Members of the public have until Friday to comment on a Seattle Police Department (SPD) proposal to massively expand its data collection on where people drive their cars. SPD retains this data for three months regardless of whether the owner of the car was connected to a crime.

To gather this data, cops use Automatic License Plate Readers (ALPR), which take pictures of license plates and records the date, time, and location of the plate as cops drive past. Less than two dozen SPD patrol and parking enforcement vehicles currently have this technology, and SPD still manages to photograph millions of license plates in a given year. Now, SPD plans to ask the City Council to approve installing ALPR in all 300 of its patrol vehicles, significantly scaling up SPD’s ability to surveil where people travel. Plus, anyone can access this data through a public information request.

Cops use ALPR technology to quickly scan license plate numbers and alert them if a plate matches one off the “hot list,” which consists of a list of plates from stolen vehicles, cars connected to a felony crime, or associated with a wanted person. Rather than cops taking their eyes off the road to check every plate they pass, the technology scans and compares for them. However, SPD also retains license plate numbers that don’t register as a “hit” on the hot list.

Given that ALPR can collect tens of thousands of license plate images in 24 hours, and that SPD would roll out the technology to all of its patrol cars, officers have a high probability of capturing an image of the average plate at some point. Photos of those plates, as well as the time, date, and location, go into a database and SPD keeps that data for 90 days.

The American Civil Liberties Union, digital privacy advocates, and researchers at the University of Washington’s Center for Human Rights have raised concerns about keeping such detailed vehicle location information on people not associated with any criminal activity. In a 2013 report, the ACLU quoted from a US Court of Appeals case that said knowing where someone travels in a day can tell you whether they’re an “unfaithful husband, an outpatient receiving medical treatment, an associate of particular individuals or political groups.”

In its 2018 report, SPD acknowledged some of the concerns about how the ALPR data could be used to track people’s movements. However, the department said it mitigated some of these worries by not automatically linking the captured data to information from the Department of Licensing, leaving the license plate information anonymous until cross-referenced with other department databases. The department, as well as the Office of Inspector General (OIG) can also audit the logs of when officers searched the database and the department limits access to the license plate image database. However, the OIG said it had no details on which officers can access the database.

Office of Police Accountability investigations give plenty of examples of how SPD officers abuse police databases. In 2021, an SPD officer used these systems to track his ex-girlfriend’s new boyfriend. In 2020, an officer accessed information about an ongoing domestic violence investigation and possibly shared that information with one of the people involved. Early this year, another officer searched whether a suicidal family member had any registered firearms. UW researchers raised concerns about how ALPR data could be used by federal agencies to track undocumented immigrants or by other states to track those coming to Washington to seek abortions.

Beyond what governmental agencies can do with the information, literally anyone can access this data through a public information request. Someone can request all SPD ALPR data from the last 90 days and if they know your license plate number, track your location. So, even if you believe in the trustworthiness of SPD, the federal government, or the protections Washington put in place sheltering people seeking abortions, you might consider whether you trust just an average person, or an ex-partner, to be able to request and access this data.

To avoid some of the privacy violations inherent in keeping ALPR data for a long period of time, other states require law enforcement agencies to quickly discard images of license plates not linked to any crime.

In New Hampshire, law enforcement officers must purge their ALPR systems of non-hit plates within three minutes. Washington State law allows SPD to keep these pictures until officers can verify that they haven’t captured a “significant image.”

In a 2018 Surveillance Impact Report, SPD Deputy Chief Marc Garth Green said investigators use this data to help solve homicides, robberies, kidnappings, and to help with tracking down missing children, serious crimes meant to help sell the importance of this technology. But a couple studies of ALPR data show just 1% to .2% of license plates captured are either on a hot list or associated with any crime at all.

In 2021, the Council reviewed the ALPR technology under the 2017 Surveillance Ordinance. At the time, Council Member Lisa Herbold asked SPD to provide a report on the feasibility of limiting the retention of the ALPR data to 48 hours. In response, SPD said it could not determine whether a license plate image may be involved in a criminal case within that time period.

Right now, just 11 of SPD’s patrol cars and eight parking enforcement vehicles have ALPR technology. Expanding to the entire fleet could result in more than a billion license plate images taken each year. However, before SPD can ask the Council for permission to expand the technology, Seattle’s 2017 surveillance ordinance requires the department to create a Surveillance Impact Report (SIR) due to the “material changes” to the use of existing technology. As part of the SIR process, SPD must solicit public comment and the comment period for the ALPR expansion ends this Friday.