The American Civil Liberties Union (ACLU), leading more than 24 other civil rights organizations, has asked Amazon to stop selling Rekognition, its facial/object recognition system, to law enforcement. Amazon introduced this online service in late 2016, offering Rekognition at a low cost through Amazon Web Services. Pitching it to law enforcement with the idea it could be used to assist in criminal investigations, Amazon signed on the Orlando Police Department in Florida and Washington County Sheriff’s Office in Oregon.

The New York Times reports that the ACLU and its allies perceive Rekognition as “mass surveillance” that can be used to track protesters, while its advocates see it as “a powerful new tool for catching criminals.” Although facial recognition is nothing new, “the organizations appear to be focusing on Amazon because of its prominence.” In a letter addressed to chief executive Jeff Bezos, they said that, “Amazon Rekognition is primed for abuse in the hands of governments.”

“This product poses a grave threat to communities, including people of color and immigrants, and to the trust and respect Amazon has worked to build,” they added.

The ACLU also released internal emails and other documents between those two law enforcement agencies and Amazon that provided “an unusual peek into the company’s ambitions with facial recognition tools, and how it has interacted with some of the officials using its products.” Amazon, notes NYT, “is one of the first major tech companies to actively market technology for conducting facial recognition to law enforcement.”

“The idea that a massive and highly resourced company like Amazon has moved decisively into this space could mark a sea change for this technology,” said Alvaro Bedoya, executive director at Georgetown University Law’s Center on Privacy & Technology.

Amazon countered that the uses of the technology are largely benign and require customers to comply with the law. Both Sky News and NYT have used the technology, and amusement parks use it to find lost children. The Center on Privacy & Technology estimates that more than 130 million U.S. adults are in facial recognition databases.

The Wall Street Journal reports that, “a string of fugitive arrests at a Cantopop star’s China concerts have spotlighted the expanding use of surveillance technology in public security.” Chinese concert organizers have been using facial recognition systems to stop scalping, but this is the “first widely reported indication that Chinese police are using facial-recognition at major musical events.”

Previously, in 2015, “Shenzhen-based Firs Technology said its facial-recognition system helped police identify drug-users, fugitives and ex-convicts at a jewelry exhibition in the city of Chenzhou.” Chinese police departments have “declined to answer queries about the accuracy of their systems.”