The Marin County Sheriff’s Office illegally shared automated license plate reader data from its Flock Safety system with out-of-state and federal agencies 254,131 times in November 2024 alone.
Demand Letter Issued Over November 2024 Audit Logs
Automated license plate readers capture vehicle images and upload their location data into a searchable, shareable network. This mass surveillance tool indiscriminately logs every passing vehicle. Network audit logs obtained by the Point Reyes Light revealed that MCSO shared its database with out-of-state and federal agencies during the final months of 2024, violating state statutes SB 34 and SB 54.
Many of the agencies conducting these searches operate in states that maintain severe restrictions on reproductive care and assist Immigration and Customs Enforcement (ICE). These states include Alabama, Indiana, Kentucky, Florida, and Texas. The demand letter states that this sharing exposed sensitive driver location information to misuse by the federal government and states lacking California privacy protections.
The 2022 Settlement Agreement Breach in Lagleva v. Marin County Sheriff
This incident marks a direct repeat of past violations. In 2021, the EFF and the ACLU sued the Marin County Sheriff on behalf of community activists for sharing millions of local license plate numbers and location data with hundreds of federal and out-of-state agencies, including ICE and Border Patrol. That lawsuit, Lagleva v. Marin County Sheriff, concluded with a 2022 settlement agreement. Under that binding agreement, the Sheriff agreed to halt all sharing of license plate and location data with agencies outside California to comply with SB 34 and SB 54.
“MCSO’s November 2024 audit report shows that your office has violated not only SB 34, but the terms of the Lagleva Settlement Agreement as well,” the civil rights organizations noted in their letter.
The EFF and the ACLU are urging the Sheriff’s Office to launch a thorough audit of its ALPR database, institute strict new compliance protocols, and assess penalties against any employee found responsible for out-of-state data sharing.
Unanswered Questions Regarding System Safeguards and Public Notification
The Sheriff’s Office has previously claimed it took deliberate steps to disable nationwide data-access capabilities and ensure its system operated within strict privacy safeguards. However, the civil rights groups point out that officials have failed to explain how outside agencies managed to bypass these barriers. The agency has not clarified how it plans to prevent future breaches or why it neglected to inform the public and the Marin County Inspector General when the unauthorized access came to light.
The full demand letter is available on the EFF document archive.
