We Demand More Information on How Marin Cops Illegally Shared Flock ALPR Data

The Marin County Sheriff’s Office (MCSO) has been caught distributing automated license‑plate‑reader (ALPR) data from its Flock Safety system to out‑of‑state and federal agencies, a practice that directly breaches California’s privacy statutes and threatens the safety of every driver in the county.

Legal Boundaries That MCSO Ignored

California law expressly forbids law‑enforcement agencies from sharing ALPR data with non‑California entities; the prohibition is codified in SB 34. The statute was designed to keep the state’s robust privacy protections from being diluted by external jurisdictions that lack comparable safeguards.

When the data is used to aid immigration enforcement, an additional layer of protection applies: SB 54 bars any collaboration that could facilitate the removal of undocumented residents. Both statutes were reaffirmed in the 2022 settlement of Lagleva v. Marin County Sheriff, which limited MCSO’s data‑sharing practices.

The demand letter sent by the Electronic Frontier Foundation (EFF) and the ACLU of Northern California invokes the California Public Records Act to compel disclosure, underscoring that the alleged conduct is not merely a policy lapse but a clear statutory violation.

Scale of the Unauthorized Data Flow

Network audit logs obtained by the Point Reyes Light reveal that MCSO accessed its ALPR database 254,131 times in November 2024 alone, exporting records to agencies beyond state borders. This volume indicates a systematic, not incidental, breach of the legal framework.

Recipients included law‑enforcement bodies in Alabama, Indiana, Kentucky, Florida, and Texas—states known for stringent restrictions on reproductive health services and active cooperation with Immigration and Customs Enforcement (ICE). The sheer frequency of queries suggests that the data was being leveraged for purposes far beyond local traffic enforcement.

Each query captures a vehicle’s location at a specific moment, creating a searchable trail that, when aggregated, can reconstruct an individual’s movements over weeks or months, effectively turning every driver into a subject of mass surveillance.

Consequences for Vulnerable Populations

The indiscriminate sharing of ALPR data disproportionately endangers immigrants, abortion seekers, and other groups targeted by federal authorities. Because the data includes precise timestamps and GPS coordinates, it can be cross‑referenced with immigration databases to pinpoint undocumented individuals.

In states with restrictive reproductive‑care laws, the data could be used to identify patients traveling for medical services, exposing them to criminal prosecution or civil penalties. The risk extends to activists and journalists whose vehicles may be flagged for surveillance based on association rather than conduct.

Beyond immediate legal jeopardy, the erosion of trust in local law‑enforcement erodes community cooperation, a critical component of effective policing. When residents fear that routine traffic stops could feed a federal database, they are less likely to report crimes or assist investigations.

What This Actually Means For You

1. Every vehicle that travels on Marin County roads has had its location recorded and potentially shared with agencies that do not honor California’s privacy standards.
2. If you are an immigrant or a person seeking reproductive health services, the shared data could be used to locate you for immigration enforcement or criminal investigations in other states.
3. Public records requests under the California Public Records Act can reveal the extent of data sharing, offering a pathway to hold agencies accountable.
4. Legal challenges based on SB 34 and SB 54 are viable; prior settlements demonstrate that courts will enforce these privacy protections.
5. Community advocacy and pressure on elected officials can compel the sheriff’s office to revise its data‑handling policies and comply with state law.

Immediate Action Steps

File a California Public Records Act request for all ALPR logs and sharing agreements from MCSO, citing the recent demand letter and the Point Reyes Light audit. Document any refusals or redactions, as they may constitute further violations.

Support the ongoing litigation by the EFF and ACLU, whether through donations, public statements, or by contacting your local representatives to demand stricter oversight of ALPR usage. Engaging with community groups can amplify pressure on the sheriff’s office to halt unlawful data transfers.

Frequently Asked Questions

Did Marin County Sheriff’s Office violate California law by sharing ALPR data?

Yes. The sharing of ALPR data with out‑of‑state and federal agencies breaches SB 34, which prohibits such disclosures, and may also violate SB 54 if the data was used for immigration enforcement.

How many times was ALPR data shared in November 2024?

Network logs show that MCSO accessed and shared its ALPR database 254,131 times during November 2024, indicating a large‑scale, systematic breach.

What protections does SB 54 provide for immigrants?

SB 54 bars California law‑enforcement agencies from cooperating with federal immigration authorities using state‑collected data, effectively shielding undocumented residents from state‑facilitated deportation efforts.

What Do You Think?

Should law‑enforcement agencies be allowed to trade local surveillance data for federal or out‑of‑state investigations when state law explicitly forbids it?