UK police have a creative new solution to the encryption problem: just snatch the phone.

Today, the BBC reported on a recent fraud case in which Scotland Yard agents staged a pre-arrest mugging in order to make sure a suspect’s iPhone was seized in unlocked mode. Investigating a credit card forger, police waited for the suspect to make a call, then snatched the phone directly out of his hand before arresting him. The result was an unlocked phone — an open book for investigators, provided they didn’t let it slip into sleep mode.

The tactic itself isn’t new. In the Silk Road case, agents made a point to pull Ross Ulbricht away from his laptop before he could close it, which would have encrypted the hard drive and shut off valuable evidence. Still, general police booking procedures mean most phones are still seized in locked form.

Police can sometimes unlock phones by compelling a fingerprint reading (or in extreme cases, 3D-printing a replica), but the process is unreliable. For iPhones, such an attempt must be made within 48 hours of the most recent login, after which the phone can only be unlocked by code. At the local level, that’s often not enough time for police to take action.

As a result, prosecutors are faced with a growing stockpile of locked iPhones. As of this month, the Manhattan district attorney has more than 400 such phones in evidence, with no method for unlocking them. For civil libertarians, that’s good news: it means a simple arrest isn’t enough for police to see years’ worth of texts and emails. But it also means that if police want your data, they know they’ll have to take it by force.