SAN FRANCISCO (KPIX) – Amazon has handed new technology that can identify faces in the crowd to law enforcement. Two states are already using it.

Now privacy watchdogs are gearing up for a surveillance showdown.

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It can identify anyone — anywhere — in real time.

Skynews just used Amazon’s facial recognition technology to identify guests at the royal wedding.

But what if it’s used to catch criminals?

The Director of Technology and Civil Liberties for the ACLU of California warns:

“Once a dangerous surveillance system like this is turned against the public, the harm can’t be undone. We’re blowing the whistle before it’s too late.”

The ACLU, along with dozens of other groups nationwide, just sent a letter to Amazon CEO Jeff Bezos demanding that the company stop providing the technology to government agencies.

“With the evolution of technology, so comes the evolution of forensics,” says Kpix 5 Security Analyst Jeff Harp.

He compares this technology to license plate readers which have been installed in many Bay Area cities.

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These have also drawn opposition from the ACLU.

The concern is that this facial recognition surveillance system will violate people’s rights and target communities of color.

Harp contends the technology doesn’t discriminate based on the color of a person’s skin.

“If you take a person’s photo, all it’s doing is applying to a mathematical equation to a shape,” he says.

According to the ACLU, some law enforcement agencies in California have shown interest in recognition technology.

Harp says if it’s used under proper guidelines, the recognition system could be beneficial in solving crimes.

“If we use this technology in public places you’ll find people you’re looking for — might even find lost children,” he says.

Right now police departments in Orlando and Oregon are using the technology. The metropolitan police in the UK also uses it.

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According to an analysis by the Independent, the results were inaccurate in 98 percent of cases.