Whenever you upload a photo of yourself or your friends to Facebook, the social network uses a facial-recognition algorithm to identify who's in the picture -- and then suggests that you tag them. This might strike some as a little creepy, but at least it's relatively transparent. The same may not be true of a massive facial-recognition setup used by the FBI, which not only combs through pictures of criminals but also allows law enforcement to search the faces of millions of other law-abiding citizens without their knowledge. And now a top federal watchdog says the program risks putting countless Americans under needless suspicion because of the system's lack of safeguards. The FBI has access to more than 410 million photographs of people's faces.

The FBI has fallen short on assessing the privacy risks and accuracy of a huge facial recognition database used by several law enforcement agencies, a government auditor has said. A new report, released by the U.S. Government Accountability Office Wednesday, shows the FBI's use of facial recognition technology is "far greater" than previously understood, said Senator Al Franken, the Minnesota Democrat who requested the GAO report. The FBI's Next Generation Identification-Interstate Photo System (NGI-IPS), which allows law enforcement agencies to search a database of more than 30 million photos of 16.9 million people, raises serious privacy concerns, Franken added in a press release. "Facial recognition technology is a new and powerful tool that holds great promise for law enforcement," he said. "But if we don't ensure its accuracy and guard against misuse, I am concerned about the risk of innocent Americans being inadvertently swept up in criminal investigations."