More than two dozen privacy and advocacy organizations urged California Gov. Gavin Newsom to remove a covert network of license plate readers deployed across Southern California, saying the devices help feed data into a U.S. Border Patrol program that they describe as monitoring drivers’ travel patterns nationwide. The groups asked Newsom’s administration to investigate and publicly release the relevant permits, revoke them, and initiate removal of the devices, according to a letter they said was sent Tuesday.
The letter’s request drew on an Associated Press investigation published in November that described how the Border Patrol hid license plate readers in ordinary traffic safety equipment and then fed the resulting data into what the AP said is a predictive intelligence program. The AP reported that the Border Patrol uses the collected license plate information to run an algorithm that flags vehicles it deems suspicious based on where they came from, where they were going, and which route they took, and that the flagged information can be used to support traffic stops and other enforcement actions.
The advocacy groups said they have identified a similar deployment in California. Their researchers, the letter said, found about 40 license plate readers in San Diego and Imperial counties, both of which border Mexico, and said more than two dozen of the readers they identified were hidden in construction barrels. The letter said some readers appeared to have been installed with state permission and cited researchers’ access to land use permits, including permits obtained from the California Department of Transportation.
The groups said they could not determine the ownership of every device. But they said the permits they reviewed showed that both the U.S. Border Patrol and the Drug Enforcement Administration applied for permission to place readers along state highways. The letter also said DEA shares license plate reader data with Border Patrol, and it cited the AP reporting about Border Patrol’s wider surveillance approach, including how cameras scan and record license plate information.
The groups’ letter pointed to examples described in court documents where Border Patrol agents used travel-history data in enforcement decisions. In one 2024 incident described in the filings, a Border Patrol agent pulled over a driver of a Nissan Altima based in part on data suggesting the driver took about six hours to travel roughly 50 miles between the U.S.-Mexican border and Oceanside, California. The agent wrote in the court document that the delay after crossing the border from Mexico is a common tactic used by people involved in illicit smuggling, according to the AP report.
In another case, Border Patrol agents described in 2023 court filings said they detained a woman at an internal checkpoint because she traveled a circuitous route between Los Angeles and Phoenix. In both examples referenced by the groups, law enforcement accused the drivers of smuggling immigrants unlawfully and sought to seize their property or pursue criminal charges, the AP report said.
The letter also argued that large-scale surveillance and predictive tools raise constitutional concerns. The groups said courts have generally upheld the use of license plate readers on public roads, but they cited concerns from civil libertarians and scholars that warrantless access to other persistent tracking technologies—such as GPS devices or cellphone location data—has been curtailed and that plate-reader systems paired with predictive algorithms could present similar Fourth Amendment issues. A spokesperson for the California Department of Transportation said state law prioritizes public safety and privacy, while the office of Gov. Newsom did not immediately respond to requests for comment.
Federal agencies did not provide new comments in response to the letter, the AP reported. A U.S. Customs and Border Protection spokesperson did not immediately respond to a request for comment, but the agency previously said it uses plate readers to identify threats and disrupt criminal networks and that the use of the technology is governed by a “stringent, multi-layered policy framework” and federal law and constitutional protections for defined security purposes. The DEA said it does not publicly discuss its investigative tools and techniques.