In the UK even customs have jumped onto the bandwagon. Laptops, disks brought into the UK are liable to be scanned. An image scan will be taken, picking up hidden and deleted files. Refusal is not an option. Encrypted files are treated in the same way as a locked suitcase, with a requirement to hand over the keys.
Refusal can lead to arrest, serving of a court order, and a charge of contempt of court.
It is not necessary for customs to establish 'grounds for reasonable search'. Both of which engender government paranoia and threaten powerful elites. Put simply, governments do not, can not control the net. Governments have awoken to this one simple fact rather late in the day and my God does it hurt. All sorts of scare stories and disinformation are fed to the media about the net.