Half of American adults may not know it, but their photos are in face-recognition databases used law enforcement, according to an investigation by a think tank at Georgetown Law. Police can compare millions of mug shots, driver’s license, and ID photos against images of unknown suspects. This technology is less accurate in identifying African American, younger, and female faces. And because African-Americas are more likely to be arrested, they are overrepresented in the databases. We talk to David Gray, law professor at the University of Maryland, who says this face-recognition technology raises questions about our right to privacy.