The Seattle Times: Tips for travelers entering U.S.: Check your visa, turn off your phone

There are generally two types of searches of an electronic device: manual and advanced, said Tom McBrien, a lawyer with the Electronic Privacy Information Center, an internet privacy nonprofit in Washington. Manual searches involve looking through an unlocked phone. Courts have generally seen this as equivalent to going through luggage and have allowed manual searches to proceed without obtaining a warrant, McBrien said. 

An advanced, or “forensic” search, involves hooking up an external device to your phone to scan its contents. Some federal districts require a warrant for this, while others do not, McBrien said. 

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