Immigration and Customs Enforcement agents are deploying cell-site simulators—devices that mimic legitimate cell towers—to track mobile phones across the United States, raising constitutional concerns as federal investigators admit they did not always follow required protocols when using the surveillance technology.

How the Technology Works

The devices operate by imitating cellphone towers, causing nearby phones to automatically connect to their signals. This allows ICE agents to identify and track specific devices with precision. According to Department of Homeland Security policy documents, the simulators provide information about signal strength and the general direction of a targeted device. The technology can also capture device identifiers from phones belonging to people not under investigation, effectively revealing the identity of all phones within a specific area.

Federal officials maintain the simulators cannot access the content of communications, including emails, text messages, contact lists, or stored images. However, civil liberties organizations dispute the scope of data collection, arguing the technology sweeps up information from innocent Americans without their knowledge or consent.

Violations of Federal Law Uncovered

A recent Inspector General report revealed that both the Secret Service and ICE’s Homeland Security Investigations office failed to comply with federal statutes and internal policies during criminal investigations. While agencies obtained search warrants in reviewed cases, they did not request court orders required under the Pen Register Act in some instances. The report also found HSI operated without an approved Privacy Impact Assessment until January 2022, violating the E-Government Act of 2002. Officials blamed resource limitations and personnel changes for the compliance failures.

Constitutional Questions Mount

Digital rights advocates warn the surveillance program may violate Fourth Amendment protections against unreasonable searches and seizures. Chris Weiland, president of Restore the 4th Minnesota, stated that using such data without court orders constitutes a constitutional violation. Cooper Quintin, senior technologist at the Electronic Frontier Foundation, expressed alarm about immigration enforcement agencies possessing advanced surveillance capabilities. Privacy experts also raised concerns about how collected data is stored and whether it might be used for purposes beyond initial investigations, particularly as the Trump administration pursues expanded deportation operations.

What This Means

The revelations come as immigration enforcement activities intensify under President Trump’s mass deportation strategy. The admission of procedural violations undermines official assurances about privacy protections, while questions about data retention and secondary use remain unanswered. With ICE continuing to deploy cell-site simulators despite acknowledged compliance failures, the technology represents a growing intersection of immigration enforcement and digital surveillance that affects all mobile phone users, not just targeted individuals.