Privacy concerns have been raised with respect to ALPRs generally, including Flock's systems. Additionally, Flock's surveillance model has also spurred debates between supporters and opponents of the technology. Flock's surveillance technology is often criticized for its broadening of public surveillance, and lead to a chilling effect on civil liberties, as described by privacy experts and organizations like the Electronic Frontier Foundation (EFF) and the American Civil Liberties Union (ACLU). The EFF argues that ALPRs create more problems than they solve.
In March 2022, the American Civil Liberties Union released a report criticizing Flock Safety's business model and products.[60] In 2023, the ACLU acknowledged some uses of ALPRS could be acceptable, but emphasized the need for careful controls:
We don't find every use of ALPRs objectionable. For example, we do not generally object to using them to check license plates against lists of stolen cars, for AMBER Alerts, or for toll collection, provided they are deployed and used fairly and subject to proper checks and balances, such as ensuring devices are not disproportionately deployed in low-income communities and communities of color, and that the "hot lists" they are run against are legitimate and up to date. But there's no reason the technology should be used to create comprehensive records of everybody's comings and goings — and that is precisely what ALPR databases like Flock's are doing. In our country, the government should not be tracking us unless it has individualized suspicion that we're engaged in wrongdoing.
Menlo Park, California opted out of a contract in 2023, bucking trends of nearby cities, but revisited the question and approved Flock cameras in 2024.
In June 2024, a judge in the Norfolk, Virginia, Circuit Court ruled that collecting location data from the city's 172 Flock ALPRs constitutes a search under the Fourth Amendment, and cannot be used as evidence in a criminal case when collected without a warrant. The ruling likened ALPR location databases to tracking devices, whose use by police was previously found unconstitutional without a warrant in United States v. Jones. Later, in October 2024, the Institute for Justice filed a federal lawsuit against the Norfolk Police Department on behalf of two local residents, similarly asserting that the department's use of Flock ALPRs constitutes illegal surveillance in violation of the Fourth Amendment. In California, state law prohibits sharing license plate reader data with federal agencies, but in 2025 it was reported that several state and municipal law enforcement agencies have nonetheless done so.
In May 2025, it was reported by 404 Media that Flock data had been queried for use in immigration enforcement. According the company, a pilot program of investigation with Customs and Border Protection and Homeland Security Investigations was initiated to help combat human trafficking and fentanyl distribution. They halted the program in August because of "confusion and concerns" about the purpose of the investigations.
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