Tesco and Asda could install a facial recognition system at their checkouts which would check a customer's age when they buy alcohol and other restricted items. The'Fastlane' software would take a picture of the customer and approve the purchase if they are clearly old enough, meaning a staff member would not need to come and intervene. Shoppers will not have to register in advance, although regular customers can sign up to an app by linking a selfie to a passport or ID document, manufacturers said. Asda, Morrisons and Tesco are the most likely to trial the software although Sainsbury's has said it will not, the Daily Telegraph reported. If the photo does not prove a customer was old enough then supermarket staff would have to check their ID in person.