Who’s watching the cops who are looking at you?

Facial recognition software really could help the cops catch bad guys, but the Chicago Police Department has no business setting up the rules of engagement on its own.

A powerful new technology such as this, which has the potential to invade the privacy of every American, should be employed by law enforcement only after clear limits and ground rules have been established by others.

The Chicago police should suspend its use of facial recognition software until that thorough public vetting is done.

In Thursday’s Sun-Times, reporter Tom Schuba detailed how CPD detectives are now using a facial recognition app that sweeps through some 3 billion photos on Facebook, YouTube, Twitter and other websites when in search of a suspect.

The technology can work. Schuba cited the example of an alleged thief who lived in Chicago’s South Shore neighborhood who was caught thanks to the facial recognition app. The suspect made the mistake of posting a couple of selfies on social media.

Unfortunately, it also can go wrong.

The technology is not flawless, and anybody’s photo could be swept up — mistakenly or intentionally — by the police. A study released in December by the National Institute of Standards and Technology found that many facial recognition systems misidentified people of color more often than whites.

Facial recognition technology also is not restricted to use by the police. Any private company, whatever its motives, can purchase the service.

Strictly speaking, CPD’s decision to use the technology did not require approval from the Chicago City Council. But you might think that a police department that has struggled to gain the trust of many Chicagoans would seek that independent assessment and approval all the same.

Where was the public discussion before the police, on Jan. 1, began using the technology? Where were the hearings before the City Council or state Legislature?

CPD says it will use the new technology responsibly, but when a police department or private company is allowed to set its own standards, those standards can change on a whim.

As Schuba reports, a lawsuit was filed in federal court this month seeking to halt the New York-based tech company with whom CPD has partnered, Clearview AI, from continuing to collect photos and crunching the data. The technology, the complainants allege, threatens to create “a massive surveillance state.”

Chicago already has the nation’s largest network of surveillance cameras, and the police department announced in September that it hopes to join forces with a video doorbell company called Ring. This could give the cops access to thousands of cameras fixed to residents’ front doors.

Due to privacy worries, San Francisco and Oakland have prohibited police entirely from using facial recognition technology, which seems like an overreaction. We’re glad, that is to say, that the Chicago police were able to nab that alleged thief in South Shore.

What’s called for is not a permanent ban, but a balancing of interests, as often is the case when new forms of technology come along that threaten rights and liberties.

Lawmakers, for example, have had to set limits on the ability of the police to access information in personal cellphones. They have had to work out rules on when and how law enforcement can use drones to track suspects. They have had to set rules on when the police can attach a GPS tracker to a person’s car.

The job of the state Legislature now must be to establish sensible rules for the use of facial recognition technology, while at the same time preserving existing privacy protections, as laid out in the state’s Biometric Information Privacy Act. That law, which provides among the strongest protections in the country against biometric information being used without a person’s consent, is under constant attack by those who would weaken it.

“Whenever we tackle this privacy issue,” state Sen. Cristina Castro, D-Elgin, told us, “you watch how many lobbyists come full-throttle to oppose the bill.”

Your privacy down the road depends on elected officials standing up for you now.

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