Senator Bernie Sanders introduced the Ban Flock Act on Friday, legislation that would bar federal agencies from using automatic license plate readers (ALPRs) or accessing data collected by locally run cameras and private vendors. Representative Alexandria Ocasio-Cortez and Senator Jeff Merkley are co-sponsors.

Despite the name, the text does not single out Flock, the largest ALPR vendor in the United States. It covers any ALPR system and carves out just two exceptions: toll collection, and uses that future legislation explicitly authorises with a data-retention limit of no longer than 48 hours.

Enforcement would be financial rather than criminal. Starting the first fiscal year after enactment, state and local governments that do not ban the technology would lose grants from five federal departments, including the Department of Justice and the Department of Homeland Security. Individuals could also sue the federal government over violations, and state attorneys general could enforce the law.

Flock, which Sanders says operates more than 120,000 cameras nationwide, said in February that its network processes more than 20 billion vehicle reads a month. Facing protests, suspended contracts and a growing number of cancellations, the company has tightened its defaults: in August chief executive Garrett Langley announced a retention period of seven days, down from 30, and customers must now run an audit tool that locks officers out of the platform when it flags unusual searches.

The pressure has been driven by concrete cases of misuse. A former Milwaukee officer pleaded guilty to misconduct after running 179 searches for his former partner and her ex, each time listing 'investigation' as the reason.

The bill's prospects are thin — it would have to clear a Republican-controlled Congress — but it is the first federal legislative attempt aimed squarely at license-plate surveillance, and it arrives as a growing number of cities quietly let their camera contracts lapse.