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Amazon $AMZN -2.43%'s Ring unit is facing a federal lawsuit alleging that its doorbell cameras collected and stored facial recognition data from passersby without their knowledge or consent.

The suit, filed Monday in federal court in Seattle by Virginia resident Charles Sigwalt, pursues class-action certification and demands a minimum of $5 million on behalf of the proposed class. At the center of the complaint is a Ring feature called "Familiar Faces," which applies AI to build a database of recognized individuals, sending homeowners or business owners personalized alerts that name the person when that individual appears again. The feature is optional for Ring users.

Sigwalt said the affected individuals "did not consent to have their privacy rights violated at the entrance way," according to the suit. "Millions of other Americans passed by a Ring security camera and unknowingly had their facial recognition information collected." Amazon declined to comment on the lawsuit.

The case is the latest in a long string of privacy controversies for Ring, which Amazon bought in 2018 for $1 billion, according to Reuters.