The Electronic Frontier Foundation has just updated its 2011 guide to Digital Privacy at the U.S. Border with an all new edition that covers the law, administrative rules, technological options and potential repercussions of crossing the US border while not undergoing the warrantless seizure and indefinite retention of all of your sensitive data — in a guide that breaks out the different risks for US citizens, US permanent residents, and visitors to the USA.
As I've previously noted, the law regarding what protections you have at the border is frustratingly unsettled, with grey zones on everything from being compelled to unlock a device to being compelled to turn over your passwords for social media and cloud services, and since the big online platforms are not designed with this threat-model in mind, you're really fighting against the tech when you try to minimize the amount of data you can access at a border crossing.
EFF's guide provides essential nuance on this, looking at recent court decisions and administrative rules, and offering its view of what Constitutional protections you should have, once more cases make their way to court and get ruled on.
But it's also an eminently practical guide to the legal and technological choices you can make, based on the sensitivity of your data, your risk tolerance, and your personal beliefs.
Two things bear repeating from this guide: you should never, ever lie to border officials, in any country, ever; and you should never, ever try to use hidden partitions or other trickery to obfuscate which data you have. The penalties for getting caught doing either of these things are substantially worse than any costs you'd pay by simply not travelling, or not carrying data, or refusing to comply with orders to unlock data.
Want to learn more about surveillance self-defense? Since you are reading this guide, you may be interested in digital security in general, and not just while you are crossing international borders. If so, check out EFF's Surveillance Self-Defense guide.
Want to help EFF protect everyone's digital privacy at the border? Contact your U.S. senators and representatives, and ask them to support legislation requiring government officials to get a warrant from a judge based on probable cause of criminal activity before searching digital devices at the border. Also, please join EFF!