An EU privacy watchdog says it's prepared to start a multibillion-dollar class-action lawsuit against Facebook owner Meta if the company goes through with plans to use user data from its platforms to train AI.

NOYB – European Center for Digital Rights is a nonprofit rights watchdog whose mission is to protect consumer rights under the EU's General Data Protection Regulation. In a new cease and desist letter, it alleges that Meta's plans for AI training violate GDPR rules, and therefore risk a lawsuit.

The letter alleges that Meta is requiring users in the EU who have already opted out of AI training to opt out a second time, which runs foul of the GDPR.

The group says this violation "further undermines any legitimate trust in Meta’s organizational ability to properly execute the necessary steps when data subjects exercise their rights."

Meta has told affected users in the EU that they have until May 27 to make their final opt-out. Noyb has told Meta it wants a response to its letter by May 21.

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Last month, a separate EU data regulator made a similar request to Meta.

The Verbraucherzentrale North Rhine-Westphalia, a data protection authority in Germany, sent a cease and desist letter to Meta on April 30. The letter alleges Meta cannot back up its claims that it has a legitimate interest in collecting data from EU users for AI training.

Instead, experts say, Meta should be asking affected users to opt in and consent to AI training.

"Meta should simply ask the affected people for their consent. But if Meta ignores EU law, there will be consequences for the whole of Europe," said Noyb chairman Max Schrems.

Meta's privacy policy says it uses "information shared on Meta Products" for AI training. "This information could be things like posts or photos and their captions."

Some information may also come from users who don't have a Meta account of their own, "if you appear anywhere in an image shared on our Products by someone who does use them or if someone mentions information about you in posts or captions that they share on our Products."