U.S. customs authorities have assigned themselves the authority to copy all data on your laptop or other electronic device when you cross a U.S. border. I wrote about this policy last year.
Now, customs authorities in Canada (and other countries, especially the U.K.) are getting into the act. I’ve received reports from several sources (among them from J. J. Luna, author of the classic How to be Invisible) describing intimidating encounters at the Canadian border. Luna reports that after being routed into a secondary inspection queue, customs officials forced him to reveal the passwords to his two laptops and USB flash drives. Then, they disappeared with these devices in hand for nearly an hour, presumably to copy and inspect them.
Your smart phone may be subject to the same type of inspection, and all your photos, text messages, online searches, and calling records copied onto a customs database.
To avoid a border inquisition, the best precaution is not to carry any electronic device across an international border. For most people, this isn’t practical, so the next-best strategy is to carry only “sanitized” devices.
For instance, I have a laptop I use only for international travel. There’s nothing on it except for the operating system and program files. I also have an “unlocked” cell phone I use only for international travel. When I arrive in a new country I purchase a domestic SIM card from a local phone dealer. This not only protects your privacy at the border, but also insures your domestic carrier has no record of your international calls. And, it eliminates roaming charges.