circuit Judge Nicole Berner wrote for the majority, and people have a reasonable expectation of privacy in a private home. The Joe Biden appointee was joined by U.S. Circuit Judge Toby Heytens, also a Biden appointee.

“This technology is akin to sense-enhancing technology that allows the government to peer into a private home, which the Supreme Court has repeatedly held requires a warrant,” she wrote. The cell-site simulator effectively “cracked open the front door” of the property to reveal Andrews, she said.

“Despite the ubiquity of cell-site simulators, no federal court of appeals has squarely addressed whether law enforcement’s use of this technology for realtime tracking of a cellphone constitutes a search for purposes of the Fourth Amendment,” she wrote. “Today, we hold that it does.”

Andrews had a reasonable expectation that his phone wouldn’t be used as a real-time tracking device by law enforcement, the panel found, and the use of the cell-site simulator constitutes a search as defined in the Fourth Amendment. The judges did not decide if the pen register order secured by the cops satisfied the Fourth Amendment’s warrant requirement.

Despite this, Andrews’ civil suit against the police department and detectives can’t proceed, because the officers are protected by qualified immunity, the panel found, upholding a lower court’s judgment in favor of the police department and its detectives.

Donald Trump-appointed U.S. Circuit Judge A. Marvin Quattlebaum Jr. concurred with the judgment, adding in a short opinion that he feels the panel should have first determined if Andrews’ constitutional rights had been violated and evaluated whether the pen register order was a valid warrant.

The police sought to arrest Andrews — who had previously worked with them as an informant — on charges of triple attempted murder after a shooting during a drug deal. The prosecution dropped the case against him after a Maryland court found officers should have first secured a warrant to use the simulator. He had spent nearly two years in pretrial detention, and later sued the department and two detectives claiming that they violated the Fourth and 14th Amendments by using the simulator.

“We are pleased that today’s ruling agreed that using privacy-invading technology—here, a device that enables law enforcement to see through walls—requires a valid search warrant,” Mike Pichini, attorney for Andrews, told Courthouse News. “Although disappointed with the overall result, we celebrate that our Constitution constrains law enforcement’s warrantless privacy invasions, especially when such invasions breach residential walls. We, the people, must be vigilant against government warrantless use of ever-evolving technology to erode our fundamental right to privacy.”

The Baltimore Police Department and detectives had argued his constitutional rights were not violated, and that their actions were reasonable as they had a warrant for his arrest and a court order allowing them to use a cellular tracking device that was functionally equivalent to a warrant. The court order did not satisfy the Fourth Amendment’s warrant requirement, Andrews argued.

The case had appeared before the Fourth Circuit before, when the panel expressed concerns the order did not specifically authorize a cell-site simulator and that the device may have searched devices other than Andrews’. The court remanded the case, directing the lower court to conduct more fact-finding.

In May 2025, the police defendants secured summary judgment, with U.S. District Judge Stephanie A. Gallagher concluding the search required a warrant but that the order the police secured was sufficient and effectively acted as a warrant. Andrews’ Fourth Amendment rights were not violated, she ruled.

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