A lawsuit alleging that Facebook photo tagging violates user privacy has cleared a crucial early hurdle. A judge in Northern California District Court today ruled against a motion by Facebook to dismiss. That leaves the larger questions around biometric privacy unanswered, but clears the way for a major legal battle over one of Facebook's most popular products.

The lawsuit alleges that Facebook's photo-tagging system violated user privacy by creating faceprints — geometric representations of a person's face — without explicit consent. Those faceprints are typically used to identify users to suggest tags for uploaded photos. According to the complaint, that's a violation of Illinois's Biometric Information Privacy Act, which forbids the collection of biometric identifiers like fingerprints or faceprints without a person's explicit consent. As Alvaro Bedoya of the Center on Privacy and Technology at Georgetown Law described it, "If you run a bar, the law doesn’t prevent you from picking up my used pint glass, but it prevents you from pulling my DNA off it."

Does Facebook's photo-tagging system violate privacy law?

The photo-tagging system is disclosed in the company's Data Policy and users can opt out of it, but it is unclear whether those measures will satisfy the legal definition of consent. "This lawsuit is without merit," a Facebook spokesperson said in an earlier statement on the case, "and we will defend ourselves vigorously."

Today's decision focused on the question of whether the Illinois law is applicable to Facebook, one of the major legal hurdles facing the plaintiffs. Facebook's Terms of Service maintains that the the company is only bound by California and federal laws, and the company had moved to dismiss the case on those grounds. But today, the judge ruled that the terms-of-service clause isn't sufficient to nullify the Illinois law. As a result, the plaintiffs have a valid claim under the Illinois biometrics law and the case can proceed.

If the plaintiffs win, it could have major implications for both Facebook and the industry at large. Facebook's photo-tagging system is one of its core products, and one that has already been copied by competitors like Twitter and Google Photos. Those systems are already beginning to see similar challenges. In March, Google was hit with a similar lawsuit alleging that the photo-tagging system in Google Photos violates the same Illinois law.

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