Smartphones can be a cop's best friend. They are packed with private information like emails, text messages, photos, and calling history. Unsurprisingly, law enforcement agencies now routinely seize and search phones. This occurs at traffic stops, during raids of a target's home or office, and during interrogations and stops at the U.S. border. These searches are frequently conducted without any court order.
Several courts around the country have blessed such searches, and so as a practical matter, if the police seize your phone, there isn't much you can do after the fact to keep your data out of their hands.