An interesting suggestion from the German Home Office, reported in The Register:
"Germany's police and secret services are pushing for a legal basis for "online house searches" – carried out without the knowledge of suspects, using spyware similar to a Trojan.
Bundeskriminalamt (BKA) president Jörg Ziercke believes the "Federal Trojan" (as the project has been dubbed by the public) is necessary because confiscating physical hard drives is almost useless. "They store their data on the internet and encrypt the hard drive. That is why we have to have access at the point of dissemination."
You can bet that the UK Home Office is watching this with some interest!