US politicians expressed concerns about the accuracy and growing use of facial recognition software, at a hearing on Wednesday. The technology is being developed by firms including Amazon and Microsoft and increasingly used by law enforcement worldwide. Civil liberties and privacy groups have raised concerns about how the data for these programs is being gathered. "This is some real-life Black Mirror stuff that we're seeing here," said New York congresswoman Alexandria Ocasio-Cortez, a reference to a science-fiction TV show that explores the dark side of technology. US lawmakers are working on a proposal for a bill to limit the use of facial recognition.