Defending Privacy at the U.S. Border: A Guide for Travelers Carrying Digital Devices

Thanks to protections enshrined in the U.S. Constitution, the government generally can’t snoop through your laptop for no reason. 

But those privacy protections don’t safeguard travelers at the U.S. border, where the U.S. government can take an electronic device, search through all the files, and keep it for a while for further scrutiny – without any suspicion of wrongdoing whatsoever. (more) (pdf guide)