The desperate need for deniable encryption

There is a good reason to develop Deniable Encryption. According to a blog entry of fefe US law enforcement agencies are allowed to copy your harddisk and to demand to get the passwords for encrypted files when you want to enter the US. Reportedly the border control is authorized to put you in coercive detention to gather the password. So you need an encryption, that is not detectable or you need two notebooks. One you use to store your confidential data and one sanitized from all confidential data with only the files you need while you visit the US. PS: Well, nice sideeffect, it would be very easy to put someone into long detention: Send him a long encrypted mail. But encrypt it with a secret key unknown to the person ;)