The California Supreme Court has given California police increased warrantless search and seizure latitude regarding personnel information on cell phones.
Police argue that lots of incriminating evidence can be found on cell phones and rely on 1970’s rulings allowing search of personal belongings by arresting officers. At the time they were looking for something hidden in a compact or the bottom of a handbag. Today, the difference is the volume you can store on a cell.
Karl Denninger at The Market Ticker has a longer piece about this. He urges strong encryption and a hidden key, which so far you don’t have to surrender on arrest.
Of course criminals use cell phones for nefarious purposes, but not everyone arrested is a criminal.