If you're at a border, they can copy all your files. They can force you to give your fingerprints; or an iPhone face view to unlock your phone. In the U.S., if

If you're at a border, they can copy all your files. They can force you to give your fingerprints; or an iPhone face view to unlock your phone. In the U.S., if you are not at a border; law enforcement needs a warrant based on probable cause.