When Mark Lanier and his young client Kaley faced Meta and Google in an LA courtroom earlier this year, it seemed a bigger battle than David v Goliath. Lanier, however, was determined to prove the companies had not just stumbled into a youth mental health crisis, but had helped to engineer it. Help support our independent journalism at <a href="https://www.theguardian.com/infocus">theguardian.com/infocus</a>