In 2018, the Supreme Court upheld landmark victories for two victims of the serial sex offender John Worboys against the Met Police, in the case known as “DSD and NBV”. The claimants alleged that Met officers had breached Article 3 of the European Convention on Human Rights, by failing to investigate Worboys’ crimes properly and thereby failing to protect victims from “inhuman or degrading treatment” and hold the perpetrator to account. It was generally thought that police were “immune” from claims by individuals alleging “operational” failings in investigations. But the Supreme Court held that “obvious and significant shortcomings” can give rise to liability. When is an operational failing “obvious and significant”? How can investigators avoid such pitfalls? Solicitor Deborah Britstone and barrister Aaron Rathmell examine how this judgment affects the police.