Facebook Photo-Scanning Suit Is a Multibillion-Dollar Threat

Facebook Inc. may have to pay a real price for claims it invaded users’ privacy: billions of dollars.

A federal judge ruled April 16 that millions of the social network’s users can proceed as a group with claims that its photo-scanning technology violated an Illinois law by gathering and storing biometric data without their consent. Damages could be steep — a fact that wasn’t lost on the judge, who was unsympathetic to Facebook’s arguments for limiting its legal exposure.

The case dates back to 2015, long before Facebook became mired in controversy over revelations that millions of its users’ private ...