Oakland-California police officers speak less respectfully to members of the public who are black than to those who are white, researchers studying body camera footage say.

Scientists developed a way to measure levels of respect, based on the officers’ language during routine traffic stops in Oakland City. The study is published in Proceedings of the National Academy of Sciences. It aims to use bodycam footage to help improve police-community relations.

While bodycam footage has been used as evidence in criminal cases - including some where complaints have been made against police - the aim of this study was to turn this continuously gathered footage into data and use that to track and improve everyday policing. “These routine interactions are important,” said lead scientist Prof Jennifer Eberhardt, “they’re the way most people encounter the police.” “And people care as much about how they’re treated as whether or not they got a [speeding] ticket. “It can affect how people view the police, how they think about the police - whether or not they want to co-operate with them.” The study was part of a unique, decade long research collaboration between Stanford University and the Oakland Police Department in California, which began when the department asked Prof Eberhardt to analyse their stop and search data. “We had location and details [of who was stopped], but we also had the camera’s recording of every interaction,” she said. “I figured we could could analyse exactly what’s happening here.” The Stanford team transcribed 1,000 interactions between police and members of the public, then picked out a random selection of 400 “utterances” made by officers during these dialogues.