The Register's guide to protecting your data when visiting the US

In practice, tourists have been stopped in national parks and asked to show their visitation paperwork, or stopped when driving down the road.

When it comes to safeguarding your personal data on devices, CBP has considerable leeway in what it can demand and copy – basically everything is up for grabs. The CBP told The Register it reserves the right to check "computers, disks, drives, tapes, mobile phones and other communication devices, cameras, music and other media players, and any other electronic or digital devices."

"All persons, baggage, and merchandise arriving in or departing from the United States are subject to inspection, search and detention," a spokesperson said.