When the police arrest someone, they can conduct a limited search of a person’s pockets or bag but they can’t start opening up closed containers nearby. For that sort of search, they need a warrant. But what about a cell phone? Can police start going through it on the spot or do they need special permission?

The rules on cell phone searches vary from state to state, which is what led the Supreme Court to announce on Friday that it will hear two criminal appeals. In the cases, which involve drug dealing and a gang shooting, the defendants were convicted on the basis of information the cops found in their phones at the time of their arrest.

The cases also reflect how quickly phone technology is evolving, and its implications for privacy. In one case, the evidence at issue is a call log that a cop obtained from a simple…