Twitter tells AI startup its face data is off limits

A mysterious company that has licensed its powerful facial recognition technology to hundreds of law enforcement agencies is facing attacks from Capitol Hill and from at least one tech giant.

San Francisco’s Twitter sent a letter this week to Clearview AI demanding that it stop taking photos and any other data from the social media website “for any reason” and delete any data that it previously collected, a Twitter spokeswoman said. The cease-and-desist letter, sent on Tuesday, accused Clearview of violating Twitter’s policies.

The New York Times reported last week that Clearview had amassed a database of more than 3 billion photos from social media sites — including Facebook, YouTube, Twitter and Venmo — and elsewhere on the internet. The vast database powers an app that can match people to their online photos and link back to the sites the images came from.

The app is used by more than 600 law enforcement agencies, ranging from local police departments to the FBI and the Department of Homeland Security. Law enforcement officials told the Times that the app had helped them identify suspects in many criminal cases.

Clearview’s database of photos dwarfs those previously used by law enforcement agencies. Other technology companies capable of building such a tool, like Google, have decided not to because of concerns about the potential for abuse.

Tor Ekeland, a lawyer for Clearview, confirmed that it had received Twitter’s letter and said the company “will respond appropriately.” He declined to comment further.

The Times article set off angry protests from Democratic lawmakers and privacy watchdogs, who said it was paving the way for universal facial recognition technology that would effectively end people’s ability to remain anonymous while in...