The data protection commissioner in Hamburg said Wednesday he had reopened his investigation, suspended in June, after repeated attempts to persuade Facebook to change its policies about its use of facial recognition technology had failed.
"We have no other option but to reopen our investigation," Johannes Caspar told The New York Times. "We have met repeatedly with Facebook but have not been able to get their cooperation on this issue, which has grave implications for personal data."
Facebook's use of recognition software to compile a photographic database of human faces from images uploaded by users has been criticized in Europe, where data protection laws require users to give explicit consent to such practices.
However, Facebook makes the facial recognition system the default and requires users to opt out instead.
Caspar said he wants Facebook to destroy its database of faces collected in Germany and revise its Web site to obtain the explicit permission of users to collect biometric data of their faces.