If you are unwilling to give something you know to someone, no amount of force can take it from you. Had that drive been encrypted using facial biometrics, they could have just knocked him out, glued his eyes open, and taken what they wanted.
What works, and what has been deemed legal, as you probably already know, are not mutually exclusive.
Technology can easily be used to encrypt a hard drive to reveal different things for different passwords. TrueCrypt does it.
Plus you can have cryptographic keys stored with friends or beacons that signify you are safe. For example you hide files on your phone before a flight, and to unhide them you need your host's wifi at your destination.
Until the friend or beacon gives the ok, you can either have your phone LOCKED or have all sorts of files that are encrypted and HIDDEN. The computer can be unlocked but won't show those files.
Why isn't this technology widespread? YOU CANT WHACK EVERYONE!
Contempt?