Another reason to take BART to SFO? Privacy concerns. An Airport Commission vote last month gave San Francisco International Airport the go-ahead to use license plate readers to record the information from every car that uses the airport's roads and garages. SFO can now keep that data on file for more than four years, accessible to 70 airport employees who can release the data to the San Francisco Police Department, the San Mateo Sheriff's Department, and the FBI. That's cause for concern, the American Civil Liberties Union tells KQED, offering up a “honeypot” to authorities.

As Matt Cagle of the ACLU in Northern California poses the question to KQED, “Why does law enforcement need to know who’s visiting SFO?... It’s one thing if a crime has been committed or if there’s a legitimate demand from law enforcement with a warrant,” he says, “but it’s another thing if the airport has decided to simply share this information with law enforcement for their own purposes.”

SFO maintains that the primary function of its license plate reading efforts will be collecting the revenue it's owed by commercial drivers on its roads and at its garages with FasTrak accounts — much the way bridge authorities now do with all cars passing over the Golden Gate Bridge. “It’s important to remember that the primary purpose for the system that we’ve established here is for revenue collection,” airport spokesman Doug Yakel tells KQED. “Is there a correlation to law enforcement efforts? Of course,” Yakel adds. “It’s a benefit to thwarting vehicle theft and other types of crimes. But that’s really not primarily how it's used."

SFO serves 53 million passengers a year, and if every car that ferries them to or from the airport has its license plate recorded, SFO's data collection could on the kind of massive scale the ACLU has repeatedly warned against. "Private companies use license plate readers to monitor airports, control access to gated communities, enforce payment in parking garages, and even help customers find their cars in shopping mall parking lots," a report created by the ACLU explains. "While these uses in and of themselves are not objectionable, private companies can scan thousands of plates each day and store information indefinitely, creating huge databases of Americans’ movements." The report's recommendations include storing data about innocent people for the briefest possible periods. "Law enforcement agencies must not store data about innocent people for any lengthy period," the report recommends. "Unless plate data has been flagged, retention periods should be measured in days or weeks, not months, and certainly not years." The ACLU also encourages that entities who use license plate recorders publicly report their usage.

In fact, SFO's policy follows legislation calling for just that: Senate Bill 34, which went into effect last year, requires security protections for data collected by plate readers and “public disclosure” about the technology's use.

Update: In a statement issued to CBS5, SFO spokesperson Yakel emphasizes that "SFO does not record every license plate of every vehicle at the airport, nor do we have the capability to do so." Nevertheless, the Airport Commission's vote would appear to give it the leeway to do just that, prompting the ACLU's objections.

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